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Structural Performance of Ferrocement Panels under Low- and High-Velocity Impact Load
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  • Sandeep Sathe
    Sandeep Sathe
    School of Civil Engineering, MIT World Peace University, Pune 411038, India
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  • Muhammed Zain Kangda
    Muhammed Zain Kangda
    Department of Civil Engineering, School of Civil Engineering, REVA University, Bengaluru 560064, India
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  • Mohammad Amir Khan*
    Mohammad Amir Khan
    Galgotia College of Engineering, Greater Noida 201310, India
    * Email: [email protected]
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    Orcidhttps://orcid.org/0009-0006-9847-2197
  • Yousef R. Alharbi
    Yousef R. Alharbi
    Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia
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  • Obaid Qamar
    Obaid Qamar
    Department of Environmental Science & Engineering, Yeungnam University, Gyeongsan 38541, South Korea
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ACS Omega

Cite this: ACS Omega 2023, 8, 44, 41120–41133
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https://doi.org/10.1021/acsomega.3c03726
Published October 24, 2023

Copyright © 2023 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY-NC-ND 4.0 .

Abstract

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The primary objective of this experimental study is to examine the response and energy absorption capacity of ferrocement panels exposed to low- and high-velocity impact loads. The panels are reinforced with two different types of mesh layers, namely, welded wire grid (WWG) and expanded wire grid (EWG), with varying percentages of steel fibers (SF). The ferrocement panel system is made up of cement mortar reinforced with 0–2% SF with an increment of 1% and wire grid layers arranged in three different layers 1, 2, and 3. A consistent water–cement ratio (w/c) of 0.4 is maintained during mortar preparation, and all panels are subjected to a 28-day curing process in water. The study utilized square-shaped ferrocement panels measuring 290 mm × 290 mm × 50 mm. The panels are exposed to repeated impact blows from a 2.5 kg falling mass dropped from a height of 0.80 m. The count of blows necessary to commence the first crack formation and the cause of ultimate failure are recorded for each panel. The study reports that an increase in SF content and the number of wire grid layers increased the number of blows needed for both the first crack and the ultimate failure. In the high-velocity impact test, 7.62 mm bullets are fired at the panels from a distance of 10 m with a striking velocity of 715 m/s. The study observed and analyzed the extent of spalling, scabbing, and perforation. The results showed that an increase in fiber content and the number of wire grid layers led to a decrease in the area of scabbing and spalling compared with the control specimens. It was also possible to see the mode of failure and crack pattern for impacts with low and high velocities.

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1. Introduction

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A fine steel wire mesh is encased in a thin layer of cement mortar to create ferrocement, which is a form of composite material. Due to its low cost, high strength, and longevity, ferrocement is increasingly being used to build homes in underdeveloped nations. Ferrocement is a useful material for many applications since it is easy to shape into different shapes and sizes. Because it uses less energy and raw materials than conventional concrete, it is also an environmentally beneficial material. Numerous residential construction projects, including roofs, walls, flooring, and water tanks, have successfully used ferrocement. (1) It is a unique thin composite material formed of cement mortar and a wire grid in the core, made up of one or more layers. The metal grid gives a thin composite material strength and flexibility, enhancing its durability. Joseph Louis Lambot originally suggested using ferrocement for shipbuilding in 1848. Traditional building materials such as cement and steel can be prohibitively expensive in many developing nations. As an alternative, ferrocement can provide low-income families a more inexpensive option. (2) By using fewer basic materials and laborers, the usage of wire mesh can also help building projects run as cheaply as possible. Due to the increase in the support area, ferrocement also has outstanding bending capabilities. As a result, it can be used to build curved and unusual structures such as barrel vaults, shells, and belts. Ferrocement is frequently used to build manhole covers, silos, pool showers, footbridges, roofing, and affordable homes. Additionally, compared to conventional concrete, ferrocement has a better bending capacity per unit weight and a higher tensile strength-to-weight ratio. This makes it perfect for water retention systems that need to be extremely durable and crack-resistant, including water tanks and reservoirs. (3,4) The efficiency of using ferrocement in the restoration of damaged structures and the strengthening of existing structures using wire mesh was examined and demonstrated by Shaheen and Abusafa. (5) The researchers came to the conclusion that the use of wire can increase the life of the structure, improve its performance, and lower the need for repairs and replacement costs because ferrocement has a high tensile strength and is durable, making it an ideal material for the repair and maintenance of existing structures. Numerous studies have recently concentrated on the bending characteristics of ferrocement panels composed of cement mortar and wire mesh. (6−9) Memon et al. (10) examined the impact of ferrocement panels’ flexural strength and the possibilities for employing waste materials such as fly ash and ground granulated blast furnace slag as a partial replacement for cement up to 60% in the production of ferrocement. This strategy maintains the product’s strength and durability while offering benefits, including waste recycling, resource conservation, and lower production costs. According to the authors, to achieve optimal flexural strength and performance, the right amount of ground granulated blast furnace slag (GGBS) is needed. Muraly et al. (11) observed that adding fibers and mesh layers improved the flexural, impact strength, ductility, and overall performance to withstand external forces in ferrocement composite panels reinforced with fibers under low-velocity bending and impact loads. Abdulla and Khatab (12) conducted a study to test the performance of multilayer composite ferrocement panels using a rubber medium cement mortar (RCM) layer. The RCM layer strengthens the panel’s resistance to static and dynamic loads and acts as an absorbent medium for the impact energy. The study discovered that increasing the thickness of the RCM layer can considerably boost the impact resistance of the panels. The thickness of the RCM layer aids in the absorption of greater impact energy, increasing the effort required to penetrate the panel. The study also discovered that increasing the rubber-to-grain ratio in the RCM layer can improve the impact resistance of the panel even further. The energy-absorbing properties of rubber granules distribute impact energy and reduce panel stress. Furthermore, the use of shear fasteners was discovered to boost the impact resistance of the panel. Shear fasteners help in distributing the impact load across the panel’s surface, preventing concentrated stress and reducing the risk of fracture and puncture. Jaraullah et al. (13) investigated the static and impact properties of ferrocement panels using green waste chemicals, and studies have shown that good performance can be achieved with metakaolin, GGBS, and limestone powder in mortars. In addition, the rupture modulus of ferrocement panels reinforced with a 3 mm diameter welded wire grid increased by 75% compared to 2 mm diameter welded wire grid-reinforced ferrocement panels with a fiber content of 0.6%. On the other hand, the impact strength of the 2 mm diameter welded wire grid and the fiber-reinforced panel is 18% higher than the 3 mm diameter welded wire grid-reinforced ferrocement panel. In a study conducted by Yerramala et al., (14) the impact strength of ferrocement panels was investigated by varying the number of grid layers and metakaolin percentages. The results indicated that an optimum content of 10% metakaolin was necessary to achieve the maximum impact strength. Additionally, when up to 15% of the cement was replaced with metakaolin, the impact strengths obtained were higher than those of the control ferrocement panel at all curing ages and for all grid layers. In the recent past, (15−20) there have been plenty of experimental as well as analytical research done on concrete block and ferrocement panels against high-velocity projectile impact, considering several variables like the addition of different types and percentages of fibers, different types of grids, and the number of layers of the grid. However, very few studies have been reported in the past decade on the behavior and performance of ferrocement panels against impact and penetration resistance with fiber content. The primary result of this study showed that the use of fibers and wire meshes as reinforcement in target specimens led to an overall reduction in penetration depth and damage on both the front and rear faces. This finding indicates that the addition of fibers and wire meshes to the target material can effectively improve its resistance to impact and penetration, thereby enhancing its overall performance in high-stress situations.

2. Significance of Research

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The flexural behavior of ferrocement panels with varied admixtures and wire meshes has been examined in earlier investigations. However, little study has been done on the impact behavior of fiber-reinforced ferrocement panels under low- and high-velocity impacts. The necessity for additional research into the impact resistance of ferrocement panels and the potential advantages of utilizing fibers as reinforcement in such applications is highlighted by this gap in the literature. A study that reported the manufacture of a fibrous ferrocement panel with WWG and EWG and evaluated the impact resistance was performed to fill in the gaps in the literature. The panel included 1, 2, and 3 layers of WWG and EWG, as well as hooked SF at doses of 1 and 2%. The results of this study are anticipated to offer important insights into the development and application of fibrous ferrocement panels that can survive impacts at both low and high speeds. Overall, this research has the potential to aid in the creation of more durable and dependable building materials that are better suited to handle stressful circumstances.
This research on the structural performance of ferrocement panels under low- and high-velocity impact loads offers unique insights not found in previous studies, which typically focus on static or moderate dynamic loads. It fills a crucial gap in knowledge, providing valuable data for the engineering and construction industries. By exploring how ferrocement panels respond to impacts, this research informs the design of safer and more resilient infrastructure, particularly in impact-prone areas such as blast-resistant structures, advancing the field of structural engineering.

3. Experimental Program

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3.1. Materials Specifications and Properties

3.1.1. Cement

The essential ingredients required for this study were procured from local suppliers, while Ordinary Portland cement (53 grade) was utilized as a binder by the Indian standards 12269:2013 (21) to produce the ferrocement matrix.

3.1.2. Sand

River sand, which is sourced from the local area, was obtained to create mortar mixes. The sand has a fineness modulus of 2.35 and a nominal maximum size of 4.75 mm with a density of 1650 kg/m3. The mortar was made using a water-to-binder ratio of 0.4 and a binder-to-sand ratio of 1:2 by weight.

3.1.3. Superplasticizer

To decrease the water content present in the mortar mixes, a poly(carboxylic ether) admixture was introduced. This admixture is known for its high range of superplasticizing properties and was added in different amounts ranging from 0.5 to 1.5 times the weight of cement used. Information supplied by the supplier indicated that the superplasticizing admixture had a relative density of 1.08 ± 0.01 at a temperature of 25 °C and its pH value fell within the range 7–9.

3.1.4. Grids

The ferrocement panel was reinforced by using locally available WWG and EWG obtained from the local market. The manufacturer provided data on the mechanical properties of the WWG and EWG in Table 1, while their geometric shapes as utilized in the ferrocement panel are illustrated in Figures 1 and 2.

Figure 1

Figure 1. Welded wire grid.

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Figure 2

Figure 2. Expanded wire grid.

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Table 1. Mechanical Properties of Meshes
type of meshwelded wire grid (WWG)expanded wire grid (EWG)
measurements in mm12.5 × 12.516.5 × 31
weight in gm/m26001660
sheet thickness in mm0.71.25
yield stress in N/mm2400250
yield strain 9.7 × 10–3
ultimate strain1.17 × 10–359.2 × 10–3
ultimate tensile strength N/mm2600380

3.1.5. Fiber

For this investigation, SF with hooked ends was utilized. The SF had a diameter of 0.6 mm, a length of 30 mm, and a tensile strength of 1100 MPa.

3.1.6. Water

The mixing of ingredients and curing process of the ferrocement panel were carried out using ordinary portable water that was locally available.

3.2. Mortar Matrix and Material Composition

The cement mortar utilized in the creation of the panel was designed specifically to attain a compressive strength of 28 days of 25 MPa. The selection of properties for the mortar mixture was based on information outlined in a report by the American Concrete Institute (ACI Committee 549). (22) To produce each mix, the cement and sand were first dry mixed for a duration of 2 min, followed by the addition of the reduced water and admixture. The SF was then added to the mix using its hooked end and continued until uniformity. Table 2 provides the specific composition of cement, sand, water, superplasticizer, and fiber for each panel. The fresh density of each mortar mixture with 0%SF, 1%SF and 2%SF is measured as 2110, 2185, and 2260 kg/m3, respectively. To conform to ASTM C 1437–07 guidelines, the water and water-reducing agent (WRA) had to be adjusted to achieve a mortar flow between 180 and 200 mm. (23) All mixtures did not experience any segregation and bleeding. Also, the workability of the mortar mixture can be stated as a medium degree of workability by considering the flow value.
Table 2. Mix Proportion
       layer thickness (mm)
specimenno of mesh layersfiber content (%)WRA (%)cement (kg/m3)sand (kg/m3)water (kg/m3)1234
CP-0–0000.5638.41276.8255.3650   
CP-0–1011.0638.41276.8255.3650   
CP-0–2021.5638.41276.8255.3650   
SP-1–0100.5638.41276.8255.362525  
SP-1–1111.0638.41276.8255.362525  
SP-1–2121.5638.41276.8255.362525  
SP-2–0200.5638.41276.8255.36152015 
SP-2–1211.0638.41276.8255.36152015 
SP-2–2221.5638.41276.8255.36152015 
SP-3–0300.5638.41276.8255.3610151510
SP-3–1311.0638.41276.8255.3610151510
SP-3–2321.5638.41276.8255.3610151510
EP-1–0100.5638.41276.8255.362525  
EP-1–1111.0638.41276.8255.362525  
EP-1–2121.5638.41276.8255.362525  
EP-2–0200.5638.41276.8255.36152015 
EP-2–1211.0638.41276.8255.36152015 
EP-2–2221.5638.41276.8255.36152015 
EP-3–0300.5638.41276.8255.3610151510
EP-3–1311.0638.41276.8255.3610151510
EP-3–2321.5638.41276.8255.3610151510

3.3. Preparation of Specimen

The evaluation of the impact resistance of the ferrocement panels was divided into three phases. In phase I, three combinations were tested with 0, 1, and 2% SF. Phase II involved nine combinations with the combined effect of SF and WWG, while phase III involved nine blends with the combined effect of SF and EWG. This study employed two different SF dosages and three different layers of WWG and EWG schemes. The specimens in phase I were labeled as CP-0–0, CP-0–1, and CP-0–2, where “CP” represents the control specimen without a wire grid and 0, 1, and 2% steel fibers were used, respectively. The specimens in phase II were labeled SP-1–0 to SP-3–2, where the first number denotes a layer of WWG and the second number indicates the dosage of SF. Similarly, the specimens in phase III were labeled as EP-1–0 to EP-3–2, where “EP” represents the ferrocement panel with EWG, the first number denotes a layer of EWG, and the second number indicates the dosage of SF. The thickness specifications of the panel layers for different phases are illustrated in Figure 3.

Figure 3

Figure 3. Panel layer thickness details.

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To construct the first layer of panels (SP-1–0, SP-1–1, and SP-1–2), we applied the mortar at the designated layer thickness. This was followed by placing the WWG on top of the first layer. Then, a second layer of mortar was placed, as illustrated in Figure 3. This process was followed to construct two layers for the specimens (SP-2–0, SP-2–1, and SP-2–2), which involved placing the WWG over the first and second layers. The specimens (SP-3–0, SP-3–1, and SP-3–2) were constructed with three-layer reinforced schemes, and for these specimens, four layers were built sequentially with WWG placed over the first, second, and third layers. Likewise, the same arrangement was made for specimens with EWG. All of the panels were cast using wooden formwork with a smooth surface finish. Forty-two panels, each measuring 290 mm × 290 mm × 50 mm, were prepared and cured by immersion for 28 days. Of the forty-two specimens, forty-one were used for low-velocity impact testing, while the remaining specimen was utilized for high-velocity impact testing. The ferrocement panel casting in the form of square and expanded mesh along with its curing process is illustrated in Figures 4–7, respectively.

Figure 4

Figure 4. Typical specimen SP-1–0.

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Figure 5

Figure 5. Typical specimen EP-1–0.

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Figure 6

Figure 6. Curing of specimens.

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Figure 7

Figure 7. Specimens after curing.

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3.4. Experimental Setup and Testing

3.4.1. Compressive Strength Test

Three cube specimens of size 100 mm were prepared with and without SF and tested using a 2000 kN capacity compression testing machine conforming to IS 516. (24) The mean values of the test results for the three specimens were reported.

3.4.2. Falling Mass Impact (Low-Velocity Impact) Test

The impact resistance of the ferrocement panels was evaluated using the falling mass test, following the ACI Committee 544 recommendations. (25) A steel hammer weighing 2.5 kg was repeatedly dropped onto the target specimen from a vertical distance of 800 mm. The test was conducted on all panels spanning 290 mm, with the target specimen secured in place by using C-clamps. The impact response was visually observed and recorded as the number of impacts that resulted in cracking (B1) and failure (B2). The energy of impact (E1 or E2) was calculated based on the number of recorded impacts, the weight of the hammer, gravitational acceleration, and vertical falling distance. The absorbed energies at cracking (E1) and failure (E2) were calculated using a simplified method as per eq 1. The falling hammer apparatus used for the test is shown in Figure 8 along with the clamping system in Figure 9.
impactenergy(E1orE2)=N×m×g×H
(1)

Figure 8

Figure 8. Falling hammer test setup.

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Figure 9

Figure 9. Clamping system.

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3.4.3. Impact Penetration (High-Velocity Impact) Tests

The experiment was conducted at the Ballistics Lab at GFSU, Gujarat, using the setup depicted in Figure 10. The gun is capable of launching projectiles within the velocity range of 715 ± 15 m/s at room temperature = 31.80 °C, and humidity = 42%. The projectiles used were 39 mm Bullets (AK-47) made of Mild Core Steel (MSC), with a diameter of 7.62 and a length of 39 mm. The specimens were mounted onto a sturdy steel frame and placed at a maximum distance of 10 m from the gun. The surface area of each specimen was 290 mm × 290 mm. After verifying the alignment of the specimen from both the front and back faces, as shown in Figure 11, it was appropriately placed onto the target frame with the help of holding support. Once the desired velocity was achieved, the projectile was loaded into the barrel and fired at the specimen. The resulting data included the failure pattern, the diameter of the craters on both the front and rear faces, the depth of penetration, and the area of damage caused to the specimen on both faces.

Figure 10

Figure 10. Gun system (penetration test setup).

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Figure 11

Figure 11. Target frame.

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4. Experimental Results and Discussion

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4.1. Compressive Strength

The addition of SF has a positive effect on the compressive strength of the cement mortar, particularly in the early stages of curing. This is because higher dosages of SF can create a network that helps to distribute stress more evenly throughout the material, resulting in an increased compressive strength. However, the long-term effectiveness of SF in enhancing compressive strength may be limited and influenced by other factors such as fiber characteristics and curing conditions. Figure 12 shows that the compressive strength of mortar cube specimens increases with the addition of SF, with a 10 and 33.33% increase in compressive strength observed after 3 days for 1 and 2% SF dosage, respectively, compared to nonfibrous specimens. The compressive strength continued to increase with a 12.5 and 47.5% increase at 7 days and a 30 and 49% increase at 28 days for 1 and 2% SF dosage, respectively. The addition of fibers in cement mortar can also delay and prevent the occurrence of cracks under tensile and shear stresses by requiring more energy to propagate when they encounter fibers, resulting in an overall increase in mortar cubes’ relative and ultimate strength. However, the effectiveness of fiber reinforcement is heavily dependent on the fiber matrix, stiffness, and dispersion, as well as the adequacy of the interfacial bond between the fibers and the surrounding matrix. Alvarez et al. (26) reported that after the fracture of test, the bonding between the fibers and mortar paste could sustain additional load before the complete separation of the specimen.

Figure 12

Figure 12. Compressive strength of mortar.

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The compressive strength is marginally improved up to 2% SF dosage, and further increase in SF percentage beyond 2% causes a marginal decrease in the strength at 3, 7, and 28 days. The improvement in the compressive strength is because of the resistance of fibers against the crack initiation and propagation. Also, as the fiber content increases, the ability of fibers to bridge and arrest cracks becomes more pronounced, leading to higher early strength. However, the compressive strength of mortar may be negatively impacted by excessive usage of SF (3% SF), leading to a reduction compressive strength because of the clustering or entanglement of fibers can occur, hindering their ability to uniformly bridge cracks. This clustering can create concentrated zones of fibers, potentially lowering the compressive strength of mortar. Therefore, further study of impact energy will restrict the utilization of SF to a maximum of 2% for the investigation.

4.2. Results and Discussion on Low-Velocity Impact Test

4.2.1. Impact Strength Results

Table 3 summarizes the recorded number of impacts that resulted in cracking (B1) and failure (B2) of the target specimens as well as the corresponding impact energy at the cracking (E1) and failure stages (E2).
Table 3. Results of Ductility Index
    number of impactsimpact energy (joule) 
designation of the test specimenno. of mesh layerfiber content (%)WRA (%)B1B2E1E2impact ductility index
CP-0–0000.51219.6239.242.00
CP-0–1011.021039.24196.205.00
CP-0–2021.522439.24470.8812.00
SP-1–0100.52639.24117.723.00
SP-1–1111.033558.86686.7011.67
SP-1–2121.535258.861020.2417.33
SP-2–0200.531658.86313.925.33
SP-2–1211.047278.481471.5018.75
SP-2–2221.5510098.101962.0020.00
SP-3–0300.542578.48490.506.25
SP-3–1311.0510098.101962.0020.00
SP-3–2321.56120117.722354.4020.00
EP-1–0100.52839.24156.964.00
EP-1–1111.035258.861020.2417.33
EP-1–2121.548578.481667.7021.25
EP-2–0200.531858.86353.166.00
EP-2–1211.048178.481589.2220.25
EP-2–2221.5512298.102393.6424.40
EP-3–0300.553198.10608.226.20
EP-3–1311.06128117.722511.3621.33
EP-3–2321.56175117.723433.529.17

4.2.2. Effect of Fibers on Impact Strength

Table 3 presents the correlation between the quantity of SF and the number of impacts that lead to cracking and failure in ferrocement panels, signifying their ability to resist impact. The addition of SF enhances the impact resistance of the WWG ferrocement panel, and as the fiber content increases, the impact resistance improves further. The CP-0–0 panel exhibited absorbed impact energies of 19.62 and 39.24 J at the cracking (E1) and failure (E2) stages, respectively.
The specimen CP-0–0, with 0% fiber content, serves as the baseline with 100% impact energy E1. Introducing 1% fiber content in CP-0–1 leads to a doubling of the impact energy, resulting in a 100% increase compared to CP-0–0. However, further increasing the fiber content to 2% in CP-0–2 does not result in any additional percentage increase in impact energy compared to CP-0–1 for E1. Therefore, the percentage increase in impact energy is substantial when transitioning from 0% to 1% fiber content, but no additional percentage increase is observed beyond 1%.
Introducing 1% fiber content in CP-0–1 results in a significant increase in impact energy E2, with a 400% percentage increase compared to CP-0–0. Furthermore, increasing the fiber content to 2% in CP-0–2 leads to a substantial additional percentage increase in impact energy, reaching 1200% compared to CP-0–0. Therefore, the percentage increase in impact energy for E2 is significant when transitioning from 0 to 1% fiber content and further increases when going from 1 to 2% fiber content.
Comparing the CP-0–1 with the CP-0–0 panels revealed that the addition of 1% fiber increased E1 and E2 by 2 and 5 times, respectively. Similarly, incorporating 2% steel fiber increased E1 and E2 by 2 and 12 times, respectively. The use of fibers promotes high potential impact energy absorption by exhibiting a bridging action that obstructs or reduces crack growth while transferring the load across the crack, increasing the required number of impacts. (27) The inclusion of fibers is a positive measure that can enhance tensile strength by controlling cracks and providing a more ductile response to impact loads. (28) Generally, panels with higher SF content showed greater energy absorption compared to panels without fiber, suggesting the beneficial use of steel fibers in ferrocement panels, as illustrated in Figures 13 and 14.

Figure 13

Figure 13. Impact energies of a panel at the cracking stage.

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Figure 14

Figure 14. Impact energies of panels at the failure stage.

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4.2.3. Combined Effect of Fibers and a Single Layer of Mesh on Impact Strength

Figures 13 and 14 depict the impact energies absorbed during the cracking and failure stages of the ferrocement panel with varying fiber dosages and mesh layers.
For the specimens with “CP” designation, increasing the fiber content from 0 to 1% in CP-0–1 results in a 100% increase in impact energy E1 compared to CP-0–0. However, increasing the fiber content further to 2% in CP-0–2 does not lead to any additional percentage increase in impact energy for E1. Moving on to the specimens with “SP” designation, introducing 1% fiber content in SP-1–1 results in a 200% increase in impact energy compared to SP-1–0, while increasing the fiber content to 2% in SP-1–2 does not yield any additional percentage increase. Lastly, for the specimens with “EP” designation, both EP-1–1 and EP-1–2, with 1 and 2% fiber content, respectively, exhibit a 50% percentage increase in impact energy compared to EP-1–0 with 0% fiber content.
Starting with the specimens labeled “CP”, increasing the fiber content from 0 to 1% in CP-0–1 results in a remarkable 400% increase in impact energy compared to CP-0–0. Further increasing the fiber content to 2% in CP-0–2 leads to an additional 1100% percentage increase in impact energy for E2. Shifting focus to the specimens labeled “SP,″ introducing 1% fiber content in SP-1–1 results in a substantial 1650% increase in impact energy compared to SP-1–0, while increasing the fiber content to 2% in SP-1–2 further boosts the impact energy by 2650% compared to SP-1–0. Lastly, for the specimens labeled “EP′′, both EP-1–1 and EP-1–2, with 1 and 2% fiber content, respectively, exhibit impressive percentage increases in impact energy for E2, with EP-1–1 showing a 600% increase compared to EP-1–0, and EP-1–2 displaying a remarkable 4200% increase compared to EP-1–0.
The results show a significant increase in impact energies when steel fibers and wire grids are included, leading to a minimum increase of 2 times in the worst-case scenario when compared to the panel without fiber (CP-0–0). The figures demonstrate that as the fiber dosage increased, the WWG panel exhibited greater impact energies during the cracking and failure stages. The presence of steel fiber and wire grid improved stress transfer along the crack, leading to enhanced crack resistance. The panels’ impact resistance after crack formation was influenced by the tensile strength of the mesh and fiber-mortar matrix, as well as the bond strength of the mesh matrix and fiber matrix. The composite action of the mesh and fibers inhibited crack opening and widening, resulting in the need for more impacts to cause debonding and subsequent failure of the panel.

4.2.4. Combined Effect of Fibers and Two Layers of Mesh on Impact Strength

Figures 13 and 14 depict the impact energies absorbed during the cracking and failure stages of the ferrocement panel with varying fiber dosages and two mesh layers.
The results indicate that adding an extra layer of a wire welded grid (WWG) leads to a significant increase in the absorbed impact energies at the cracking and failure stages.
This is demonstrated by the increase in E1 and E2 values from 39.24 and 117.72 J to approximately 58.86 and 313.92 J, respectively, when the number of WWG layers is increased from 1 to 2. Furthermore, the inclusion of 1 and 2% fiber dosage and two layers of expanded wire grid (EWG) results in higher E1 and E2 values, suggesting that adding fibers has a significant impact on improving the impact resistance of the ferrocement panel.
For the specimens with “CP” designation, increasing the fiber content from 0 to 1% in CP-0–1 results in a 100% increase in impact energy compared to CP-0–0. However, further increasing the fiber content to 2% in CP-0–2 does not result in any additional percentage increase in impact energy for E1. Turning to the specimens with “SP” designation, introducing 1% fiber content in SP-2–1 leads to a 50% increase in impact energy compared to SP-2–0, while increasing the fiber content to 2% in SP-2–2 does not yield any further percentage increase. Similarly, for the specimens with “EP” designation, both EP-2–1 and EP-2–2, with 1 and 2% fiber content, respectively, exhibit a 33.3% percentage increase in impact energy compared to EP-2–0 with 0% fiber content.
Examining the specimens labeled “CP”, increasing the fiber content from 0 to 1% in CP-0–1 results in a substantial 400% increase in impact energy compared to CP-0–0. Furthermore, increasing the fiber content to 2% in CP-0–2 leads to an additional 1100% percentage increase in impact energy for E2. Shifting focus to the specimens labeled “SP”, introducing 1% fiber content in SP-2–1 results in a remarkable 365% increase in impact energy compared to SP-2–0, while increasing the fiber content to 2% in SP-2–2 further boosts the impact energy by 525% compared to SP-2–0. Likewise, for the specimens labeled “EP,” both EP-2–1 and EP-2–2, with 1 and 2% fiber content, respectively, exhibit significant percentage increases in impact energy for E2, with EP-2–1 showing a 350% increase compared to EP-2–0, and EP-2–2 displaying a remarkable 580% increase compared to EP-2–0.
The SP-2–0 panel shows significantly higher E1 and E2 values compared to the CP-0–0 panel, with about 2- and 8-times higher values, respectively. Compared to the SP-1–0 panel, the E1 and E2 values for the SP-2–0 panel are higher by about 1.5 and 2.67 times, respectively. Similarly, the SP-2–1 panel displays E1 and E2 values about 4 and 37.52 times higher than those of the CP-0–0 panel, and compared to the SP-1–1 panel, the E1 and E2 values for the SP-2–1 panel are higher by 1.33 and 2.14 times, respectively. The SP-2–2 panel exhibits E1 and E2 values about 5 and 50 times higher than the CP-0–0 panel, respectively, and compared with the SP-1–2 panel, the E1 and E2 values for the SP-2–2 panel are higher by 1.68 and 1.92 times, respectively.
Furthermore, the addition of an extra layer of EWG leads to a significant increase in the impact energies absorbed at cracking and failure, as shown in Figures 12 and 13. Increasing the EWG layer from 1 to 2 results in an increase in E1 and E2 from 39.24 and 156.96 J to approximately 58.86 and 353.16 J, respectively. In addition, the inclusion of fibers at 1 and 2% dosage, along with two layers of EWG, further increases E1 and E2, indicating that adding fibers significantly influences the ferrocement panel’s ability to absorb high-impact energies.
Overall, the improved energy absorption capacity and higher impact energies at cracking and failure are due to the random dispersion of fibers within the mortar matrix, which acts as small-scale energy-absorbing components. The shielding activity of the fibers and mesh layers before crack initiation reduces tensile stresses and allows the mesh to absorb some of the applied impact energy, leading to an overall increase in impact capacity. After crack formation, the mesh acts as a shock barrier, arresting cracks between the layers and slowing crack propagation. The combined effect of these actions results in a higher efficiency and better mesh performance at the breakdown stage than at the cracking stage.

4.2.5. Combined Effect of Fibers and Three Layers of Mesh on Impact Strength

Figures 13 and 14 depict the impact energies absorbed during the cracking and failure stages of the ferrocement panel with varying fiber dosages and three mesh layers.
The combined impact of fibers and the number of mesh layers resulted in a significant increase in impact energy absorption when using three-layer WWG or EWG along with fiber. For the specimens labeled “CP”, increasing the fiber content from 0 to 1% in CP-0–1 results in a 100% increase in impact energy compared to CP-0–0. However, further increasing the fiber content to 2% in CP-0–2 does not result in any additional percentage increase in impact energy for E1. Shifting focus to the specimens labeled “SP”, introducing 1% fiber content in SP-3–1 leads to a 25% increase in impact energy compared to SP-3–0, while increasing the fiber content to 2% in SP-3–2 does not yield any further percentage increase. Similarly, for the specimens labeled “EP′′, both EP-3–1 and EP-3–2, with 1 and 2% fiber content, respectively, exhibit a 20% percentage increase in impact energy compared to EP-3–0 with 0% fiber content.
Looking at the specimens labeled “CP”, increasing the fiber content from 0 to 1% in CP-0–1 results in a substantial 400% increase in impact energy compared to CP-0–0. Furthermore, increasing the fiber content to 2% in CP-0–2 leads to an additional 1100% percentage increase in impact energy for E2. Shifting focus to the specimens labeled “SP”, introducing 1% fiber content in SP-3–1 results in an impressive 300% increase in impact energy compared to SP-3–0, while increasing the fiber content to 2% in SP-3–2 further boosts the impact energy by 380% compared to SP-3–0. Likewise, for the specimens labeled “EP,″ both EP-3–1 and EP-3–2, with 1 and 2% fiber content, respectively, exhibit significant percentage increases in impact energy for E2, with EP-3–1 showing a 310% increase compared to EP-3–0, and EP-3–2 displaying a remarkable 460% increase compared to EP-3–0. These findings highlight that the percentage increase in impact energy for E2 is strongly influenced by the fiber content and can vary significantly based on the specific specimen designation.
The SP-3–0 panel reveals that including three layers of WWG boosted E1 and E2 by 4 and 12.5 times, respectively, compared to the CP-0–0 panel, and in the EP-3–0 panel, it is clear that adding three layers of EWG increased E1 and E2 by 5 and 15.5 times, respectively, compared to the CP-0–0 panel.
The preceding discussions suggest that incorporating three layers of mesh with a 2% fiber dosage greatly improves impact energies. This outcome is likely attributed to the fiber’s ability to restrict cracks and promote effective stress transfer through fiber-bridging mechanisms, as previously explained.

4.2.6. Impact Ductility Index (IDI)

Ductility refers to the ability of a material to withstand plastic deformation when subjected to a load, and it can be assessed using flexural and tensile tests. (29) The Impact Ductility Index (IDI) of a panel is determined by the ratio of E2 to E1. Table 3 displays the value of the IDI rounded to two decimal places. A higher IDI value indicates that the panel has better ductility and postcracking behavior when subjected to an impact load. (30,31) Previous studies (30−3132) have used this definition to observe how fibers can alter the composite behavior of material from brittle to ductile when subjected to impact loading. (30−32) Interestingly, EP-3–2 panels showed a more significant improvement in IDI than other panel types. Analyzing the specimens labeled “CP” it is observed that increasing the fiber content from 0 to 1% in CP-0–1 leads to a significant 150% increase in the ductility index compared to CP-0–0. Further increasing the fiber content to 2% in CP-0–2 results in an additional 500% percentage increase in the ductility index. Shifting focus to the specimens labeled “SP” it can be observed that increasing the number of mesh layers from 1 to 2 in SP-2–0 leads to a moderate 77% increase in the ductility index. Moreover, introducing 1% fiber content in SP-2–1 results in a substantial 525% increase in the ductility index compared to SP-2–0, while maintaining the same fiber content of 1% in SP-3–1 and SP-3–2 results in a consistent maximum ductility index value of 20%. Similarly, for the specimens labeled “EP”, increasing the number of mesh layers from 1 to 2 in EP-2–0 leads to a moderate 50% increase in the ductility index. Furthermore, introducing 1% fiber content in EP-2–1 results in a significant 425% increase in the ductility index compared to EP-2–0, while maintaining the same fiber content of 1% in EP-3–1 results in a maximum ductility index value of 21.33%. Additionally, increasing the fiber content to 2% in EP-2–2 and EP-3–2 leads to substantial percentage increases in the ductility index, with EP-2–2 showing a remarkable 440% increase and EP-3–2 displaying an impressive 1167% increase compared to their respective EP-2–0 and EP-3–0 counterparts. From Figure 15, the IDI values for fibrous panels ranged from 3 to 20 for WWG and 4 to 29.17 for EWG. This suggests that WWG panels have lower ductility and postcrack energy absorption compared to EWG panels. The IDI values observed for single-layer WWG and EWG panels ranged between 3 and 17.33 and 4 and 21.25, respectively, indicating that EWG panels have better ductility. For two-layer WWG and EWG panels, an improvement in IDI was observed, with values ranging from 5.33 to 20 and 6 to 24.40, respectively, as shown in Figure 15. The highest IDI was observed in three-layer EWG panels, ranging from 6.20 to 29.17, while the three-layer WWG panel had an IDI ranging from 6.25 to 20. The results indicate that increasing the number of mesh layers and fiber dosage leads to a significant increase in IDI. This is because the fiber-bridging action enhances the material’s ability to absorb impact energy after cracking, thereby delaying failure and increasing the number of impacts that can be absorbed. As a result, the IDI is higher, reflecting the improved impact energy absorption capacity of the material.

Figure 15

Figure 15. Impact ductility index of the ferrocement panel under impact load.

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4.2.7. Failure Mode of Ferrocement Panel under Impact Load

The CP-0–0 panel had a low impact resistance and failed in a brittle manner after a few impacts. The cracks initiated at the bottom surface and propagated toward the top surface due to the absence of bonding elements that maintain the connection along each crack. (33,34) The fibrous panels, such as SP-1–0, SP-2–0, EP-1–0, and EP-2–0, also failed suddenly, withstanding only slightly more impacts than the CP-0–0 panel. However, the addition of fibers and EWG in all fibrous panels improved their energy absorption during impact significantly. The cracks that developed on the bottom surface of the panels were restricted from further expansion by the fiber-bridging action and mesh, leading to ductile failure, where the panel absorbed more impact energy and delayed failure after cracking as shown in Figure 16. The ductile failure occurred due to two mechanisms: the fiber’s orientation and the bonding between the mesh/fiber and surrounding mortar matrix. Fibers with planar alignment exhibited better impact load performance than those with random orientation, while the bonding behavior between the mesh/fiber and surrounding mortar matrix played a significant role in higher impact energy absorption. (35) Therefore, fibrous panels with planar fiber orientation can absorb more energy than nonfibrous panels.

Figure 16

Figure 16. Typical mode of failure of ferrocement panel. (a) Damage on the front face and (b) damage on the rear face.

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4.2.8. Failure Mechanism of Panel under Impact Load

The process of how ferrocement specimens fracture under repeated falling mass impact is shown in Figure 17. The fracture occurs in four stages: damage at the point of contact, failure of the mortar matrix, failure of the fiber/mesh, and debonding. The direction of the impact force leads to the breaking apart of the mortar matrix, resulting in damage at the point of contact. Internal debonding of the panel happens due to transverse shear strain/stress. (36) Compression bending results in the failure of the fiber matrix and mesh matrix, while tensile bending at the bottom face causes debonding of fiber and mesh from the surrounding matrix. The severity of this incident during the fracture process has a significant influence on the strength of the panels and their overall integrity. These effects happen quickly, making them challenging to detect during use. After cracking, kinetic energy transfers from the mortar matrix to the fiber and mesh, which help restrict crack development and dissipate more energy to the surrounding mortar matrix. However, when the fibers and mesh can no longer restrict crack development, debonding happens, resulting in panel failure due to stress distribution in the ferrocement panel during impact.

Figure 17

Figure 17. Schematic description of the activated failure mechanism under the repeated falling mass impact.

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4.3. Results and Discussion on High-Velocity Impact Test

To conduct the study, a high-velocity impact test was performed on a ferrocement specimen that measured 290 mm × 290 mm × 50 mm. The test involved using bullets with a caliber of 7.62 mm, which was fired at a striking velocity of approximately 720 m/s from a distance of 10 m. The data obtained from the test was recorded in Table 4, which included measurements of the damaged areas, penetration depths, and orthogonal dimensions of the front and rear craters. For targets that were not perforated, the measurements included the lengths of the two perpendicular axes D1 and D2. The damaged area at the front or rear face was calculated using the equation Darea = D1×D2 (15) which approximated the crater boundaries by an ellipse, as shown in Figure 18(a).

Figure 18

Figure 18. (a) Evaluation of the equivalent diameter of the damaged area. (b) Bullet projectile.

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Table 4. Experimental Results of High-Velocity Impact Tests on Ferrocement Panel Specimens
specimensnumber of meshfiber content (%)dimension of damage on front facedimension of damage on rear face
HCP-0–000spalling area (115.4) cm2 with 4 long hair cracks (collapse).scabbing area (230.45) cm2 with 4 long hair cracks (collapse).
HCP-0–101spalling area (94.41) cm2 with hair cracks (collapse).scabbing area (157.36) cm2 with 3 long hair cracks (collapse).
HCP-0–202spalling area (85.90) cm2 with 4 short hair cracksscabbing area (147.52) cm2 with 5 short hair cracks.
HSP-1–010spalling area (82.56) cm2 with 4 short hair cracksscabbing area (136.48) cm2 with 5 short hair cracks.
HSP-1–111spalling area (50.23) cm2 with 1 long hair crackscabbing area (94.10) cm2 with 3 short hair cracks.
HSP-1–212spalling area (48.89) cm2 with 1 long hair crackscabbing area (82.17) cm2 with 1 long hair crack.
HSP-2–020spalling area (70.12) cm2 with 3 short hair cracksscabbing area (110.58) cm2 with 4 short hair cracks.
HSP-2–121spalling area (44.22) cm2 with 1 long hair crackscabbing area (71.12) cm2 with 3 short hair cracks.
HSP-2–222spalling area (38.12) cm2 without cracksscabbing area (66.54) cm2 without cracks.
HSP-3–030Spalling Area (35.14) cm2 with 2 short hair cracksScabbing Area (78.12) cm2 with 3 short hair cracks.
HSP-3–131spalling area (30.57) cm2 without cracksscabbing area (62.12) cm2 without cracks.
HSP-3–232spalling area (26.63) cm2 without cracksscabbing area (55.29) cm2 without cracks.
HEP-1–010spalling area (80.21) cm2 with 3 short hair cracksscabbing area (131.74) cm2 with 5 short hair cracks.
HEP-1–111spalling area (48.51) cm2 with 1 long hair crackscabbing area (90.00) cm2 with 4 short hair cracks.
HEP-1–212spalling area (43.59) cm2 with 1 long hair crackscabbing area (79.23) cm2 with 1 long hair crack.
HEP-2–020spalling area (65.23) cm2 with 3 short hair cracksscabbing area (103.25) cm2 with 4 short hair cracks.
HEP-2–121spalling area (40.85) cm2 with 1 long hair crackscabbing area (67.21) cm2 with 2 short hair cracks.
HEP-2–222spalling area (36.12) cm2 without cracksscabbing area (60.27) cm2 without cracks.
HEP-3–030spalling area (35.76) cm2 with 2 short hair cracksscabbing area (78.12) cm2 with 2 short hair cracks.
HEP-3–131spalling area (28.22) cm2 without cracksscabbing area (56.19) cm2 without cracks.
HEP-3–232spalling area (22.63) cm2 without cracksscabbing area (48.84) cm2 without cracks.
It is worth noting that the damage levels observed in the specimens provide a reliable indication of the amount of energy dissipated during impact. This criterion is considered valid because the hardened-steel projectiles used did not undergo any significant deformation during impact, although some minor scratches were observed on their noses, as shown in Figure 18(b). Therefore, the energy dissipated in the deformation of the projectiles was deemed negligible compared to the energy dissipated in damaging the target. Under the impact loads, the specimens generally exhibited three distinct fracture regions, namely, the crater region, the crushed aggregate region, and the extensive cracking region, as illustrated in Figure 19. (37,38) (37,38)

Figure 19

Figure 19. Damage regions in the mortar subjected to impact forces.

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Spalling on the front face resulted in the formation of a crater due to the concentrated forces crushing the mortar surface. The shape and size of the craters on both faces varied according to the dynamic loading, measured by the impact velocity and the strength of the mortar. The variation of crater diameters in the front and rear faces of various ferrocement specimens is demonstrated in Table 4. The propagation of elastic stress waves is considered to be the primary cause for the formation of the observed cracking region. The impact generated compressive longitudinal waves, which traveled spherically into the mortar. Upon reaching the rear surface, these waves were normally reflected as tensile waves. The compressive wave and the reflected tensile wave are superimposed, resulting in a compressive wave that rapidly decreases and is followed by an increasingly tensile wave. A crack in the mortar was observed when the amplitude of the resulting tensile stress wave exceeded the dynamic tensile strength at any point in the matrix, and scabbing at the rear face occurred when the amplitude of the resulting wave, which built up near the surface, caused the tensile stresses to exceed the dynamic tensile strength. The scabbing/separation of the mortar material from the rear face of the panel is because of the tensile stresses. The formation of craters of various sizes, accompanied by some cracks near the craters, was observed on the front face, indicating that the SF effectively confined local damage within the craters. Almost all specimens showed cracks on their rear faces, regardless of whether they were perforated or not. It was observed that the specimen containing SF showed a decrease in brittleness during impact loading. Table 4 presents a comparison of the dimensions of craters between the ferrocement panel with and without SF. Analyzing the specimens labeled “HCP,″ it is observed that as the fiber content increases from 0 to 1% in HCP-0–1, there is a reduction in the dimension of damage on both the front and rear faces, with a decrease in the spalling area and the number of hair cracks. The dimensions of the damage continue to decrease as the fiber content is increased in HCP-0–2 to 2%, demonstrating greater impact resistance. By turning attention to the “HSP” specimens, it is possible to see that in HSP-2–0, increasing the number of mesh layers from one to two results in less spalling and scabbing areas as well as fewer hair cracks. Additionally, adding 1% of fiber content to HSP-2–1 reduces the extent of damage, including the area of spalling and the quantity of hair breaks. Notably, HSP-2–2 exhibits no obvious cracks or damage on either face due to the presence of a 2% fiber content with two mesh layers. The spalling and scabbing areas as well as the quantity of hair cracks decrease for the specimens with the designation “HEP” when the number of mesh layers is increased from 1 to 2 in HEP-2–0. Additionally, adding 1% of fiber content to HEP-2–1 decreases damage further and results in fewer hair breaks. Notably, HEP-2–2 exhibits no obvious cracks or damage on either face despite having a 2% fiber content and two mesh layers. Additionally, it can be shown from the analysis of the specimens (HSP-3–0, HSP-3–1, HSP-3–2, HEP-3–0, HEP-3–1, HEP-3–2) with various fiber contents but no mesh layers that there is a considerable decrease in or complete lack of visible cracks or damage, indicating increased impact resistance.
According to the findings, adding SF helps to stop cracks from spreading further, reducing the size of the crater and the affected area. The inclusion of SF in the ferrocement specimen results in a decrease in spalling and scabbing area compared to specimens without fibers. Furthermore, increasing the SF content from 0 to 2% in ferrocement specimens leads to a reduction in the detached mass from the front and rear faces of the ferrocement specimen. Additionally, an increase in the SF percentage decreases the number and length of cracks observed. The observed behavior may be attributed to the strengthened bond between the SF and mortar matrix, particularly at distances farther away from the center of the contact zone where energy intensity decreases. Table 4 indicates that while the addition of SF significantly reduces scabbing, it does not have a significant impact on the penetration depth. Furthermore, it was observed that specimens reinforced with three layers of wire grid exhibited less spalling area compared to those reinforced with one to two layers of wire grid.

5. Conclusions

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Based on the results presented in this report, the following conclusions can be drawn:
(1)

The addition of steel fibers (SF) in cement mortar enhances both the compressive strength and impact resistance of ferrocement panels. In terms of compressive strength, higher dosages of SF result in increased strength, particularly in the early stages of curing. After 3 days, the addition of 1% SF leads to a 10% increase in compressive strength, while 2% SF dosage results in a 33.33% increase compared to nonfibrous specimens. The compressive strength continues to increase over time, with a 12.5 and 47.5% increase at 7 days and a 30 and 49% increase at 28 days for 1 and 2% SF dosage, respectively.

(2)

When it comes to impact strength, the inclusion of SF significantly improves the panel’s ability to resist impact. The impact resistance increases with higher fiber content, with the greatest improvement observed when transitioning from 0 to 1% fiber content. Introducing 1% SF results in a doubling of impact energy compared to panels without fiber, while increasing the fiber content to 2% does not lead to additional percentage increases in impact energy at the cracking stage (E1). However, for the failure stage (E2), the addition of 1% SF leads to a 400% increase compared to panels without fiber, and increasing the fiber content to 2% further increases the impact energy by 1200%.

(3)

The combined effect of fibers and a single layer of wire welded grid (WWG) or expanded wire grid (EWG) on impact strength shows significant improvements. Introducing fibers at 1% dosage increases impact energy by 100% compared to panels without fiber (CP-0–0). Further increasing the fiber content to 2% does not result in additional percentage increases in impact energy for E1. However, when considering panels with one layer of WWG (SP-1–0), the inclusion of 1% fiber content leads to a 200% increase in impact energy, while 2% fiber content does not yield any further percentage increase. Similarly, panels with one layer of EWG (EP-1–0) exhibit a 50% increase in impact energy for 1% fiber content, without any additional percentage increase for 2% fiber content.

(4)

Adding an extra layer of WWG or EWG further enhances impact energy absorption. Increasing the number of WWG layers from 1 to 2 results in higher impact energies at the cracking and failure stages. Similarly, increasing the number of EWG layers from 1 to 2 leads to significant increases in impact energy. The inclusion of 1 and 2% fiber dosage along with two layers of WWG or EWG increases impact energy, indicating that fibers play a crucial role in improving impact resistance.

(5)

Moreover, the combined effect of fibers and three layers of WWG or EWG shows a substantial increase in impact energy absorption. Introducing 1% fiber content results in a 100% increase in impact energy compared to panels without fiber, with no additional percentage increase observed for 2% fiber content at the cracking stage (E1). At the failure stage (E2), the addition of 1% fiber content leads to a remarkable 400% increase in impact energy compared to panels without fiber, and increasing the fiber content to 2% further increases the impact energy by 1100%.

(6)

The addition of steel fibers to the mortar in ferrocement panels increased their resistance to penetration, resulting in reduced spalling and scabbing damage and smaller crater volumes. The observed phenomenon of larger crater diameters on the rear faces than the front face can be attributed to the reflection of a compressive wave to a tensile wave in the back face of specimens. The inclusion of SF in the ferrocement panels effectively restricted crack development and minimized the size of the damaged area, resulting in the reduced ejection of mortar mass from the specimens. Moreover, increasing the number of wire grid layers enhanced stability and prevented collapse, with ferrocement panels reinforced with two layers of wire grid showing less spalling area compared to those reinforced with one layer. The study concludes that adding three layers of wire grid and steel fibers could further improve the impact resistance of ferrocement panels at both the cracking and failure stages. The improved impact resistance and reduced damage make ferrocement panels with wire mesh and SF a viable option for use in structures such as partition walls, footbridges, roof shells, silos, swimming pools, and manhole covers subject to repeated impacts.

(7)

As the number of reinforcement layers increased, there was a noticeable reduction in the number of fragments that flew out from the back face of the specimens. This suggested that there were fewer and shorter cracks, possibly due to the stronger bond between the fibers and mortar matrix as the distance from the center of the contact zone increased and energy intensity decreased. However, additional experimental and theoretical research is needed to identify the exact role of steel fibers in controlling the ejection of fragments. Finally, the inclusion of steel fibers in cement mortar enhances the compressive strength and impact resistance of ferrocement panels. The percentage increases in compressive strength range from 10 to 49% for 1 and 2% fiber dosage, respectively. The percentage increases in impact energy at the cracking stage (E1) range from 100 to 400% for 1% fiber content, and the percentage increases at the failure stage (E2) range from 400 to 1200% for 1 and 2% fiber dosage, respectively. The addition of multiple layers of WWG or EWG further improves impact energy absorption, with percentage increases varying depending on the fiber dosage and mesh layers used.

Author Information

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  • Corresponding Author
  • Authors
    • Sandeep Sathe - School of Civil Engineering, MIT World Peace University, Pune 411038, India
    • Muhammed Zain Kangda - Department of Civil Engineering, School of Civil Engineering, REVA University, Bengaluru 560064, India
    • Yousef R. Alharbi - Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia
    • Obaid Qamar - Department of Environmental Science & Engineering, Yeungnam University, Gyeongsan 38541, South Korea
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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The authors acknowledge the support provided by Researcher Supporting Project Number RSP2023R271, King Saud University, Riyadh, Saudi Arabia.

References

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    Ferrocement panels, while offering various benefits, do not cover instances of low and moderated velocity impact. To address this problem and to enhance the impact strength against low-velocity impact, a fibrous ferrocement panel is proposed and investigated. This study aims to assess the flexural and low-velocity impact response of simply supported ferrocement panels reinforced with expanded wire mesh (EWM) and steel fibers. The exptl. program covered 12 different ferrocement panel prototypes and was tested against a three-point flexural load and falling mass impact test. The ferrocement panel system comprises mortar reinforced with 1% and 2% dosage of steel fibers and an EWM arranged in 1, 2, and 3 layers. For mortar prepn., a water-cement (w/c) ratio of 0.4 was maintained and all panels were cured in water for 28 days. The primary endpoints of the investigation are first crack and ultimate load capacity, deflection corresponding to first crack and ultimate load, ductility index, flexural strength, crack width at ultimate load, a no. of impacts needed to induce crack commencement and failure, ductility ratio, and failure mode. The finding revealed that the three-layers of EWM inclusion and steel fibers resulted in an addnl. impact resistance improvement at cracking and failure stages of ferrocement panels. With superior ultimate load capacity, flexural strength, crack resistance, impact resistance, and ductile response, as witnessed in the expt. program, ferrocement panel can be a pos. choice for many construction applications subjected to repeated low-velocity impacts.
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    Lab. investigation was undertaken to study the behavior of multilayer composite ferrocement slabs. The slabs include two ferrocement layers with an intermediate rubberized cement mortar layer. The aim of this investigation is to find out the effect of an intermediate layer rubberized cement mortar (RCM) on the behavior of multilayer ferrocement slabs subject to static and dynamic loads. Different rubber ratios, different thickness of RCM layer, and shear connectors to connect the upper and lower reinforcement layers were used. The specimens were cast in 500 × 500 mm, with an overall thickness not exceeding 50 mm. Compressive strength, modulus of rupture, and impact resistance were also tested for RCM cubes, prisms, and cylindrical cement mortar specimens to illustrate mech. properties for using cement mortar. The increase in the RCM layer thickness, with an increase in the crumb rubber ratio, and using shear connectors; it increases impact energy to cause first a crack and then full perforation. Static test results show that thicker RCM layers reduce yield load and slab stiffness at yield, but using shear connectors increases yield load and slab stiffness. The results show that the RCM layer enhances the impact resistance of the ferrocement composite slab. The results also show the effect of the shear connector is small in static and dynamic loads: that are using a RCM with the thickness 0.4 of the total thickness of the slab; or those using a rubber ratio that is more than or equal to 50 % in the RCM layer.
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    In this study, the impact performance of ferrocement with metakaolin was investigated to explore potential uses of both ferrocement and metakaolin in construction industry. A series of ferrocement specimens were cast with varying no. of mesh layers and with varying metakaolin percentages. The specimens were normal water-cured for 180 days. The effect of metakaolin percentage (5-25%); curing period (7, 28, 90 and 180 days); and no. of mesh layers (one, three and five) on impact strength was investigated. The results show that, 10 % metakaolin is the optimum content to obtain max. impact strength. Up to 15% metakaolin replacement the strengths are higher than control ferrocement at all curing ages and for all the mesh layers. The results further indicated that metakaolin replacements equal and higher than 20% yields lower strengths than control ferrocement for all the mesh layers.
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    Construction and Building Materials (2019), 203 (), 56-68CODEN: CBUMEZ; ISSN:1879-0526. (Elsevier Ltd.)
    The latest research data indicates that geopolymer concrete reinforced with mono fiber has a remarkable enhancement in its impact strength and fracture toughness, which is well documented. Nevertheless, many aspects of impact behavior of Hybrid Fibrous Geopolymer Composites (HFGC) are still unexplored, which are of primary importance for defense projects in the world. For the first time, the impact behavior under falling wt. collision of HFGC were evaluated and further analyzed. The HFGC mixts. were fabricated using three different fibers viz., 5D hooked end steel, polypropylene and glass. The main parameters studied were the fiber dosage and amalgamations of different fibers. Totally seven mixes were prepd. and further investigations were conducted in two phases. In the first phase, five cylindrical specimens were fabricated for each mix and tested as per the ACI committee 544 falling wt. collision test recommendations. Subsequently, a comprehensive two-parameter Weibull distribution was executed to scrutinise the scattered exptl. test results of cylindrical specimens and presented in terms of reliability function. In the second phase, prism specimens were fabricated and tested under the same falling wt. collision. Then, an anal. model was formulated for evaluating the impact energy at failure of HFGC prism specimens and comparisons were made with exptl. data. The hybridization of the above three fibers at a certain dosage and incorporation in geopolymer composites led to an enhanced impact performance and ductility properties. Further, the obtained impact energy at failure from modeling well agrees with the exptl. results. Henceforth, it is a successful research data that is presented herein which will be eminently valuable for understanding the performance of new fibrous geopolymer composites (FGC) made with hybrid fibers that which are available all over the world.
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    A review. Two-stage fiber-reinforced concrete (TSFRC) is a novel fibrous concrete that differs from the conventional fiber-reinforced concrete (FRC) in several aspects including its placement technique, implementation, fabrication methodol., and high coarse aggregate content. Consequently, the available data from the open literature on the behavior of the conventional FRC exposed to falling wt. collision may not be applicable to TSFRC. For instance, the impact strength performance of the conventional FRC is well documented; however, for TSFRC this has not been duly examd. For the first time, this study pioneers the concept of impact strength of TSFRC under falling wt. collision. For this purpose, short crimped fibers and long hooked end steel fibers at 1.5, 3.0, and 5.0% dosage were used in two-stage concrete (TSC). To this end, seven different mixes were prepd. and tested under falling wt. collision as per ACI committee 544. In addn., a statistical anal. has been performed to analyze the scattered test results by Weibull distribution. For detg. Weibull parameters, 20 probability estimators have been used, and the best estimators are taken for the reliability anal. Based on the obtained Weibull parameters, the impact strength of TSFRC has been reported in terms of reliability. The results revealed that the ability of using higher fiber dosages allows achieving greater impact resistance properties for novel manufg. TSFRC. Indeed, the TSC with steel fiber dosages exceeding 5%, can be produced easily thus making this innovative, yet simple to produce concrete, a strong contender in many construction applications. The two-parameter Weibull theory has been found to be adequately suitable for analyzing the variations in the no. of impacts that induces first crack and failure of all group of TSFRC specimens.
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  1. Reza Geravand, Alireza Mortezaei, Ahmad Azizi. Experimental and numerical evaluation of fibre-reinforced concrete vault forming slabs subjected to low-velocity impact loading. European Journal of Environmental and Civil Engineering 2025, 29 (5) , 983-1008. https://doi.org/10.1080/19648189.2024.2423877
  2. Sandeep Sathe, Shahbaz Dandin, Mohd Zain Kangda. Comparative study on structural behavior of fibrous-ferro-cement panel reinforced with welded and expanded wire grid subjected to flexural loads. Multiscale and Multidisciplinary Modeling, Experiments and Design 2025, 8 (1) https://doi.org/10.1007/s41939-024-00632-y
  3. Sandeep Sathe, Shahbaz Dandin, Makrand Wagale, Pankaj R. Mali. Effective combinations of different fiber reinforcements and super-plasticizers for optimal performance of geo-polymer concrete. World Journal of Engineering 2024, 75 https://doi.org/10.1108/WJE-04-2024-0216
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  • Abstract

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    Figure 1

    Figure 1. Welded wire grid.

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    Figure 2

    Figure 2. Expanded wire grid.

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    Figure 3

    Figure 3. Panel layer thickness details.

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    Figure 4

    Figure 4. Typical specimen SP-1–0.

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    Figure 5

    Figure 5. Typical specimen EP-1–0.

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    Figure 6

    Figure 6. Curing of specimens.

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    Figure 7

    Figure 7. Specimens after curing.

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    Figure 8

    Figure 8. Falling hammer test setup.

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    Figure 9

    Figure 9. Clamping system.

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    Figure 10

    Figure 10. Gun system (penetration test setup).

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    Figure 11

    Figure 11. Target frame.

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    Figure 12

    Figure 12. Compressive strength of mortar.

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    Figure 13

    Figure 13. Impact energies of a panel at the cracking stage.

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    Figure 14

    Figure 14. Impact energies of panels at the failure stage.

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    Figure 15

    Figure 15. Impact ductility index of the ferrocement panel under impact load.

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    Figure 16

    Figure 16. Typical mode of failure of ferrocement panel. (a) Damage on the front face and (b) damage on the rear face.

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    Figure 17

    Figure 17. Schematic description of the activated failure mechanism under the repeated falling mass impact.

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    Figure 18

    Figure 18. (a) Evaluation of the equivalent diameter of the damaged area. (b) Bullet projectile.

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    Figure 19

    Figure 19. Damage regions in the mortar subjected to impact forces.

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      Structural behavior of fibrous-ferrocement panel subjected to flexural and impact loads
      Murali, Gunasekaran; Amran, Mugahed; Fediuk, Roman; Vatin, Nikolai; Raman, Sudharshan N.; Maithreyi, Gundu; Sumathi, Arunachalam
      Materials (2020), 13 (24), 5648CODEN: MATEG9; ISSN:1996-1944. (MDPI AG)
      Ferrocement panels, while offering various benefits, do not cover instances of low and moderated velocity impact. To address this problem and to enhance the impact strength against low-velocity impact, a fibrous ferrocement panel is proposed and investigated. This study aims to assess the flexural and low-velocity impact response of simply supported ferrocement panels reinforced with expanded wire mesh (EWM) and steel fibers. The exptl. program covered 12 different ferrocement panel prototypes and was tested against a three-point flexural load and falling mass impact test. The ferrocement panel system comprises mortar reinforced with 1% and 2% dosage of steel fibers and an EWM arranged in 1, 2, and 3 layers. For mortar prepn., a water-cement (w/c) ratio of 0.4 was maintained and all panels were cured in water for 28 days. The primary endpoints of the investigation are first crack and ultimate load capacity, deflection corresponding to first crack and ultimate load, ductility index, flexural strength, crack width at ultimate load, a no. of impacts needed to induce crack commencement and failure, ductility ratio, and failure mode. The finding revealed that the three-layers of EWM inclusion and steel fibers resulted in an addnl. impact resistance improvement at cracking and failure stages of ferrocement panels. With superior ultimate load capacity, flexural strength, crack resistance, impact resistance, and ductile response, as witnessed in the expt. program, ferrocement panel can be a pos. choice for many construction applications subjected to repeated low-velocity impacts.
    12. 12
      Abdulla, A. I.; Khatab, H. R. Behaviour of multilayer composite ferrocement slabs with intermediate rubberized cement mortar layer. Arabian J. Sci. Eng. 2014, 39, 5929– 5941,  DOI: 10.1007/s13369-014-1171-y
      12
      Behavior of Multilayer Composite Ferrocement Slabs with Intermediate Rubberized Cement Mortar Layer
      Abdulla, Aziz Ibrahim; Khatab, Hadeel Reiadh
      Arabian Journal for Science and Engineering (2014), 39 (8), 5929-5941CODEN: AJSEBW; ISSN:2191-4281. (Springer)
      Lab. investigation was undertaken to study the behavior of multilayer composite ferrocement slabs. The slabs include two ferrocement layers with an intermediate rubberized cement mortar layer. The aim of this investigation is to find out the effect of an intermediate layer rubberized cement mortar (RCM) on the behavior of multilayer ferrocement slabs subject to static and dynamic loads. Different rubber ratios, different thickness of RCM layer, and shear connectors to connect the upper and lower reinforcement layers were used. The specimens were cast in 500 × 500 mm, with an overall thickness not exceeding 50 mm. Compressive strength, modulus of rupture, and impact resistance were also tested for RCM cubes, prisms, and cylindrical cement mortar specimens to illustrate mech. properties for using cement mortar. The increase in the RCM layer thickness, with an increase in the crumb rubber ratio, and using shear connectors; it increases impact energy to cause first a crack and then full perforation. Static test results show that thicker RCM layers reduce yield load and slab stiffness at yield, but using shear connectors increases yield load and slab stiffness. The results show that the RCM layer enhances the impact resistance of the ferrocement composite slab. The results also show the effect of the shear connector is small in static and dynamic loads: that are using a RCM with the thickness 0.4 of the total thickness of the slab; or those using a rubber ratio that is more than or equal to 50 % in the RCM layer.
    13. 13
      Jaraullah, M. N. A.; Dawood, E. T.; Abdullah, M. H. Static and impact mechanical properties of ferrocement slabs produced from green mortar. Case Stud. Constr. Mater. 2022, 16, e00995  DOI: 10.1016/j.cscm.2022.e00995
      There is no corresponding record for this reference.
    14. 14
      Yerramala, A.; Rama Chandurdu, C.; Bhaskar Desai, V. Impact strength of metakaolin ferrocement. Mater. Struct. 2016, 49 (1–2), 5– 15,  DOI: 10.1617/s11527-014-0469-2
      14
      Impact strength of metakaolin ferrocement
      Yerramala, Amarnath; Rama Chandurdu, C.; Bhaskar Desai, V.
      Materials and Structures (Dordrecht, Netherlands) (2016), 49 (1-2), 5-15CODEN: MASTED; ISSN:1359-5997. (Springer)
      In this study, the impact performance of ferrocement with metakaolin was investigated to explore potential uses of both ferrocement and metakaolin in construction industry. A series of ferrocement specimens were cast with varying no. of mesh layers and with varying metakaolin percentages. The specimens were normal water-cured for 180 days. The effect of metakaolin percentage (5-25%); curing period (7, 28, 90 and 180 days); and no. of mesh layers (one, three and five) on impact strength was investigated. The results show that, 10 % metakaolin is the optimum content to obtain max. impact strength. Up to 15% metakaolin replacement the strengths are higher than control ferrocement at all curing ages and for all the mesh layers. The results further indicated that metakaolin replacements equal and higher than 20% yields lower strengths than control ferrocement for all the mesh layers.
    15. 15
      Dancygier, A. N.; Yankelevsky, D. Z.; Jaegermann, C. Response of high-performance concrete plates to impact of non-deforming projectiles. Int. J. Impact Eng. 2007, 34 (11), 1768– 1779,  DOI: 10.1016/j.ijimpeng.2006.09.094
      There is no corresponding record for this reference.
    16. 16
      Quek, S. T.; Lin, V. W. J.; Maalej, M. Development of functionally-graded cementitious panel against high-velocity small projectile impact. Int. J. Impact Eng. 2010, 37 (8), 928– 941,  DOI: 10.1016/j.ijimpeng.2010.02.002
      There is no corresponding record for this reference.
    17. 17
      Lin, V. W. J.; Quek, S. T.; Maalej, M.; Lee, S. C. Finite element model of functionally-graded cementitious panel under small projectile impact. Int. J. Prot. Struct. 2010, 1 (2), 271– 297,  DOI: 10.1260/2041-4196.1.2.271
      There is no corresponding record for this reference.
    18. 18
      Kamal, I. M.; Eltehewy, E. M. Projectile penetration of reinforced concrete blocks: test and analysis. Theor. Appl. Fract. Mech. 2012, 60 (1), 31– 37,  DOI: 10.1016/j.tafmec.2012.06.005
      There is no corresponding record for this reference.
    19. 19
      Almusallam, T. H.; Siddiqui, N. A.; Iqbal, R. A.; Abbas, H. Response of hybrid-fibre reinforced concrete slabs to hard projectile impact. Int. J. Impact Eng. 2013, 58, 17– 30,  DOI: 10.1016/j.ijimpeng.2013.02.005
      There is no corresponding record for this reference.
    20. 20
      Lai, J.; Wang, H.; Yang, H.; Zheng, X.; Wang, Q. Dynamic properties and SPH simulation of functionally graded cementitious composite subjected to repeated penetration. Constr. Build. Mater. 2017, 146, 54– 65,  DOI: 10.1016/j.conbuildmat.2017.04.023
      20
      Dynamic properties and SPH simulation of functionally graded cementitious composite subjected to repeated penetration
      Lai, Jianzhong; Wang, Huifang; Yang, Haoruo; Zheng, Xiaobo; Wang, Qiang
      Construction and Building Materials (2017), 146 (), 54-65CODEN: CBUMEZ; ISSN:1879-0526. (Elsevier Ltd.)
      Functionally graded cementitious composite (FGCC) was prepd. by varying distribution of high strength fibers and aggregates. The anti-penetration layer and crack resistance layer of FGCC were made of ultra high performance coarse aggregate concrete and ultra high performance steel fiber reinforced concrete resp. The resistance of FGCC against repeated penetration was researched. The penetration depth, fracture pattern and penetration damage of different concrete targets were measured. Results show that the penetration depth, crater area and penetration damage were decreased greatly by the synergistic effects of high strength fibers and coarse aggregates. The cracking and spalling of concrete target were prevented by the combined actions of the anti-penetration and crack resistance layers. The fracture process and damage development of FGCC subjected to projectile impact were simulated by smoothed particle hydrodynamics (SPH) method. The effects of coarse aggregates distance on the penetration depth and damage of FGCC were investigated.
    21. 21
      IS:12269-2013. Ordinary Portland cement,53 grade-Specification; Bureau of Indian Standards: New Delhi, India; 2000.
      There is no corresponding record for this reference.
    22. 22
      ACI 549.1R-93. Guide for the Design, Construction, and Repair of Ferrocement; ACI Committee 549: Farmington Hills, MI, USA; 1993, Reapproved 1999.
      There is no corresponding record for this reference.
    23. 23
      ASTM C 1437–07. Standard Test Method for Flow of Hydraulic Cement. PA19428–2959, Mortar, PO Box C700, West Conshohocken, United States.
      There is no corresponding record for this reference.
    24. 24
      IS:516-1959. Method of Test for Strength of Concrete Bureau of Indian Standards: New Delhi, India; 2000.
      There is no corresponding record for this reference.
    25. 25
      ACI 544.2R-89. Measurement of Properties of Fibre Reinforced Concrete ACI Committee 544: Farmington Hills, MI, USA; 1999, Reapproved 1999.
      There is no corresponding record for this reference.
    26. 26
      Alvarez, G. L.; Nazari, A.; Bagheri, A.; Sanjayan, J. G.; De Lange, C. Microstructure, electrical and mechanical properties of steel fibres reinforced cement mortars with partial metakaolin and limestone addition. Constr. Build. Mater. 2017, 135, 8– 20,  DOI: 10.1016/j.conbuildmat.2016.12.170
      26
      Microstructure, electrical and mechanical properties of steel fibres reinforced cement mortars with partial metakaolin and limestone addition
      Alvarez, Graciela Lopez; Nazari, Ali; Bagheri, Ali; Sanjayan, Jay G.; De Lange, Christo
      Construction and Building Materials (2017), 135 (), 8-20CODEN: CBUMEZ; ISSN:1879-0526. (Elsevier Ltd.)
      This paper investigates binary and ternary binders of ordinary Portland cement, metakaolin and limestone as a possible soln. to reduce the amt. of cement content in mortar mixes. Furthermore, the mortar mixts. were reinforced with steel fibers and their properties were investigated. The effectiveness of metakaolin and limestone on compressive and flexural strength of mortar samples as mech. properties was analyzed. Results indicated that partial substitution of metakaolin in mortar mixts. provides higher compressive strength values at early ages; combined mixts. of limestone and metakaolin enhanced compressive strength comparing with 100% ordinary Portland cement (OPC) as the binder. Flexural strength values improved by increasing the no. of steel fibers in mixts.; variations in metakaolin and limestone on mixts. seemed not to affect on final flexural results significantly. Elec. resistivity results revealed substantial improvements on the likelihood corrosion and corrosion rate of mortar mixts. The addn. of steel fibers to the admixt. significantly decreased the ER mainly due to the cond. of the fibers.
    27. 27
      Alabduljabbar, H.; Alyousef, R.; Alrshoudi, F.; Alaskar, A.; Fathi, A.; Mustafa Mohamed, A. Mechanical effect of steel fibre on the cement replacement materials of self-compacting concrete. Fibres 2019, 7 (4), 36,  DOI: 10.3390/fib7040036
      There is no corresponding record for this reference.
    28. 28
      Abid, S. R.; Abdul-Hussein, M. L.; Ayoob, N. S.; Ali, S. H.; Kadhum, A. L. Repeated drop-weight impact tests on self-compacting concrete reinforced with micro-steel fibre. Heliyon 2020, 6 (1), e03198  DOI: 10.1016/j.heliyon.2020.e03198
      There is no corresponding record for this reference.
    29. 29
      Asrani, N. P.; Murali, G.; Parthiban, K.; Surya, K.; Prakash, A.; Rathika, K.; Chandru, U. A feasibility of enhancing the impact resistance of hybrid fibrous geopolymer composites: Experiments and modelling. Constr. Build. Mater. 2019, 203, 56– 68,  DOI: 10.1016/j.conbuildmat.2019.01.072
      29
      A feasibility of enhancing the impact resistance of hybrid fibrous geopolymer composites: Experiments and modelling
      Asrani, Neha P.; Murali, G.; Parthiban, K.; Surya, K.; Prakash, A.; Rathika, K.; Chandru, Uma
      Construction and Building Materials (2019), 203 (), 56-68CODEN: CBUMEZ; ISSN:1879-0526. (Elsevier Ltd.)
      The latest research data indicates that geopolymer concrete reinforced with mono fiber has a remarkable enhancement in its impact strength and fracture toughness, which is well documented. Nevertheless, many aspects of impact behavior of Hybrid Fibrous Geopolymer Composites (HFGC) are still unexplored, which are of primary importance for defense projects in the world. For the first time, the impact behavior under falling wt. collision of HFGC were evaluated and further analyzed. The HFGC mixts. were fabricated using three different fibers viz., 5D hooked end steel, polypropylene and glass. The main parameters studied were the fiber dosage and amalgamations of different fibers. Totally seven mixes were prepd. and further investigations were conducted in two phases. In the first phase, five cylindrical specimens were fabricated for each mix and tested as per the ACI committee 544 falling wt. collision test recommendations. Subsequently, a comprehensive two-parameter Weibull distribution was executed to scrutinise the scattered exptl. test results of cylindrical specimens and presented in terms of reliability function. In the second phase, prism specimens were fabricated and tested under the same falling wt. collision. Then, an anal. model was formulated for evaluating the impact energy at failure of HFGC prism specimens and comparisons were made with exptl. data. The hybridization of the above three fibers at a certain dosage and incorporation in geopolymer composites led to an enhanced impact performance and ductility properties. Further, the obtained impact energy at failure from modeling well agrees with the exptl. results. Henceforth, it is a successful research data that is presented herein which will be eminently valuable for understanding the performance of new fibrous geopolymer composites (FGC) made with hybrid fibers that which are available all over the world.
    30. 30
      Abirami, T.; Murali, G.; Mohan, K. S. R.; Salaimanimagudam, M. P.; Nagaveni, P.; Bhargavi, P. Multi-layered two stage fibrous composites against low-velocity falling mass and projectile impact. Constr. Build. Mater. 2020, 248, 118631  DOI: 10.1016/j.conbuildmat.2020.118631
      There is no corresponding record for this reference.
    31. 31
      Abirami, T.; Loganaganandan, M.; Murali, G.; Fediuk, R.; Sreekrishna, R. V.; Vignesh, T.; Karthikeyan, K. Experimental research on impact response of novel steel fibrous concretes under falling mass impact. Constr. Build. Mater. 2019, 222, 447– 457
      There is no corresponding record for this reference.
    32. 32
      Murali, G.; Asrani, N. P.; Ramkumar, V. R.; Siva, A.; Haridharan, M. K. Impact Resistance and Strength Reliability of Novel Two-Stage Fibre-Reinforced Concrete. Arabian J. Sci. Eng. 2019, 44, 4477– 4490,  DOI: 10.1007/s13369-018-3466-x
      32
      Impact Resistance and Strength Reliability of Novel Two-Stage Fibre-Reinforced Concrete
      Murali, G.; Asrani, Neha P.; Ramkumar, V. R.; Siva, A.; Haridharan, M. K.
      Arabian Journal for Science and Engineering (2019), 44 (5), 4477-4490CODEN: AJSEBW; ISSN:2191-4281. (Springer)
      A review. Two-stage fiber-reinforced concrete (TSFRC) is a novel fibrous concrete that differs from the conventional fiber-reinforced concrete (FRC) in several aspects including its placement technique, implementation, fabrication methodol., and high coarse aggregate content. Consequently, the available data from the open literature on the behavior of the conventional FRC exposed to falling wt. collision may not be applicable to TSFRC. For instance, the impact strength performance of the conventional FRC is well documented; however, for TSFRC this has not been duly examd. For the first time, this study pioneers the concept of impact strength of TSFRC under falling wt. collision. For this purpose, short crimped fibers and long hooked end steel fibers at 1.5, 3.0, and 5.0% dosage were used in two-stage concrete (TSC). To this end, seven different mixes were prepd. and tested under falling wt. collision as per ACI committee 544. In addn., a statistical anal. has been performed to analyze the scattered test results by Weibull distribution. For detg. Weibull parameters, 20 probability estimators have been used, and the best estimators are taken for the reliability anal. Based on the obtained Weibull parameters, the impact strength of TSFRC has been reported in terms of reliability. The results revealed that the ability of using higher fiber dosages allows achieving greater impact resistance properties for novel manufg. TSFRC. Indeed, the TSC with steel fiber dosages exceeding 5%, can be produced easily thus making this innovative, yet simple to produce concrete, a strong contender in many construction applications. The two-parameter Weibull theory has been found to be adequately suitable for analyzing the variations in the no. of impacts that induces first crack and failure of all group of TSFRC specimens.
    33. 33
      Wang, S.; Naaman, A. E.; Li, V. C. Bending response of hybrid ferrocement plates with meshes and fibres. 2004.
      There is no corresponding record for this reference.
    34. 34
      Yerramala, A.; Ramachandurdu, C.; Desai, V. B. Flexural strength of metakaolin ferrocement. Composites, Part B 2013, 55, 176– 183,  DOI: 10.1016/J.COMPOSITESB.2013.06.029
      34
      Flexural strength of metakaolin ferrocement
      Yerramala, Amarnath; Ramachandurdu, C.; Bhaskar Desai, V.
      Composites, Part B: Engineering (2013), 55 (), 176-183CODEN: CPBEFF; ISSN:1359-8368. (Elsevier Ltd.)
      Flexural strength of metakaolin ferrocements was evaluated through lab. investigation. Ref. mortar with OPC of 43 grade and metakaolin mortars with 5-25% metakaolin replacement in the increments of 5% with cement were made. Const. water to cementitious ratio of 0.5 was maintained for all the mortars. Galvanized oven mesh (chicken mesh) was incorporated in the tension zone in one, three and five-layers to investigate the influence of reinforcement. The samples were water-cured for 7, 28, 90 and 180 days. The results show that, up to 15% metakaolin replacement, flexural strengths were higher than control ferrocement at all curing ages and for all mesh layers. However, replacements equal and higher than 20% had lower strengths than control ferrocement for all mesh layers. It was further found that 10% metakaolin is the optimum content for max. flexural strength. The data presented in this paper are a part of study conducted on ferrocement.
    35. 35
      Mastali, M.; Naghibdehi, M. G.; Naghipour, M.; Rabiee, S. M. Experimental assessment of functionally graded reinforced concrete (FGRC) slabs under drop weight and projectile impacts. Constr. Build. Mater. 2015, 95, 296– 311,  DOI: 10.1016/j.conbuildmat.2015.07.153
      There is no corresponding record for this reference.
    36. 36
      Murali, G.; Fediuk, R. A Taguchi approach for study on impact response of ultra-high-performance polypropylene fibrous cementitious composite. J. Build. Eng. 2020, 30, 101301  DOI: 10.1016/j.jobe.2020.101301
      There is no corresponding record for this reference.
    37. 37
      James, R.; Clifton Penetration Resistance of Concrete -A Review; National Bureau of Standards Special Publication, 1982; p 480.
      There is no corresponding record for this reference.
    38. 38
      Sathe, S.; Rathod, R. Flexural Behaviour of Ferrocement Slab Panels Using Expanded Metal Mesh 2020.
      There is no corresponding record for this reference.