Mechanical Properties Of Concrete Research Articles

MECHANICAL PROPERTIES AND MICROSTRUCTURE OF CONCRETE INCORPORATING SYNTHETIC ZEOLITE

The effect of natural and synthetic zeolite on the microstructure of cement matrix and mechanical properties of concretes was studied in the article. Results show that the addition of these pozzolanic materials results in the increase both compressive and flexural strength after 28 days of hardening. The concrete incorporating 10 mass.% of synthetic zeolite Na-P1 characterizes the highest compressive and flexural strength that reaches 53.5 and 7.8 MPa and exceeds the strength of reference concrete by 18 and 24%, respectively. This increase is the result of the improvement of the concrete on the microstructural level due to the formation of the additional amount of fibre-like crystals of hydrosilicates in the non-clinker part of the cement matrix providing its self-reinforcement.

Impact of geopolymer aggregate on the mechanical properties and durability characteristics of concrete

This study examined the use of geopolymer aggregate (GPA), produced from slag and an alkaline solution, as a substitute for coarse aggregate in conventional concrete. The research aimed to evaluate how different proportions of GPA (25%, 50%, 75%, and 100% replacement) affect the durability and mechanical properties of concrete. A series of tests were conducted, including slump, compressive strength, flexural strength, chloride resistance, sulfate resistance, sorptivity, and water absorption. The results demonstrated significant improvements in concrete properties with the inclusion of GPA. The compressive strength of GPA concrete ranged from 31 to 38 MPa, showing a 10%–15% increase over that of standard concrete. Flexural strength improved by 6% at 7 days and 7.5% at 28 days compared to control mixes. Water absorption was reduced by 42.58%, and sorptivity decreased by 47.9% compared to ordinary aggregate concrete. GPA concrete also excelled in acid resistance, with a weight loss of 28.6% and a lower reduction in strength compared to traditional acidic aggregates. In sulfate resistance tests, GPA concrete showed a 31% reduction in both weight and strength loss. These results highlight the advantages of using GPA as an alternative to conventional coarse aggregates. GPA not only enhances the mechanical and durability properties of concrete but also presents a more sustainable option, contributing to reduced environmental impacts associated with traditional aggregate materials.

Effect of Super Retarder on Recycled Water and Concrete Properties of Waste Slurry in Mixing Plant

A large amount of waste slurry water will be generated in the production process of concrete mixing plant, due to the complex composition of waste slurry water, if it is not handled in time when stored, serious coagulation will occur, which will accelerate the loss of equipment and reduce the utilization rate. In this paper, a super retarder suitable for waste slurry recycled water from concrete mixing plant was prepared using composite technology. The waste slurry recycled water mixed with super retarding agent was characterized by using microscopic testing means XRD, TG and DTG. The waste slurry recycled water mixed with super retarding agent was used to replace tap water in the production of concrete, and its effect on the workability and mechanical properties of concrete was investigated. It was found that the compounding of Butane 2-phospho-1,2,4-tricarboxylic acid (PBTCA) with Reclaimed water treatment agent (ACS) resulted in a setting time of 64 h for 10% concentration of recycled water, with optimal retarding effect. When PBTCA:ACS was 1:20, mixed at 1.5% of the mass of recycled water, the 1 h slump of concrete had no loss, the loss of extension was 15 mm, the 7 days compressive strength was increased by 3.5 MPa, and the 28 days compressive strength was increased by 3.0 MPa. The microscopic results showed that the use of ACS and PBTCA does not affect the type of cement hydration products, but only affects the the rate of hydration product generation.

Analysis of stress-strain curve of POM fiber reinforced concrete

ABSTRACT As a new type of synthetic fiber, polyoxymethylene (POM) fiber has the advantages of high tensile strength, good dispersibility, and high bonding strength with cement interface. It has broad application prospects. However, there is limited research on POM fiber reinforced concrete. In order to provide scientific basis for promoting the application of POM fiber, this paper adopts a combination of indoor experiments and numerical simulations to obtain the axial stress-strain complete curves of POM fiber reinforced concrete with different volume dosages and studies the uniaxial compressive properties of POM fiber reinforced concrete. Finally, the constitutive equation parameters of POM fiber reinforced concrete were fitted using the Guo Zhenhai model, and the optimal fiber content was determined. The results indicate that at a POM fiber content of 1.5 kg/m3, the load-displacement curve exhibits optimal shape with the highest residual strength. With increasing fiber content, compressive stress-strain curve parameters initially increase and then decrease, peaking at 1.5 kg/m3, optimizing the mechanical properties of concrete. POM fiber has minimal impact on initial elastic modulus. Thus, optimal mechanical property enhancement is achieved with 1.5 kg/m3 POM fiber content.

Study of coarse and fine natural aggregates at high temperature in Algeria

Under high temperature, concrete undergoes changes which occurred in the hardened cement past and aggregates. These changes modified the mechanical and physical properties of concrete. The main objective of this study is to observe and identify the influence of high temperature on the physical properties of different nature of aggregates used to cast concrete. Four types of aggregates were studied in this research, siliceous sand (SS), calcareous sand (CS), white calcareous aggregates (WCA) and gray calcareous aggregates (GCA). These aggregates were subjected to different temperatures, from 100°C to 900°C. The mass loss, absorption coefficient, water porosity and density were determined before and after the exposure to the high temperatures. The results show that gray calcareous aggregates (GCA) suffered more deterioration than the other types of aggregates after the high temperature exposures. The results presented in this paper allow improving the knowledge of aggregate’s deterioration phenomena and the evolutions of physical properties of these different aggregates can be used to explain the evolution of physical and mechanical properties of concretes.

Experimental study and numerical simulation of the effect of different fiber types on the basic mechanical properties of shotcrete

This study analyzed the enhancement effects and mechanisms of steel, glass, and polypropylene fibers on the mechanical properties of concrete, aiming to guide the selection of suitable fiber types and dosages for shotcrete projects. Through laboratory tests, numerical simulations, and field experiments, it investigated the enhancement laws of flexural and compressive strengths of concrete with different dosages of these three fibers. Results showed: (1) After 28 days of curing, flexural strength peaked with 2.0% steel, 1.5% glass, and 2.0% polypropylene fibers, increasing by 118.6%, 42.86%, and 138.6%, respectively, over plain concrete. Compressive strength increased by 2.13%, 10%, and 18.3% at optimal dosages of 0.5%, 1.0%, and 2.0% for steel, glass, and polypropylene fibers. Fiber effects on compressive strength were less significant than on flexural strength, with polypropylene fibers outperforming the others. (2) Based on ABAQUS numerical simulations, microscopic analysis indicates that fibers, due to their high yield capacity, enhance the connections between concrete elements, reduce stress concentration, and improve the mechanical properties of concrete. (3) For shotcrete, 2.0% polypropylene fibers were preferred due to high flexural strength and reduced agglomeration. (4) The optimal dosage was applied to a mine’s wet shotcrete support, effectively controlling tunnel deformation. These findings provide practical guidance for shotcrete applications.

Durability and mechanical properties of concretes with limestone filler with particle packing

This study aims to present alternatives to reduce the demand of cement in concrete production based on particle packing concepts. Physical and mechanical characteristics of concretes, as well as the resistance to chlorides action were analyzed. The tests conducted in this study included compressive strength, chloride migration, capillary absorption tests and wetting and drying cycles in 1M sodium chloride solution. Mixtures containing limestone filler presented satisfactory results compared to the reference mixture with particle packing. Excellent results were obtained for concrete with cement consumption of 253.34 kg.m-3 in terms of compressive strength, binder index, capillary absorption and depassivation time of rebars, thus reinforcing the concept that partial cement replacement by limestone filler yields positive results in these properties. Worse results were obtained for concrete with a cement consumption of 161.86 kg.m-3, because it had a higher proportion of filler than cement. The electrochemical monitoring of the steel bars also shows that the packing of the aggregates was essential to delay the initiation of corrosion.

Microstructural analysis of geopolymer pastes contaminated with crude oil: Impact on efflorescence, physical properties, and mechanical performance

Geopolymer concrete represents a more sustainable alternative to traditional cement in particular production processes, reducing carbon emissions, recycling industrial by-products, and promoting energy efficiency. However, a notable challenge is the potential for efflorescence, which can impair material performance due to microstructural changes from alkali leaching and carbonation. Various additives have been explored to mitigate efflorescence. Using oil-contaminated sand in geopolymer and concrete cement production is emerging as a cost-effective rehabilitation strategy that also addresses environmental concerns. This study investigates the impact of crude oil contamination on geopolymer pastes, focusing on efflorescence susceptibility. Under normal ambient conditions, the geopolymer pastes did not show signs of efflorescence. However, exposure to water led to the formation of efflorescence-type products. Notably, crude oil contamination significantly influenced this outcome. Crude oil significantly decreased the occurrence of efflorescence, mainly when contamination levels ranged from 2 % to 10 %. This reduction is attributed to the oil’s effects on the paste’s pore structure, fluid migration dynamics, and viscosity, which affected water adhesion and movement through the paste. Additionally, crude oil contamination altered the chemical properties of the geopolymer pastes, causing fluctuations in the pH of leaching solutions, which affected chemical equilibrium and electrical conductivity. Compressive strength improved with 1 % crude oil contamination but decreased with higher contamination levels. Geopolymer paste with 1 % crude oil content generally increases material density and reduces porosity, enhancing mechanical properties and reducing efflorescence. However, excessive contamination undermined these benefits and negatively impacted material performance. Therefore, moderate oil contamination can be effectively used as an additive to reduce efflorescence and enhance geopolymer concrete's physical and mechanical properties. The findings provide valuable insights into the potential applications and limitations of using fly ash-based geopolymers in environments prone to oil contamination.

Hybrid Fiber Reinforcement in HDPE–Concrete: Predictive Analysis of Fresh and Hardened Properties Using Response Surface Methodology

Plastic waste accumulation has driven research into recycling solutions, such as using plastics as partial aggregate substitutes in concrete to meet construction needs, conserve resources, and reduce environmental impact. However, studies reveal that plastic aggregates weaken concrete strength, creating the need for reinforcement methods in plastic-containing concrete. This study used experimental data from 225 tested specimens to develop prediction models for the properties of concrete containing macro-synthetic fibers (MSFs), steel fibers (SFs), and high-density polyethylene (HDPE) plastic as a partial substitute for natural coarse aggregate (NCA) by volume utilizing response surface methodology (RSM). HDPE plastics were used as a partial substitute for NCA by volume at levels of 10%, 30%, and 50%. MSFs were added at levels of 0, 0.25%, 0.5%, and 1% by volume of concrete, while SFs were added at levels of 0, 0.5%, 1%, 1.5%, and 2% by volume of concrete. The input parameters for the models are the ratio of HDPE, the dose of MSF, and the dose of SF. The responses are the slump value, the compressive strength (CS), the splitting tensile strength (TS), and the flexural strength (FS) of concrete. The significance and suitability of the developed models were assessed and validated, and the parameters’ contribution was investigated using analysis of variance (ANOVA) and other statistical tests. Numerical optimization was used to determine the best HDPE, MSF, and SF ratios for optimizing the mechanical properties of concrete. The results demonstrated that replacing NCA with HDPE plastics increased the workability and decreased the strength of concrete. The results demonstrated the applicability of the developed models for predicting the properties of HDPE–concrete containing MSFs and SFs, which agreed well with the data from experiments. The created models have R2 values more than 0.92, adequate precision more than 4, and p-values less than 0.05, showing high correlation levels for prediction. The RSM modeling results indicate that the inclusion of MSFs and SFs improved the mechanical properties of HDPE–concrete. The optimum doses of MSFs and SFs were 0.73% and 0.74%, respectively, of volume of concrete, leading to improvement in the mechanical properties of HDPE–concrete. This approach reduces plastic waste and its detrimental environmental impact. Further development of models is needed to simulate the combined effects of different fiber types, shapes, and dosages on the performance and durability of plastic-containing concrete.

Complex additive for improving the strength properties of heavy concrete based on industrial waste

The article presents the results of using a complex modified additive to improve concrete's physical and mechanical properties. The complex additive includes industrial production wastes: metallurgical slag and alcohol production wastes (post-alcohol bard). To stabilize the hydrogen index the alkali KON is included in the composition of the additive. A set of laboratory studies was carried out to measure the strength, absorption, and frost resistance of test specimens to assess the effect of the additive on the properties of concrete. A comparison of physical and mechanical properties was made for samples of different concentrations of slag. The ratio of slag components to cement was from 5 to 25% by the total mass of the binder, a multiple of 5%. The optimal composition of the mixture, with maximum strength values, corresponds to the percentage of slag 15%, post-alcohol bard 22.5 liters, and alkali 150 grams. In general, the results obtained from data points of the compared parameters showed consistent results with minimal variation in the data. The results obtained are of practical value related to the reduction of the cost of production of structural concrete with an increase in its strength indicators.

Effect of temperature rise caused by fire on the physical and mechanical properties of concrete

In the past few years, several concrete constructions have suffered major fires, causing very significant damage to the structure. The fire resistance of concrete depends on some of its characteristics such as the nature of the components used for its formulation, permeability, water content and mechanical resistance. In the places most exposed to fire, all the coating can be expelled, which seriously threatens the bearing capacity of the construction. In addition, the financial loss due to repair over a long period can reach several million Euros. This paper presents the physical and chemical transformations caused by the increase in the temperature of concrete in the event of a fire. These transformations mainly have an effect on the microstructure, the mechanical properties and the thermal deformation of concrete. The two phenomena of flaking and spalling of concrete were also studied in order to know their origins and found the methods of preventive. Indeed, flaking can manifest itself explosively, and have significant consequences on the resistance of concrete. It thus reduces the cross-section of the structure and also decreases its bearing capacity, which leads to an increase in the risk of structural failure. The factors influencing the flaking phenomenon were also presented.

Influence of Utilization of Natural Waste Fibers Pyrolysis on Mechanical Properties and Microstructure of Concrete

ABSTRACT The main purpose of this paper is to investigate the impact of the thermal processing of natural fibers on the strength of what is considered fiber-reinforced concrete. Natural fibers extracted from palm trees and bamboo residues were collected and pyrolyzed. The investigation of the morphological alterations that occur during the pyrolysis of natural fibers at a temperature of 200°C showed the impact of the cementitious environment on this process. In addition, the mechanical characteristics of fiber-reinforced concrete were conducted on different dosages (1, 1.5, 2, and 5% wt.) of treated and untreated palm oil, date kernel, and bamboo fibers. The results demonstrated that the inclusion of fibers up to 1.5% wt. enhanced the concrete mixes mechanical properties, which included pyrolyzed fibers. Analyzes of the concrete microstructure revealed that the treated fibers were not damaged. The 1.5% wt. addition of fibers after pyrolysis process can effectively improve their adhesion to the matrix and reduce the width and number of cracks. The analysis of variance results for flexural strength indicated that all sources had no significant impact on the flexural strength of untreated or pyrolysis treated natural fiber reinforced concrete.

Test of Mechanical Properties of Composite Recycled Concrete After Medium and High Temperature

Compressive strength is one of the important indexes to test the mechanical properties of concrete. The compressive strength of recycled composite concrete after high temperature is studied by single factor experimental analysis and double factor experimental analysis. Combined with variance analysis, the influence of replacement rate of recycled aggregate, volume incorporation amount of polypropylene fiber and volume incorporation amount of nani CaCO3 on compressive strength of recycled concrete after high temperature was systematically studied. The results show that when the replacement rate of recycled aggregate is 50%, the volume incorporation amount of polypropylene fiber is 0.08%, and nani CaCO3 is 1.2%, the compressive strength of composite recycled concrete reaches the maximum value. Nano CaCO3 is the most significant factor affecting the compressive strength of recycled concrete after high temperature. The significant influencing factors are the incorporation amount of polypropylene fiber and the replacement rate of recycled aggregate.

Modeling nonlinear stress-strain model for sulfate dry-wet cycle erosion of concrete: considerations for the initial compaction stage

Sulfate dry-wet cycle erosion significantly affects the mechanical properties of concrete. Investigating the uniaxial compressive stress-strain relationship under these conditions is essential for developing accurate constitutive models. This study analyzes the uniaxial stress-strain curves of concrete subjected to dry-wet cycles in 5% and 15% sulfate solutions. The results show that the initial compaction phase in the stress-strain relationship is particularly pronounced under increasing sulfate concentrations and cycle counts. The concrete experiences an extended compaction phase, which accounts for up to 35.71% of the total strain process. This finding challenge traditional constitutive models, which struggle to accurately describe this phase. To address this issue, the study develops a nonlinear stress-strain model for concrete, incorporating the initial damage caused by sulfate dry-wet cycle erosion, based on Weibull statistical damage mechanics principles. The research indicates that the effects of sulfate concentration and cycle count are predominantly reflected in the pronounced nonlinearity of the skeleton strain function’s opening size (a) and shape characteristics (b), modeled using a fourth-degree polynomial. The model demonstrates an excellent fit to experimental data with an R2 value of 0.99989, showing that the proposed nonlinear stress-strain relationship effectively captures the uniaxial mechanical behavior of concrete under sulfate dry-wet cycle erosion and provides a robust framework for developing constitutive models in such environments.

Machine learning prediction method for the interface bond strength between fiber reinforced polymer bars and concrete based on multi-feature driven analysis

In severe service conditions, corrosion of reinforcement poses a significant challenge for concrete structures. Fiber reinforced polymer (FRP) materials, characterized by their low weight, high strength, and superior corrosion resistance, are effective in enhancing the durability of these structures. The interfacial bond performance between FRP bars and concrete is crucial for their synergistic action and is pivotal for the design and safety evaluation of FRP-reinforced concrete structures. This paper conducts a comprehensive analysis of factors including the material and mechanical properties of FRP bars, concrete mechanical properties, and bond length. Utilizing an exhaustive search strategy, it identifies the optimal characteristic parameters for assessing the bond strength between FRP bars and concrete. Subsequently, these parameters are integrated with four machine learning (ML) algorithms—DT, SVM, RF and XGB—to train the nonlinear mapping relationship between influencing factors and bond strength, proposing a unified and interpretable prediction method for the FRP bar-concrete interface bond strength. The model's predictive accuracy is then validated using a test dataset, and a comparative analysis is performed among the predictive models generated by the four ML algorithms, as well as against empirical calculation formulas. The findings indicate that the ML models offer superior predictive performance and accuracy over empirical formulas, with the XGB algorithm demonstrating the highest overall accuracy and best performance. Moreover, to address the black-box nature of ML algorithms, the SHAP method is employed to enhance the interpretability of the bond strength prediction process. The newly developed hybrid ML model holds promise as a novel approach for accurately assessing the bond strength at the FRP bar-concrete interface.

Behavior of recycled aggregates treated with cement paste with respect to capillary absorption and flexion

Recycling waste from destroyed structure as a new resource of aggregates has several technical, economic and environmental advantages although it should be noted that these aggregates have disadvantages which can reduce the mechanical concrete properties, one of the most important is the water absorption problem. The waste valorisation industry stands as an alternative solution, effectively managing waste while also preserving natural resources. In this context, the present study consists to recover waste resulting from demolition of old Sonalgaz (Electrical poles) columns built in 1947 in the wilaya of Mostaganem. The obtained aggregates are enveloped by the old cement paste, which is known for its porous nature, resulting in a significant water absorption capacity. For that purpose, it was advisable to determine the required absorbed water quantity to saturate a specific recycled aggregates (RA) volume. In this work, we have opted for the method of cement paste treatment of the aggregates 3/8 mm and 8/16 mm. This method involves covering them by a film of cement paste and letting them dry for 28 days. Additionally, this study includes an analysis of the physical properties of natural and recycled aggregates, both before and after treatment, along with their impact on the mechanical properties of concrete mixes containing fully pre-saturated aggregates (100% RA) and a blend of half recycled and half natural aggregates (50% RA + 50% NA). These results are compared to reference concrete made solely with 100% natural aggregates (NA).

Investigating the effect of polypropylene fibres and curing parameters on the workability and mechanical properties of concrete

Polypropylene fibers possess certain characteristics that make them an ideal counterpart to attain explicit advantages when used for building works, more specifically, when added to concrete. In this investigation, polypropylene fibers were added by weight of cement (0.25%, 0.5%, and 0.75%) in M20 grade of concrete and their impact on workability, compressive strength, and flexural strength were assessed and analyzed. The slump test revealed that as the polypropylene fiber loading in the concrete mix was increased, the workability of the mixture continued to decrease; the workability decreased by 11.11%, 19.44%, and 45.83% upon the addition of 0.25 %, 0.5%, and 0.75% fibers respectively in the concrete. The compressive strength, as well as the flexural strength of the concrete, increased monotonously with an increase in the curing time and fiber loading. For instance, in the case of acidic water curing, the compressive strength enhanced from 19.08 MPa to 22.85 MPa upon increasing the fiber content from 0.25% to 0.75%. Adding 0.25% polypropylene fiber resulted in an increase in the flexural strength of conventional concrete mix by 15.78% and 10.29% when cured in normal water for 28 days and 56 days, respectively. Both the compressive and flexural strength of the samples cured in normal water was found to be higher than the samples cured in acidic water and it was observed that the fibre-reinforced concretes were more resistant to acids than the normal unreinforced concrete.

Aggregate blending optimisation in quarries to improve of the mechanical and environmental properties of concrete

ABSTRACT In this study, concrete mix optimisation was carried out with materials provided by Catalca (Ca) and Cendere (Ce) quarries in the region of Istanbul, Turkey which produce concrete aggregate from different rock formations. Accordingly, the properties of six different concrete aggregates produced from these quarries (3 regions in Catalca quarry and 3 regions in Cendere quarry) and the amounts of CO2-e released into the atmosphere by producing these aggregates were determined. Then, these aggregates were used in different proportions in concrete mixtures and the effects of aggregate types on the mechanical properties of concrete were statistically demonstrated by the experimental design method. According to the results, the mechanical properties of concrete were statistically significantly affected by the use of aggregate in different formations. In addition, empirical approaches that can be used in estimating the compressive strength, tensile strength and elasticity modulus of concrete have been found and using these approaches, mixtures that maximise these mechanical properties of concrete have been determined. Accordingly, mechanical properties of concrete were maximised in mixtures where Ca 1st Region 25% - Ca 2nd Region 75%, Ca 1st Region 60% - Ca 3rd Region 40%, Ca 2nd Region 13% - Ca 3rd Region 87%, Ce 1st Region 10% - Ce 3rd Region 90%, Ce 1st Region 63% - Ca 2nd Region 37%, and Ca 1st Region 35% - Ca 2nd Region 5% - Ca 3rd Region 60% were used. The CO2-e values of these mixtures were calculated as 8.405, 8.248, 8.529, 8.630, 8.476, and 8.365 kg/t respectively.

A Mesoscale Comparative Analysis of the Elastic Modulus in Rock-Filled Concrete for Structural Applications

Rock-filled concrete (RFC) is an advanced construction material that integrates high-performance self-compacting concrete (HSCC) with large rocks exceeding 300 mm, providing advantages such as reduced hydration heat and increased construction processes. The elastic modulus of RFC is a critical parameter that directly influences its structural performance, making it vital for modern construction applications that require strength and stiffness. However, there is a scientific gap in understanding the effects of rock size, shape, arrangement, and volumetric ratio on this parameter. This study investigates these factors using mesoscale finite element models (FEMs) with spherical and polyhedral rocks. The results reveal that polyhedral rocks increase the elastic modulus compared to spherical rocks, enhancing RFC’s load-bearing capacity. Additionally, a 5% increase in the elastic modulus was observed when the rockfill ratio was increased from 50% to 60%, demonstrating a direct correlation between rock volume and mechanical performance. Furthermore, the elastic modulus rises significantly in the early stages of placement, followed by a gradual increase over time. Optimal rock sizes and a balanced mix of rock shapes allow for improved concrete flow and mechanical properties, making RFC a highly efficient material for construction. These findings offer valuable insights for designers and engineers looking to optimize RFC for structural applications.

Investigation of polyurea coating influence on dynamic mechanical properties of concrete

To investigate the influence of polyurea coating on the dynamic mechanical properties of concrete, this study explores the energy absorption characteristics, stress-time curves, and failure modes of polyurea-coated concrete composite specimens under dynamic loading. The variations in the dynamic mechanical properties of polyurea-coated concrete composite specimens under complex conditions, such as different polyurea coating thicknesses and locations, as well as different strengths of coated concrete, are analyzed. The results indicate that, under the same impact velocity, with the increase of polyurea coating thickness, the energy dissipation coefficient and the percentage increase in energy dissipation first gradually increase to a certain value and then decrease. Polyurea coating significantly increases the deformation capacity of concrete specimens and effectively delays the time of concrete failure. The cracks and fragments of concrete on both sides, the impact side and the back impact side, gradually decrease with the increase of polyurea coating thickness, and the impact side coated with polyurea is superior to the back impact side, but this trend becomes less significant when the coating thickness reaches around 5 mm. With the increase of concrete strength, the percentage increase in peak stress time for both the back impact side and the impact side of polyurea-coated concrete gradually decreases. Under the same impact velocity, the energy dissipation effect of polyurea-coated concrete composite specimens is superior to that of concrete specimens.The polyurea coating enhances the toughness of concrete and improves its brittleness.