Concrete Test Research Articles

The case for a circular Blue Card for young non-EU professionals

Due to the challenging demographics in Europe, a new approach to labour migration to the EU is necessary. Such an approach should be more targeted and thus entail a more proactive and integrated stance. Whilst some moves in this direction have been made in recent years, more are required. This article charts one possible route to a more proactive and integrated policy by proposing the creation of European university campuses outside of Europe to act as hubs of academic, cultural, linguistic and labour exchange, similar to the American system. This approach would not only address the current labour force challenges but would also hold the potential to significantly enhance academic and cultural exchange. Many of the required elements are already in place: numerous bilateral universities, for example, already exist, such as the German Jordanian University, as do various European research and cultural institutes. Such campuses, combined with a new circular Blue Card for young non-EU professionals, would have benefits for both the member states and the selected partner countries. The article concludes by proposing the implementation of concrete test cases in the European neighbourhood.

Evaluation of non-destructive testing and long-term durability of geopolymer aggregate concrete

Recent advancements in concrete technology focus more on increasing strength than durability. Concrete with good durability will withstand adverse conditions like frost, chloride penetration, sulfate assault, alkali-aggregate reaction, steel corrosion, etc., which will lower the strength of the concrete. Strength is vital, but so is durability. The present study examined and discussed the durability parameters of conventional concrete made with geopolymer aggregate (GPA) as a partial substitute for natural aggregate. Strength studies in this research found that the optimal level of substitution for natural coarse aggregate by GPA was 100% replacement to produce the performing concrete. Replacement of natural coarse aggregate by geopolymer aggregate exhibits 9%–15% higher compressive strength than natural aggregate concrete. The findings reveal that concrete with 100% geopolymer aggregate exhibits a compressive strength increase of 9%–15% over that of concrete made with natural aggregates. Ultrasonic pulse velocity measurements for geopolymer aggregate concrete range between 4 km/s and 4.5 km/s, indicating good quality according to IS specifications. Additionally, Rebound Hammer test results further support the enhanced quality of geopolymer aggregate concrete. However, the porosity of geopolymer aggregates results in a sorptivity that is 10%–30% higher than that of natural aggregate concrete. Despite this, the increased resistance to acid and sulfate attacks is noted, attributed to the strong bonding between geopolymer aggregates and the cement matrix.

Abrasion resistance of cement concretes on heavy aggregates

The paper presents the results of research on the influence of three different types of heavy aggregate (basalt, barite and magnetite) and natural gravel on the abrasion resistance of concrete. Concrete mixtures are designed to obtain maximum resistance to concrete abrasion. Concrete abrasion test was performed using a Böhme disc. The influence of compressive strength and physical and mechanical properties of the used aggregates on the abrasion resistance of the tested concretes was analyzed

Effects of C-S-H Seed Prepared by Wet Grinding on the Properties of Cement Containing Large Amounts of Silica Fume

This study aimed to utilize the hydration characteristics of cement through wet grinding techniques to efficiently and conveniently prepare a stable C-S-H seed suspension, providing key parameters and a scientific basis for their large-scale production, which ensures the stability of the C-S-H suspension during production, transportation, and application. This preparation aimed to mitigate the adverse effects of high-volume silica fume on the early mechanical properties of high-performance cement concrete. The properties of C-S-H seed were characterized in detail by SEM, XRD, and TD. In the concrete performance test, silica fume was used to replace part of the cement, and different contents of C-S-H seed were added to test its effect on the compressive strength of concrete, with XRD and SEM used to analyze the performance differences. The results show that the particle size and hydration degree of cement no longer developed after 90 min of wet grinding. Polycarboxylate ether (PCE) superplasticizer can increase the fluidity of the crystal C-S-H seed suspension when the content exceeds 1.5%. When the content of PCE exceeded 2%, the C-S-H seed suspension precipitated. Adding 5% C-S-H seed can increase the compressive strength of cement concrete by 10% under the condition of reducing the amount of cement and increasing the amount of silica fume. And Ca(OH)2 (CH) was produced by cement hydration consumed by silica fumes to generate C-S-H gel, by which the concrete became denser with more strength. However, when the amount of C-S-H seed exceeded 7%, the compressive strength of the concrete decreased.

Study of the effect of elevated temperatures on selected properties of concrete with the addition of ceramic cullet in terms of its durability

The article presents the results of tests of concretes based on natural aggregate and recycled ceramic aggregate (ceramic sanitary aggregate). Two types of recycled aggregates were used: FFC – ceramic aggregate without fireclay and VC – ceramic aggregate with fireclay). The recipe composition for the reference mixture was designed experimentally, assuming a w/c = 0,5 and plastic consistency. In the next stage of the research, 30% and 60% of the natural aggregate was replaced with recycled ceramic aggregate and the obtained results were analyzed. Water absorption, compressive strength and compressive strength after calcining were tested (max. temperature 750C)

Experimental and numerical analysis of L-shaped concrete-filled steel tube stub columns

This paper reports experimental and numerical studies on the cross-sectional compression resistance and behaviour of a novel L-shaped concrete-filled steel tube system. The novel composite system is proposed to eliminate concave corners and enhance the confinement of the outer steel tube to the concrete infill. A testing programme was firstly conducted, including nine tensile steel coupon tests, six compressive concrete cube tests and ten stub column tests. Upon testing, all the ten L-shaped concrete-filled steel tube stub column specimens were found to fail by local buckling. Finite-element models were then developed in the finite-element analysis software ABAQUS and validated against test results. The validated models were then employed to perform parametric studies to obtain an additional set of 48 numerical data. Test and numerical results were used to perform a design analysis, in which the suitability of the design rules in the European code EN 1994–1-1, the American specification ANSI/AISC 360 and the Chinese code GB 50936 for the developed L-shaped concrete-filled steel tube stub column system was assessed. The analysis results reveal that both EN 1994–1-1 and GB 50936 yield unsafe compression resistance predictions for the studied L-shaped concrete-filled steel tube stub columns, owing to the improper consideration of the contributions of the outer steel tube and the concrete infill to the overall capacity, while ANSI/AISC 360 offers safe design with high accuracy. The research findings are expected to contribute to the safe and wide use of the proposed novel L-shaped concrete-filled steel tube system in structural engineering and also to the further development of the current international design standards.

Rapid Assessment of Sulfate Resistance in Mortar and Concrete.

Extensive research has been conducted on the sulfate attack of concrete structures; however, the need to adopt the use of more sustainable materials is driving a need for a quicker test method to assess sulfate resistance. This work presents accelerated methods that can reduce the time required for assessing the sulfate resistance of mixtures by 70%. Class F fly ash has historically been used in concrete mixtures to improve sulfate resistance. However, environmental considerations and the evolving energy industry have decreased its availability, requiring the identification of economically viable and environmentally friendly alternatives to fly ash. Another challenge in addressing sulfate attack durability issues in concrete is that the standard sulfate attack test (ASTM C1012) is time-consuming and designed for only standard mortars (not concrete mixtures). To expedite the testing process, accelerated testing methods for both mortar and concrete mixtures were adopted from previous work to further the development of the accelerated tests and to assess the feasibility of testing the sulfate resistance of mortar and concrete mixtures rapidly. This study also established criteria for interpreting sulfate resistance for each of the test methods used in this work. A total of 14 mortar mixtures and four concrete mixtures using two types of Portland cement (Type I and Type I/II) and various supplementary cementitious materials (SCMs) were evaluated in this study. The accelerated testing methods significantly reduced the evaluation time from 12 months to 21 days for mortar mixtures and from 6 months to 56 days for concrete mixtures. The proposed interpretation method for mortar accelerated test results showed acceptable consistency with the ACI 318-19 interpretations for ASTM C1012 results. The interpretation methods proposed for the two concrete sulfate attack tests demonstrated excellent consistency with the ASTM C1012 results from mortar mixtures with the same cementitious materials combinations. Metakaolin was shown to improve sulfate resistance for both mortar and concrete mixtures, while silica fume and natural pozzolan had a limited impact. Using 15% metakaolin in mortar or concrete mixtures with Type I/II cement provided the best sulfate resistance.

Study of Acoustic Emission Signal Noise Attenuation Based on Unsupervised Skip Neural Network.

Acoustic emission (AE) technology, as a non-destructive testing methodology, is extensively utilized to monitor various materials' structural integrity. However, AE signals captured during experimental processes are often tainted with assorted noise factors that degrade the signal clarity and integrity, complicating precise analytical evaluations of the experimental outcomes. In response to these challenges, this paper introduces an unsupervised deep learning-based denoising model tailored for AE signals. It juxtaposes its efficacy against established methods, such as wavelet packet denoising, Hilbert transform denoising, and complete ensemble empirical mode decomposition with adaptive noise denoising. The results demonstrate that the unsupervised skip autoencoder model exhibits substantial potential in noise reduction, marking a significant advancement in AE signal processing. Subsequently, the paper focuses on applying this advanced denoising technique to AE signals collected during the tensile testing of steel fiber-reinforced concrete (SFRC), the tensile testing of steel, and flexural experiments of reinforced concrete beam, and it meticulously discusses the variations in the waveform and the spectrogram of the original signal and the signal after noise reduction. The results show that the model can also remove the noise of AE signals.

Damage evolution behavior of tunnel lining concrete with non‐through crack under single‐sided sulfate attack

AbstractIn order to study the dynamic damage evolution law of tunnel‐lining concrete with non‐through crack under single‐side sulfate attack, a 420‐day sulfate attack concrete test was conducted and the uniaxial compression and acoustic emission (AE) tests were carried out on each corrosion time. The test results showed that the compressive strength of each group can be divided into rising stage and falling stage, and the existence of non‐through crack reduced the compressive strength of concrete specimens and accelerated the corrosion of concrete specimens by sulfate. AE ringing count can be divided into compaction stage, elastic stage, yield stage, and post‐peak stage; the variation patterns of AE varied at different stages. Sulfate attack caused the yield point of concrete to advance. With the increase of corrosion time, microcracks increased gradually, cement mortar was consumed continuously, concrete spalling occurred, the proportion of AE cumulative ringing count Stage II decreased gradually, and the proportion of Stage III increased. Non‐through crack changed the energy storage of Stages II and III and reduced the AE activity of concrete after corrosion. The deeper the crack was, the smaller the average cumulative ringing count was and the lower the AE activity was. AE cumulative ringing counts can be used to characterize the damage evolution of corroded concrete.

Study of freeze-thaw deterioration of saturated and unsaturated hydraulic concrete based on measured strain

In actual concrete water projects, areas such as the back surface, above-water surface, and even areas where the water level fluctuates are in the unsaturated freeze-thaw state. The complexity of freeze-thaw tests of unsaturated hydraulic concrete has thus far prevented a sound understanding of the mechanisms at work in freeze-thaw deterioration of unsaturated hydraulic concrete. Given this situation, this study first compares three different unsaturated hydraulic concrete freeze-thaw test processes (polyurea seal, paraffin seal, and vacuum-bag seal) and then uses the vacuum-bag seal method to implement freeze-thaw tests of unsaturated hydraulic concrete. Afterward, three test schemes (unsaturated sealed freeze-thaw, water-freeze-thaw without air-entraining agent, and water-freeze-thaw with air-entraining agents) are conducted and the mechanisms of freeze-thaw deterioration of saturated and unsaturated hydraulic concrete are evaluated based on the measured temperature and strain of the concrete specimens. The results reveal a continuous and irreversible deterioration leading to the freeze-thaw damage of unsaturated sealed freeze-thaw specimens and water-freeze-thaw specimens with and without an air-entraining agent. After 200 freeze-thaw cycles, the cumulative residual strain of the aforementioned three test schemes reach 47 με, 616 με, and 273 με, respectively. The thermal expansion coefficient of concrete remains relatively constant with increasing freeze-thaw cycles. Water-freeze-thaw specimens without air-entraining agents have a greater thermal expansion coefficient than those with air-entraining agents, and unsaturated sealed freeze-thaw specimens have the smallest thermal expansion coefficient. The frost heave coefficient increases with increasing freeze-thaw cycles, and water-freeze-thaw specimens without air-entraining agents have greater frost heave coefficients than those with air-entraining agents.

Peningkatan Kompetensi dan Pembuatan Teknologi Terbaru Beton Porous di Jurusan Teknik Konstruksi dan Perumahan SMKN 1 Balikpapan

The city of Balikpapan has many flood points every year,.Flood events are a priority issue for the Balikpapan City Government, in 2017 there was an increase in flood events by 89 incidents. To solve this problem is to apply the construction with the latest environmentally friendly technology, namely porous concrete so that surface water can seep into the ground and can become a groundwater reserve. Porous concrete is the latest type of concrete technology with high porosity which is applied as a concrete plate which allows rainwater and water from other sources to pass through. Limited facilities and infrastructure, lack of teaching staff relevant to the Construction and Housing Study Program at SMKN 1 Balikpapan School so that they cannot carry out concrete manufacturing and testing because this is a basic competency that every student must have. The activity began by formulating a program that was relevant to the knowledge and research of the PkM team of the Civil Engineering Department of the Balikpapan State Polytechnic and the problems that exist around Balikpanan City. SMKN 1 Balikpapan to carry out follow-up activities or programs to be implemented, activity planning, activity schedules and activity output. The activities were carried out for 2 days which included socialization and practice of making porous concret.

A path-dependent stress-strain model of FRP-confined circular concrete columns derived from an energy balance approach

It is generally believed that the use of fibre-reinforced polymer (FRP) confinement can effectively improve the strength and ductility of concrete. Passive confinement is one of the key features of the behavior of FRP-confined concrete. Analysis-oriented models for passively confined concrete have been established on the base of the active confinement model by many researchers. Among them, a stress path-independent assumption was made for those passively confined concrete. However, in recent years, numerous researchers have found that the influence of stress path on the stress-strain relationship of confined concrete cannot be neglected. Therefore, in order to further understand and simulate the uniaxial behavior of FRP-confined concrete, this paper presents a stress path-dependent model of FRP-confined concrete based on an energy balance approach in which the extra work done by the active confining pressure in the stress path-independent model is considered. Firstly, experimental data comprising 341 sets of FRP jacket confined concrete tests and 28 sets of concrete-filled FRP tube (CFFT) tests were collected. Subsequently, the stress paths of the two types of specimens were identified based on the properties of FRP materials, and then the energy balance assumption was introduced, and finally a new stress path-dependent model was established using the energy balance approach. By comparing the predictions of the proposed model with collected experimental data and those of several existing models, it was observed that the proposed model can more accurately predict the ultimate stress of FRP-confined concrete and exhibit good agreement with the experimental stress-strain curves.

Pengaruh Air Laut terhadap Kuat Tekan, Permeabilitas, dan Mikrostruktur Beton Geopolimer dengan Flyash dan Tanah Putih sebagai Pengganti Semen

The increasing infrastructure development of an area is sometimes located in an aggressive environment, one of which is in coastal areas so that direct contact with sea air cannot be avoided. This research aims to determine the effect of sea water on geopolymer concrete using fly ash and white soil as cement substitutes with testing parameters for compressive strength, permeability and microstructure. The test objects used were cylindrical in shape measuring 150x300 mm and 100x200 mm. The ratio of fly ash and white soil used was 85%:15% and the activator used was NaOH 8M and Na2SiO3 with a ratio of 1:2,5. The mixture proportion using a ratio of 1 fly ash: 1,497 sand: 2 split: 0,451 alkali activator with a mutual plan is 35 MPa. Tests were carried out after the concrete had gone through a curing process for 56 days, then the concrete was conditioned without soaking and with soaking for 28 days. Tests were carried out at concrete ages of 56 and 87 days. The test results show that geopolymer concrete with the influence of sea water has a higher compressive strength value and a smaller permeability coefficient compared to concrete without the influence of sea water. Microstructural testing of geopolymer concrete under the influence of sea air produces a matrix-shaped structure morphology that is denser with fewer pores compared to concrete without the influence of sea air.

Performance evaluation of indented macro synthetic polypropylene fibers in high strength self-compacting concrete (SCC)

Concrete is used worldwide as a construction material in many projects. It exhibits a brittle nature, and fibers' addition to it improves its mechanical properties. Polypropylene (PP) fibers stand out as widely employed fibers in concrete. However, conventional micro-PP fibers pose challenges due to their smooth texture, affecting bonding within concrete and their propensity to clump during mixing due to their thin and soft nature. Addressing these concerns, a novel type of PP fiber is proposed by gluing thin fibers jointly and incorporating surface indentations to enhance mechanical anchorage. This study investigates the incorporation of macro-PP fibers into high-strength concrete, examining its fresh and mechanical properties. Three different concrete strengths 40 MPa, 45 MPa, and 50 MPa, were studied with fiber content of 0–1.5% v/f. ASTM specifications were utilized to test the fresh and mechanical properties, while the RILEM specifications were adopted to test the bond of bar reinforcements in concrete. Test results indicate a decrease in workability, increased air content, and no substantial shift in fresh concrete density. Hardened concrete tests, adding macro-PP fibers, show a significant increase in splitting tensile strength, bond strength, and flexural strength with a maximum increase of 34.5%, 35%, and 100%, respectively. Concrete exhibits strain-hardening behavior with 1% and 1.5% fiber content, and the flexural toughness increases remarkably from 2.2 to 47.1. Thus, macro PP fibers can effectively improve concrete's mechanical properties and resistance against crack initiation and spread.

Effect of GGBFS on the mechanical properties of metakaolin-based self-compacting geopolymer concrete

The focus of this study is the production and testing of a new self-compacting geopolymer concrete（SCGC）. The concrete has excellent self-compacting properties, mechanical properties and environmental advantages, showing great potential for engineering applications. Due to the high specific surface area of metakaolin (MK), it is challenging to produce a self-compacting geopolymer concrete using metakaolin as the main material. A self-compacting geopolymer concrete with excellent properties was produced by partially replacing metakaolin with ground granulated blast furnace slag (GGBFS). This innovation enriches the diversity of powder material choices for self-compacting geopolymer concrete. The experimental results showed that the addition of ground granulated blast furnace slag significantly enhanced the filling capacity and interstitial passage capacity and wet packing density of ground granulated self-compacting concrete. The best working performance of the concrete was achieved at 40 % GGBFS replacement. The test data were slump extension of 749 mm, T50 time of 3.23 s, V-funnel test time of 8.2 s, L-box test result of 0.96, and wet packing density of 1.946 g/cm3. With the increase in the replacement rate of the ground granulated blast furnace slag, the compressive strength of self-compacting ground polymer concrete and the split tensile strength showed a trend of increasing and then decreasing. The maximum compressive strength of 55.2 MPa and splitting tensile strength of 4.11 MPa were obtained when the substitution rate of ground granulated blast furnace slag was 20 %. The drying shrinkage of self-compacted geopolymer concrete was significantly increased by the addition of excess ground granulated blast furnace slag. The drying shrinkage was increased by 147 % at 40 % substitution rate compared to 0 % substitution rate. Scanning electron microscope (SEM) tests and thermogravimetric analysis were performed on all samples. At ground granulated blast furnace slag substitution rate of 20 %, a uniform and dense gel structure was formed inside. At 40 % ground granulated blast furnace slag substitution rate, the weight loss of the specimens reached 13.4 %, which was 4.22 % more than the control group with 0 % substitution rate. The results showed that GGBFS effectively promoted the generation of internal cementitious structures in SCGC. This study provides the necessary information for the development of metakaolin-based self-compacting geopolymer concrete and contributes to the popularization of metakaolin-based self-compacting geopolymer concrete. It will also broaden the scope of use of metakaolin in self-compacting geopolymer concrete, which will contribute to the diversification of building materials and the development of the construction industry towards a low-carbon and sustainable future.

Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete

The chemical reaction between CO2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation results are often reported. The RILEM TC 281-CCC ‘Carbonation of Concrete with Supplementary Cementitious Materials’ has conducted a critical analysis of the standardised testing methodologies that are currently applied to determine carbonation resistance of concrete in different regions. There are at least 17 different standards or recommendations being actively used for this purpose, with significant differences in sample curing, pre-conditioning, carbonation exposure conditions, and methods used for determination of carbonation depth after exposure. These differences strongly influence the carbonation depths recorded and the carbonation coefficient values calculated. Considering the importance of accurately determining carbonation potential of concrete, not just for predicting their durability performance, but also for determining the amount of CO2 that concrete can re-absorb during or after its service life, it is imperative to recognise the applicability and limitations of the results obtained from different tests. This will enable researchers and practitioners to adopt the most appropriate testing methodologies to evaluate carbonation resistance, depending on the purpose of the conclusions derived from such testing (e. g. materials selection, service life prediction, CO2 capture potential).

Effects of Volcanic Tuff Use on the Rheological and Mechanical Properties of Self-Compacting Concrete

The rise in demand of concrete products has led to overexploitation of river sand the main fine aggregate in concrete resulting in major environmental degradation. As a result, researchers have focused their efforts on developing eco-friendly concrete using alternative renewable materials like volcanic tuff and other natural pozzolana types. This study therefore, aims at investigating the use of Kenyan, Kitengela volcanic tuff as a partial replacement of river sand in self-compacting concrete, and determining the effects it will have on the rheological and mechanical properties of the self-compacting concrete. The study involved partially replacing river sand with volcanic tuff in percentages of 0%, 2.5%, 5%, 7.5% and 10% and carrying out rheological tests (V-funnel test, L-box test, T-500 test and J-ring test) on fresh concrete and mechanical tests (compressive strength and tensile strength tests) on hardened self-compacting concrete on days 7, 14, and 28 to determine the effects of volcanic tuff on properties of both fresh and hardened self-compacting concrete. There was a general decrease in rheological properties (flow and passing abilities) of self-compacting concrete with increase in volcanic tuff percentage replacement from 0 % to 10%, with least flow and passing abilities recorded at 10% replacement. Similarly, increase in volcanic tuff percentage replacement led to decrease in both compressive and tensile strength of self-compacting concrete with lowest values recorded at 10% volcanic tuff replacement.

Using digital image correlation to evaluate fracture toughness and crack propagation in the mode I testing of concretes involving fly ash and synthetic nano-SiO2

Using digital image correlation to evaluate fracture toughness and crack propagation in the mode I testing of concretes involving fly ash and synthetic nano-SiO2

Quality Control Analysis in Construction Works of 80/100 U-Ditch Channel with 15 Ton Axle Cover (Jl. Manyar Indah)

This research records experiences and findings during the Work Practice Internship (MPK) on the 80/100 U-Ditch channel construction project with 15 Ton Axle Cover on JL. Manyar Indah, Surabaya. This MPK is part of the Bachelor of Building Engineering Education curriculum at Surabaya State University and aims to provide students with insight and practical experience that cannot be obtained in the classroom. This project, which will run from April to June 2024, provides an opportunity for students to understand the difference between academic theory and practice in the field, as well as getting to know construction implementation methods directly. The main focus of this project is quality control in construction, especially in the use of precast methods for drainage channels. Effective quality control is essential to ensure that construction meets established standards, prevent wasted costs, and guarantee the quality of the final result. In this project, quality control is carried out through several methods, including Quality Control (QC) for wiremesh, Fc'30 Ready Mix concrete, and core concrete compressive strength tests (core drill test). Each stage of quality control aims to ensure that materials and construction implementation comply with established specifications. The quality of the wire mesh used is checked through measurements and structural verification to ensure durability and sturdiness. Fc'30 Ready Mix concrete is tested through a slump test and laboratory compression test to ensure its strength. Core drill testing was carried out on the completed U-Ditch structure to evaluate the strength of the installed concrete. The findings from MPK show that strict quality control and the application of precast technology can improve construction efficiency and quality. The practical experience students gain in the field not only enriches their knowledge but also strengthens the technical and professional skills required in the construction industry. In addition, this MPK helps students build relationships with professionals in the industry, expand their network, and prepare them for careers in the building engineering field. It is hoped that this experience can improve students' competence as prospective professionals in the field of building engineering. This research also highlights the importance of collaboration between universities and industry. This collaboration not only provides benefits for students in the form of practical experience but also provides opportunities for universities to strengthen relationships with industry and expand partnership networks. Thus, this MPK not only contributes to improving the quality of building engineering education but also to the development of better construction industry practices. It is hoped that this research can make a positive contribution to the development of the building engineering education curriculum and encourage increased collaboration between universities and the construction industry. Through effective quality control and the use of precast methods, this project can be used as an example in creating efficient and high-quality construction, in line with the needs and expectations of stakeholders.

Experimental and Numerical Analysis of Flexural Properties and Mesoscopic Failure Mechanism of Single-Shell Lining Concrete

Despite ongoing research efforts aimed at understanding the structural response of steel fiber reinforced concrete (SFRC), there is very limited research on the failure characteristics and mesoscopic damage mechanism of SFRC, specifically when under flexure. In this study, a four-point bending test of plain concrete (PC) and SFRC with different fiber contents is carried out to investigate the flexural performance of SFRC. The crack propagation process, cracking load, ultimate load, and load-deflection curves of PC and SFRC beams are obtained. Additionally, the discrete element method (DEM), using PFC2D 6.0 software, is adopted to explore the mesoscopic properties of PC and SFRC. The test and simulation results of PC and SFRC beams are compared and analyzed, and some conclusions are drawn. The results show that steel fiber can efficiently improve the compressive strength of concrete when the fiber content is 30 kg/m3, and significantly improve the deformation resistance, crack resistance, and flexural capacity of concrete. The refined numerical models of PC and SFRC beams are established based on compressive strength and aggregate screening results. Through the numerical four-point bending test, the mesoscopic mechanical behaviors of models reveal the damage mechanism of SFRC. The horizontally distributed steel fibers bridge both sides of the cracks to resist crack development, and the vertically distributed steel fibers guide the cracks to the place with strong contact, thus resisting crack height development. The test results show that, for flexural properties, the optimal steel fiber content of SFRC is 31 kg/m3.