Microcrack Initiation Research Articles

Effect of hydride orientation on tensile properties and crack formation in zirconium alloy cladding tubes

Hydride precipitation and reorientation are of great importance to evaluate considering their detrimental influence on mechanical properties of nuclear fuel claddings. In this work, a fully recrystallized Zr-Sn-Nb cladding tube was hydrided with 120 and 220 wppm concentration, followed by thermo-mechanical treatment to produce specimens with varying hydrogen contents and hydride orientations. Ring tensile test demonstrates that in contrast to circumferential ones, the radial hydrides lead to significant reductions in plastic elongation of cladding tubes. Scatter in values of mechanical properties are observed in the case of 220 wppm radial hydrides, which could be attributed to irregular distribution of interconnected radial hydrides. Microstructure characterization reveals that microvoids initiate at the junction boundaries of hydride platelets under the tension effect of surrounding α-matrix deformation. These microvoids are proposed to propagate along the interior of brittle hydrides, rather than the interface, eventually leading to premature fracture failure given the alignment of radial hydrides perpendicular to the external tensile stress. The presented results are expected to shed light on microcrack initiation and propagation with respect to hydride orientation in zirconium-based nuclear fuel claddings.

Experimental investigation of the intensity and conditions for strainburst triggering in intact hard rocks

Strainburst occurs during deep hard rock excavations. A series of single-free-face true triaxial compression (TTC) tests were conducted on seven hard rock types to investigate strainburst intensity and triggering conditions. Five of the seven rock types failed by strainburst, and two failed by spalling. The differences between the strainburst intensities are attributed to the mineral composition and structure. High-hardness minerals and mosaic-type microstructures facilitate stress conduction, which promotes rock microcrack initiation and propagation, causing severe rock fragmentation and fragment ejection, as observed for the Jinzhou granite. However, if the proportions of high- and low-hardness rock minerals are high and the microstructure is stable, such as in the triangular microstructure of the Chifeng basalt, then microcrack initiation and propagation are inhibited, decreasing the likelihood of rock fragmentation. The triggering conditions for strainburst were further analysed by considering the source of kinetic energy. For intact rock specimens, the kinetic energy for rock fragment ejection mainly originates from the intrinsic potential energy (Wbk) released by the specimen itself; thus, strainburst triggering requires that the applied maximum principal stress exceeds the bearing capacity and that the rock Wbk exceeds zero. However, a high Wbk is needed to trigger strainburst for structural rock specimens. Based on these findings, the possibility of triggering strainburst during excavation is greater when the Wbk (>9.1 kJ/m3), rock quality designation (>75%), and in situ stress of the rock are all high.

Verification of Sustainable Asphalt Concrete through the Energy Dissipation

The kinetic energy created in the asphalt concrete due to practicing dynamic loading is absorbed and consumed to retain the properties of the asphalt mixture through its flexibility; however, part of the energy is dissipated in the initiation of microcracking and other types of distresses. In this work, the influence of additives (fly ash and silica fumes) on controlling the energy dissipation of asphalt concrete mixtures was assessed. Beam specimens of asphalt mixture were obtained from the roller compacted slab samples and tested for fatigue under three constant strain levels by implementation of the four points bending beam. It was noticed that for fly ash treated mixture, the consumed time for energy dissipation decline by (75, and 97.5) % while the dissipated energy declines by (84.8, and 99.5) % when the constant strain level increases from (250 to 400 and 750) micro strain respectively. However, for silica fumes treated mixture, the energy dissipation declines by (3.3, and 95) % when the constant strain level rises from (250 to 400, and 750) micro strain respectively. It was noticed that the damage resistance as indicated by the increment in dissipated energy increases by (60, and 140) % when fly ash and silica fumes were implicated respectively. However, the silica fumes additive consumes the energy at lower time of 60 seconds than the case of control mixture. The fly ash additive exhibits no significant variation in consuming the energy when compared with the control mixture.

Influence of prior austenite grain size on martensite-austenite islands morphology and decomposition characteristics during two-step tempering in Mn-Ni-Mo steel

Martensite-austenite (M/A) islands are typical in the quenched microstructure of Mn-Ni-Mo steel, frequently utilized for fabricating reactor pressure vessels (RPV). These islands can decompose into harmful long rod-shaped Fe3C carbides during tempering above 600°C, quantifying the negative effect of M/A island decomposition on mechanical properties and indicating a potential issue in RPV fabrication. To address this issue, the present study investigates a two-step tempering process on three different prior austenite grain size (PAGS) specimens (5 µm, 47 µm, and 119 µm). The effect of PAGS on M/A island decomposition characteristics during sub-600°C tempering and their impact on precipitated carbide morphology is investigated. A preliminary pre-tempering treatment at 200°C, 350°C, and 500°C for 2 hours was followed by a 3-hour final tempering step at 650°C. The findings revealed unique temperature-dependent decomposition characteristics of M/A islands. For example, at 200°C, partial M/A island decomposition took place, resulting in long rod-shaped carbides during final tempering. Meanwhile, the 350°C pre-tempering specimen revealed aggregated carbide precipitates of varying sizes in former M/A island locations. In contrast, the 500°C pre-tempering specimen showed coarse globular carbides and the absence of carbide precipitate clustering. This result can be attributed to the decrease in surface energy associated with the carbide-matrix interface as size increases. After tempering, all specimens produced three types of precipitates: rod-shaped Fe3C carbides, rhombus-shaped Mn7C3, and globular-shaped Mn23C6 carbides. The formation of long rod-shaped carbides during M/A island decomposition reduces the critical cleavage stress for micro-crack initiation, jeopardizing steel mechanical properties. Aggregated carbides cause the simultaneous formation of numerous micro-voids in close proximity, which eventually merge to form a large crack, resulting in material failure. When compared to other pre-tempered and directly tempered specimens, pre-tempering at 500°C produced the most favorable microstructure in terms of impact properties.

Modeling of spalling failure of in-situ rock mass for quantification of the source mechanics with flat-joint model and moment tensor

Spalling failure caused by excavation unloading in tunnels under high in situ stress is a common phenomenon. Here, we attempt to use a three-dimensional flat-joint model (FJM3D) combined with a moment tensor to simulate the process of spalling failure. FJM3D simulation showing the process of micro-crack initiation and propagation in the surrounding rock from a micro-perspective. The nature of the source mechanism is quantitatively assessed by moment tensor analysis. There are a large number of micro-cracks extending deep at the shoulder and foot of the tunnel. This model reproduces similar thin slabs and fracture orientations in Mine-by Experiment (MBE). The excavation disturbed zone (EDZ) characteristics around the MBE show that the tunnel crown and invert are dominated by tensile mechanisms, the tunnel sidewalls are dominated by implosive and shear mechanisms, and the tunnel shoulders are butterfly shaped with tensile and implosive sources. The nature of these sources are not purely tensile/shear cracks, but some isotropic/deviatoric components also play a role. The magnitude and orientation of the principal stress near the excavation face are linked to the advancement of the tunnel face and are related to the direction of micro-cracks initiation and propagation, which sheds new light on the failure mechanics of spalling failure.

Toughening epoxy by nano-structured block copolymer to mitigate matrix microcracking of carbon fibre composites at cryogenic temperatures

The incorporation of rigid nanoparticles has proven to enhance microcracking resistance in carbon fibre reinforced polymer (CFRP) composites at cryogenic temperatures, enabling CFRP tanks to store cryogenic liquid like hydrogen without requiring liners. Herein, we investigate efficacy of low-modulus soft nanoparticles in addressing the microcracking challenges inherent in CFRP at cryogenic temperatures. By incorporating a tri-block copolymer (BCP) into an epoxy, nano-structured fillers with an average diameter of approximately 100 nm are formed. Experimental results reveal that, at a 2.5 wt% loading, the BCP significantly increase the fracture energy of the nanocomposite by 392% at −196 °C while maintaining stiffness and strength. More importantly, composite laminates made with the BCP-modified nanocomposite matrix can withstand cryogenic temperatures without matrix microcracking, even when they contain multiple plies with the same orientation, such as [04/904]s, which are known to be highly susceptible to matrix microcracking at cryogenic temperatures. An advanced high-fidelity micromechanical model revealed that the observed toughening effect of nanostructured block copolymer at cryogenic temperatures can be attributed to the increased fracture resistance of the nanocomposite matrix. The findings of this research demonstrate that low concentration of block copolymer can effectively mitigate the initiation and propagation of matrix microcracks in carbon fibre composites at ultra-cold temperatures.

Experiment and Numerical Simulation on Thermal Cycling Performance of YSZ-Based Sealing Coatings with “Brick-Mud” Layered Structure

The failure of premature thermal cycling spalling off is the bottleneck problem currently faced by yttrium oxide partially stabilized zirconia (YSZ) ceramic-based sealing coatings. Studies on the thermal cycling performance of coatings with “brick-mud” structures were carried out by experimental and simulation methods in this paper. The results showed that, as the thickness of “mud” layer increased, the bonding strength of the “brick-mud” structure coatings gradually decreased. When the thickness of the “mud” layer was about 3 μm and 10 μm, the thermal cycling lives of the T1 and T2 coatings were improved by 90.0% and 135.7%, respectively, compared with conventional coating (T0 coating), while that of the T3 coating (containing thick “mud” layers of about 20 μm) was decreased by 81.4%. The stress field of M2 “mud” layers with different thicknesses was subjected to a comprehensive effect by thermal mismatch stress and pores in “brick” layer. Compared with the medium and thick “mud” layers, the thin “mud” layer sustained obvious larger σ22 max and σ12 max, indicating its potential for the preferential initiation of transverse microcracks. In addition, the thin “mud” layer withstood the largest σ11 max and had the strongest potential for longitudinal crack growth. Both transverse and longitudinal cracking could consume energy during thermal cycling and reduce the stress concentration at the top coating/bond coating interface. These were the main reasons for the improvements in the thermal cycling performances of the T1 and T2 coatings. The degree of crack deflection and the capacity of energy dissipation in the “mud” layer increased significantly with its thickness. However, the propagation length of transverse cracks also gradually increased in the meantime. Especially when the “mud” layer was 20 μm, the length of the transverse cracks increased rapidly. Thus, early interlayer delamination failure occurred in the T3 coating during thermal cycling.

Study on creep characteristics of granite of deep tunnel affected by joint orientation

Joints are an important part of rock masses and the spatial relationship between joint orientation and in situ stress (or tunnel axis) has a significant impact on the deformation, strength, and failure behavior of the surrounding rock. To study the influence of joint orientation on creep characteristics of deep hard rock, the true triaxial creep tests were performed in the laboratory on natural jointed granite under different loading angles ω (defined as the angle between the strike of the joint plane and σ2-direction) conditions. The test results show that ω has a significant effect on the time-dependent deformation and failure characteristics of the jointed rock. As ω increases, there is a decrease in creep deformation, steady creep rate in the σ3-direction, and value of the DI index (used to evaluate the difference in the time-dependent deformation in the σ2- and σ3-directions). Stress-structure-controlled failure (sliding along the joint plane) occurs when ω ≤ 30°. However, when ω > 30°, the failure of the jointed granite is not affected by joint and stress-controlled failure occurs. The stress-structure-controlled time-dependent failure evolution enters a stage that is dominated by shear cracks earlier than stress-controlled failure according to AE results. In addition, the time-dependent failure went through stages of microcracks initiation and interaction, stable crack growth and unstable crack propagation. And when the time-dependent failure evolution enters the unstable crack propagation stage, the nature of the cracks changed from tensile-dominated to shear-dominated.

Influence of shear yield strength of rail material on the shakedown limit in shakedown map

Rail materials with different shear yield strengths can exhibit different rolling contact fatigue (RCF) damage response during cyclic contact loading. The objective of this work is to achieve the actual shakedown limits in the shakedown map for rail materials with different shear yield strengths through RCF simulation tests of wheel-rail, and to investigate the relationship between the shear yield strength (ke) and the shakedown limit. Rolling-sliding tests were performed to investigate the RCF damage states of three types of rail materials with different shear yield strengths. Then, according to the differences of RCF damage states for each rail material and the method of nonlinear curve fitting, the actual shakedown limits for three types of rail materials were obtained. The actual shakedown limits for the three types of rail materials were lower than the original one in the classical shakedown map. With an increase in the shear yield strength (ke) of the rail material, the actual shakedown limit is reduced. Moreover, a relationship emerged which allowed a simple method to be proposed to obtain the actual shakedown limit based on the shear yield strength. The changing process and differences in the impact of different shear stress levels on the microstructural damage transformation of rail materials from the perspective of contact mechanics have been discussed. The behavior of severe accumulation of residual stresses during cyclic loading and more likely initiation of microcracks are the main reasons why rail materials with a higher shear yield strength (ke) under great contact loads are more prone to developing RCF crack damages. That is, the shakedown limit for the material with a higher shear yield strength (ke) is much lower. In view of the application of the shakedown map in the evaluation and prediction for RCF damage of rail materials with different shear yield strengths, different shakedown limits should be applied to different rail materials when analyzing their likely performance.

Study on Fatigue Life of Aluminum Alloy 6061-T6 Based on Random Defect Characteristics.

A certain number of hole-like defects will occur in aluminum alloys under cyclic loading. The internal holes will reduce the strength of the material and cause stress concentration, which will aggravate the development of fatigue damage. A classification method of defect features based on X-ray CT damage data is proposed. The random hole distribution model is established through the linear congruence method and the region division method. The hole parameter is introduced as the intermediate variable of the 3D reconstruction model of internal defects. In the mesoscopic stage, the function relationship between the distribution of random holes and the fatigue life is established based on the coupling relationship between the number and proportion of pores and the fatigue life. In the macroscopic stage, the relationship between the random holes and the macroscopic crack growth life is established by taking the crack length as the damage variable. The crack propagation rate decreased with the increase in the number of holes. The prediction model of the whole life stage is established using the life function from microcrack initiation to macroscopic crack propagation. Finally, the validity of the whole stage fatigue life prediction model is demonstrated through the comparison and verification of experiments, which provides a certain engineering value for the life estimation of 6061-T6 aluminum alloy materials.

Influence of hybrid steel-polyacrylonitrile fibers on the mechanical toughness and freeze-thaw resistance of sulfoaluminate cement composites

Sulfoaluminate cement (SAC), an environmentally friendly low-carbon cement, is commonly applied for rapid repair and construction. However, limited studies were conducted to elevate the performance of SAC-based materials by using the hybrid fiber modification, especially the durability. This study investigated the mechanical behaviors and freeze-thaw (F-T) resistance of SAC-based materials with hybrid steel-polyacrylonitrile (PAN) fibers, as well as their enhancement mechanism characterized using X-ray computed-tomography (CT) and scanning electron microscope. The results showed that incorporating hybrid fibers remarkably increased the flexural and compressive toughness of mortars, with steel fibers contributing the most critically. The fiber hybridization also significantly enhanced the F-T resistance of mortars, with PAN fiber being the main contributor. Specifically, the use of hybrid fibers caused a 61.0% improvement in the relative dynamic elastic modulus of mortars after 300 F-T cycles. CT scanning demonstrated that incorporating PAN fibers reduced the porosity of mortars and restrained the initiation and propagation of microcracks, while uniformly and randomly distributed steel fibers interspersed between macrocracks. Morphology observation illustrated that PAN fiber addition was conducive to enhance the anchoring force of steel fiber. Accordingly, the hybrid steel-PAN fibers contributed to suppress cracking at different scales and achieved a positive hybrid effect. At last, the results of this work provide a promising design solution for SAC-based composites to achieve better toughness and frost resistance.

Model test on failure mechanisms of deep high-stress soft rock roadways based on excavation compensation method

Traditional support (TS) is not sufficient to address the issue of large deformations in deep soft rock roadways with high stress. Based on model tests, this study considered the superposition effects of the evolution of tangential stress σ1 and radial stress σ3 on the crack propagation of excavated rock mass. Moreover, it explored the response characteristics and failure mechanisms of surrounding rock under different support modes. The results showed that, compared with the TS, the compensation support (CS) reduces the surrounding rock deformation, fracture and expansion area, and crack length by 73.7, 86.5, and 37.7%, respectively, while the roadway cross-sectional area increases by 36.8%. At 0.5R, σ3 of the shallow surrounding rock increases by 68.3%, and the peak value of σ1 at this location drops by 18.2%. The excavation effect causes σ3 and σ1 of the surrounding rock to decrease and increase, respectively. The decrease in σ3 leads to initiation of microcracks in the shallow surrounding rock, whereas the increase in σ1 causes the cracks to further open and propagate deeper. Finally, the dislocation, slippage and overturning of the fractured rock blocks along the structural planes result in bulking deformation of the shallow surrounding rock. The occurrence of microcracks in the deep surrounding rock leads to dilatation deformation. The CS strongly compensates for the stress of surrounding rock through negative Poisson’s ratio (NPR) cables, giving full play to the triaxial strength of the surrounding rock and mobilising the self-bearing capacity of the deep rock mass, thereby inhibiting the propagation and penetration of cracks. In contrast, the TS cables have a low prestress and weak excavation compensation effect, which makes it difficult to inhibit the evolution and coalescence of cracks, leading to large deformations in the surrounding rock.

Mechanical Properties of Rock Specimens Containing Pre-Existing Cracks with Different Dip Angles Based on Energy Theory and Cohesive Element Method

To investigate the influence of the crack dip angle on the strength of rock specimens, uniaxial compression tests were conducted on granite specimens containing pre-existing cracks. The strain energy evolution during the loading process was analyzed, and the loading-induced cracking process was simulated using the cohesive element method. Both the experimental and numerical results indicate that cracks significantly impact the plastic-yielding stage of the stress–strain curve more than the initial and elastic deformation stages. When the crack dip angle is less than 45°, the stress concentration near the crack is significant, which is an important factor affecting the strength and elastic strain energy distribution of rock specimens. When the crack dip angle is greater than 45°, the degree of stress concentration decreases, and the uniformity of the elastic strain energy distribution and the possibility of crack bifurcation increase. Combining the energy theory with the cohesive element method helps comprehensively understand the initiation, propagation, and coalescence of microcracks near pre-existing crack tips. These research results can provide a reference for geotechnical engineering design and structural stability assessment.

The influence of multi-scale second-phase particles on micro-crack initiation and propagation in Al–Zn–Mg–Cu alloy

This study investigates the effects of multi-scale second phases on micro-crack initiation and propagation in an Al–Zn–Mg–Cu alloy through in-situ observations using transmission electron microscopy (TEM) and a coupled in-situ stretching device. The results demonstrate that the fracture modes of the alloy are mainly intergranular with a minor amount of transcrystalline fracture. Furthermore, the size and location of the second phase significantly influence the micro-crack initiation and propagation. Submicron-sized MgZn2 particles located along the grain boundaries mostly induce micro-crack initiation through interface debonding or self-rupture, while those in the grain interior improve fracture strength and reduce the crack propagation rate of the alloy. In addition, the nano-sized Al3Zr, η′, and η phases are cut by dislocations and enhance crack propagation resistance, although their effect on the propagation path is limited. These findings provide theoretical implications for optimizing the chemical composition, mechanical properties, and fatigue resistance of Al–Zn–Mg–Cu alloys.

Simulation of the surface and volume stress in the contact archwire/bracket for classical friction and critical contact angle

AbstractAimThe occlusion of the teeth is affected due to the appearance of micro-cracks resulting from maximum stresses in the contact zones between the wire and the bracket under normal and tangential loading. The objective of this study is to evaluate the surface and volume constraints in the presence of bonding and partial sliding zones on the contact surface between wires and supports. Knowledge of these stress fields will make it possible to better limit the surfaces where most of the micro-cracks occur. Indeed, the evaluation of the stress will facilitate the modelling or application of established micro crack models on this subject, because the initiation of micro-cracks often appears on the contact surface or just below it.Materials and methodsIn this study, the two most common situations of contact between the wire and the bracket were studied; the first corresponds to the situation where the wire is positioned in the center of the support (classic friction), and the second corresponds to the situation where the inclined wire touches the ends of the supports (critical contact angle).The MATHCAD software was used to simulate the damage zones for normal loading in the two cases studied (classic friction, critical contact angle). We proposed a Hertzian loading for the first case and a linear loading for the second case. Also, the effect of the additional load during wire tightening applied by the orthodontist was studied.ResultsThe charge concentration is located above the contact zone, of the order of 0.3P0 (pressure per unit of arbitrary normal length), according to Mathcad simulation results. The adhesion zone/micro-slip zone contact generates the largest tangential load, which is directed towards the side experiencing the most stress. We also observed that the stick area shifts towards the recessed side when the additional load is applied. Additionally, comparing the configurations, the critical contact angle resulted in a higher maximum shear stress.

Deformation Characteristics and Constitutive Model of Construction and Demolition Waste Stabilized with Alkali-Activated Fly Ash

This study employed triaxial compression tests to investigate the deformation characteristics and damage evolution of construction and demolition waste (C&D) stabilized with alkali-activated fly ash (FA). Furthermore, the study explored the mechanisms of microcracks initiation, propagation, and the stress-strain behavior of stabilized C&D under varying stress conditions. A strain-softening damage model was employed to investigate the mechanism of damage evolution in the specimens. The test results revealed that the internal damage process of the stabilized recycled concrete aggregate (RCA) exhibited five stages: elastic recovery, damage initiation, damage acceleration, damage deceleration, and damage completion. The confining pressure had a significant influence on the deformation characteristics of the specimens. Additionally, the deformation characteristics of the stabilized C&D and rock materials exhibited remarkable similarities. By employing a model of rock strain softening and intrinsic structural damage the damage evolution trends and the equation of the intrinsic structure of the main component RCA-FA. The results demonstrated a good agreement between the test data and the predictions of the proposed constitutive model.

Damage deterioration mechanism and damage constitutive modelling of marble after cyclic impact loading

Rock mass in tunnel, underground chamber and other underground engineering is inevitably affected by multiple blasting impact, rock mass cracking and failure are often affected by these damaged rock mass, so it is meaningful to study the rock mass affected by dynamic damage. To explore the influence of cyclic impact on the internal structure of marble, NMR (Nuclear Magnetic Resonance) technique was adopted to test the marble. It was found that the impact would rise the porosity of marble, and the pore size distribution would also change greatly. Then uniaxial compression experiments were conducted on core samples. The results show that the impact will cause significant damage to the marble, and the mechanical properties of the marble will be obviously degraded. With the increase of impact times, the peak strength and tangential deformation modulus tend to decrease. The impact effect promotes the initiation and development of rock microcracks, pushes forward the development of the compaction stage, and increases the strain at the full compaction point. In addition, the damage constitutive model with the combination of different disturbances and loads was constructed in stages according to the principle of statistics, and the experimental results were used to verify the damage constitutive model. The crack closure and failure of the samples subjected to different impact times were well reflected in the model, and the practical significance of the parameters in the model was analyzed. The failure mode of the sample subjected to different impact times is discussed and verified by acoustic emission technology.

Pioneering research on the role of strain burst in the early-stage stress corrosion crack propagation

This work pioneered the study on the effect of cyclic-loading-induced strain burst on Stage-1b stress corrosion crack (SCC) growth under alternating static and cyclic loading. Results show that Stage-1b growth occurred by microcrack initiation and its linking to the main crack's tip. Increasing static hold duration caused crack growth rate per cycle to increase after an incubation period. This was because the occurrence of strain burst induced a high strain rate, leading to film rupture, and thus microcrack initiation. The effects of different stress levels and durations of static hold, and their interactions with cyclic loading, on crack growth were systematically studied.

Research on the propagation mechanisms and meso-mechanical responses of reflective cracking on the asphalt overlays on concrete airfield pavement by Fiber Bragg Grating sensing technology

This study evaluated the propagation mechanisms and dynamic meso-mechanical responses of reflective cracking on the asphalt overlays on concrete airfield pavement based on flexible Fiber Bragg Grating (FBG) sensors. The encapsulated FBG sensors were efficiently calibrated, possessing outstanding capability for the measurement of transverse expansion of lateral reflective cracking propagation. Virtual three-point bending test model was proposed and validated by macroscopic indoor experiments. The DEM model facilitated quantifying the proliferation of reflective cracks, unraveling the trajectory from micro-crack inception to visible macroscopic manifestation. Results indicated that the emergence and elongation of the composite structure experienced three phases: the initiation and accumulation of microcracks, the extension of reflective cracking, and the ultimate penetration. The DEM simulation and FBG sensors were recommended to establish a mutually reinforcing mechanism for nuanced validation of reflective crack formation on the composite structures of asphalt overlays on concrete airfield pavement.

Durability Properties of Macro-Polypropylene Fiber Reinforced Self-Compacting Concrete.

Concrete is one of the most commonly used construction materials; however, its durability plays a pivotal role in areas where the concrete is exposed to severe environmental conditions, which initiate cracks inside and disintegrate it. Randomly distributed short fibers arrest the initiation and propagation of micro-cracks in the concrete and maintain its integrity. Traditional polypropylene fibers are thin and encounter the problem of balling effects during concrete mixing, leading to uneven fiber distribution. Thus, a new polypropylene fiber is developed by gluing thin ones together, forming macro-polypropylene fibers. Thus, different amounts of fibers, 0-1.5% v/f with an increment of 0.5% v/f, are used in different grades of concrete to study their impact on durability properties, including resistance to freezing and thawing cycles, sulfate, and acid attacks. A total of 432 cube samples were tested at 28, 56, and 92 days. The results reveal that the maximum durability, in terms of compressive strength loss, is noted with a fiber content of 1% with improved resistance of 72%, 54%, and 24% against freeze-thaw cycles, sulfate attack, and hydrochloric acid attack, respectively, at 92 days. Thus, the resulting fiber-reinforced concrete may be effective in areas where these extreme exposure conditions are expected.