Fiber Bridging Capacity Research Articles

Peanut shaped auxetic cementitious cellular composite (ACCC)

Auxetic cementitious cellular composites (ACCCs) exhibit desirable mechanical properties (e.g., high fracture resistance and energy dissipation), due to their unique deformation characteristics. In this study, a new type of cementitious auxetic material, referred to as peanut shaped ACCC, has been designed and subsequently architected using additive manufacturing techniques. Two peanut shaped ACCCs specimens with different pseudo-minor axes have been tested under uniaxial compression with Digital Image Correlation (DIC) to assess their compressive behavior, peak strength, Poisson’s ratio, and energy dissipation capacity. Additionally, cyclic tests were conducted to investigate their compressive resilience properties, further elucidated through microstructural analysis using a digital optical microscope. The mechanical test results were also compared with those of previously developed elliptical-shaped ACCCs. Furthermore, a numerical model was used to simulate the mechanical behavior of peanut shaped ACCCs under uniaxial compression, and showed a good agreement with the experimental data. The auxetic behavior observed in peanut shaped ACCCs arises from the rotation of sections facilitated by fiber bridging at the ligament of adjacent holes within the cementitious unit cell. In comparison to elliptical-shaped ACCCs, peanut shaped ACCCs can exhibit a slightly more negative Poisson's ratio and mitigate stress concentration. The reduction of stress concentration enables peanut shaped ACCCs to dissipate substantial energy, showcasing enhanced ductility and toughness. In cyclic tests, peanut shaped ACCCs exhibit superior recoverable deformation elasticity, attributed to robust fiber bridging capacity. The exceptional mechanical properties exhibited by peanut shaped ACCCs offer a scalable solution for developing energy-absorbent and multifunctional cementitious materials for smart infrastructure.

Impact of reinforcing ratio and fiber volume on flexural hardening behavior of steel reinforced UHPC beams

The gradual hardening failure of steel reinforced UHPC beams is desirable for high drift capacity and resilient structural design. However, the occurrence sequence of the crack localization and steel yield needs to be clarified. The investigation on the load-drift capacity response after the crack localization in the hardening failure is warranted. The present study conducts flexural tests on the steel reinforced UHPC beams with different fiber volumes and reinforcing ratios. All the beams show gradual hardening failure, and crack localization and steel yield occur simultaneously from the experimental observations and neutral axis height changes. The relative change - the fiber bridging capacity loss and steel strain hardening capacity after the crack localization dominates the hardening length of the load-drift capacity response. High fiber volume tends to extend the hardening length; while high reinforcing ratio tends to first extend the hardening length, then shortens the hardening length due to more and quick fiber bridging capacity loss. The ductility loss and residual tensile UHPC contribution reduction at high reinforcement ratio of 2.83% support this proposal. Moreover, increasing fiber volume is effective to enhance flexural cracking resistance at the initial stage, while increasing reinforcing ratio leads to greater improvement at the later crack development stage, which provides new design path for steel reinforced UHPC beams.

Synergy effect of hybrid steel-polyvinyl alcohol fibers in engineered cementitious composites: Fiber distribution and mechanical performance

The fiber distribution is a crucial factor governing the superb strain-hardening and multiple cracking behavior of engineered cementitious composites (ECC). However, the desired uniform distribution of fibers is challenging in ECC with large amounts of binders and fibers, especially for hybrid fiber system. In the present study, we employed image analysis to investigate the fiber distribution characteristics in hybrid steel-polyvinyl alcohol (PVA) fiber ECC and its influence on the mechanical performance. Special attention was paid to the impact of additional steel fiber content and its size. The results show that the dispersion coefficient of PVA fibers in hybrid fiber system was at most 50% higher than that of mono fiber system. Fiber hybridization rendered more fibers distributed in smaller angles of 0°–40°, which helped to enhance the fiber bridging capacity. The addition of steel fibers significantly improved the flexural properties of ECC, with maximized strength at steel fiber content of 1.0% and maximized deformability at 0.6% dosage. The incorporation of steel fibers greatly enhanced the crack control ability of hybrid fiber ECC. The average crack width was reduced to 36.1 μm when the volume fraction of steel fiber gone to 1.0%. Furthermore, larger sized steel fibers played a more pronounced role in improving the fiber dispersion, fiber orientation and mechanical properties than that with smaller size. Synergy effect of hybrid steel-PVA fiber on fiber distribution and mechanical properties was revealed. The findings are expected to contribute to the blending ratio design of hybrid fibers and the selection of fiber size in preparing ECC. And the obtained robust ECC can provide strong support for performance enhancement and maintenance of building engineering.

A Modified Fiber Bridging Model for High Ductility Cementitious Composites Based on Debonding-Slipping Rupture Analysis

Modified micromechanical bridging model is established with consideration of the fiber rupture effect at debonding and slipping stages. The bridging model includes the debonding and slipping rupture of fibers and establishes the fiber/matrix interfacial parameters (friction τ 0 , chemical bonding force G d , slip-hardening coefficient β ). A different interfacial bonding can cause fiber rupture. The influence of the interfacial conditions on the fiber rupture risk was investigated. In the modified bridging model, the effective bridging stress, the debonding rupture stress, and the slipping rupture stress were clearly identified. Finally, single-fiber pullout tests with different embedded lengths were carried out to validate the bridging model. The relationship between the fiber bridging stress and the crack opening predicted by the bridging model was consistent with the experimental results. This modified micromechanical bridging model can be used to quantitatively calculate the actual fiber bridging capacity and to predict the ductility of the high ductility cementitious composites reinforced by different types of fibers.

Evaluation on the performance of magnesium phosphate cement-based engineered cementitious composites (MPC-ECC) with blended fly ash/silica fume

To develop magnesium phosphate cement-based engineered cementitious composites (MPC-ECC) that can be well used for rapid building repair, this study explores the influence of blended fly ash/silica fume on the compressive strength, direct tensile properties, and micromechanical properties of MPC-ECC. And the relationship between two pseudo strain-hardening indices (PSHσ and PSHJ) and ultimate tensile strain is established. The micromechanical analysis indicates that the blending of 30% fly ash and 10% silica fume significantly improves the fiber bridging capacity and fiber bridging complementary energy; however, the blended fly ash/silica fume reduces the tensile cracking strength, elastic modulus, and fracture toughness of the matrix. In addition, the blended fly ash/silica fume increases the compressive strength, up to 41.67 MPa, and also improves the tensile properties of MPC-ECC. The strain hardening behavior is more improved as the fly ash/silica fume content increases. Besides, the ultimate tensile strain and the pseudo-strain hardening indices are positively correlated, showing that the pseudo-strain hardening indices can be used to design MPC-ECC with specific ultimate tensile strains. To ensure that the MPC-ECC achieves an ultimate tensile strain of above 3%, PSHσ and PSHJ are recommended to reach 2.12 and 21.32, respectively, or more at the same time.

Feasibility of ECC with high contents of post-processed bagasse ash as partial cement replacement

This study investigated the feasibility of using high contents of post-processed sugarcane bagasse ash (PBA) as a partial replacement of cement for the development of Engineered cementitious composites (ECCs) with low amounts (1.5% by volume) of non-oil-coated polyvinyl alcohol (PVA) fibers. PBA was prepared by sieving, burning, and grinding raw sugarcane bagasse ash collected from a sugar mill. Composites using three different replacement levels of cement with PBA (i.e., 40%, 50%, and 60% by mass) were evaluated and compared to a composite without PBA (i.e., PBA-0) and a composite using Class F fly ash (FA) at 60% cement replacement (i.e., FA-60). This study evaluated fiber-bridging properties via single crack tensile tests (SCTT), matrix properties via fracture toughness tests, mechanical properties via compressive strength and uniaxial tensile tests, and physical properties via surface resistivity and flow tests. Results showed that the workability of the mixtures decreased with the increase in PBA content. Furthermore, the incorporation of PBA resulted in a reduction in compressive strength (up to 39.1%) and improvements in surface resistivity. Importantly, PBA composites outperformed the FA composite in compressive strength and surface resistivity. The use of PBA produced reduction in the crack-tip fracture toughness (Jtip). SCTT revealed that the complementary energy of the fiber-bridging relation (Jb') was positively affected by PBA up to 50% cement replacement; yet, at 60% cement replacement, Jb' substantially decreased compared to PBA-0. Jb' increments were attributed to a likely decrease in the fiber/matrix interface chemical bond, whereas the decrease at the 60% cement replacement was attributed to fiber clumping due to the poor workability of the mixture. The fiber-bridging capacity and tensile strength of the composites exhibited a similar trend, where the mixture using 40% cement replacement with PBA showed the highest values and the one using 60% showed the lowest value. All PBA-composites exhibited higher tensile strain capacity compared to PBA-0, and the highest improvement (i.e., 82.1%) was observed at 50% cement replacement with PBA. However, the tensile ductility of the PBA composites was significantly lower than that of FA-60. It is concluded that PBA can generate comparable fiber-bridging properties as those produced by FA; however, FA is more effective at reducing Jtip, thus producing better conditions for pseudo-strain hardening behavior. Furthermore, the use of high contents of PBA significantly reduces the workability of the composites inhibiting proper fiber dispersion. Therefore, large amounts of PBA as partial cement replacement cannot be used to produce ECCs in conjunction with low amounts of non-oil-coated PVA fibers.

Carbonation curing for precast Engineered Cementitious Composites

The ultra-durable Engineered Cementitious Composites (ECC) provides an opportunity for sequestering CO2 during construction while reducing operational emissions in use phase. Here, ECC carbonation curing was investigated as a precast route of CO2 sequestration. Results suggest that ECC sequesters 29.6% CO2 by cement mass through early-age carbonation. The ultimate tensile and compressive strengths at 2 days were increased by 57.2% and 40.9%, respectively, while the tensile strain capacity attained 3.7%. Carbonation curing was found to densify the fiber/matrix interface resulting in higher interfacial bond, tighter crack widths, and more robust fiber bridging capacity. Consequently, the composite ultimate tensile strength increased by 22.7% while maintaining comparable strain capacity at 28 days. The tighter crack widths further decrease the material water permeability in loaded condition. These findings prove the feasibility of ECC carbonation curing and establish the scientific foundation of carbon utilization and permanent sequestration in ECC for precast construction elements.

Photocatalytic high-performance fiber-reinforced cement composites with white Portland cement, titanium dioxide, and surface treated polyethylene fibers

In this study, titanium dioxide (TiO2) and polyethylene (PE) fibers were employed to develop photocatalytic high-performance fiber-reinforced cement composites (HPFRCCs). To achieve high NOx removal capacity, it was necessary to confirm the dispersion of the TiO2 powder. For this purpose, various amounts of viscosity-modifying agent (VMA), ranging from 0% to 1% by weight to cement, were considered along with two types of white Portland cement: Union and Aalborg. Additionally, the PE fiber surface was modified via cold gas plasma and chromic acid treatment to improve the tensile performance of the HPFRCCs. The experimental results indicated that the plastic viscosity of the mortar increases with the addition of VMA. Optimum NOx removal capacities of 5.72 and 8.10 μmol were respectively achieved for the Aalborg and Union cement types in the mortar at a VMA content of 0.5%. The compressive strength of the tested photocatalytic HPFRCC was approximately 72.7–91.8 MPa. In the case of the hybrid argon (Ar) and oxygen (O2) gases being subjected to plasma treatment, optimum tensile performance—in terms of tensile strength, strain capacity, and g-value—was achieved, whereas the samples subjected to chromic acid treatment exhibited poorer tensile performance. Moreover, the single Ar–or O2-gas-based plasma treatment yielded an intermediate tensile performance. The cracking behavior showed trends similar to those of the g-value: the hybrid plasma treatment produced the most microcracks because of its high fiber bridging capacity.

Effect of Raw Sugarcane Bagasse Ash as Sand Replacement on the Fiber-Bridging Properties of Engineered Cementitious Composites

The use of raw sugarcane bagasse ash (SCBA) as sand replacement in the production of engineered cementitious composites (ECCs) can improve its cost-effectiveness and practicality. A recent study by the authors showed that the use of raw SCBA as a replacement to sand in ECC mixtures substantially enhances the tensile ductility and provides mild improvements in tensile strength; however, it also indicated a need to further elucidate the mechanisms producing such improvements. Therefore, the present study examined the effects of raw SCBA as a sand replacement in ECC’s fundamental fiber-bridging relationship, [Formula: see text], through single crack tensile test (SCTT) using 1% polyvinyl alcohol (PVA) fiber volume fraction. The PVA fiber volume fraction was reduced from 1.5% in the previous study to 1% in this study to ensure that a single crack was produced, which is a necessary condition to obtain the fundamental [Formula: see text] relationship. A total of five mixtures were evaluated at different replacement levels of sand with raw SCBA (i.e., 0%, 25%, 50%, 75%, and 100%). SCTT results revealed that raw SCBA produced minor effects on the fiber-bridging capacity but significantly increased the complementary energy ( [Formula: see text]). A positive correlation was observed between the pseudo strain-hardening (PSH) strength index and raw SCBA content. Since the PSH strength index was higher than the recommended value (i.e., 1.3) for robust PSH behavior, it was concluded that the main factor contributing to tensile ductility enhancements was the increase in the PSH energy index resulting from the notable increase of [Formula: see text] and potential decrease in matrix fracture toughness.

Performance enhancement of green high-ductility engineered cementitious composites by nano-silica incorporation

To promote the sustainable development of construction materials, the green high-ductility engineered cementitious composites (GHD-ECC) incorporating 100% recycled fine aggregate (RFA) was developed. The effect of nano-silica (NS) at different dosages (0, 1%, 2%, and 3%) on the microstructural features and the macroscopic strength of GHD-ECC was investigated. The results of a comprehensive experimental study indicate that: (1) the four types of cementitious composites all exhibit multiple cracking characteristics, and the mechanical resistance of GHD-ECC is significantly improved owing to the addition of NS; (2) NS with high pozzolanic reactivity promotes the hydration reaction process, and the additionally formed hydration products fill the micropores and densify the microstructure of GHD-ECC; (3) the increase of both the matrix strength and matrix toughness leads to the enhancement of frictional bonding between fiber and matrix, which induces the transition of the failure mode from fiber pulled-out to fiber rupture and thus causes, to a certain extent, the degradation of the fiber bridging capacity. Based on the comprehensive investigation, the 1% NS dosage is found to be the optimal content, which not only meets the workability requirement but also contributes to the achievement of saturated cracking state and high mechanical resistance.

Effects of corrosion level and inhibitor on pullout behavior of deformed steel fiber embedded in high performance concrete

This study investigated effects of corrosion level and inhibitor on the pullout behavior of deformed steel fibers. Two types of deformed (hooked and twisted) steel fiber, were embedded in two different matrices (28 MPa and 84 MPa). The calcium nitrite corrosion inhibitor (CNI) was added at a volume of 25 l/m3. An impressed current technique was used to generate different corrosion levels in the steel fibers. As the corrosion level increased, the pullout resistance of deformed steel fibers increased by maintaining fiber pullout mode and even slip hardening behavior. However, beyond a certain corrosion level, the pullout resistance was deteriorated due to fiber breakage and a sudden drop of pullout load at very small slip. The maximum corrosion level of deformed steel fibers should be limited to 12% for ensuring fiber bridging capacity at the composite level. The addition of CNI was beneficial for maintaining fiber pullout mode even at high corrosion level. By adding CNI, the maximum corrosion level of deformed steel fiber could be limited to 18%.

Polyvinyl Alcohol Fiber Length Optimization for High Ductility Cementitious Composites with Different Compressive Strength Grades

The fiber length has a significant impact on the fiber bridging capacity and the mechanical properties of high ductility cementitious composites (HDCCs), which is related to fiber/matrix interfacial bonding. However, this fundamental knowledge of HDCCs design has rarely been investigated systematically. To this end, this study deeply investigates the effect of the fiber length on the bridging stress and the complementary energy with various fiber/matrix interfacial bonds in theory. Then, the mechanical performances of HDCCs with various fiber lengths and compressive strengths were evaluated experimentally. In micromechanical design, longer fibers can achieve stronger bridging stress and more sufficient complementary energy regardless of the fiber/matrix interfacial bonding properties. However, it should be noted that the increase in bridging capacity was quite slow for the overlong fibers and excessive interfacial bonding. The experiments indicated that overlong fibers (18 mm and 24 mm) easily twined on the mixer blade and were hard to disperse evenly. The HDCCs with shorter fibers displayed better workability. The compressive strength was less affected by the fiber length, and most striking differences were less than 5.0%, while the flexural properties and the tensile properties first increased and then decreased when the fiber length ranged from 6 mm to 24 mm. Consequently, the fibers with lengths of 9 mm and the fibers with lengths of 12 mm were better candidates for the HDCCs with compressive strengths of 30 MPa to 80 MPa, and fibers with lengths of 9 mm caused the HDCCs to exhibit higher ductility properties in general.

Feasibility of incorporating recycled fine aggregate in high performance green lightweight engineered cementitious composites

The high-quality reutilization of recycled concrete aggregate, particularly the valorization of recycled fine aggregate (RFA) that exhibits inherent defects, is of great importance to mitigate environmental concerns associated with aggregate depletion and waste concrete disposition. In this study, RFA and industrial wastes were successfully used to develop high performance green lightweight engineered cementitious composites (HPGLW-ECC) through proper tailoring of the components. The designed eco-friendly material exhibiting a density of 1733 kg/m3, tensile strength up to 6.42 MPa and tensile strain capacity to 7.46% features impressive mechanical properties. It is remarked that the incorporation of 0–1 mm RFA contributes to the continuous grading of HPGLW-ECC and minimizes the gaps between the particles, which improves the overall compactness of the material. The high roughness of RFA favors the interlocking effect between fiber and matrix and contributes to the development of fiber bridging capacity. Moreover, the self-cementing of RFA further densifies the microstructure of HPGLW-ECC. The enhancement effects of 0–1 mm RFA on the mechanical performance of HPGLW-ECC were characterized by the refinement of microstructural pores as well as by the failure morphology features of fiber and matrix.

Development of gypsum‐based composites with tensile strain‐hardening characteristics

AbstractBrittle nature of gypsum restrains its wide application in construction industry. For improvement, a novel type of composite material, gypsum‐based engineered cementitious composites (GS‐ECC), was developed using specially chosen polyethylene (PE) fibers. This study investigated the rheological and mechanical properties of GS‐ECC, that is, workability, uniaxial tensile and compressive behavior, flexural strength, etc The investigation showed that GS‐ECC possessed excellent tensile strain‐hardening behavior and saturated cracking characteristics with the average tensile strain capacity more than 5%. To explore the underlying mechanism, the microstructure of interface transition zone (ITZ) between gypsum crystals and PE fibers were investigated through the use of SEM. Single fiber pull‐out test, bending‐fracture test, and single crack tension test were conducted to investigate the mesoscopic properties from fiber/matrix interface to matrix toughness and fiber bridging capacity. This study demonstrates the feasibility of achieving strain‐hardening gypsum‐based composites by adding the PE fibers.

Influence of flexural loading and chloride exposure on the fatigue behavior of high-performance lightweight engineered cementitious composites

The flexural fatigue behavior of high-performance lightweight engineered cementitious composites (HPLW-ECC) with tensile strength of 7.16 MPa and tensile strain capacity of 8.91% was investigated. The flexural repetitive loading demonstrated a pronounced influence on the fiber bridging capacity of HPLW-ECC. In contrast, the multiple cracking characteristics of HPLW-ECC under chloride exposure were maintained though its fatigue life decreased. The low-density HPLW-ECC exhibited high resistance to chloride penetration, and the fiber bridging capacity remained almost intact. Moreover, the flexural fatigue performance of HPLW-ECC possessing higher strength was comparable to that of conventional lightweight ECC. A fatigue life prediction model was proposed, and the model’s failure probability was discussed based on the probabilistic reliability analyses.

Orientation distribution of polyvinyl alcohol fibers and its influence on bridging capacity and mechanical performances for high ductility cementitious composites

Fibers spatial orientation distribution has a profound impact on the fiber bridging capacity and mechanical properties of high ductility cementitious composites (HDCCs), and the affected extent need to be quantitatively evaluated to provide guidance for engineering application of HDCCs. For this purposes, this study aims to clarify the micromechanical mechanism of fiber orientation distribution in the fiber rupture effect and bridging capacity based on the fiber bridging theory. In addition, experimental programs were conducted, including uniaxial tension test and four-point bending test. The fiber orientation distribution was detected using backscatter electron imaging (BSE) and digital image processing. The HDCC specimens were prepared with three types of fiber orientation distribution. Studies have shown that the fibers in HDCC with larger orientation present lower bridging stress σ0, weaker complementary energy Jb' and higher probability of fiber rupture during the crack-bridging process. The first cracking strength of the composites showed a slight decline, and the flexural properties and tensile properties exhibited a significant decline. The strain/deflection hardening behaviour even disappeared in some specimens with larger fibers orientation. Thus, it need to be note that the degradation of mechanical properties caused by fiber orientation distribution should be considered in HDCC structure designs.

Corrosion effect on tensile behavior of ultra-high-performance concrete reinforced with straight steel fibers

In this study, the effect of steel fiber corrosion on the tensile behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) was examined. Macro straight steel fibers with five different corrosion degrees ranging from 0 to 8% were used, and unwashed and washed corrosion fibers were simultaneously used to evaluate the effect of the rust layer formed at the fiber surface on the tensile performance. The post-cracking tensile response of the strain-hardening UHPFRC is strongly affected by the fiber bridging capacity, which is related to the interfacial bond resistance. Thus, the surface roughness of plain and corroded steel fibers was also quantitatively evaluated based on scanning electron microscope (SEM) images. The test results indicated that the surface roughness of steel fiber increases with an increase in the corrosion degree, and a severe and irregular roughened surface is found at a high-corrosion degree of greater than 8% by weight. The tensile behavior of UHPFRC was generally improved by the steel fiber corrosion up to a certain value of 4 or 6%, leading to the complete pullout failure mode without any breakage, whereas beyond the threshold value, it was rather deteriorated due to the fiber ruptures. Even though there was deterioration in the tensile performance, UHPFRC with the maximum corrosion degree of 8% even satisfied the international recommendations on the strength and energy absorption capacity limits. Lastly, the unwashed, corroded fibers exhibited a better tensile performance than the washed ones because of the appropriately moderated bond resistance.

Deformability enhancement of fiber-reinforced cementitious composite by incorporating recycled powder

Recycled powder (RP) from construction and demolish waste was used to replace fly ash and silica sand to enhance the tensile behavior of engineered cementitious composite (ECC) in the research. The average diameter of RP is less than 45 μm. Four mixtures of RP-ECCs were prepared, in which 50% and 100% of fly ash or silica sand were replaced by RP. The tensile strain-hardening and multiple cracking behaviors of RP-ECC specimens were extensively observed with the increasing tensile load. Results demonstrate that the replacement of fly ash and sand by RP promote the strain capacity of ECC specimens. Moreover, specimens with 50% RP showed superior tensile and compressive strength over those with 100% replacement ratio and the reference specimens. The analyses at micro-scale and meso-scale indicate that the replacement of fly ash by RP does not change the fracture toughness of the cementitious matrix, but significantly enhanced the fiber bridging capacity. While the replacement of sand by RP lowers the matrix fracture toughness and has a negligible effect on the fiber bridging capacity. Finally, the superior tensile strain capacity of RP-ECC is well-explained by the pseudo-strain hardening index.

Multiple-scale investigations on self-healing induced mechanical property recovery of ECC

The self-healing behavior of Engineered Cementitious Composites (ECC) has attracted much research in the past decade. Nonetheless, very few study attempted to reveal the underlying mechanism of self-healing induced mechanical recovery of pre-damaged ECC. In this paper, the influence of self-healing on the material properties of ECC was investigated on multiple length scales. Plausible underlying mechanisms of mechanical properties recovery of ECC are proposed. The results show obvious regaining of tensile/flexural properties of pre-damaged ECC at macro-scale due to self-healing. At the meso-scale, self-healing leads to fiber bridging strength recovery to about the same level as that of virgin specimens. At the micro-scale, self-healing is found associated with recovery of frictional bond strength between the fiber and matrix. However, chemical bond recovery appears to be absent. The regaining in fiber/matrix interfacial friction results in the recovery of fiber bridging capacity, which forms the root cause for recovery of the mechanical properties of self-healed ECC.

Using Green Supplementary Materials to Achieve More Ductile ECC.

To improve the greenness and deformability of engineered cementitious composites (ECC), recycled powder (RP) from construction and demolition waste with an average size of 45 μm and crumb rubber (CR) of two particle sizes (40CR and 80CR) were used as supplements in the mix. In the present study, fly ash and silica sand used in ECC were replaced by RP (50% and 100% by weight) and CR (13% and 30% by weight), respectively. The tension test and compression test demonstrated that RP and CR incorporation has a positive effect on the deformability of ECC, especially on the tensile strain capacity. The highest tensile strain capacity was up to 12%, which is almost 3 times that of the average ECC. The fiber bridging capacity obtained from a single crack tension test and the matrix fracture toughness obtained from 3-point bending were used to analyze the influence of RP and CR at the meso-scale. It is indicated that the replacement of sand by CR lowers the matrix fracture toughness without decreasing the fiber bridging capacity. Accordingly, an explanation was achieved for the exceeding deformability of ECC incorporated with RP and CR based on the pseudo-strain hardening (PSH) index.