Matrix design for pseudo-strain-hardening fibre reinforced cementitious composites

Li, Victor C.; Mishra, Dhanada K.; Wu, Hao

doi:10.1007/bf02473191

Cited by 399 publications

(176 citation statements)

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“…And the deformation of ECC2 cured under all conditions is higher than ECC1, which may be explained that SAPs act as artificial flaws to trigger initiative crack easily occurred in matrix, which can help ECC specimens to realize pseudo strain-hardening performance [15]. From Fig.3 (a) and (b), it can be observed that the deformability of ECC2 is relatively well after incorporating SAPs.…”

Section: Four Point Bending Testmentioning

confidence: 90%

Influence of superabsorbent polymer (SAP) particles on the self-healing of engineered cementitious composites (ECC)

Deng¹,

Qian²

2016

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures

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Self-healing behavior of engineered cementitious composites (ECC) with superabsorbent polymers (SAPs) was investigated in this paper. Four point bending tests were used to precrack ECC specimens at the age of 7 and 28 days, respectively. The precracked samples were then cured in 99%RH curing and 99%RH/room air cycle curing to promote the occurrence of self-healing behavior and in room air curing for control. The addition of SAPs help tighten the crack width, resulting in enhanced flexural stiffness for the 99%RH cured and 99%RH/room air cycle cured samples. Furthermore, the effect of SAPs also promotes a larger degree recovery of deformation capacity, despite of much lower the initial deformation capacity for ECC2. The self-healed samples were observed by environment scanning electron microscope (ESEM) to reveal the products of self-healing behavior.

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Section: Four Point Bending Testmentioning

confidence: 90%

Influence of superabsorbent polymer (SAP) particles on the self-healing of engineered cementitious composites (ECC)

Deng¹,

Qian²

2016

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures

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“…The standards do not specify a measure of stress intensity factor of cementing materials. However, the method stated by ASTM E399: LinearElastic Plane-Strain Fracture Toughness K IC of Metallic Materials was found to be applicable to the cement matrix [22,23] and was therefore used throughout the study. Matrix specimens were kept in plastic bags at 95 ± 5 % RH, 23 ± 2°C and toughness tests were performed at the end of 7 and 28 days by using four beams on each date.…”

Section: Specimen Preparation and Testingmentioning

confidence: 99%

“…Therefore, when LWA volume increases, higher number of weak LWA particles are available in the path of crack, resulting in smoother cracking path and less energy needed for cracking, and then lower values of fracture toughness. Since higher matrix toughness could be detrimental to achieving the desired mechanical properties, and reducing the tendency to develop multiple-cracking [22], the use of LWA in ECC production should be helpful for achieving strainhardening behavior.…”

Section: Fracture Toughnessmentioning

confidence: 99%

“…When the deflection values of HES-ECC_1 and HES-ECC_2 mixtures are considered, specimens with lower S/PC ratio (HES-ECC_2 mixtures) at the same W/CM ratio exhibited lower deflection values in general. According to the micromechanical model of steady state cracking, which is essential for achieving strain hardening behavior, high matrix fracture toughness reduces the margin to obtain multiple microcracking behavior [22]. The decreased deflection values in the HES-ECC_2 specimens compared with the other mixtures could be due to higher fracture toughness, bond strength and friction between the HES-ECC_2 matrix and the fibers (please see Fracture Toughness section).…”

Section: Mid-span Beam Deflection Capacitymentioning

confidence: 99%

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High-early-strength ductile cementitious composites with characteristics of low early-age shrinkage for repair of infrastructures

et al. 2013

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Reduced performance in concrete infrastructures is mainly caused by the formation of cracks, which may arise due to deteriorating mechanisms during service life. In most cases, reduced performance calls for urgent repairs to the degraded section. Therefore, it is highly desirable to develop dimensionally stable, ductile repair materials that can attain adequately high strength in a limited amount of time, compensate for significant deformation due to mechanical and environmental loadings, and prevent early-age shrinkage cracks. In this paper, the performance of such a material (high-early-strength engineered cementitious composites, HES-ECC, with very low early-age shrinkage capacity) was investigated by studying mechanical properties and dimensional stability. Composites were produced with different water to cementitious materials and slag to Portland cement ratios. In order to enhance composite properties in terms of ductility and early-age shrinkage characteristics, saturated lightweight aggregates replaced sand in the mixtures. The experimental results show that the majority of HES-ECC mixtures developed in this study attained compressive strength values of more than 20.0 MPa and minimum flexural strength of 6.0 MPa within 6 h. Moreover, the HES-ECC mixtures exhibited strain-hardening behavior with strain capacities comparable to normal strength ECC, as well as substantially reduced autogenous shrinkage strain, both of which are unlikely to trigger the formation of cracks in tension at early ages. The integration of these conflicting parameters suggests that HES-ECC can easily meet the need for fast and durable repairs.

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“…Esse comportamento, denominado "strain-hardening", é apresentado de forma simplificada na curva (a) da Figura 1, e se caracteriza pelo surgimento de múl-tiplas fissuras na matriz. Mesmo utilizando fibra polimérica, comportamento similar foi obtido por Li et al (1995), em um compósito denominado ECC ("Engineered Cementitious Composites"), que apresenta um pequeno aumento da resistên-cia após a primeira fissura, e somente após atingir grandes deformações, em um comportamento denominado pelos autores de "pseudo strain hardening" e representado pela curva (b) da Figura 1. Comportamento similar foi obtido recentemente em compósitos reforçados com fibras curtas de sisal (Ferreira, 2012) após a utilização de matrizes de cimento com reologia adequada.…”

Section: Introductionunclassified

Mecanismo De Fissuraçao Sob Tração Direta De Compósitos Cimentícios Reforçados Com Fibras Curtas De Sisal

2012

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Resumo: Embora a utilização de fibras vegetais como reforço de matrizes a base de cimento remonte à década de 70, poucos estudos têm sido realizados para investigação experimental e analítica desses compósitos sob tração direta. Nesse trabalho, foi avaliado o comportamento de argamassas reforçadas com fibras curtas de sisal sob ensaio de tração. O diagrama carga-deslocamento foi expresso em termos de tensão-deformação até a abertura da fissura e, após esse ponto, em termos de tensão-abertura de fissura. Comparados com a matriz, que apresentou ruptura frágil, os compósitos reforçados com 1%, 2% e 3% de fibras de sisal apresentaram propagação da fissura a grandes deslocamentos com manutenção de uma resistência residual. Modelos analíticos baseados na Mecânica da Fratura foram utilizados para determinação da tenacidade de fratura e comprimento característico do material e demonstraram que a adição de fibra aumenta a capacidade de absorção de energia do material. Palavras-Chave:mecânica da fratura;argamassa; fibras vegetaisAbstract:Although the use of vegetables fibers as reinforcement in cement based matrices goes back to the 70s, few studies have been performed for analytical and experimental investigation of these composites in direct tensile. In this study, It was evaluated the tensile behavior of composite mortars reinforced with 1%, 2% and 3% of short sisal fibers. The softening curve was represented by stress-strain diagram until first crack and, after this point, it was represented by stress-crack opening diagram. Compared with the matrix, which showed brittle fracture, the composites showed crack propagation to large displacements with maintenance of residual stress. Analytical models based Fracture Mechanics were used to determine fracture energy and characteristic length of material and the results showed that presence of fibers increment the toughness of cement based mortar under tensile.

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Matrix design for pseudo-strain-hardening fibre reinforced cementitious composites

Cited by 399 publications

References 8 publications

Influence of superabsorbent polymer (SAP) particles on the self-healing of engineered cementitious composites (ECC)

Influence of superabsorbent polymer (SAP) particles on the self-healing of engineered cementitious composites (ECC)

High-early-strength ductile cementitious composites with characteristics of low early-age shrinkage for repair of infrastructures

Mecanismo De Fissuraçao Sob Tração Direta De Compósitos Cimentícios Reforçados Com Fibras Curtas De Sisal

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