Abstract
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.
Highlights
In order to address the brittleness of concrete, two superior materials are developed, that is, ultra-high-performance concrete (UHPC) [1] and engineered cementitious composites (ECC) [2]
ECC is a special class of high-performance fiber reinforced concrete, which was designed based on the micromechanics theory proposed by Li et al in the 1990s [2] as a ductile alternative to conventional concrete
The incorporation of fly ash may lead to negative effect to the tensile strain capacity of PE-ECC, the concern turns to how to enhance the connection between fiber and matrix
Summary
The tensile strain capacities of the majority of existing fiber reinforced concrete (FRC), including ECC, are still far below this level It implies that, when a structure made of FRC and steel reinforcement is loaded to its ultimate limit state, the steel reinforcement may sustain its contribution, but FRC will probably fail when subjected to excessive stretch. Hajiesmaeili and Denairé [16] studied the replacement of steel fibers by PE fibers to develop generation strain hardening ultra high-performance fiber reinforced concrete (SH-UHPFRC) for sustainable structural applications. The hydrophobic nature of PE fiber induces weak bond at fiber/matrix interface [17,18,19] In this case, the incorporation of fly ash may lead to negative effect to the tensile strain capacity of PE-ECC, the concern turns to how to enhance the connection between fiber and matrix.
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