An economical ultra-high ductile engineered cementitious composite with large amount of coarse river sand

Conventional engineered cementitious composites (ECCs) are produced with low-volume and expensive ultrafine silica sand (maximum size 250 µm), which imposed negative influence on dry-shrinkage, cost and the practical application of ECC. In this study, an economical ultra-high ductile engineered cementitious composite featuring large-particle and high-volume ordinary river sand (RS) is developed. The gradation of ordinary river sand is consistent with that of fine aggregate in traditional concrete and its maximum size (4750 µm) is almost 20 times that of ultrafine silica sand (USS) in traditional ECC. Price of RS is about 1/30 of that of USS. The experimental results show that all river-sand ECCs (RS-ECC) present the strain-hardening and multiple-crack phenomena. Especially, the average tensile strain of RS-ECC with maximum sand size of 4750 µm and a sand/binder ratio of 0.55 is over 9%. Meanwhile, the cost of composites is reduced by more than 10%. The pseudo strain-hardening (PSH) indices of RS-ECCs are more than 30, which indicates that replacing USS with high-volume and large-particle RS in ECC is sufficient to meet the requirement of the ultra-high ductility although the use of RS increases the fracture toughness and decreases the fiber bridging complementary energy.

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