Investigation of matrix cracking properties of engineered cementitious composites (ECCs) incorporating river sands

Typical ECC mix design omits normal aggregates and adopts only fine micro silica sands. Few studies report the possibility of using river sands in ECC mix design. While the resulting ECC is more economical with improved time-dependent properties, a very different tensile strain-hardening behavior is also observed. The current study reveals the fundamental mechanisms by investigating the matrix cracking properties ECC incorporating river sands. Results show that the use of river sands alters the matrix fracture toughness and introduces microcracks along the aggregate/matrix interface. As a result, the matrix cracking strength of the high strength ECC with river sands is reduced, which favors multiple cracking and tensile strain-hardening. In contrary, the matrix cracking strength of the normal strength ECC with river sands is increased, which hinders multiple cracking and tensile strain-hardening.