Mechanical properties of sustainable high strength ECC with substitution of cement by limestone powder

The high strength ECC normally contains high cement amount due to the absence of coarse aggregate, which negatively impact its environmental friendliness. In this paper, the limestone powder (LP) was utilized to partially substitute cement in high strength ECC, and thus improve its tensile performance and sustainability. The experimental results show that the substitution of cement by LP decreased the hydration products in ECC upon the reduced cement usage; as a result, the compressive and first tensile cracking strength of ECCs was diminished, however, the finer LP can compensate the above negative effect. Nevertheless, the LP addition is profitable to the tensile strain capacity of ECC since it can be increased to 7.83% as compared with 3.29% that of control ECC mixture, moreover, this positive effect can be further enhanced as the usage of finer LP. In another aspect, the increased LP-to-cement replacement ratio tended to lower tensile strength of ECC, except for the ECC mixture with replacement ratio of 20%, in which the tensile strength was enhanced by 11.9% owing to the dilution effect upon the increased water-to-cement ratio. In addition, the incorporation of LP can effectively reduce the environmental impact of ECCs.