Tensile properties and constitutive model of ECC with waste basalt powder and basalt sand

In this study, ultrafine basalt powder (UBP) and basalt sand (BS) were utilized to replace fly ash and quartz sand, respectively, in the preparation of Engineered Cementitious Composites (ECC). The substitution rates of UBP and BS were established at 0%, 25%, 50%, and 100%. Uniaxial tensile experiments were conducted on the prepared ECC specimens to examine the tensile strength and ductility of ECC under varying mix ratios. A constitutive model (L&C) integrating a straight line and a curve was established based on the Sigmoid function. The findings indicate that when UBP was utilized as a complete substitute for fly ash, the ultimate strain, fracture elongation, and tensile strength of ECC exhibited increases of 140.1%, 187.1%, and 44.7%, respectively. In addition, the pseudo strain strengthening coefficients, specifically σ 0 /σ c and J b /J tip , increased from 2.30±0.22 and 14.58±1.86 in the control group to 2.97±0.29 and 27.49±1.95, respectively. When BS completely replaced quartz sand, tensile strength decreased by 23.4%. However, the ratios σ 0 /σ c and J b /J tip improved from 1.42±0.08 and 13.49±1.18 in the control group to 1.90±0.13 and 19.58±1.51, respectively, enabling ECC to better satisfy strength and energy criteria. Consequently, ultimate tensile elongation and fracture elongation increased by 42.2% and 53.1%, respectively. After conducting a thorough analysis and comparison, it is evident that the L&C model, which is based on the Sigmoid function, demonstrates a higher correlation than the traditional bilinear model.