36 / 2022-03-21 11:32:18

Experimental and numerical investigation on the long-term performance of Engineered Cementitious Composites (ECC) with high-volume fly ash

ECC; Fly Ash; Long-Term Performance; Micromechanics; Tensile Properties

High-volume fly ash (FA) has been widely adopted in the material design of engineered cementitious composites (ECCs) to improve the mechanical properties of the material, and to develop a green approach for preparing ECCs. Previous studies have mainly focused on the mechanical performance of ECCs cured for 28 days. The secondary hydration of fly ash leads to delayed strength gain after 28 days, which may cause the composites to violate the long-term strain hardening criterion. In this study, multiple-scale experiments were conducted on ECC with high-volume FA at curing ages of 28, 90, 180, and 365 days, to investigate the long-term performance of ECC with evolving micromechanical properties. The results showed that after 28 days, the fiber/matrix interfacial bonding, matrix compressive strength, and fracture toughness gradually increased with curing time and plateaued at a certain value after 180 days, while the tensile strain capacity of the specimens continued to decrease with age. Based on the micromechanical parameters tested at different ages, a physical model was developed to simulate and predict the tensile performance of ECCs as it evolves with time. The simulation results were in agreement with those of the experimental tests. Therefore, design guidelines were proposed based on the predictions to enhance the robustness of the ECC’s long-term performance.