Microstructure and mechanical behaviors of engineered cementitious composites with high-volume fly ash

To study the effects of fly ash, polyvinyl alcohol (PVA) fibers and curing schemes on the microstructure and mechanical behaviors of Engineered Cementitious Composites (ECC) with high-volume fly ash, two kinds of fly ash and two PVA fibers were used in ECC. Besides, two curing schemes were adopted. The microstructure and mechanical properties of ECC were investigated by mercury intrusion porosimetry (MIP), scanning electron microscope (SEM), uniaxial compression test and three-point bending test. The results show that curing schemes and adding PVA fibers have a great influence on the differential curves of the pore size distribution of ECC and matrix in the range of 0–100 nm. There is a positive relationship between the deflection capacity or ultimate tensile strain of ECC and its macro pore volume fraction. Number of cracks increases with increasing the capillary pore volume fraction. On the contrary, the deflection capacity, ultimate tensile strain and number of cracks decrease when the transitional pore volume percent in ECC increases.