Engineered cementitious composites (ECC) with a high volume of volcanic ash: Rheological, mechanical, and micro performance

Environmental and economic concerns impel construction materials to employ as many local supplementary cementitious materials as feasible. In this research, a durable Engineered Cementitious Composites (ECC) is developed with the total substitution of fly ash (FA) by volcanic ash (VA). The rheological, mechanical, and micro performance of VA ECC reinforced with polyethylene fibers were comprehensively investigated. Specifically, the severe segregation of VA paste was overcome by systematic engineering of the paste rheology. A minimum paste viscosity of 6 Pa s was found to be effective for fiber dispersion. The compromised compressive strength of VA ECC due to the larger particle size and less pozzolanic activity (compared to FA) was successfully counteracted by the addition of silica fume and the reduction of water to binder ratio. The strain-hardening VA ECC attained 6.7–12.5% of tensile ductility with 46–91 μm of crack width. Moreover, robust self-healing capacity with crack sealing and strength enhancement was demonstrated. The durable ECC holds promise for new constructions and repair of aging infrastructures.