Design-driven approach for engineered geopolymer composite with recorded low fiber content

Abstract

How to design an engineered cementitious composite (ECC) achieving both economic viability and ultra-sustainability has been the longstanding goal of ECC community. This study presents a design-driven approach to tackle this challenge through yielding a low matrix fracture toughness and a sufficiently strong interfacial bonding between fiber and matrix concurrently. As a result, only 0.2 % fiber content was sufficient for achieving robust strain-hardening in Engineered Geopolymer Composite (EGC), which, to the authors’ knowledge, is the lowest recorded thus far. The tensile strain-to-fiber content ratio reached 25, a remarkable 233 % higher than the existing strain-hardening composites. Besides, the compressive strength was around 40 MPa, marking the highest specific strength among the ECCs with a density below 1450 kg/m3. Leveraging the high porosity of 38 % and the presence of shrinkage micro-cracks in the matrix, a low fracture toughness, combined with a robust friction between fiber and matrix, facilitated the noticeable strain-hardening. The reaction product was identified as a dense alkaline aluminosilicate hydrate (N-A-S-H) gel, benefiting the interfacial bonding and compressive strength. The embodied energy and carbon of the EGC diminished by 27 % and 63 % compared to ordinary concrete, respectively, and the corresponding cost was 79 % lower than the classic M45-ECC, contributing significantly to ultra-sustainability.