Sustainable and cost-effective ultra-lightweight engineered cementitious composite: Design and material characterization

Lightweight ECC (LWECC) has been extensively concerned due to its superior tensile performance, durability and low self-weight. However, the high environmental impact and material cost of ECC impede its broader engi-neering applications. The objective of this research is to develop a novel sustainable and cost-effective ultra-lightweight engineered cementitious composite (ULECC) under the micro-mechanical design theory. Five lightweight ECCs were designed using different lightweight fillers (LF) and replacement ratios with three mix-tures being categorized as ULECC. The impacts of LF content and curing regimes (standard or hot-water curing) on the density, mechanical, and microstructural properties were investigated. The proposed ULECC exhibited impressive tensile behavior and a low density of 950-1260 kg/m3. The specific tensile strengths (strength-to-density ratio) and strain capacities of ULECC were 110% and 70% higher than conventional M45-ECC. Compared to the conventional LWECC, ULECC offered the competitive strength and ductility with a substantial increase in sustainability and reduction of material cost. Hot-water curing played a vital role in improving ductility-related performance. The micro-mechanical design theory and SEM analysis of ULECC well explained the test results. This research lays the groundwork for developing the sustainable and economical ULECC for future structural application.