Preparation and mechanical properties of ultra-lightweight engineered cementitious composites

Abstract:

To address the issues of low strength and high material costs associated with ultra-lightweight engineered cementitious composites (ULECC), a sustainable ULECC that balances strength and cost has been developed based on micro-mechanical design theory. Two types of lightweight fillers were used: fly ash cenospheres (FAC) and hollow glass microspheres (HGM), along with cellulose filaments (CF) for nano-enhancement. The influence of the water-binder ratio was also examined. A total of five different mix ratios were designed, three of which can be classified as ULECC. The results indicate that the proposed ULECC, with only 1% PE fiber addition, achieves a density as low as 1 296 kg/m³, a strength of 41.9 MPa, and a tensile strain of 10.28%. The water-binder ratio is a key factor affecting ULECC′s mechanical properties. As this ratio decreases, the compressive strength, initial cracking strength, and tensile strength of ULECC gradually increase, while ductility first decreases and then increases. Scanning electron microscopy (SEM) analysis shows that incorporating lightweight fillers increases porosity and reduces the matrix′s fracture toughness, leading to a significant rise in ductility. Compared to traditional engineered cementitious composites (ECC), ULECC provides competitive deformation capability without excessive damage strength, which greatly improves sustainability and reduces material costs.