Preparation and properties of ultra-high performance lightweight concrete

摘要

Based on orthogonal experiments, the ultra-high-strength lightweight concrete (UHPLC) with a strength exceeding 100?MPa was prepared using pottery sand (PS) and hollow glass microspheres (HGM) as the weight-reducing material and steel fibres as reinforcement. Through workability, apparent density, strength and early autogenous shrinkage tests, as well as scanning electron microscopy examinations, the effect of various material parameters on the basic performance of UHPLC was investigated, and their mechanisms were explored. The results revealed the optimal mix ratio of ordinary Portland cement : fly ash : silica fume : PS : HGM?=?1?:?0.200?:?0.133?:?0.533?:?0.067, a water/binder ratio of 0.16 and a volume ratio of steel fibres of 2. Under steam curing at 90°C for 48?h, the prepared UHPLC had an apparent density of 2031?kg/m~(3), compressive/flexural strengths of 112/16?MPa a slump/expansion of 260/590?mm, and specific strength of 0.055, achieving the goal of light weight and high strength. As the filler of composite materials, HGM can achieve lightweight and high strengthening of cement-based materials. HGM had a large water demand, increasing the autogenous shrinkage of UHPLC to a certain extent. The incorporation of steel fibres significantly increased the strength and apparent density of UHPLC, and its high elastic modulus inhibited the UHPLC shrinkage.