Preparation and properties of ultra-high performance lightweight concrete

Abstract

Based on orthogonal experiments, an ordinary Portland cement (OPC)-fly ash (FA)-silica fume (SF) ternary cementitious material system was developed. 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 fibers as reinforcement. Through workability, apparent density, strength, and early autogenous shrinkage tests, as well as SEM 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 OPC : FA : SF : PS : HGM = 1 : 0.200 : 0.133 : 0.533 : 0.067, a water-binder ratio of 0.16, and a volume ratio of steel fibers of 2%. Under steam curing at 90°C for 48 h, the prepared UHPLC had an apparent density of 2031 kg/m3, 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 fibers significantly increased the strength and apparent density of UHPLC, and its high elastic modulus inhibited the UHPLC shrinkage.