轻集料对轻质超高性能混凝土性能影响研究

Research on the Influence of Lightweight Aggregate on the Performance of Lightweight Ultra High Performance Concrete

以万州新田长江大桥工程为依托,通过试验研究了轻集料的颗粒级配、粒径、粒型、筒压强度和预湿程度等对轻质超高性能混凝土(LUHPC)工作性能、力学性能和收缩的影响,同时通过轻集料孔结构分析和SEM初探了轻集料改善LUHPC性能的微观机理。研究结果表明:随着轻集料最大粒径的减小和筒压强度的增大,LUHPC的表观密度增大,力学性能提高;当细轻集料粒径2.36~4.75mm∶1.18~2.36mm为7∶3时,细轻集料与各种粉料间的堆积程度最大,抗压强度最高;圆球型细轻集料制备最适合制备LUHPC;随着轻集料预湿饱水程度增加,LUHPC内部相对湿度提高,LUHPC收缩减小。高强细轻集料的多孔结构,可以吸收大量水分,混凝土在凝结硬化后可形成轻集料-水泥石界面处的嵌锁结构,从而大幅度提升LUHPC性能。

Relying on the Wanzhou Xintian Yangtze River Bridge project,the effects of particle size,particle size,particle type,cylinder pressure strength and pre-wetting degree of light aggregate on the working performance,mechanical properties and shrinkage of light ultra-high-performance concrete(LUHPC)were studied.At the same time,the micromechanism of light aggregate to improve the performance of LUHPC was preliminarily explored through light aggregate pore structure analysis and SEM.The results show that with the decrease of the maximum particle size of the light aggregate and the increase of the cylinder pressure strength,the apparent density of the LUHPC increases and the mechanical properties improve.When the particle size of the fine light aggregate is 2.36~4.75mm∶1.18~2.36mm is 7∶3,the accumulation degree between the fine light aggregate and various powders is the largest,and the compressive strength is the highest.Ball type thin and light aggregate preparation is most suitable for preparing LUHPC.As the degree of pre-wet saturation of light aggregate increases,the relative humidity inside LUHPC increases and the shrinkage of LUHPC decreases.The porous structure of high-strength,fine and light aggregate can absorb a lot of water.After setting and hardening of concrete,it can form an interlocking structure at the interface between light aggregate and cement stone,thereby greatly improving the performance of LUHPC.