利用膨胀珍珠岩制备超高性能轻及次轻骨料混凝土

The preparation of ultra-high performance lightweight and semi-lightweight aggregate concrete with expanded perlite

基于颗粒紧密堆积理论,使用超高性能混凝土(UHPC)和广泛易得的低强度轻骨料(筒压强度0.3 MPa)膨胀珍珠岩(EP),制备了干表观密度为1800 kg/m^(3)、强度为121.9 MPa的超高性能轻骨料混凝土(UHPLWAC)和干表观密度为1989 kg/m^(3)、强度为140.9 MPa的超高性能次轻骨料混凝土(UHPSLWAC)。除强度评价外,电通量和RCM测试结果表明制备的轻(次轻)骨料混凝土也具有优异的抗渗性能,属于超高性能混凝土范畴;此外,抗冲击试验结果表明,膨胀珍珠岩取代石英砂能有效提升UHPC抗冲击性能。使用近场动力学模拟分析膨胀珍珠岩对UHPLWAC和UHPSLWAC力学性能的影响机制,结果表明通过降低轻骨料粒径,提高其分散性,进而显著降低材料的应力集中现象,是UHPLWAC和UHPSLWAC获得优异力学性能的关键。本研究为低强度轻骨料在高强、超高强轻骨料混凝土的应用上提供了新思路。

Based on the close packing theory,ultra-high performance lightweight aggregate concrete(UHPLWAC)with dry apparent density of 1800 kg/m3 and compressive strength of 121.9 MPa and ultra-high performance semi-lightweight aggregate concrete(UHPSLWAC)with dry apparent density of 1989 kg/m3 and compressive strength of 140.9 MPa have been prepared by the blending of ultra-high performance concrete(UHPC)and a low strength lightweight aggregate(cylinder compressive strength of 0.3 MPa),i.e.expanded perlite(EP).In addition to the strength evaluation,the electric flux and RCM test results show that the prepared lightweight(semi-lightweight)aggregate concrete also has excellent impermeability,which belongs to the category of ultra-high performance concrete.Besides,the impact test results show that the expanded perlite,instead of quartz sand,can effectively improve the impact resistance of UHPC.The influence mechanism of expanded perlite on the mechanical properties of UHPLWAC and UHPSLWAC is analyzed by peridynamics simulation.The results show that the stress concentration can be effectively reduced by decreasing the particle size of lightweight aggregate,as well as increasing the dispersion of aggregate.This study provides a novel idea for the application of low strength lightweight aggregate in the development of high strength and ultra-high strength lightweight concrete with enhanced properties.