自密实轻骨料混凝土抗离析性控制与试验方法

Segregation resistance control and test methods for self-compacting lightweight concrete

轻骨料混凝土容易出现因轻骨料上浮而导致的混凝土离析现象,严重影响混凝土质量.通过对混凝土基体中骨料的受力和运动状态进行分析,研究了影响混凝土骨料上浮和下沉的主要因素.并在此基础上,结合普通自密实混凝土和轻骨料混凝土的配合比设计方法,设计了2种28d抗压强度分别为42.6MPa和50.1MPa的自密实轻骨料混凝土,通过湿筛试验、粗骨料分层试验、试件断面切片试验以及观察的方法验证了所设计的自密实轻骨料混凝土具有良好的抗离析性能.

Lightweight coarse aggregates are easy to float up in the paste matrix of lightweight concrete that can impact the concrete quality seriously. Force and movement analyses on lightweight aggregate in the paste matrix were made. The main factors which influenced the floating and sinking of the aggregate were obtained. Two kinds of self-compacting lightweight concretes,with 28-day compressive strength of 42.6 MPa and 50.1 MPa respectively,were designed based on the aggregate floating analysis combining with the design method of lightweight concrete and conventional self-compacting concrete. It is verified that the designed self-compacting lightweight concretes have good segregation resistance property by the wet sieve segregation test,column segregation test,slice test and visual observation.