关键词: 轻质高强混凝土;烧结粉煤灰陶粒;超细粉煤灰;力学性能;微观结构

Abstract: Lightweight and high strength concrete was prepared by using sintered fly ash ceramsites as coarse aggregates , partially substituting cement with ultra-fine fly ash and the first grade original fly ash . The effects of the blending ratio of two kinds of fly ashes and the total content of fly ash on the mechanics performance , dry apparent density and the microstructure of concrete were investigated .The results show that the addition of ultra-fine fly ash can refine the crystal size of the cement hydration product , upset the growth orientation of calcium hydroxide and reduce the internal structure defects of concrete , which makes the paste more uniform .When the blending ratio of the ultra-fine fly ash to the first grade original fly ash is 1:1 , and the total content of fly ash is 40%, the LC50 grade lightweight and high strength concrete, with the compressive strength of 58.6 MPa at 28 d and the dry apparent density of 1900 kg/m3 , is prepared .

Key words: lightweight&high strength concrete;sintered fly ash ceramsite;ultra-fine fly ash;mechanical property;microstructure