固硫灰中CaO含量一般高于粉煤灰而SiO2含量则低于粉煤灰,因此粉煤灰加气混凝土的钙硅比不宜直接用于固硫灰加气混凝土。改变燃煤灰渣和石灰的相对含量以调节蒸压混凝土的钙硅比,并研究钙硅比对水化产物、干密度、抗压强度及干燥收缩性能的影响。结果显示,干密度随钙硅比增大而增大;存在某一钙硅比使其抗压强度最高且干缩性能最小。当设计固硫灰蒸压混凝土配合比时,为达到较高的力学性能,其钙硅比应高于粉煤灰加气混凝土。
Circulating fluidized bed combustion(CFBC)fly ash generally has more CaO but less SiO2 than pulverized coal combustion(PCC)fly ash,so the optimum Ca/Si ratio of autoclaved concrete containing PCC fly ash may not be suitable for AAC containing CFBC fly ash.In this study,different Ca/Si ratio was set by changing the ratio of lime to coal fly ash,and the effect of Ca/Si ratio on the hydrates,dry density,compressive strength and dry shrinkage were then investigated.The results show that the dry density increases with the increase of Ca/Si ratio,and the maximum compressive strength and minimum dry shrinkage are simultaneously achieved at a certain Ca/Si ratio.It is confirmed that a higher Ca/Si ratio should be employed for AAC containing CFBC fly ash as compared with AAC containing PCC fly ash to achieve satisfactory mechanical properties.