颗粒分布对水泥与减水剂相容性的影响

Influence of Particle Size Distribution of Cement on Compatibility of Cement and Superplasticizer

采用Marsh筒法与净浆流动度法研究了用相同熟料粉磨制得的颗粒分布不同的水泥样品与减水剂的相容性,分别探讨了粉体比表面积、均匀性系数(n)、特征粒径(x′)、堆积孔隙率与相容性的关系.结果表明:样品比表面积、n和堆积空隙率越大,x′越小,水泥与减水剂的相容性越差;当比表面积与x′相近时,n越大,浆体的流动性越差,饱和点掺量越大或饱和点Marsh时间越长,流动度经时损失越小;随着样品比表面积的增大,水泥与减水剂的相容性变差;对于n大的样品,比表面积增大对相容性的不利影响更为显著;降低堆积空隙率能使水泥颗粒分布连续而较宽;自身需水性较低的微细粉体有利于改善水泥与减水剂的相容性.

The compatibility of superplasticizer and cement with the same clinker but different particle size distributions （PSDs） was investigated via the Marsh cone method and the paste fluidity method, and the effects of the specific surface area of powders, the uniformity coefficient n, the characteristic diameter x′ and the packing porosity on the compatibility were analyzed. The results show that （ 1 ） the compatibility becomes poor with the increase of the specific surface area, n and the packing porosity, and with the decrease of x′; （2） when the specific surface area is approximately equal to x′, with the increase of n, the paste fluidity becomes poor, the saturation point dosage and the Marsh time increase, and the loss of fluidity with time reduces; （3） with the increase of specific surface area, the compatibility becomes poor, and the negative influence of specific surface area on the compatibility becomes critical at a narrow PSD; （4） low packing porosity may result in continuous and wide distribution of cement particles： and （5） powders with low water reqiirement are more suitable for imoroving the compatibility.