摘   要：以C30自密实混凝土为研究对象，研究了单掺和复掺不同类型的减水剂、粉煤灰掺量和砂率对自密实混凝土工作性能和抗压强度的影响，并获得了C30自密实混凝土的最佳配合比。结果表明，高效型聚羧酸减水剂与保坍型聚羧酸减水剂复掺总量0.7%，质量比在3:7时，混凝土的工作性能满足一级性能指标要求，且1h扩展度损失仅为70mm。粉煤灰的掺加能有效改善自密实混凝土的流动性，掺量30%时相比10%，扩展度由590mm提高到690mm，扩展时间T50由14.3s降低至8.4s，且28d抗压强度较空白样仅降低15%。砂率在52%时流动性最好，扩展度为710mm，T50为6.1s，且对抗压强度的影响较低。

Abstract: The influence of different kinds of superplasticizer, fly ash and sand ratio on working performance and compressive strength of C30 slef-compacting concrete are researched to get the optimum mix proportion. The experimental results show that workability of self-compacting concrete is reached first level performance target and the loss of extension degree at 1h is decreased to only 70mm after adding 0.7% high efficient type of polycarboxylate superplasticizer and slump retaining type of polycarboxylate superplasticizer whose mass ratio is 3:7. Liquidity of self-compacting concrete can be improved significantly by adding fly ash. Extension degree is increased from 590mm to 690mm, and extension time T50 is decreased from 14.3s to 8.4s when the mixing amount of fly ash is 30% compared to 10% with only 15% reduction of 28d compressive strength. Under the condition of 52% sand ratio which has been proved to be good at liquidity of self-compacting concrete, the expansion degree is 710mm, the T50 is 6.1s, and the influence on the compressive strength is low.