聚羧酸减水剂对活性粉末混凝土性能影响

Effect of Polycarboxylate Superplasticizer on the Properties of Reactive Powder Concrete

研究了不同类型及不同掺量的聚羧酸减水剂对活性粉末混凝土工作性能、力学性能、生成物及微观结构的影响。研究结果表明:聚羧酸减水剂主要通过释放自由水来影响活性粉末混凝土的水化进程。建议聚羧酸减水剂有效成分掺量范围为0.5%-0.8%。活性粉末混凝土流动性、抗压和抗折强度随减水剂有效成分掺量的增加呈先升后降的趋势。掺早强型减水剂的活性粉末混凝土力学性能更优,而掺缓凝型减水剂的活性粉末混凝土施工性更高。两种减水剂都具有非常显著的缓凝效果。减水剂掺量适当提高及高温养护能够促进活性粉末水化并改善微观结构。早强型减水剂有利于钙矾石的生成,而缓凝型减水剂则能促C_(3)S的水化。

The effects of different types and different amounts of polycarboxylate superplasticizer on the workability, mechanical properties, products and microstructure of reactive powder concrete are studied in the paper. The results show that polycarboxylate superplasticizer mainly affects the hydration process of reactive powder concrete by releasing free water. The content range of polycarboxylate superplasticizer is suggested between 0.5%~0.8%. The fluidity, compressive strength and flexural strength of reactive powder concrete increase first and then decrease with the increase of the content of water reducing agent. The mechanical properties of RPC with early strength superplasticizer are better, while the workability of RPC with retarding superplasticizer is higher. The two kinds of water reducing agents have very significant retarding effect. Appropriate increase of water reducer and high temperature curing condition can promote the hydration process of reactive powder and improve the microstructure of RPC. Early strength superplasticizer is beneficial to the formation of ettringite, while the retarding superplasticizer can promote the hydration of C;S.