聚羧酸类混凝土引气剂的工程性能

针对高性能混凝土高施工性、高耐久性要求,通过掺用具有梳型结构的聚羧酸类引气剂实现高性能混凝土,研究了聚羧酸类引气剂对混凝土含气量、气泡间距系数、工作性、强度和抗冻融耐久性的影响及其与减水剂的相容性,分析了聚羧酸类引气剂改善混凝土性能的机理.研究表明:聚羧酸类引气剂在掺量为0.006%时,混凝土含气量和气泡间距系数便可满足高性能混凝土工程使用要求;该类引气剂与常用混凝土减水剂、缓凝剂相容,可与减水剂、缓凝剂复合使用;除引气作用外,聚羧酸类引气剂还具有塑化和保塑作用,尤其适用于低水胶质量比混凝土,可在不降低混凝土强度的情况下,提高混凝土抗冻融耐久性.因此,聚羧酸类引气剂可用于配制高性能混凝土和自密实混凝土.

Engineering performance of polycarboxylate based air entraining agent

To achieve high workability and high durability of high performance concrete(HPC) polycarboxylate based air entraining agent(AEA) with comb-type structures is adopted.The effects of polycarboxylate based AEA on air content,spacing factor,workability,strength,freeze and thaw durability of concrete,and its compatibility to water reducers were investigated.It is found that,when 0.006% dosage of polycarboxylate based AEA is used,the air content and spacing factor of concrete can meet the needs of HPC engineering.And it has good compatibility to common types of water reducers and set-retarders. Besides entraining air to concrete,the polycarboxylate based AEA may enhance the fluidity and the slump retention ability of concrete.It can be used especially for concrete with lower ratio of water to cementations materials.Polycarboxylate based AEA may modify the freeze and thaw durability of concrete without strength reduction.Therefore polycarboxylate based AEA may be used to produce HPC and self compacting concrete.