高效缓凝减水剂与氧化镁膨胀剂对混凝土性能的影响

Influence of high-efficiency retarding and water reducing agents and magnesium oxide expansion agents on the performance of concrete

研究了不同高效缓凝减水剂(柠檬酸、葡萄糖酸钠、柠檬酸镁、柠檬酸锂)分别与氧化镁膨胀剂的共同作用对混凝土工作性、力学性能、干燥收缩、抗裂性能的影响。结果表明:柠檬酸锂对掺氧化镁膨胀剂混凝土拌合物的坍落度有负面影响,但柠檬酸、葡萄糖酸钠、柠檬酸镁能在一定程度上改善混凝土的工作性;各高效缓凝减水剂均可提高混凝土的力学性能;葡萄糖酸钠、柠檬酸镁、柠檬酸锂均可减少混凝土的干燥收缩;柠檬酸、葡萄糖酸钠、柠檬酸镁均对氧化镁膨胀剂在混凝土中的补偿收缩作用有正向影响,其中,柠檬酸镁、葡萄糖酸钠的效果相对更好;柠檬酸对掺氧化镁膨胀剂的混凝土早期开裂性能有负面影响,会促进裂缝的产生。

The effects of different high-efficiency retarding(citric acid,sodium gluconate,magnesium citrate and lithium citrate)and water reducing agent combined with magnesium oxide expansion agent on the workability,mechanical properties,drying shrinkage,and crack resistance of concrete were studied.The results show that lithium citrate has a negative impact on the slump of concrete with magnesium oxide expansion agents,but the citric acid,sodium gluconate,and magnesium citrate can improve the workability of concrete to a certain extent.All high-efficiency retarding and water reducing agents can improve the mechanical properties of concrete.Sodium gluconate,magnesium citrate,and lithium citrate can all reduce the drying shrinkage of concrete.Citric acid,sodium gluconate,and magnesium citrate all have a positive effect on the compensatory shrinkage of magnesium oxide expansion agents in concrete,among which magnesium citrate and sodium gluconate have relatively better effects.Citric acid has a negative impact on the early cracking performance of concrete mixed with magnesium oxide expansion agent,which can promote the generation of cracks.