聚羧酸减水剂分子结构对早强性能的影响

Effect of the structure of polycarboxylate superplasticizer on property of early strength

通过调整侧链长度、酸醚比、链转移剂用量和功能单体制备12种聚羧酸减水剂,探讨其对早强、减水率和水化热的影响。结果表明:随着侧链长度增加、酸醚比降低,阳离子单体的引入,混凝土早期强度提高;当侧链长度n=90、酸醚比为3.5、功能单体采用DAC、链转移剂用量为3.5%时,所制备聚羧酸减水剂90PC3.5-DAC1的早强效果最佳,与SIKA-Z相比,混凝土20 h、24 h抗压强度比分别为109%、114%;聚羧酸减水剂会延缓水泥水化,且掺量增加延迟加剧;相同掺量下,减水剂90PC3.5-DAC1延缓水化能力明显弱于减水剂54PC4.5,即90PC3.5-DAC1能使水泥正常水化,产生较高的早期强度。

Twelve polycarboxylate superplasticizers were synthesized by adjusting the length of side chain,the mole ratio of acid-ether,the amount of chain transfer agent and the functional monomer.The effects on early strength,water-reducing rate and hydration heat were discussed.It was found that,the early strength of concrete increased with the increase of side chain length and the decrease of acid-ether mole ratio and the introduction of cationic monomer.When the side chain length was n=90,the acid-ether mole ratio was 3.5,the functional monomer was DAC,and the amount of chain transfer agent was 3.5%,90PC3.5-DAC1 has the best ability on early-strength.Compared with SIKA-Z,the compressive strength ratio of concrete at 20 h and 24 h are 109%and 114%respectively.Polycarboxylate superplasticizer can delay cement hydration and the delay intensifies with the increase of the dosage.At the same dosage,the delayed hydration ability of 90PC3.5-DAC1 was significantly weaker than that of 54PC4.5,90PC3.5-DAC1 can make the normal hydration of cement,produce higher early strength.