无碱无氯液体速凝剂的性能及其作用机理

Performance and Mechanism of a New Alkali-free and Chloride-free Liquid Accelerator

对实验室制备的一种新型无碱无氯液体速凝剂进行了凝结时间、抗压强度等宏观性能的检测,并利用XRD、SEM等现代测试手段进行了微观机理分析。结果表明,当速凝剂掺量为4.0%～6.0%时,试样凝结时间、1d抗压强度及28d抗压强度比均满足JC477-2005《喷射混凝土用速凝剂》标准的要求;同时,速凝剂掺量为4.0%～4.5%时,试样后期(28d)强度基本不损失;速凝剂的掺入加快了水泥早期水化,消耗了大部分水泥水化生成的氢氧化钙,同时生成大量结晶程度良好的钙矾石晶体,促进早期强度的发展。

A new alkali-free and chloride-free liquid accelerator was synthesized in laboratory and its macroscopical performances such as setting time and compressive strength were systematically evaluated,meanwhile the microscopical mechanism was also analyzed by modern testing methods like XRD and SEM.The results indicate that the setting time,1 day compressive strength,and 28 day compressive strength ratio of the samples with 4.0%~6.0% accelerator can meet the standard of JC477-2005,and the 28 day compressive strength of the sample has almost no loss with 4.0%~4.5% accelerator dosage.Furthermore,the accelerator can promote the early hydration speed of cement,consume most of calcium hydroxide produced by cement hydration,meanwhile bring a large number of ettringite crystallites with good crystallization,and promote the development of the early strength.