本文采用氟硅渣对硫酸铝基无碱液体速凝剂进行了改性,并测试了氟硅渣改性后无碱液体速凝剂的性能指标.采用XRD、TG-DTG和SEM表征手段分析了氟硅渣改性硫酸铝基无碱液体速凝剂对水泥水化过程的作用机理.结果表明:随着氟硅渣用量的增加,砂浆的快凝效果和强度均呈先增大后减小的趋势;用氟硅渣改性无碱液体速凝剂时,氟硅渣的掺量以5.0％(质量分数)为宜,此时掺改性速凝剂水泥试件的初凝时间为1 min 20 s,终凝时间为5 min 20 s,l d抗压强度为13.8 MPa,28 d抗压强度为52.4 MPa.氟硅渣中的二氧化硅与水泥水化产物氢氧化钙反应形成水化硅酸钙,有利于提高水泥的早期强度,但氟与氢氧化钙反应会产生大量的氟化钙沉淀,阻碍水泥水化硬化过程.
Effect of Aluminum Sulfate Base Alkali-Free Liquid Accelerating Agent Modified by Fluorine Silicon Slag on Cement Properties
In this paper,the aluminum sulfate based alkali-free liquid accelerating agent was modified by fluorine silicon slag,and the performance index of alkali-free liquid accelerating agent modified by fluorine silicon slag was tested.XRD,TG-DTG and SEM were used to explore the action mechanism of aluminum sulfate base alkali-free liquid accelerating agent modified by fluorine silicon slag on cement hydration process.The results show that with the increase of fluorine silicon slag content,the rapid setting effect and strength of mortar increase first and then decrease.When the alkali-free liquid accelerating agent is modified by fluorine silicon slag,the appropriate content of fluorine silicon slag is 5.0％(mass fraction).At this time,the initial setting time is 1 min 20 s,the final setting time is 5 min 20 s,1 d compressive strength is 13.8 MPa,and 28 d compressive strength is 52.4 MPa.Calcium silicate hydrate is formed by the reaction of silica in fluorine silicon slag and cement hydration product calcium hydroxide,which is beneficial to improve the early strength of cement.However,the process of cement hydration and hardening process is hindered by the reaction of fluorine and calcium hydroxide to produce a large amount of calcium fluoride precipitation.
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