粉煤灰对铁铝酸盐水泥水化过程的影响

Effect of fly ash on the hydration process of ferroaluminate cement

通过测试流动度、凝结时间、水化热、电阻率、抗压强度、pH值以及水化产物等研究了不同掺量粉煤灰对铁铝酸盐水泥水化过程的影响。结果表明,掺入粉煤灰提高了水泥浆体的流动度,并缩短了凝结时间。铁铝酸盐水泥的早期水化速率较快,表现为早期水化放热较快,电阻率快速增长。掺入粉煤灰使得试件抗压强度降低,掺入30%粉煤灰的试件在3、28 d时的抗压强度较空白组相应值分别下降了40.4%、50.7%。在90 d龄期内,孔溶液的pH值呈现出先升高后降低的趋势,空白组试件的pH值在水化3 h时为11.09,在水化48 h时升至11.59,而后逐渐降低,在水化90 d时降至10.87。掺入粉煤灰可提高孔溶液的pH值。铁铝酸盐水泥的主要水化产物为钙矾石,而粉煤灰由于水化环境碱度不足未能发挥火山灰效应。

Through tests on fluidity,setting time,hydration heat,electrical resistivity,compressive strength,pH value,and hydration products,the influence of different fly ash contents on the hydration process of ferroaluminate cement was investigated.The results indicate that the addition of fly ash enhances the fluidity of the cement paste and reduces the setting time.The early hydration of ferroaluminate cement is rapid,characterized by faster early hydration heat release and rapid increase in electrical resistivity.The addition of fly ash results in a decrease in compressive strength of specimens.At 3 d,specimen with 30%fly ash shows a 40.4%reduction in compressive strength compared with the control specimen,and at 28 d,it decreases by 50.7%.The pH value of the pore solution exhibits an initial increase followed by a decrease during 90 days.For the control specimen,the pH value is 11.09 at 3 h,rises to 11.59 at 48 h,and gradually decreases,reaching 10.87 at 90 d.Adding fly ash can increase the pH value of the pore solution.The primary hydration product of ferroaluminate cement is ettringite,while fly ash,due to insufficient alkalinity in the hydration environment,fails to exhibit a pozzolanic effect.