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大体积混凝土极易产生收缩裂缝,因此常使用膨胀剂补偿收缩;矿物掺合料在大体积混凝土中使用,能降低水化热和温升,对避免温度裂缝的产生起到重要作用.但是,矿物掺合料的加入可能会影响膨胀剂的膨胀效能.研究了在模拟大体积混凝土温度下,粉煤灰掺量、补加石膏对限制膨胀率和强度的影响规律,并采用X-射线衍射(XRD)、热分析(TG-DTG)和扫描电子显微镜(SEM)进行了进一步分析.结果表明:在模拟大体积混凝土温度养护条件下,随着粉煤灰掺量的增加,限制膨胀率和强度降低;补加石膏可促进钙矾石(AFt)的生成,从而提高大掺量粉煤灰试件的限制膨胀率和强度.
Mass concrete can easily produce shrinkage cracks, so often use expansive agent to compensate shrinkage; Mineral admixture used in mass concrete can reduce heat of hydration and temperature rise, to avoid temperature cracks play an important role.However, The addition of mineral admixture may affect the expansion efficiency of expansive agent.The effects of fly ash dosage and additional gypsum on the expansion rate and strength at simulated bulk concrete temperature were studied and the effects of XRD, (XRD), thermal analysis (TG-DTG) and scanning electron microscopy (SEM). The results show that under the conditions of simulated mass concrete temperature curing, with the increase of fly ash content, Strength can be reduced. The addition of gypsum can promote the formation of ettringite (AFt), so as to increase the limited expansion rate and strength of high-volume fly ash samples.