膨胀剂在大体积混凝土环境下的膨胀效能研究  

The effects of fly ash dosage and adding gypsum on the expansion effect of expansive agent at simulation large volume concrete environment

作　　者：李国新[1] 张歌[1] 史琛[1] 黄汝杰[1] 

机构地区：[1]西安建筑科技大学材料与矿资学院,陕西西安710055

出　　处：《西安建筑科技大学学报（自然科学版）》2016年第2期289-295,共7页Journal of Xi'an University of Architecture & Technology(Natural Science Edition)

基　　金：陕西省自然科学基础研究计划基金资助项目(2014JQ7251)

摘　　要：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.Shrinkage cracks usually occur in mass concrete easily,so the expansive agent is often used to compensate the shrinkage.Both the heat of hydration and temperature rise in the mass concrete can drop due to using the mineral admixtures which benefit to avoiding the produce of temperature crakes.However,the adding of mineral admixture may significantly affect the expansive agent.The effects of the fly ash dosage and adding gypsum on the limit expansion rate and compressive strength under the simulated mass concrete temperature were researched.Furthermore,the methods of XRD,TG-DTG,and SEM were used to research the reasons.The results show that as the dosage of fly ash increased,the limit expansion rate and compressive strength reduced,and both the limit expansion rate and strength were improved by adding dehydrates gypsum due to the more ettringite.

关 键 词：大体积混凝土 粉煤灰 硫铝酸盐膨胀剂 钙矾石 

分 类 号：TU528[建筑科学—建筑技术科学]