含MgO膨胀剂的水泥砂浆在恒温和变温养护制度下的限制膨胀率  

Restricted Expansion Rate of Cement Mortar Containing MgO Expansive Agent under Constant and Variable Temperature Curing Conditions

作　　者：段劲松[1] 崔勇 付勇攀 宋奇达 于晓 王涛[1] 凌研方 房奎圳 DUAN Jinsong;CUI Yong;FU Yongpan;SONG Qida;YU Xiao;WANG Tao;LING Yanfang;FANG Kuizhen(Beijing Urban Construction Group Co.,Ltd.,Beijing 100088,China;CCTEG Coal Mining Research Institute,Beijing 100013,China;School of Civil Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]北京城建集团有限责任公司,北京100088 [2]中煤科工开采研究院有限公司,北京100013 [3]清华大学土木工程系,北京100084

出　　处：《硅酸盐通报》2024年第9期3149-3156,共8页Bulletin of the Chinese Ceramic Society

基　　金：国家自然科学基金面上项目(51778334)。

摘　　要：温度对MgO膨胀剂在水泥基材料中补偿效果的影响至关重要。本文通过测试不同养护制度下水泥砂浆的限制膨胀率、水化产物矿物组成、产物形貌和分布以及MgO膨胀剂的水化程度,揭示了MgO膨胀剂在水泥基材料中的温度敏感性。结果表明,随着养护温度升高,含8%(质量分数)中速型MgO水泥砂浆的限制膨胀率显著增加,特别是在50℃养护条件下,其28 d限制膨胀率是25℃下的1.7倍。不同养护制度对MgO膨胀性的影响规律存在差异,在高温升-慢冷却的变温养护制度中,含快速型MgO的水泥砂浆限制膨胀率最大,且降温过程膨胀率降低趋势明显,而在低温升-快冷却的变温养护制度下,体系水化持续进行,MgO膨胀效果可持续发挥。此外,MgO在水泥净浆中的反应程度也随养护温度的升高而增加,为25%~65%,水化产物Mg(OH)_(2)主要以凝胶状态存在,但随着温度升高到50℃,部分凝胶状的Mg(OH)_(2)转化为片状晶体,从而进一步优化了水泥基材料的微观结构和膨胀性能。该研究为理解和优化MgO膨胀剂在水泥基材料中的应用提供参考。The influence of temperature on the compensation effect of MgO expansive agent in cement-based materials is crucial.This article reveals the temperature sensitivity of MgO expansive agent in cement-based materials by testing the restricted expansion rate,mineral composition,morphology and distribution of hydration products,and hydration degree of MgO expansive agent of cement mortar under different curing conditions.The results show that with the increase of curing temperature,the restricted expansion rate of medium speed MgO cement mortar containing 8%(mass fraction) significantly increases,especially under the curing condition of 50 ℃,and 28 d restricted expansion rate is 1.7 times that of 25 ℃.There are differences in the impact of different curing conditions on the expansion of MgO.In the high-temperature rise slow cooling variable temperature curing condition,the cement mortar containing rapid MgO has the highest restricted expansion rate,and the expansion rate decreases significantly during the cooling process.However,in the low-temperature rise fast cooling variable temperature curing condition,the hydration of the system continues,and the MgO expansive effect can be sustained.In addition,the reaction degree of MgO in cement paste also increases with the increase of curing temperature,which is 25%~65%.The hydration product Mg(OH)_(2) mainly exists in the gel state,but with the temperature rising to 50 ℃,some gel like Mg(OH)_(2) is transformed into lamellar crystals,further optimizing the microstructure and expansion performance of cement-based materials.This study provides a reference for understanding and optimizing the application of MgO expansive agent in cement-based materials.

关 键 词：MGO膨胀剂 水泥基材料 温度敏感性 限制膨胀率 变温养护 

分 类 号：TU528[建筑科学—建筑技术科学]