煅烧温度对MgO膨胀剂反应活性及膨胀特性的影响

Effect of Calcination Temperature on Reactivity and Expansion Characteristics of MgO Expansive Agent

为拓宽活性MgO在大体积混凝土中应用,对不同煅烧温度下制得MgO的反应活性和微观结构进行了研究,并通过胶砂和混凝土的限制膨胀率研究其膨胀性能。结果表明:煅烧温度800℃~1000℃范围内,随着煅烧温度的提高,MgO化学活性显著降低,颗粒粒径逐渐增大,水化放热速率降低,并且MgO衍射峰逐渐尖锐且衍射强度增大;高活性MgO早期膨胀较快,补偿收缩明显,最终的膨胀量较小,低活性MgO的膨胀性能则相反。

MgO expansive agent had the characteristics of delayed expansion,stable expansion products and small hydration water demand,which can help solve the shrinkage and cracking problem of mass concrete,thus being applied in engineering practice.In order to broaden the application of active MgO in mass concrete,the reactivity and microstructure of MgO prepared at different calcination temperatures were studied in this paper,and its expansion performance was studied through the limited expansion rate of mortar and concrete.The results showed that with the increase of calcination temperature,the chemical activity of MgO decreased significantly,the particle size increased gradually,the hydration heat release rate decreases,and the diffraction peak of MgO gradually become sharp and the diffraction intensity increased in the range of calcination temperature 800℃~1000℃.High-activity MgO expanded rapidly in the early stage,with obvious compensation shrinkage,and the final expansion amount was small,while the expansion performance of high-activity MgO was opposite.