养护温度对MgO微膨胀混凝土变形性能的影响

研究了养护温度对MgO微膨胀混凝土变形性能的影响,利用XRD、DSC-TG和SEM分析了MgO在水泥浆体中的水化机理和膨胀特性。结果表明:养护温度对外掺MgO砂浆的自由膨胀率影响显著,养护温度越高,早期膨胀越大,膨胀曲线也越早达到稳定。养护温度的升高加快了MgO的水化速率、加速Mg(OH)_2晶体的形成和增大,这是由于温度的升高加速了MgO水化后Mg²⁺和OH^-的迁移速率,使得Mg(OH)_2晶体的形成速度也相应加快,膨胀效应提前。随着养护温度的升高,Mg(OH)_2微观结构也发生了一定的变化,由短片状的晶体变成纤维状,并伴有微裂纹生成。

Influence of curing temperature on the deformation properties of MgO micro-expansive concrete

The influence of curing temperature on the deformation properties of MgO micro-expansive concrete were studied.Hydration mechanism and expansion characteristics of MgO in cement paste were analyzed by XRD、DSC-TG and SEM.Results indicated curing temperature had a great effect on free expansion ratio of MgO mortar,the higher the curing temperature,the bigger the early expansion,the sooner the inflation curves stabilized.Curing temperature accelerated the hydration rate of MgO and the formation of Mg(OH)2 crystals and increasment,because the increased temperature accelerated migration rate of Mg^2+ and OH^- after the MgO hydrating,then made the formation of Mg(OH)2 crystal to be accelerated accordingly and expansion effect in advance.With the increase of curing temperature,there were some changes in microstructure of Mg(OH)2,the short lamellar crystals turned fibrous which accompanied micro cracks.