外掺氧化镁混凝土水化宏细观试验研究

外掺氧化镁能够补偿混凝土的收缩变形 ,对于大体积混凝土结构的抗裂有重大意义 ,得到了广泛的工程应用。本文通过一系列宏观试验检验了氧化镁对混凝土物理力学性能的影响 ,发现外掺氧化镁会降低混凝土的抗压强度和抗冻、抗渗性能。借助高倍连续变焦显微系统对外掺氧化镁混凝土的水化过程进行了细观观察 ,细观尺度下氧化镁颗粒按粒径、颜色和表面形态可以分为三种 ,其中小粒径青色球状透明颗粒即氧化镁高度水化的形态 ;水泥水化过程中 ,颗粒连接形成具有强度的细观结构 ,而氧化镁的水化过程中 ,较多的以细小游离颗粒形态存在 ;氧化镁颗粒在水化过程中发生崩解 ,释放能量 ;并运用细观试验研究结论解释相关宏观试验结果

Experimental study on hydration process of cement added with magnesia in macro level and meso level

Adding magnesia can compensate shrinkage of concrete and prevent crack of concrete, this technique is applied widely.Several experiments show that compression strength and frost resistance of concrete declines when magnesia is added. The hydration of cement with adding magnesia is observed in meso level. The grains can be sorted into three types by grain size, color and form of grain surface. One type of the grains with green crystal globosity is the form of highly hydrated magnesia. The cement grains unite into meso structure with strength during the hydration of cement while magnesia exists as fine dissociated grains during hydration of magnesia. Hydrated magnesia grains break up and release energy. The result of mesoscopical observation can be used to explain the interrelated macroscopical experiment.