The X-ray powder diffraction analysis and the infrared absorption spectrum analysis testified that when the composite magnesia cementitious material, Which was made up of the caustic dolomite and the calcined magnesite by way of mixing according to suitable proportion between the caustic dolomite and the calcined magnesite, is mixed with the aqueous solution of MgCl2 according to the 5 mole ratio of MgO to MgCl2, the hydration phase of the hardened composite magnesium oxychloride cement is Mg3(OH),Cl·4H2O. Its microscopic characteristic possess the morphology of the main large gel phase and not needle-bar-like crystals. The needle-bar-like crystals only exist in the holes. It is considered that the main large gel phase is the source of very high mechanical strength of the composite magnesium oxychloride cement.%利用苛性苦土与苛性白云石按一定比例混合而成的复合型镁质胶凝材料与氯化镁水溶液按摩尔比MgO/MgCl2=5拌和后,采用XRD和IR测试方法证明形成的硬化体为5相结晶体,其显微特征主要是大量的凝胶体形貌而非针(棒)状结晶结构.呈放射状的针(棒)状晶体仅在孔洞中存在.认为凝胶体是复合型镁质胶凝材料硬化体具有很高强度的来源.
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