含镁铝尖晶石的铝酸钙水泥中物相分布状态对流变特性的影响

Effect of Phase Distribution on Rheological Behavior of Calcium Aluminate Cement With Built-in Alumina-Magnesia Spinel

合成了3种不同配比含镁铝尖晶石的铝酸钙水泥(CAM)。借助X射线衍射和扫描电子显微镜对合成的水泥试样进行了物相组成和显微结构分析,使用电导率仪、维卡仪和流变仪测定了CAM水泥净浆的水化和流变特性。结果表明:当水泥中镁铝尖晶石(MgAl2O4,MA)分布在一铝酸钙(CaAl2O4,CA)周围时,MA阻碍了CA与水的接触,水泥水化较难进行,水泥砂浆凝结时间较长,水泥净浆的屈服应力、表观黏度和触变性较小,储能模量G’增长速率也较小。MA和CA交错分布时,CA晶粒外形不规整,与水接触面积较大,水泥水化较易进行,水泥砂浆凝结时间较短,水泥净浆的屈服应力、表观黏度和触变性较大,储能模量G’增长速率也较大。而当MA分布于CA晶粒之间时,CA晶粒发育完整,水泥溶解过程较慢,水泥凝结时间和流变参数都处于中间值。

Three kinds of calcium aluminate cements(CaAl2O4,CA)with built-in alumina-magnesia spinel(MA)were prepared.The mineral composition and microstructure characteristics were investigated by techniques of X-ray diffraction and scanning electron microscopy.Their setting time and rheological behavior were also analyzed.The results indicated that when MA phases distributed among CA phases,MA could hinder CA contacting with H2 O.It is thus difficult to perform the cement hydration and its setting time was longest.The values of both yield stress,viscosity,thixotropic character and the increasing rate of storage modulus G'become the minimum value.When MA and CA phases distributed crossly,the contact area between the irregular CA grain and H2 O is the greatest,the cement hydration is the fastest,and the setting time is the shortest.The yield stress,viscosity,thixotropic character and the increasing rate of G'are the maximum values.When CA phases were formed into the skeleton and MA distributed among CA phases,CA grains grow well and the cement dissolution process is slower.The setting time and the rheological parameters are the values between the maximum and the minimum.