中文摘要：

为了探索科学合理地确定MgO外掺量的试验方法，通过室内试验测定了不同尺寸的外掺MgO水泥净浆试件的压蒸膨胀率，并对压蒸后的试样进行相对抗压强度试验、扫描电镜分析及X射线能谱检测。试验结果表明：随着MgO掺量的增加，水泥净浆压蒸膨胀率逐渐增大，试件结构越来越疏松；当MgO掺量小于4％时，试件压蒸膨胀率的变化规律是：试件长度与截面边长之比越大，膨胀率越大；当MgO掺量不低于4％时，则是试件长度与截面边长之比越小，膨胀率越大。

英文摘要：

Searching for a kind of scientific and reasonable test method to determine MgO content, the autoclave-treated expansibility of different dimensional cement paste maxed with magnesium oxide（MgO ）, has been obtained by tests, as well as the compressive strength after autoclaving, analysis of scanning electron microscopy and X-ray energy spectrum detection.The test results indicated that the auto- clave-treated expansibility of cement paste enlarged gradually with the MgO content increasing, and the specimens＇ structure also became more and more loose;when the MgO content was less than 4%, the law of autoclave-treated expansibility presented as following：the high- er ratio of specimen＇s length and cross-section dimension, the greater expansibility was;on the contrary, when the MgO content was not less than 4%, the result was turned out to be this： the lower ratio of length and cross-section dimension, the greater expansibility was.