摘要
为了探讨高温引起水泥基材料力学性能劣化的机理,通过强度、X射线衍射和扫描电镜观测试验,研究了高温对水泥基材料抗压强度和微观结构的影响。结果表明:200℃时水泥砂浆抗压强度下降14.8%,400℃时强度有所恢复,600℃和800℃时,水泥砂浆抗压强度分别下降39.9%和72.3%。200℃时水泥浆体中钙矾石的衍射峰消失,高于400℃时Ca(OH)2开始脱水分解,高于600℃时CaCO3开始脱水分解;随着温度升高,水泥水化产物分解得到的CaO、C2S和C3S等逐渐增多。低于400℃时,水泥浆体微观形貌没有明显变化,超过400℃时,随着温度的升高,水泥浆体微观形态由致密的层状和絮凝状变为疏松多孔的片状和碎屑状。高温引起水泥水化产物脱水分解、孔隙增多是水泥基材料力学性能劣化的主要因素。
With the help of intensity, X-ray diffraction and scanning electron microscopy, the compressive strength and the micro structure of cement-based materials under high temperature were studied to explore the mechanism of mechanical properties degradation of cement-based materials caused by high temperature. The results show that: at 200 ℃,the compressive strength of cement mortar decreases by 14. 8% and recovers at 400 ℃. At 600 ℃ and 800 ℃,the compressive strength of cement mortar decreases by 39. 9% and 72. 3% respectively. The diffraction peak of ettringite in the cement paste disappears at 200 ℃. When the temperature is higher than 400 ℃, Ca( OH)2 begins to decompose. CaCO3 begins to dehydrate and decompose when the temperature is above 600 ℃. The CaO,C2S and C3S obtained by the decomposition of cement hydration products gradually increase with the increase of temperature. When the temperature is lower than 400 ℃,the micro structure of the cement paste does not change significantly. When the temperature exceeds 400 ℃,the microscopic morphology of the cement paste changes itself from the dense layered and flocculated form to the loose porous sheet and clastic form. Dehydration decomposition of cement hydration products caused by high temperature is the main factor for the deterioration of mechanical properties of cement-based materials.
作者
吴相豪
戴圣男
李志卫
李文远
汪家昆
WU Xiang-hao;DAI Sheng-nan;LI Zhi-wei;LI Wen-yuan;WANG Jia-kun(College of Ocean Science and Engineering,Shanghai Maritime University,Shanghai 201306,China)
出处
《硅酸盐通报》
CAS
北大核心
2019年第6期1755-1758,1763,共5页
Bulletin of the Chinese Ceramic Society
关键词
高温
水泥砂浆
水泥浆体
抗压强度
微观结构
high temperature
cement mortar
cement paste
compressive strength
microstructure
