摘要
水泥基材料是由水泥、骨料等组成的复合材料,高温作用后材料内部产生严重的热损伤,导致其力学及耐久性能降低。通过数码显微镜观察了经过105、200、400、600、800℃温度作用后水泥砂浆的表面形貌,发现砂浆表面热损伤裂缝的宽度随着温度的升高而逐渐增大。通过称重法对高温作用后水泥砂浆的毛细吸水性能进行测试后发现:热损伤作用对于水泥砂浆的一维吸水过程有着明显影响,毛细吸水系数随着温度的升高而急剧增加,经过800℃高温作用后的砂浆样品的毛细吸水系数为105℃下烘干的砂浆样品毛细吸水系数的5.7倍。通过抗压、抗折和劈裂抗拉试验研究了高温后砂浆的力学性能,证实了砂浆的抗压、抗折和劈裂抗拉强度随着温度的升高而衰减的规律,800℃作用后砂浆样品的抗压、抗折和劈裂抗拉强度分别为20℃时的31%、61%、19%。同时,测得的试验数据表明:高温损伤砂浆毛细吸水系数与其抗压、抗折及劈裂抗拉强度间均存在着明显的线性关系,因此吸水性系数可作为高温损伤水泥基材料力学及耐久性能评价的重要指标。
The cement-based material is a composite material composed of cement and aggregate.High temperature will cause cracks in cement-based materials,which will reduce its durability.The surface morphology of cement mortar after 105,200,400,600℃and 800℃temperature was observed by digital microscope.It was found that the width of the thermal damage crack on the surface of the mortar gradually widened with increasing temperature.Through the weighing method,the capillary water absorption performance of cement mortar after high temperature action is studied.It is found that thermal damage has a significant impact on the one-dimensional water absorption process of mortar.The capillary absorption coefficient increases sharply with increasing temperature.When the temperature is 800℃,the capillary absorption coefficient of the mortars is 5.7 times that of 105℃.The mechanical properties of the mortar after high temperature were studied by the compressive,flexural and splitting tensile tests.It is confirmed that the compressive,flexural and splitting tensile strength of mortar decays with increasing temperature.The compressive,flexural and splitting tensile strengths at 800℃were 31%,61%and 19%that of 20℃,respectively.At the same time,the experimental data obtained show that there is a significant linear relationship between the capillary water absorption coefficient of high temperature damage mortar and its compressive,flexural and splitting tensile strength.Therefore,the water absorption coefficient can be used as an important index for the evaluation of mechanical and durability properties of cement-based materials at high temperature damage.
作者
董帅锋
薛善彬
张鹏
孟繁强
乔允
DONG Shuaifeng;XUE Shanbin;ZHANG Peng;MENG Fanqiang;QIAO Yun(School of Civil Engineering,Qingdao University of Technology,Qingdao 266033,China;Cooperative Innovation Center fo Engineering Construction and Safety in Shandong Blue Economic Zone,Qingdao University of Technology,Qingdao 266033,China)
出处
《混凝土》
CAS
北大核心
2021年第2期101-105,共5页
Concrete
基金
国家自然科学基金项目(51922052,51778309,U1706222,51420105015)
山东省优秀青年基金(ZR2018JL018)。
关键词
高温
水泥砂浆
毛细吸水
力学性能
hgih temperature
cement mortar
capillary water absorption
mechanical properties
