钢纤维和聚合物对混凝土断裂特征的影响及机理分析  

Influence of Steel Fiber and Polymer on Fracture Characteristics of Concrete and Mechanism Analysis

作　　者：郭广磊[1] 孙世强 李颖 郑艺伟 梅迎军[2] GUO Guang-lei;SUN Shi-qiang;LI Ying;ZHENG Yi-wei;MEI Ying-jun(South Engineering Co.,Ltd.of Road&Bridge International Co.,Ltd.,Beijing 101121,China;National&Local Joint Engineering Laboratory of Transport Civil Engineering Materials,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]中交路桥南方工程有限公司,北京101121 [2]重庆交通大学交通土建工程材料国家地方联合工程实验室,重庆400074

出　　处：《公路交通科技》2023年第4期53-60,共8页Journal of Highway and Transportation Research and Development

基　　金：重庆市科技局科技项目(cstc2019jscx-msxmX00140);中交路桥南方工程有限公司科技项目(科技-2020-342)。

摘　　要：为了改善混凝土微观结构特征与断裂韧性采取在混凝土中复掺钢纤维和聚合物乳液,通过三点弯曲断裂试验得到了普通混凝土、钢纤维混凝土、聚合物乳液改性混凝土及钢纤维聚合物混凝土荷载-变形曲线及相应裂纹张开宽度,计算得到了断裂能、临界应力强度因子和裂纹尖端张开位移等断裂特征参数。通过氮吸附试验和压汞试验,得到了混凝土总孔隙体积、总比表面积、中值孔径及平均孔径等微观孔结构特征参数,分析了钢纤维和聚合物乳液对混凝土增强增韧的机理。结果表明:掺入钢纤维后,混凝土压折比从8下降到5.29~6.21,临界荷载及变形分别增加了48.9%~112.3%和10.7%~136.1%,断裂能、临界应力强度因子和裂纹尖端张开位移分别增加了595.4%~1936.4%,96.8%~177.7%,158.3%~233.3%,总孔隙体积、总比表面积和中值孔径分别降低了2.2%~45.9%,8.0%~75.2%,6.7%~43.7%;与钢纤维混凝土相比,复掺聚合物乳液后,混凝土压折比降低到4.85,且聚合物乳液掺量越大,压折比越小,三点弯曲断裂临界荷载及对应的变形增加幅度不明显,断裂能、临界应力强度因子和裂纹尖端张开位移分别增加了24.4%~61.0%,7.9%~54.0%,27.8%~144.4%,混凝土总孔隙体积和总比表面积分别减小了28.1%~43.7%和42.5%~67.7%,复掺聚合物乳液能有效提高钢纤维混凝土断裂性能;混凝土三点弯曲荷载-变形曲线更饱满,下降段更加平缓,且复掺效果优于单掺。In order to improve the microstructure characteristics and fracture toughness of concrete by mixing steel fiber and polymer emulsion in concrete,the load-deformation curves and crack opening widths of ordinary concrete,steel fiber reinforced concrete,polymer emulsion modified concrete and steel fiber polymer concrete are obtained by three-point bending fracture test,and the fracture characteristic parameters such as fracture energy,critical stress intensity factor and crack tip opening displacement are calculated.By nitrogen adsorption test and mercury injection test,the total pore volume,total specific surface area,median pore diameter and average pore diameter of concrete are obtained,and the mechanism of strengthening and toughening concrete by the incorporation of steel fiber and polymer is analyzed.The result shows that(1)After mixing steel fiber,the ratio of compression strength to flexural strength of concrete decreased from 8 to 5.29-6.21,the critical load and deformation increased by 48.9%-112.3%and 10.7%-136.1%respectively,the fracture energy,critical stress intensity factor and crack tip opening displacement increased by 595.4%-1936.4%,96.8%-177.7%and 158.3%-233.3%respectively,and the total pore volume,total specific surface area and median pore diameter decreased by 2.2%-45.9%,8.0%-75.2%and 6.7%-43.7%respectively.(2)Compared with steel fiber reinforced concrete,after mixing polymer emulsion,the ratio of compressive strength to flexural strength decreased to 4.85.The more the polymer content,the smaller the ratio of the compressive strength to flexural strength.The increments of critical load and corresponding deformation of three-point bending fracture are not significant.The fracture energy,critical stress intensity factor and crack tip opening displacement increased by 24.4%-61.0%,7.9%-54.0%,27.8%-144.4%respectively,the total pore volume and total specific surface area of concrete decreased by 28.1%-43.7%and 42.5%-67.7%respectively.The composite polymer emulsion can effectively improve the fracture

关 键 词：道路工程 断裂韧性 三点弯曲断裂试验 水泥混凝土 钢纤维 聚合物乳液 临界应力强度因子 裂纹尖端张开位移 

分 类 号：TU528.572[建筑科学—建筑技术科学]