冻融循环作用下聚丙烯纤维混凝土抗拉性能及孔隙结构特征OA北大核心CSTPCD

In order to improve the mechanical properties of concrete under freeze-thaw environment,the tensile properties of concrete and the development of pore structure under different polypropylene fiber content and freeze-thaw cycles were studied by splitting tensile test and nuclear magnetic resonance test(NMR).The research result shows that the content of polypropylene fibers is positively correlated with the splitting tensile strength and peak tensile strain of concrete.The number of freeze-thaw cycles is negatively correlated with the splitting tensile strength,but positively correlated with the peak tensile strain.The pore volume of concrete is positively correlated with the number of freeze-thaw cycles,but negatively correlated with the content of polypropylene fibers.A relationship formula was established between the content of polypropylene fibers,the number of freeze-thaw cycles,and the splitting tensile strength.The pore size with the greatest impact on the splitting tensile strength of concrete is(100,500]μm,followed by(500,1 000]μm,and the impact of pore size(10,100]μm is relatively small.The research results provide theoretical support for improving the performance of concrete in freeze-thaw environments.