低温环境下钢纤维膨胀珍珠岩混凝土的力学性能研究

Study on mechanical properties of steel fiber-expanded perlite concrete under low temperature environment

为开展钢纤维膨胀珍珠岩混凝土在低温条件下的力学性能研究工作,本文选取使用时的温度、钢纤维体积率、膨胀珍珠岩取代率为研究参数,使用温度设为23、-10、-20和-30℃,钢纤维的体积率为0、0.5%、1.0%和1.5%,膨胀珍珠岩取代率为0、10%、20%和30%。采用正交试验设计方法设计制作了32组、共计96个试块,分别对试块进行抗压试验和劈裂抗拉试验,获得了钢纤维膨胀珍珠岩混凝土在荷载作用下的破坏形态和极限承载力等实测数据。并以此为基础,开展了低温环境下钢纤维膨胀珍珠岩混凝土力学性能的分析,通过极差分析得出各个因素对试验结果的影响程度。结果表明:随着温度的降低,钢纤维膨胀珍珠岩混凝土的立方体抗压及劈裂抗拉强度均增大,-30℃增幅最为显著。随着钢纤维体积率的增加,可以抑制试块裂缝的发展,增加膨胀珍珠岩混凝土的韧性,提高其强度。在3个研究参数中,温度对钢纤维膨胀珍珠岩混凝土力学性能影响最大,钢纤维体积率次之,而膨胀珍珠岩取代率对混凝土抗拉和抗压的影响均较小。进而通过电镜扫描结果并结合试验数据分析了钢纤维膨胀珍珠岩混凝土的破坏机理。根据实测结果提出:在混凝土制作时建议取用1%的钢纤维体积率和10%的膨胀珍珠岩取代率,此配比能够有效提高混凝土的力学性能。

To study the mechanical properties of steel fiber-expanded perlite(SF-EP)concrete under low temperature conditions,this study focuses on three key parameters:temperature(23℃,-10℃,-20℃,and-30℃),steel fiber volume fraction(0%,0.5%,1.0%,and 1.5%),and expanded perlite replacement ratio(0%,10%,20%,and 30%).Using orthogonal experimental design,a total of 32 groups of 96 test blocks are prepared and subjected to compressive and splitting tensile tests respectively,and the measured data such as failure mode and ultimate bearing capacity of SF-EP concrete under load are obtained.These tests reveal the failure modes and ultimate bearing capacities of SF-EP concrete under load.Based on this,the mechanical properties of SF-EP concrete under low temperature environment are analyzed,and the influence of various factors on the test results is obtained by range analysis.The results show that as temperature decreased,both the compressive and splitting tensile strengths of SF-EP concrete increased,with the most significant enhancement at-30℃.An increase in steel fiber volume fraction help mitigate crack formation,enhancing the toughness and strength of the concrete.Among the three parameters,temperature have the greatest influence on the mechanical properties of SF-EP concrete follow by steel fiber volume fraction,while the expanded perlite replacement ratio have a relatively minor effect on both tensile and compressive strengths.The failure mechanism of SF-EP concrete is further analyzed using electron microscopy and experimental data.Based on these findings,it is recommended to use a steel fiber volume fraction of 1%and an expanded perlite replacement ratio of 10%in concrete production to effectively enhance its mechanical property.