摘要
目的研究聚丙烯纤维对水泥土的增强增韧作用,对比聚丙烯纤维掺量对水泥净浆及水泥土力学性能的影响规律和作用机制,提高水泥土的力学性能.方法在活性矿粉改性水泥土的优化配比基础上,将适量聚丙烯纤维掺入至水泥净浆和水泥土,测定其立方体抗压强度及圆柱体劈裂抗拉强度,同时利用扫描电子显微镜观察试件的断面形貌.结果随纤维体积掺量由0逐步提高至2%,水泥净浆的抗压强度和劈裂抗拉强度均明显增大,在2%纤维掺量情况下,7 d、28 d抗压强度分别提高了62.69%和50.28%,抗拉强度提高122.28%和57.30%,7 d和28 d拉压比也分别提高至0.13和0.10.聚丙烯纤维在水泥土中表现出更为显著的增强作用,0.5%体积掺量下的28 d抗压强度提高了60.23%,但纤维掺量进一步提高反而导致强度的下降;水泥土的抗压强度随胶凝材料掺量的提高而不断增大.结论聚丙烯纤维的引入可明显提高水泥基材料如水泥土的力学性能,尤其是早期的抗拉强度和拉压比即断裂韧性,但以水泥为基本功能组分的胶凝材料仍是水泥土力学性能的基本保证.
In order to explore the strengthening and toughening effect of polypropylene fiber,to compare the influence rule and serving mechanism of polypropylene fibers upon the mechanical properties of cement paste and cementing soil,and to improve the mechanical properties of cement soil,polypropylene fibers was introduced into the cement soil.Based on the cementing soil optimized with ultrafine slag powder,the compressive strength on cubic pieces and splitting tensile strength on cylinder pieces were investigated simultaneously,as well as the microscopic characterization of the fracture surface invest igated on scanning electron microscope(SEM).The contribution of polypropylene fiber content to the mechanical strength and the strength ratio of tension-to-compression of cement paste at the age of 7 d and 28 d was investigated and discussed in detail,while the compressive strength of cement soil was analyzed with the respects of fiber content and the amount of cementing materials.It was found that with the increasing of fiber content from 0 to 2%,the compressive and splitting tensile strength of the cement paste gradually increased,giving rise of an improvement of 62.69%to the compressive strength at 7 d and 50.28%at 28 d,while the 7 d and 28 d tensile strength increased by a rate of 122.28%and 57.30%,respectively.In the meanwhile,the strength ratio of tension-to-compression also enhanced to 0.13 and 0.10,respectively at 7 d and 28 d.In the case cementing soil,the involvement of polypropylene fiber aroused a much more remarkable enhancement to the compressive strength of cementing soil,i.e.the 28 d compressive strength increased by 60.23%at the fiber content of 0.5%,but further increasing of fiber content resulted in a relative low compressive strength.It is also identified that the compressive strength of cementing soil increased linearly with the increasing content of cementitious materials.Accordingly,the introduction of polypropylene fibers must make an evident contribution to the mechanical properties of cement-based composites including cementing soil,especially the tensile strength and the strength ratio of tension-to-compression at early age,as well as the fractural toughness,by the existence of cementitous matrix being mainly composed of Portland cement must be the most fundamental to realize a reasonable mechanical strength for cementing soil.
作者
佟钰
刘阳
罗超
丁向群
TONG Yu;LIU Yang;LUO Chao;DING Xiangqun(School of Materials Science and Engineering,Shenyang Jianzhu University,Shenyang,China,110168;China Railway Express No.9 Bureau Testing Co.Ltd.,Shenyang,China,110025)
出处
《沈阳建筑大学学报（自然科学版）》
CAS
CSCD
北大核心
2020年第3期507-513,共7页
Journal of Shenyang Jianzhu University：Natural Science
基金
国家自然科学基金项目(51678374)
辽宁省自然科学基金项目(20180550092)。
关键词
水泥土
聚丙烯纤维
超细矿粉
强度
拉压比
cementing soil
polypropylene fibers
ultrafine slag powder
strength
strength ratio of tension-to-compression
