盐冻耦合作用下掺纤维面板混凝土耐久性研究

Study on concrete durability of fiber-doped panels under salt-freezing coupling

为了研究盐冻耦合作用下掺纤维面板混凝土的耐久性问题,采用不同纤维种类(聚丙烯、聚丙烯腈、钢纤维)及不同掺量的面板混凝土在不同氯盐浓度(2.0%、3.5%、5.0%)中进行冻融循环试验,并对冻融后的试件开展电镜扫描试验。研究表明:当盐冻侵蚀作用增强时,掺纤维面板混凝土试件的质量损失率先减小再增大,抗压强度则持续降低;氯盐浓度对盐冻耦合作用影响较大,其中氯盐浓度为3.5%时试件的质量损失率最高,抗压强度降低最快;不同类型的纤维可以有效地改善面板混凝土的抗盐冻性能,聚丙烯和聚丙烯腈纤维掺量在1.0 kg/m^(3)时、钢纤维掺量在70 kg/m^(3)时,试件的质量损失率较少,抗压强度降低幅度较小,抗盐冻性能较好。

In order to explore the concrete durability of salt mineral fiber-doped panels under the coupled action of freezing,panel concrete of different fiber types(polypropylene,polyacrylonitrile,steel fiber)under different dosages in different chlorine salt concentrations(2.0%,3.5%,5.0%)were tested in the freeze-thaw cycles,and the specimens were then inspected using a scanning electron microscope(SEM)after the freeze-thaw test.The results show that with the increase of salt-freezing cycles the mass loss rate of the concrete specimens first decreased and then increased,while the compressive strength continued to decrease.The chlorine concentration had a great influence on the salt-freezing coupling effect,among which the mass loss rate was the highest and the compressive strength decreased the fastest when the chlorine concentration was 3.5%.Different types of fiber could effectively enhance the salt-freezing resistance of concrete.When the content of polypropylene and polyacrylonitrile fiber was 1.0 kg/m^(3),and the content of steel fiber was 70 kg/m^(3),the increase of mass loss rate of the specimens slowed down,so did the decrease of the compressive strength.So the salt-freezing resistance performance of the specimens is satisfactory under these conditions.