复掺轻骨料纤维喷射混凝土力学及导热性能试验研究*

为有效隔绝高地温公路隧道、深部高温巷道施工过程中的围岩散热，利用正交试验方法，以不同复合陶粒、陶砂掺量、聚丙烯纤维为影响因素，设计出1种隔热效应的轻骨料纤维喷射混凝土（Lightweight Aggregate Fiber Shotcrete，LAFS），进行含水率、抗压、劈裂抗拉及导热性能试验，并借助X射线衍射、扫描电镜对LAFS进行机理分析。结果表明:3种因素对LAFS力学及导热性能的影响程度均为陶粒掺量>陶砂掺量>聚丙烯纤维掺量，本试验条件下，复合双掺陶粒、陶砂分别取代石子、砂子的最佳体积率为12%，6%，聚丙烯纤维的最佳掺量范围为0.2%~0.3%。建立的LAFS各性能预测模型可为工程应用LAFS确定其配比时提供试验依据。

Experimental study on mechanical and thermal conductivity properties of compound lightweight aggregate fiber shotcrete

In order to effectively isolate the heat dissipation of surrounding rock during the construction of high ground temperature highway tunnel and deep high temperature roadway,a lightweight aggregate fiber shotcrete (LAFS) with the heat insulation effect was designed by using the orthogonal test method with different composite ceramsite,ceramic sand content and polypropylene fiber as influencing factors.The tests of water content,compressive strength,splitting tensile strength and thermal conductivity were carried out,and the mechanism of LAFS was analyzed by using the X-ray diffraction and scanning electron microscope.The results showed that all the influence degree of three factors on the mechanical and thermal conductivity propertied of LAFS was ceramsite content > ceramsite sand content > polypropylene fiber content.Under the experimental conditions,the optimal volume ratio of compound double-doped ceramsite and ceramsite sand to replace stone and sand was 12% and 6%,respectively,and the optimal content range of polypropylene fiber was 0.2%~0.3%.The established property prediction model of LAFS can provide experimental basis for the engineering application of LAFS and the determination of its ratio.