玄武岩纤维喷射混凝土在热害环境下的性能试验研究

Experimental study of the performance of basalt fiber shotcrete under heat damage

以隧道热害问题为背景,通过模型试验、近似模拟湿喷技术、定量分析及微观测试相结合的方法研究不同掺量玄武岩纤维喷射混凝土劈裂强度和粘结强度等力学性能的影响,横向对比标准养护和干热养护下的不同体积掺量的玄武岩纤维混凝土的力学性能,同时也加入硅灰以及钢钎维作为参照,以便从机理程度上提出更有效的解决热害措施。试验研究表明:在混凝土中加入玄武岩纤维,对混凝土起到了增强和阻裂的作用,改善了混凝土的脆性易裂的破坏状况。干热环境下,加入少量的玄武岩纤维能够提高混凝土的力学性能。当玄武岩掺量为0.1%玄+5%硅灰时,喷射混凝土的力学性能最好,加入0.2%玄武岩纤维掺量,也有一定程度的改善。实际隧道施工中,可通过加入适量的玄武岩纤维和适量的硅灰,可降低混凝土在热害环境下的危害。

We studied the effect of different amount of basalt fiber on the splitting strength,bond strength and other mechanical properties of shotcrete under the context of tunnel heat-harm by using a combined method of model test,approximate simulation wet shotcrete technique,quantitative analysis and microscopic testing.Then we compared mechanical properties of shotcrete with different amount of basalt fiber both under standard curing and dry heating curing,and added silica fume and steel fiber into shotcrete to find an effective way to solve heat-harm.The results show that the basalt fiber added to the shotcrete can increase the strength of the shotcrete and resist cracks,which improves the fragility of shotcrete.Moreover,in dry and hot environment,a small amount of basalt fiber added can improve the mechanical properties of shotcrete.When the mixing amount of basalt consists of 0.1percent basalt fiber and 5percent silica fume,the mechanical properties of shotcrete is the best,and 0.2percent basalt fiber added can also improve to a certain degree.In practice,adding moderate amount of basalt fiber and silica fume into shotcrete can reduce the damage of concrete under heat-harm.