隧道喷射混凝土外掺料抗钙溶蚀结晶试验研究

Experimental Study on Resistance of Calcium Leaching and Crystallization of Tunnel Shotcrete Admixtures

为了减缓隧道喷射混凝土钙溶蚀导致的排水系统结晶堵塞现象,在调研了多种混凝土外掺料的基础上,从消耗游离Ca(OH)_(2)、填充混凝土孔隙两方面,分别选取抗碱剂和纳米二氧化硅、粉煤灰和纳米碳酸钙进行室内单掺试验。试验主要从排水管上结晶情况、溶出液中钙离子浓度、溶出液流量变化和算得的钙溶出总量4个方面,通过不同掺料之间的组内比较和同种掺料不同掺量下的比较,比选出减少钙溶蚀结晶效果较好的外掺料及其最优掺量。结果表明:在消耗游离Ca(OH)_(2)方面,9%掺量下的抗碱剂抗钙溶蚀结晶效果最佳;在填充混凝土孔隙方面,6%掺量下的纳米碳酸钙抗钙溶蚀结晶效果最佳。研究结果可为隧道排水系统结晶堵塞病害的预防提供一定参考。

In order to alleviate the crystallization blockage of drainage system caused by calcium leaching of tunnel shotcrete,based on the investigation of a variety of concrete admixtures,anti-alkali agent and nano-SiO2,fly ash and nano-CaCO_(3)were selected from two aspects of consuming free Ca(OH)_(2)and filling concrete pores,for indoor single-mixing test.From four aspects of the crystallization of the drainage pipe,the concentration of calcium ion in the leaching solution,the change of the flow rate of the leaching solution and the total amount of calcium leaching calculated,the admixture with better effect of reducing calcium leaching and crystallization and its optimal dosage were selected through the intra-group comparison between different admixtures and the comparison under different dosages of the same admixture in the test.The results show that:anti-alkali agent with 9%dosage has the best effect of the resistance of calcium leaching and crystallization in the aspect of consuming free Ca(OH)_(2);nano-CaCO_(3)with 6%dosage has the best effect of the resistance of calcium leaching and crystallization in the aspect of filling concrete pores.The results of the study can provide some reference for the prevention of the disease of crystallization blockage in tunnel drainage system.