不同侵蚀环境下喷射混凝土耐久性提升技术及作用机理

摘要/Abstract

摘要： 为了揭示不同侵蚀环境下喷射混凝土的钙溶蚀行为,并探究羧酸酯型侵蚀抑制剂和硅灰对喷射混凝土抗侵蚀性能的影响,本文通过抗压强度及腐蚀溶液钙离子浓度测试对比了氯化铵溶蚀和复合盐侵蚀作用下喷射混凝土的强度损失率和钙离子溶出率的时变规律,并采用TG分析改性喷射混凝土侵蚀前的孔结构和可溶固相钙含量,最后采用XRD和 SEM测试分析混凝土侵蚀后的物相组成和微观形貌。结果表明,复合盐侵蚀作用下较多钙矾石等腐蚀产物填充孔隙,导致混凝土强度损失和钙离子溶出率均低于氯化铵溶蚀。氯化铵溶蚀和复合盐侵蚀作用下,喷射混凝土的强度损失率与钙离子溶出率呈线性相关。4%(质量分数)侵蚀抑制剂+2%(质量分数)硅灰复合的作用效果较佳,可使喷射混凝土复合盐侵蚀28 d后的强度损失率和钙离子溶出率分别较空白组降低46.7%和50.9%。羧酸酯型侵蚀抑制剂和硅灰均可通过细化混凝土孔结构、降低氢氧化钙和钙矾石含量来提升喷射混凝土的耐久性。

关键词: 喷射混凝土, 溶蚀, 复合盐侵蚀, 孔结构, 可溶固相钙, 耐久性

Abstract: For revealing the calcium leaching behaviors of shotcrete suffered from different salt corrosion and exploring the effects of carboxylic ester corrosion inhibitor and silica fume on the erosion resistance of shotcrete. The time-varying patterns of strength loss rate and calcium dissolution rate of shotcrete under the erosion of ammonium chloride and composite salt were compared through compressive strength and corrosion solution calcium ion concentration tests. TG analysis was used to examine the pore structure and soluble solid calcium content of modified shotcrete before erosion. Finally, XRD and SEM tests were used to analyze the phase composition and microstructure of concrete after erosion. The results show that under compound salt erosion environment, more ettringite and other corrosion products fill the pores and increase the compactness of concrete, resulting in a lower strength loss and a lower calcium leaching rate compared to that exposed to ammonium chloride. There is a good linear correlation between the strength loss and calcium leaching rate of sprayed concrete exposed to ammonium chloride induced leaching and compound salt erosion. The improvement of the combination of 4% (mass fraction) carboxylic ester corrosion inhibitor and 2% (mass fraction) silica fume is remarkable, which can reduce the strength loss rate and calcium ion dissolution rate of shotcrete after 28 d of salt corrosion compared to the blank group by 46.7% and 50.9%, respectively. The addition of carboxylic ester type corrosion inhibitor and silica fume can reduce air bubbles content, calcium hydroxide and ettringite content of hardened concrete, thereby improving the durability of shotcrete.

Key words: shotcrete, leaching, compound salt erosion, pore structure, soluble solid calcium, durability

中图分类号:

TU528

张全红, 王涛, 穆松, 蔡佳豪, 刘凯, 周莹, 刘光严. 不同侵蚀环境下喷射混凝土耐久性提升技术及作用机理[J]. 硅酸盐通报, 2024, 43(4): 1410-1419.

ZHANG Quanhong, WANG Tao, MU Song, CAI Jiahao, LIU Kai, ZHOU Ying, LIU Guangyan. Durability Improvement and Mechanism of Shotcrete under Different Corrosion Environments[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2024, 43(4): 1410-1419.

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