不同侵蚀环境下喷射混凝土耐久性提升技术及作用机理OA北大核心CSTPCD

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.