酸腐蚀下混凝土性能的变化

PROPERTIES VARIATION OF CONCRETE ATTACKED BY ACIDIC SOLUTIONS

根据酸雨的特点配制了5种具有不同pH值、不同硫酸根离子浓度的酸性溶液,研究了混凝土在干湿循环、酸性溶液侵蚀30 d到150 d强度的变化、表层混凝土的吸水性以及其孔结构的变化。经过含有硫酸盐溶液的侵蚀后,混凝土强度的变化经过一个先降后升、然后再降低的过程;而经过不含硫酸盐溶液的侵蚀后,混凝土的强度持续下降。受不含硫酸根离子的酸性溶液侵蚀后,表层混凝土的孔隙结构变化较大,孔隙率增加、孔径增大。硫酸盐侵蚀产物的形成过程与混凝土的宏观性能的变化密切相关。

Rapid development of industry caused increase of acidic medium concentration in environments, and the deterioration of concrete performance caused by acidic attack had been paid more attention. In the present paper, five acidic solutions with different pH, different SO4^2- concentration were prepared to simulate acidic rains. The strength variation, sorptivity and pore structure of concrete were measured after acidic attack for 30 - 150 d, in a dry-wet regimen. Results showed that, after attack of acidic solutions with SO4^2- , the strength of concrete reduced at firstly, then increased and reduced at last. It is possible that the reaction products of cement hydrates in concrete with SO4^2- governing property variation of acid attacked concrete. However, after attack of acidic solution without SO4^2- , the strength decreased continuously. The reason might be the quality degradation of pore structure after pure acidic attack.