碳酸侵蚀条件下水泥基材料性能劣化试验研究

Experimental Study on Property Deterioration of Cement-Based Materials under Carbonic Acid Erosion

模拟碳酸型侵蚀水质情况,分析水泥净浆质量损失、水泥砂浆抗压强度损失以及微观结构和化学组成变化,研究水泥基材料性能的劣化发展规律和劣化机理.研究结果表明:粉煤灰掺量(质量分数,下同)在20%以内时,可以提高水泥浆体抗碳酸侵蚀能力,体系各龄期的质量损失率和抗压强度损失率均低于纯水泥浆体;粉煤灰掺量大于30%时,水泥浆体更易遭受碳酸侵蚀破坏,体系的质量损失率大于纯水泥浆体,90d龄期后的抗压强度损失率高于纯水泥浆体.微观结构分析表明,水泥浆体受碳酸侵蚀破坏反应是由表及里逐渐发生的.侵蚀早期,侵蚀产物主要为碳酸钙、微量SiO2和铁相产物;侵蚀后期,水泥浆体表层的C-S-H遭受严重破坏,主要侵蚀产物为SiO2和铁相产物.

Effects of carbonic acid erosion on compressive strength loss of mortars,mass loss,microstructure and composition change of cement pastes were studied to reveal the degradation process and deterioration mechanism of cement-based materials.The results indicate that the resistance to carbonic acid erosion of cement pastes is improved when the content（by mass） of fly ash is less than 20 ％.The mass loss rate and compressive strength loss rate of fly ash-cement pastes at various ages after carbonic acid erosion are lower than those of control cement pastes.The cement pastes are more vulnerable to carbonic acid erosion damage when the content of fly ash is greater than 30％.Carbonic acid erosion occurs gradually from the surface to the inner part of cement pastes.At early erosion,the erosion products are mainly calcium carbonate and a small quantity of SiO2 and ferrite phases.After long period of erosion,the C-S-H at the surface of cement pastes suffers serious damage,and the main products of erosion are SiO2 and ferrite phases.