胶凝材料硬化浆体中氢氧化钙含量及其抗碳化性能随粉煤灰掺量的变化规律

Variation of Ca(OH)2content and carbonation of binder hardened paste in Portland cement and fly-ash system with fly-ash added

就粉煤灰掺量和养护条件对基准水泥和粉煤灰硬化浆体中氢氧化钙含量及其抗碳化性能的影响进行了研究。试验结果表明:在使用I型硅酸盐水泥的基础上,随着粉煤灰掺量的提高,硬化胶凝材料浆体中的氢氧化钙含量明显降低,同时抗碳化性能也明显降低。在粉煤灰掺量为40%和养护条件分别为20℃水中养护到60d、以及分别再进行90℃水中养护72h和再蒸压(200℃)养护8h的条件下,硬化浆体中氢氧化钙的含量分别为10.4%、7.8%和0。在20℃水中养护7 d+20℃空气中养护53 d的条件下,对于基准水泥和粉煤灰硬化浆体,在保证具有50年抗碳化能力的条件下,粉煤灰掺量不应超过40%。

Effect of fly-ash added on Ca（OH）2 content and carbonation of binder hardened paste in Portland cement and fly-ash system was studied. Results indicate that both Ca（OH）2 content in the binder hardened paste and ability of anti-carbonation of the paste obviously decreased with fly-ash increasing on the basis of using I category Portland cement. For example,Ca（OH）2 contents in the pastes with the 40% fly-ash were 10.4%,7.8% and 0% respectively in the three conditions：①cured in water at 20 ℃ for 60 days; ②①＋cured in water at 90 ℃ for 72 h： ③①＋cured in autoclave at 200 ℃ for 8 h. When cured in water at 20℃ for 7 days and then cured in the air at 20% for 53 days,the fly-ash content did not exceed 40% in the conditions of anti carbonation ability within 50 years.