NaOH改善粉煤灰混凝土微结构及抗风蚀-冻融耐久性能
Improvement of microstructure and coupling wind erosion with freeze-thaw durability of fly ash concrete by sodium hydroxide
张启懿 1邹春霞 1郭晓松 1宋育鑫 1郑建庭 1赵溢2
作者信息
- 1. 内蒙古农业大学水利与土木建筑工程学院,内蒙古 呼和浩特 010018
- 2. 内蒙古农业大学水利与土木建筑工程学院,内蒙古 呼和浩特 010018;中国建筑第八工程局有限公司西北分公司,陕西西安 710065
- 折叠
摘要
为改善水工混凝土风蚀-冻融耐久性能,提高固废粉煤灰的利用率,选择NaOH碱性激发剂制备加碱粉煤灰混凝土.通过红外光谱试验、核磁共振试验、室内冻融和风蚀-冻融试验研究常温养护下加碱粉煤灰混凝土反应产物、孔隙特征及抗冻、抗风蚀-冻融耐久性劣化规律.结果表明:常温掺加质量分数为 5%的NaOH有利于激发粉煤灰活性,提高其对水泥的替代率;加碱后红外光谱中粉煤灰玻璃体的特征峰消失,出现了N-A-S-H凝胶的典型特征峰且凝胶聚合度更高;核磁共振中相应的T2谱起始弛豫时间和谱面积均减小,孔结构更优;粉煤灰替代率为 40%,NaOH质量分数为 5%时混凝土的孔隙结构优于粉煤灰替代率为 20%的普通混凝土.以相对动弹性模量为指标,建立加碱粉煤灰混凝土耐久性指标的优化残差-马尔可夫(Markov)模型并对其服役寿命进行预测,相对误差在 5%左右,证实了常温条件外加碱性激发剂有助于提高粉煤灰在胶凝材料中的使用率,改善混凝土的抗风蚀-冻融耐久性能,为风蚀严寒区绿色水工混凝土的开发、推广提供理论支撑.
Abstract
To enhance the coupling wind erosion with freeze-thaw durability in concrete and increase the utilization rate of solid waste fly ash,an experimental study was conducted on alkali-added fly ash concrete using a NaOH activator.The investigation focused on the reaction products,pore characteristics,and durability deterioration of alkali-added fly ash concrete under normal temperature curing through infrared spectroscopy,nuclear magnetic resonance,indoor freeze-thaw,and coupling wind erosion with freeze-thaw tests.The findings showed that the addition of 5%NaOH effectively enhanced the reactivity of fly ash and increased its replacement ratio of cement.The characteristic peak of vitreous fly ash in the infrared spectrum disappeared after alkali addition,while the typical characteristic peak of N-A-S-H gel became prominent,indicating higher gel polymerization.The pore structure was improved because both the initial relaxation time and spectral area of the corresponding T2 spectrum decrease in NMR.The concrete with 40%fly ash and 5%alkali exhibited better pore structure than ordinary concrete with 20%fly ash.An optimized residual-Markov model was established to predict the durability index and service life of alkali-added fly ash concrete with relative error of approximately 5%,based on the relative dynamic elastic modulus.The alkaline activator proved beneficial in enhancing the utilization rate of fly ash in cementitious materials and improving the durability of concrete against coupling wind erosion with freeze-thaw cycles.These findings provided theoretical support for the development and promotion of environmentally friendly hydraulic concrete in cold regions prone to wind erosion.
关键词
加碱粉煤灰混凝土/红外光谱/核磁共振/风蚀-冻融/灰色残差-Markov模型/常温养护Key words
alkali-added fly ash concrete/infrared spectroscopy/nuclear magnetic resonance/coupling wind erosion with freeze-thaw/grey residual-Markov model/maintenance at normal temperature引用本文复制引用
基金项目
内蒙古自治区自然科学基金资助项目(2022MS05043)
内蒙古自治区高等学校科学技术研究自然科学重点资助项目(NJZZ22518)
内蒙古自治区高等学校科学技术研究自然科学重点资助项目(NJZZ22517)
内蒙古自治区水利科学研究专项资助项目(NSK2016-S11)
内蒙古自治区研究生教育教学改革资助项目(JGCG2023066)
出版年
2024
NETL
NSTL
万方数据