纳米偏高岭土对铁尾矿砂-再生混凝土抗压性能影响及微观结构分析
Influence of nano-metakaolin on the compressive strength of iron tailing sand-recycled concrete and microstructure analysis
阎杰 1赖镇泉 2左军鹏 2庄永程 2谢军1
作者信息
- 1. 河北建筑工程学院 土木工程学院,河北 张家口 075000;河北省高校绿色建材与建筑改造应用技术研发中心,河北 张家口 075000
- 2. 河北建筑工程学院 土木工程学院,河北 张家口 075000
- 折叠
摘要
为综合利用固体废弃物,以再生粗骨料部分取代天然骨料、以铁尾矿砂部分取代天然砂分别作为粗、细骨料,同时以纳米偏高岭土(NMK)部分取代水泥作为胶凝材料制成铁尾矿砂-再生混凝土(IRC),进行立方体抗压强度试验,探究NMK对IRC抗压强度的影响.利用扫描电镜(SEM)及氮吸附法(BJH)研究再生混凝土微观结构的变化规律.研究结果表明:铁尾矿砂取代率的增加会提高再生混凝土强度变化率,且取代率越大,抗压强度变化率越高;适量掺入NMK可以提高再生混凝土的抗压强度,当NMK取代率为 5%时,抗压强度最大;掺入适量的NMK可以通过促进二次水化反应生成大量的C-S-H凝胶,提高砂浆内部及砂浆与骨料之间的密实度,提升界面过渡区强度,优化内部孔隙结构,进而提升IRC的抗压强度.
Abstract
In order to comprehensively utilize solid waste,recycled coarse aggregate is partially replaced by natural aggregate,and iron tailings sand is partially substituted for natural sand as coarse and fine aggregate,respectively.Additionally,nano-metakaolin(NMK)is used as a partial replacement for cement as the binding material,resulting in the production of iron tailings sand-recycled concrete(IRC).A cube compressive strength test was conducted to investigate the impact of NMK on the compressive strength of Iron tailings sand-recycled concrete(IRC).The changes in the microstructure of recycled concrete were examined using scanning electron microscopy(SEM)and the nitrogen adsorption method(BJH).The results indicate that the strength of recycled concrete exhibits an increasing rate of change with higher iron tailings replacement rates.The greater the replacement rate,the higher the change rate of compressive strength.The addition of an appropriate amount of NMK proves beneficial in enhancing the compressive strength of recycled concrete,reaching its maximum when the NMK content is 5%.The introduction of an optimal amount of NMK promotes a significant increase in C-S-H gel through secondary hydration reactions.This,in turn,improves the compactness within the mortar and between the mortar and the aggregate.Furthermore,it enhances the strength of the interfacial transition zone,optimizes the internal structure of the pores,and ultimately enhances the compressive strength of IRC.
关键词
纳米偏高岭土/铁尾矿砂-再生混凝土/抗压强度/微观结构Key words
nano-metakaolin/iron tailings sand-recycled concrete/compressive strength/internal structure引用本文复制引用
基金项目
张家口市重点研发计划项目(2322145D)
河北省高等学校科学研究项目(ZC2024136)
出版年
2024
国家科技期刊平台
NSTL
万方数据