Study on Mechanical Properties and Microstructure of Recycled Aggregate Concrete Containing Steel Slag Powder and Metakaolin
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摘要: 为了提高钢渣粉(SSP)作为矿物添加剂在水泥基材料中的利用率,以及增强再生混凝土(RAC)的力学性能,探究了SSP和偏高岭土(MK)复掺对RAC力学性能和微观结构的影响。试验结果表明:当MK占矿物添加剂30%的质量分数时,试样第28、90天的抗压强度较基准组分别提高了13.3%和18%,弹性模量的变化趋势与抗压强度相似。微观测试表明,SSP和MK复掺降低了Ca(OH)2的峰值强度,并且生成更多额外的C-S-H凝胶以及提高了高密度C-S-H在C-S-H中的百分比,使RAC后期的微观结构和界面过渡区得到显著改善,这归因于SSP和MK复掺表现出更好的火山灰活性和微集料填充效应。Abstract: To improve the utilization rate of steel slag powder (SSP) as mineral admixture in cement-based materials, and to enhance the mechanical properties of recycled aggregate concrete (RAC), the influences of SSP and MK on the mechanical properties and microstructure of RAC were studied. The mechanical test results showed that the compressive strength of the mineral admixture at 28 d and 90 d was respectively increased by 13.3% and 18% as the mass fraction of MK in mineral admixture was 30%, compared with that of the reference group, and the changing trend of elastic modulus was similar to that of the compressive strength. Microstructural tests indicated that SSP and MK mixed with Ca(OH)2 decreased the peak strength, generated additional C-S-H gel and increased the percentage of high density C-S-H, which significantly improved the microstructure and interfacial transition zone of RAC in the later stage. These were attributed to the better volcanic ash activity and micro-aggregate filling effect of SSP and MK mixed mixture.
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Key words:
- recycled aggregate concrete /
- metakaolin /
- steel slag powder /
- mechanical properties /
- microstructure
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