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| 氧化镁膨胀剂对再生砂UHPC力学与收缩性能影响研究 |
| Effect of magnesium oxide expander on mechanical and shrinkage properties of UHPC incorporating recycled sand |
| 投稿时间：2026-03-06 修订日期：2026-03-06 |
| DOI： |
| 中文关键词: 超高性能混凝土 再生砂 氧化镁膨胀剂 力学性能 收缩性能 |
| 英文关键词: Ultra-high performance concrete Recycled sand Magnesium oxide expansive agent Mechanical properties Shrinkage properties |
| 基金项目:武汉工程大学第十六届研究生教育创新基金 |
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| 中文摘要: |
| 氧化镁膨胀剂(MEA)和内养护对缓解超高性能混凝土(UHPC)的收缩都有着积极的作用，但协同工作的研究较少。本研究以再生砂替代石英砂制备UHPC，并将不同活性（R型和S型）MEA以4%、6%和8%（质量分数）掺入再生砂UHPC中，旨在研究不同活性和掺量MEA对再生砂UHPC的力学性能、收缩性能和微观结构的影响。结果表明：R型和S型MEA均会降低再生砂UHPC力学性能，但能明显缓解自收缩和干燥收缩，其中R型MEA改善效果较好，其7d自收缩和150d干燥收缩分别降低了26.4%和76.9%；微观测试表明，高活性R型MEA水化生成的Mg(OH)2晶体更多，其微观结构更加密实。综合考虑再生UHPC的力学性能和收缩性能，宜选用R型MEA，其最优掺量为6%。 |
| 英文摘要: |
| Both magnesium oxide expansive agent (MEA) and internal curing are effective strategies for mitigating shrinkage in ultra-high performance concrete (UHPC). However, limited research has addressed their combined effects. This study investigates the synergistic influence of MEA reactivity and dosage on the mechanical properties, shrinkage behavior, and microstructure of recycled sand UHPC, in which recycled sand was used as a full replacement for quartz sand. Two types of MEA with different reactivity levels (designated as R-type and S-type) were incorporated at mass fractions of 4%, 6%, and 8%. The results indicate that while both MEA types lead to a slight reduction in mechanical strength, they significantly reduce both autogenous and drying shrinkage. R-type MEA exhibits superior performance, reducing 7-day autogenous shrinkage and 150-day drying shrinkage by 26.4% and 76.9%, respectively. Microscopic analysis reveals that the higher reactivity of R-type MEA promotes the formation of Mg(OH)₂ crystals, contributing to a denser microstructure. Based on the comprehensive evaluation of mechanical and shrinkage performance, R-type MEA with an optimal dosage of 6% is recommended for recycled sand UHPC applications. |
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