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硅酸盐通报 ›› 2023, Vol. 42 ›› Issue (2): 478-486.

所属专题: 水泥混凝土

• 水泥混凝土 • 上一篇    下一篇

真空去水压制成型对机制砂混凝土性能的影响

周朋1, 王有旗1, 赵双林1, 刘普前1, 崔立朕1, 孟勇1, 徐晶2, 詹培敏2   

  1. 1.中铁二十五局集团第五工程有限公司,青岛 266101;
    2.同济大学材料科学与工程学院,上海 201804
  • 收稿日期:2022-09-12 修订日期:2022-11-09 出版日期:2023-02-15 发布日期:2023-03-07
  • 通信作者: 徐 晶,博士,副研究员。E-mail:nanonewman@126.com
  • 作者简介:周 朋(1989—),男,工程师。主要从事混凝土结构耐久性和材料力学研究。E-mail:755709808@qq.com

Influence on Performances of Machine-Made Sand Concrete Fabricated by Vacuum Water-Removal and Compression Technique

ZHOU Peng1, WANG Youqi1, ZHAO Shuanglin1, LIU Puqian1, CUI Lizhen1, MENG Yong1, XU Jing2, ZHAN Peimin2   

  1. 1. The 5th Engineering Co., Ltd., China Railway 25th Bureau Group Co., Ltd., Qingdao 266101, China;
    2. School of Materials Science and Engineering, Tongji University, Shanghai 201804, China
  • Received:2022-09-12 Revised:2022-11-09 Online:2023-02-15 Published:2023-03-07

摘要: 为顺应当今建筑工业化和固废资源化趋势,工程界提出了采用真空去水压制成型新工艺,以实现机制砂混凝土的高效预制生产。本文研究了真空去水压制成型时间对不同初始水灰比(W/C)机制砂混凝土性能的影响,结果表明:与天然砂混凝土相比,真空去水压制能更显著提升机制砂混凝土的强度,主要是由于在高密实成型条件下,机制砂充分发挥了嵌锁效应,经真空负压-0.07 MPa及压制15 MPa处理100 s后,机制砂混凝土初始W/C从0.58降低至0.32,抗压强度提升了44.6%,延长处理时间性能提升效果减弱,尤其是对W/C较小的混凝土;压汞测孔(MIP)发现真空去水压制后混凝土硬化体孔隙率大幅降低,尤其是大于50 nm的有害孔,与压制前相比,其比例下降均超过70%,孔径分布得到了改善,且水化程度均提高至0.6以上;扫描电子显微镜(SEM)和X射线衍射(XRD)表明,经真空去水压制处理后,混凝土内硬化浆体变得更密实,定向排列的针状钙矾石及片状Ca(OH)2含量减少,而界面过渡区(ITZ)黏结性能提高。采用真空去水压制成型机制砂混凝土,符合现代预制混凝土构件生产的绿色、节能、环保发展要求。

关键词: 机制砂混凝土, 预制构件, 真空去水, 压制, 孔结构, 微观组织

Abstract: In order to adapt to the current trend of building industrialization and solid waste recycling, a new technology of vacuum water-removal and compression was proposed in the engineering field to achieve a highly efficient pre-fabrication of machine-made sand concrete. In this study, the effect of the time of vacuum water-removal and compression treatment on the performances of machine-made sand concrete with varied initial water-to-cement ratio (W/C) was investigated. Results show that vacuum water-removal and compression can significantly improve the strength of machine-made sand concrete as compared to natural sand concrete, primarily due to the locking effect of the machine-made sand under the condition of high compaction by the treatment. The initial W/C of machine-made sand concrete decreases from 0.58 to 0.32 and the compressive strength increases by 44.6% after being treated with -0.07 MPa vacuum pressure and 15 MPa compression for 100 s. However, the improvement of performances weakens with prolonged treatment time, especially for concrete with lower W/C. Mercury intrusion porosimetry (MIP) results reveal that the porosity of concrete decreases significantly after vacuum water-removal and compression treatment. In particular, the proportion of capillary pores with pore size larger than 50 nm decreases by more than 70%. Thus, the pore size distribution is improved. The hydration degree also increases to more than 0.6. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) show that the hardened paste in concrete is densified, the amounts of aligned needle-shaped ettringite and plate-shaped Ca(OH)2 are reduced, and the bonding property of interfacial transition zone (ITZ) is improved by vacuum water-removal and compression. The machine-made sand concrete fabricated by vacuum water-removal and compression is in line with the developing trend of green, energy saving and environmental protection for the production of modern pre-cast concrete members.

Key words: machine-made sand concrete, precast member, vacuum water-removal, compression, pore structure, microstructure

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