LI Ying, KANG Xiaoming, CHEN Xi, DAI Dahu

(School of Civil Engineering；Qinghai Provincial Key Laboratory of Energy Saving Building Materials and Engineering Safety, Qinghai University, Xining 810016, China)

Abstract: By using the Andreasen theory of the dense packing powder, the effect of the particle size distribution of the recycled concrete powders(RCP)on microstructure and strength of cement gel was discussed in this paper.The RCP powders were milled in different time and incorporated into the cement mortar in the same substitution to investigate the relationship between particle size distribution of powder materials in cement gels and mortar strength, cement stone pore structure and micro-morphology.It is demonstrated that with the grinding time increases, the particle gradation of the powder material in the cement gel is improved, the content of particles with the size under 10 μm is continuously increasing, and it can exert a good filling effect after being used in mortar, and improve the microstructure of cement gel.The total porosity of mortar prepared with RCP-30 increased by 18.2% compared with the mortar by using unscrupulous RCP powders, while the average pore size decreased by 51.9%, the harmous holes with the diameter under 20 nm increased by 25%, and the pore diameter was gradually refined.The pore structure has been improved and the structure of cement paste tends to be density, and the mortar 28 d compressive strength reached 43.9 MPa.

Keywords: recycled concrete powder; particle size distribution; dense packing; pore structure

中图分类号： TU528.041                          文献标志码：A

文章编号：1008-5548(2022)03-0107-09

DOI:10.13732/j.issn.1008-5548.2022.03.013

收稿日期： 2021-10-29， 修回日期：2022-03-07，在线出版时间：2022-04-22。

基金项目：国家自然科学基金项目，编号：51668025；青海省科学技术厅基础研究计划项目，编号：2017-ZJ-787。

第一作者简介：李滢(1974—)，女，教授，硕士，硕士生导师，研究方向为建筑垃圾再生利用。E-mail：liying.qh@163.com。