CHENG Yinyin^a, LI Hongbo, KANG Xinrui^a, DING Yongfa^a,TONGYufei^a

(a. School of Civil and Hydraulic Engineering, b. Ningxia Engineering and Technology Research Center for Water-saving Irrigation and Water Resources Regulation, c. Ningxia Engineering Technology Research Center for Civil Engineering Seismic and Disaster Mitigation, Ningxia University ,Yinchuan 750021, China)

Abstract：In order to reduce the amount of natural gravel mining and solve the problem of large amount of industrial waste and construction solid waste accumulation, cement and fly ash were used to stabilize steel slag and concrete regeneration gravel, and subgrade mixture was prepared. The better quality ratio of steel slag and concrete regeneration gravel was determined by dry and wet cycle test when the content range of cement and fly ash was determined. On the basis of selecting the better quality ratio of steel slag and concrete regeneration gravel, the mechanical properties of the mixture were tested by triaxial test to further optimize the content of cement and fly ash. X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectrum were used to analyze the composition, microstructure and changes of the characteristic products ofhydration reaction of mixtures of different ages, and the formation mechanism and strength influencing factors of mixtures were studied. The results prove that the relative strength of the mixture is the highest and the mass loss fraction is the lowest when the mass ratio of steel slag and concrete regeneration gravel is 3∶1. When the cement mass fraction is 5%, the fly ash mass fraction is 16%, and the mass ratio of steel slag and concrete regeneration gravel is 3∶1, the mixture has the strongest cohesion, the largest shear strength and better mechanical properties. The addition of steel slag in the early stage of mixture hydration can increase the amount of ettringite generation and improve the strength of the mixture. The hydration products of the mixture are mainly calcium silicate hydrate, calcium hydroxide and ettringite. The increasing of calcium ion concentration increases the alkalinity of the system, shortens the silicon-oxygen tetrahedral chain in calcium silicate hydrateand reduces the polymerization degree of the mixture.

Keywords：fly ash; steel slag-concrete regeneration gravel; subgrade mixture; dry and wet cycle test; triaxialtest

Get Citation：CHENG Y Y, LI H B, KANG X R, et al. Preparation and properties of subgrade mixture made of steel slag-concrete regeneration gravel stabilized with cement and fly ash[J]. China Powder Science and Technology, 2023, 29(4): 11-21.

DOI：10.13732/j.issn.1008-5548.2023.04.002

Received：2022-12-15,Revised：2023-05-04,Online：2023-05-26 11:24。

Funding Project：宁夏重点研发计划项目,编号:2021BDE92002;宁夏高等学校一流学科(水利工程学科)资助项目,编号:NXYLXK2021A03。

First Author：程银银(1999—),女,硕士研究生,研究方向为土木工程新材料。E-mail: cyynxu@163.com。

Corresponding Author：李宏波(1977—),男,副教授,博士,硕士生导师,研究方向为土木工程新材料。E-mail: lhbiongo@126.com。