Mechanical Properties and Microscopic Mechanism of Slag-white Mud Solidified Loess

To explore the feasibility of slag-white mud solid waste material for loess subgrade reinforcement and to solve the problems of low strength and high pollution in the production of lime loess, this study prepared a slag-white mud cementing material and used different dosages (0%, 5%, 10%, and 15%) of slag-white mud cementing material to solidify the loess. The unconfined compressive strength and durability of the solidified loess were investigated based on its physical and chemical properties, and the microscopic mechanism was revealed through X-ray diffraction, thermogravimetry/differential thermogravimetry, and scanning electron microscopy. Results show that the higher the proportion of slag in the slag-white mud cementing material, the greater is the strength growth potential. However, when the slag proportion is greater than 70%, the sample cannot be formed. An appropriate increase in the proportion of white mud can improve the pH and early strength. The best slag is that with a white mud ratio of 60:40 under the consideration of cost and strength. Under a no-soaking condition, the unconfincd compressive strength of slag-white mud solidified loess at 28 d is 4. 9 MPa at a 10% dosage, which is 2. 2 times higher than that of lime solidified loess, and the water stability coefficient is 0. 45 times higher than that of the lime solidified loess. The strength and quality of the solidified loess with 10% and 15% dosages change by less than 2% after 14 freeze-thaw cycles. The strength of the solidified loess first increases and then decreases with the number of dry-wet cycles, and the strength of the solidified loess after 12 dry-wet cycles is higher than that after 28 d. Microscopic experiments show that white mud promotes the slag hydration reaction. The main hydration products of slag-white mud cementing materials are CSH-type gels. The cementation of the CSH gel is the main source of strength and durability improvement, where the filling effect plays a secondary role. © 2024 Chang'an University. All rights reserved.