Study on the mechanical response and mechanism of high-performance mineral-based cementitious materials solidifying discarded ballast in aqueous-saline environments

The reloading of railway ballast cleaning operations will produce a significant quantity of discarded ballast, and its comprehensive utilization can facilitate the green transformation and advancement of the social economy. To achieve the comprehensive utilization of discarded ballast, this article employs self-developed High-Performance Mineral-Based Cementitious Materials (HMCM) and PO42.5 cement for the industrial production of non-fired bricks. It compares and tests the mechanical properties of these bricks under varying curing and erosion environments, while also incorporating FTIR analysis to investigate the phase transformation behaviors of non-fired bricks subjected to different curing and erosion conditions. The results indicate that: (1) The mechanical properties of standard cured non-fired brick samples improved by approximately 20% compared to those subjected to natural curing. Furthermore, the mechanical properties of HMCM bricks are markedly superior to those of cement-based bricks, exhibiting a compressive strength that can reach three times that of cement bricks within just three days. (2) HMCM bricks exhibit superior resistance to erosion from both clear water and saltwater compared to cement bricks, with a strength loss rate of merely 50% relative to their cement counterparts. Notably, the damage inflicted by saltwater erosion is considerably greater than that caused by clear water, while the anti-erosion performance of standard cured specimens is even more remarkable. (3) HMCM exhibits superior corrosion resistance under standard curing conditions, as it facilitates the transformation of monomer Si-O and Al-O bonds within the reaction system into high-polymerization Si-O-Si and Si-O-Al bonds. This process enhances the degree of polymerization and crystallinity of the cementing system. Furthermore, by developing a compressive strength damage model, the damage evolution patterns of non-fired bricks in erosive environments have been elucidated, thereby validating the practicality of utilizing discarded ballast non-fired bricks and establishing a theoretical foundation for their engineering applications.