A Review of Frost-Salt-Mechanical Coupled Deterioration Mechanisms in Vibropressed Concrete for Pavement Applications

ABSTRACT: Freeze-thaw cycling, deicing salt attack, and traffic-induced mechanical loading are major causes of durability loss in concrete pavements in cold and seasonally frozen regions. Vibropressed concrete (VPC), manufactured with low water-to-binder ratios, dry-consistency mixtures, and intensive vibration-compaction, is widely used in paving blocks, kerbs, slabs, and other precast pavement units. Although VPC often exhibits high density, dimensional stability, and early strength, its connected capillary pores, weak interfacial transition zones, and compaction-related anisotropy may make it vulnerable once moisture, salt solution, and load-induced microcracks interact. Based on the first three chapters of the existing dissertation draft, this paper reviews the deterioration mechanisms of VPC under coupled frost-salt-mechanical exposure, including freeze-thaw damage, chloride transport, deicing salt scaling, load-induced cracking, ultrasonic pulse velocity (UPV) monitoring, and predictive modelling. The review shows that the mechanisms of single-factor freeze-thaw damage, salt-frost scaling, and mechanical deterioration in ordinary concrete have been extensively studied, whereas quantitative interaction effects, early-warning UPV thresholds, and service-oriented prediction models for VPC remain insufficient. Future research should integrate initial material structure, coupled exposure paths, non-destructive monitoring, and multi-indicator modelling to support durability design and service-life assessment of precast concrete pavement elements in cold regions. Keywords: vibropressed concrete; freeze-thaw cycles; chloride attack; mechanical loading; ultrasonic pulse velocity; durability