A Review on the Modification of Cold‑Mix Asphalt for Pavement Construction

Abstract

Cold mix asphalt (CMA) reduces energy input and greenhouse gas emissions through production and placement at ambient temperatures. The chief limitations entail high air-void content, long curing time, and initial low strength. This systematic review aggregates recent experimental work related to additives targeting these disadvantages. Geopolymer additives develop hardened structures improving Marshall stability and, when used at optimal asphalt-geopolymer ratio, allow short curing times. Industrial by-product fillers, i.e., paper sludge ash and cement kiln dust, increase stiffness and reduce cure times and offer more environmentally friendly substitutes for conventional fillers. Nanomaterials have been widely studied in hot-mix asphalt and binder contexts; they can modify viscosity and increase rut resistance but at the potential cost of sacrificing low-temperature ductility. Very few studies have directly applied nanoparticles to CMA in peer-reviewed research, and this represents an important gap in research findings. Among CMA studies investigated here, overall CMA performance was generally boosted in terms of resilient modulus, resilient and permanent deformation, and moisture resistance; excessive stiffening could, however, undermine fatigue resistance. The review highlights important research questions related to long-term durability, life-cycle performance, and dosage optimization and highlights priorities for future CMA research.