Warm Mix Asphalt: Natural Additives and Sustainable Technologies for Reducing Environmental Pollution

Warm Mix Asphalt (WMA) has emerged as a promising sustainable alternative to traditional Hot Mix Asphalt (HMA), offering substantial environmental and performance advantages by enabling asphalt production and compaction at lower temperatures. This review paper explores the role of natural and renewable additives—such as bio-based waxes, vegetable oils, natural zeolites, and bio-binders—in enhancing the workability, compatibility, and durability of WMA while significantly reducing energy consumption, greenhouse gas emissions, and environmental pollution. Particular emphasis is placed on how these additives improve binder performance, enable higher incorporation of Reclaimed Asphalt Pavement (RAP), and contribute to circular economy principles by valorizing bio-waste and industrial by-products. The paper also discusses the limitations and challenges associated with variability of natural feedstocks, field performance uncertainties, and standardization needs. By synthesizing recent research and field applications, this study highlights the practical potential of bio-based WMA technologies to advance sustainable road construction and identifies critical areas for future research and large-scale implementation.