A Review Studies on Performance Characteristics of Bituminous Mix Using Proteinous and Non-Proteinous Wastes of Leather

The rapid growth of the leather industry has resulted in the generation of substantial amounts of solid waste, including both proteinous and non-proteinous materials such as chrome shavings, limed fleshing, and buffing dust. These wastes, if not managed properly, pose serious environmental and health risks due to their chemical content, particularly chromium compounds. In recent years, there has been growing interest in utilizing such wastes in civil engineering applications, especially in bituminous road construction. This review paper compiles and critically analyzes existing research on the use of leather industry wastes in the design and performance enhancement of Stone Matrix Asphalt (SMA) mixtures. It explores the potential benefits of incorporating leather waste as stabilizing additives and fillers, including improved mechanical strength, enhanced rutting and moisture resistance, and reduced environmental impact. The paper also compares leather waste-based SMA mixes with those modified using other industrial by-products such as rubber, fly ash, and plastic waste. The findings from various studies highlight that leather waste, when processed and applied appropriately, can serve as an effective alternative material in road construction. This not only supports sustainable waste management practices but also contributes to cost-effective and durable pavement solutions. The review concludes with recommendations for future research directions, focusing on large-scale implementation, long-term performance evaluation, and environmental safety.