Research Projects

India's expansive road network, predominantly composed of bituminous pavements, undergoes continuous resurfacing, rehabilitation, and reconstruction, resulting in substantial generation of Reclaimed Asphalt Pavement (RAP). With a theoretical recovery potential of 90–95% of the original asphalt layer (FHWA-RD-97-148), RAP represents a valuable resource for new pavement construction. However, actual reuse remains limited to 30–60%, largely due to the absence of standardized mix design methodologies and performance-based specifications tailored to Indian climatic, material, and traffic conditions. Emphasizing 100% RAP reuse could significantly reduce reliance on virgin aggregates and bitumen, lower life-cycle costs, and mitigate environmental impacts, aligning with national objectives for sustainable infrastructure and circular economy promotion. To harness the full potential of RAP in a sustainable and technically viable manner, innovative recycling approaches are essential. Among these, cold recycling has emerged as a promising alternative to conventional hot mix technologies, offering environmental and economic advantages alongside compatibility with large-scale RAP usage. In particular, Cold In-Plant Recycling (CIP) is recognized for its centralized control, energy savings of up to 63%, and cost reductions of 40–50%. Compared to Cold In-Place Recycling (CIPR), which faces challenges in consistency and quality control, CIP ensures improved material handling and uniformity. In India, design guidelines (IRC:120-2015) support foamed bitumen-based CIP; however, this method requires heating bitumen to 150–160°C, injecting water under pressure, and modifying existing asphalt plants, thereby limiting its broader applicability. In contrast, emulsion-based CIP recycling, widely adopted internationally, permits ambient temperature mixing without plant modifications and has demonstrated comparable or superior performance in terms of moisture resistance, fatigue life, and rutting behavior. Despite these advantages, emulsion-based CIP remains unaddressed in Indian standards, with no dedicated mix design protocol or performance specification for its field use. To address this gap, the present study aims to develop a comprehensive mix design and performance specification framework for emulsion-treated CIP mixtures, calibrated to Indian conditions. The research will establish volumetric and mechanical mix design protocols by optimizing aggregate gradation, emulsion content, and stabilizer dosage. Particular focus will be placed on understanding the interactions among RAP aggregates, bitumen emulsion, and stabilizing agents (e.g., cement, lime), supported by microstructural analyses using FESEM integrated with EDS to examine interfacial bonding. The final mixes will be evaluated through a suite of mechanical tests, including Marshall Stability (AASHTO T 245), Indirect Tensile Strength (AASHTO T 283), Hamburg Wheel Tracking Test (AASHTO T 324), and fatigue performance via IDEAL-CT, SCB, and four-point beam fatigue tests (ASTM D7460), ensuring resistance to key distresses like rutting, fatigue cracking, and moisture damage. In addition, the study will undertake Life Cycle Cost Analysis (LCCA) and Life Cycle Assessment (LCA) to establish the economic and environmental viability of emulsion-based CIP mixtures. By accounting for material variability, regional climate conditions, and realistic loading scenarios, this research is expected to produce field-applicable design guidelines and performance benchmarks for Indian road infrastructure. Ultimately, this work will contribute to the nationwide advancement of sustainable, performance-driven pavement recycling practices. It will support full-scale RAP utilization and help establish resilient, energy-efficient, and cost-effective solutions that can be readily implemented in both national highway and urban road projects.