Sustainable Reuse of Limestone Quarry Fines and RAP in Pavement Base/Subbase Layers

The advantages of utilizing recycled materials/byproducts in pavement construction are numerous. The reduction in landfilling resulting from the adoption of recycled materials in large quanitites primarily promotes their usage. Most of the recycled materials are used successfully throughout the world as embankment fill or subgrade foundation material. Although the utilization of the recycled materials/byproducts as pavement bases has been gaining increased acceptance, comprehensive geotechnical characterization of these materials is still lacking. In a research project, Limestone quarry fines (QF), which are a residue deposit produced from limestone quarries, and reclaimed asphalt pavement (RAP) aggregates, obtained from milling existing hot-mix asphalt (HMA) pavement layers, were characterized in both laboratory and field conditions. Before the usage of these materials as pavement bases, a series of laboratory tests were conducted to verify their engineering behavior and suitability. Shear strength and consolidation tests were performed to evaluate both strength and compressibility characteristics. Repeated load triaxial tests were conducted to obtain the resilient behavior of these recycled materials. Because the QF material exhibited both low strength and low moduli, cement stabilization was performed to enhance the material properties. The treated materials were then used as bases in test sections built as a part of the state highway. These test sections were instrumented and monitored for approximately 3 years. However, the long-term performance of the new materials is crucial for highways. Henceforth, numerical simulations were performed to predict the-performance of the test sections. This paper presents a summary of test results obtained from the laboratory, field, and numerical studies, and the results were analysed to evaluate the efficacy of these materials as pavement bases.