Abstract
With the rapid growth of traffic volumes and axle loads, the use of efficient and cost-effective stabilization methods is imperative. The use of foam bitumen stabilization is rapidly growing because of its environmentally friendly benefits and its high field performance properties. In this study, a detailed investigation of the mechanical properties of foam-stabilized mixes was carried out. The experimental work presented compares the mechanical properties of foam-stabilized mixes created with two different gradations and eight bitumen types from six different sources. Different types of mineral fillers, including hydrated lime, fly ash type C, portland cement, and pond ash, were used in the mix design. The volumetric properties, resilient moduli, indirect tensile strengths, fracture energies, and California bearing ratio (CBR) values were investigated. Temperature and moisture susceptibilities were studied and compared for different types and grades of bitumen. Foam-stabilized mixes provided lower temperature susceptibility than did hot-mix asphalt. The effect of bitumen source and grade on moisture susceptibility was inspected. The foam-stabilized mixes provided reasonable moisture resistance as the index of retained strength exceeded 80% to 90% after 5 days of soaking. The effect of aggregate gradation and mineral fillers on the indirect tensile strength and the fracture energy was evident. Hot-mix asphalts provided higher tensile strength and fracture energy than did foam-stabilized mixes. Foamed bitumen stabilization significantly enhanced the CBR values as the soaked CBR of foam-treated specimens provided higher CBR values than the conventional untreated aggregates.
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