Development of Fly Ash Stabilized Recycled Base Material (FRB) for Indian Highways

Abstract

Reclaimed asphalt pavement (RAP) materials in pavement base courses has proven to be a viable alternative not only to conserve the natural resources but also to reduce the environmental pollution and landfilling. Since RAP is ineffective to be used as a pavement base material, they are often blended with virgin aggregates (VA) or stabilized with cementitious materials. This study, an attempt has been made to develop a fly ash stabilized recycled base material (FRB) by utilizing RAP and class F fly ash. To develop a potential design base mix, RAP:VA mixes stabilized with alkali activated fly ash was considered. The alkali activation is proposed to increase the reactivity of the fly ash to further enhance the strength of the mixes as the presence of aged bitumen coat over the RAP aggregates may affect the long-term strength and durability of the design mixes. Hence, the present study also verifies the durability of the mixes by subjecting the specimens to aggressive wet-dry cycles to quantify the weight loss. The permanency of the stabilizer/activator is also verified through leachate studies. The comprehensive experimental test results indicated that the RAP:VA mixes are durable and found suitable for the base course applications. Based on the experimental data, design charts were proposed to design a pavement system with recycled materials.