Modeling the Influence of Additives on Deterioration of the Creep Stiffness of Asphalt Binder

Thermal cracking in asphalt concrete pavement represents a significant pavement distress in cold environment. As the temperature drops below freezing limit, thermal stress starts to increase in the restrained asphalt pavement layer. The flexural-creep stiffness of asphalt cement binder is considered as a good indicator of the resistance to cracking of the binder at low temperature which is measured with the aid of Bending Beam Rheometer (BBR). An attempt has been made in the present study to evaluate and model the influence of additives (hydrated lime, and coal fly ash) on the deterioration of the creep stiffness of asphalt cement binder with penetration grades (40-50) and (60-70). Conventional asphalt binders were found to be highly sensitive to stress at low temperatures. However, modification of the asphalt cement binder with additives can control the deterioration in the flexural-creep stiffness. It was concluded that the rate of decline in the creep stiffness throughout the loading period for (40-50) and (60-70) binders was (21.5, 22.2, and 14.5) % and (20, 19, and 16.6) % for control, coal fly ash modified, and hydrated lime modified asphalt binder respectively. For (40-50) and (60-70) binders at failure stage, there is a significant increase in the creep stiffness of (5 and 32.5) % and (6.2 and 25) % for coal fly ash and hydrated lime modified asphalt binder specimens respectively as compared with the control binder. The mathematical power models are recommended to predict the Influence of additives on deterioration of the creep stiffness of asphalt binder.