Premature Cracking in Foamed Asphalt Pavement: Peru-Brazil Highway Case Study

Abstract

The granular base stabilization with foamed bitumen is an alternative whose application is expanding by the increasing demand to preserve and minimize the use of virgin materials and reduce energy consumption. The purpose of this paper is to analyze the origin of premature cracks in the asphalt foaming of the road section I of Brazil Peru that began within hours of completion of the construction process and the evolution continued even when the surface treatment was placed. The scope of this work includes the evaluation and analysis of three critical components, the construction process, the mix design and structural capacity based on an extensive laboratory program and in situ evaluations. The total extension of the project is 470 miles, with foamed bitumen sections of 200 miles (the largest section of foamed bitumen built in South America) of which approximately 50 miles showed premature failure. The failures were mainly concentrated in areas with altitudes between 8,000 and 15,000 feet above sea level. Premature cracks were mainly due to a combination of poor curing process, low relative humidity, excessive fines content, and reduced structural capacity. It is recommended that similar projects should consider an early curing process, a quick surface seal, and adopt standards that consider at least a minimum required thickness, a tolerable range for fine contents, and a maximum allowable deflection.