Asphalt mixtures with waste materials: possibilities and constraints

Abstract

Sustainable developments in flexible pavements strongly promote protection of the natural resources from earth. One possibility is to use recycled/waste materials as aggregates. A number of waste materials were studied on their application into asphalt mixtures. Materials tested were sintered granulate from burned household waste, plastic waste as (soft) granular material, ceramic waste from electrical insulators, and foundry sand. Large fractions of sintered household waste, plastic waste and crushed ceramics can be used as partial replacement for the coarse aggregate fraction. Foundry sand could partially replace natural sand in asphalt mixtures. In all cases it was necessary to check basic requirements and for some properties like leaching behavior need to be determined. Basically aggregates of reference mixtures were replaced. Mechanical tests were done on several mixtures with waste components to determine indirect tensile strength, stiffness, fatigue. In order to estimate the water sensitivity of some mixtures, retained indirect tension tests were done. The properties are reported and compared with each other and reference mixtures. From the research it becomes clear that replacement of virgin materials in asphalt mixtures with waste materials is not straight forward. Each waste material has its specific problems.