Recycling Solid Wastes as Road Construction Materials: An Environmentally Sustainable Approach

Abstract

Improved environmental performance in industry and society is a concept now a quarter-century old. Efforts in this regard have yielded much in the way of environmental improvement. It is easy to demonstrate that most of the activities of today's industrial society are unsustainable. Unfortunately, much of the talk about sustainability lacks a basic understanding of what truly sustainable activity would be. To set sustainability as a target or a goal for our industrial society, it is important to quantify that target or goal.

Currently, the transportation industry is under increasing pressure to use alternate or secondary materials because of its high-volume consumption of bulk materials (such as natural fine and coarse aggregates) in road construction. Materials including industrial by-products, concrete aggregates, old asphalt pavement, scrap tires, fly ash, steel slag, and plastics are often used as alternate materials for natural aggregates. As these products are not normal construction materials, there are concerns about their environmental suitability, recyclability and sustainability in concrete and road pavement applications, as well as their environmental impact on surface and ground waters.

The present chapter (a) evaluates the general concepts of sustainability, (b) reviews and evaluates the various types of solid wastes that are currently used as road construction and repair (C&R) materials, (c) discusses both the chemical and physical properties of such wastes and their engineering uses, and finally (d) presents the general project approaches of a major research program to investigate the environmental impact of highway C&R materials on surface and ground waters.