Use Of Recycled Materials In Asphalt Pavements In Support Of Sustainable Construction

Use of secondary aggregates, in preference to quarried minerals, in civil construction is commonplace. This has the 'dual sustainability benefits' of reducing the amount of waste for landfill disposal and reducing demand for extraction of depleting resources. Pressures from a number of stakeholders emerge in the past decade, in a concerted effort to maximize the portion of recycled and secondary aggregates in construction supplies. Yet in practice a few concerns have a serious effect on this recycling attempt.The construction and maintenance of asphalt pavements require materials in both quantity and quality. A few industrial by-product and municipal waste possess comparatively inert and consistent properties, making them suitable for road use. Pavement surface, directly subject to tyre loading and weathering, introduces therefore a few more requirements for both composing aggregates and final asphalt. Review of relevant standards and literature helps identify these requirements, and performance of pavement structure containing those recycled constituents. Use of waste glass and steel slag in surface asphalt is analysed in this paper.Road surface asphalt represents a value application with continuous demand. A sustained supply of waste materials suitable for economy recycling into target use is necessary for commercial acceptance. A study of waste arising and management indicates that although potential supply is good, a few factors, the cost issue in particular, have effectively discouraged the recycling in practice. It is believed that those barriers are also applicable to other waste materials, and a few measures are suggested for their removal.Pavement construction has a few features indicating its environmental significance, which calls for unbiased and accredited techniques for assessing the impact of materials replacement. Life Cycle Assessment (LCA) emerges as a useful tool to compare and evaluate environmental loadings by quantifying the total environmental costs associated with recycled materials use. This paper reviews the relevance of LCA to the asphalt industry, identify the main phases of pavement work, and describe LCA resources in academia and industry which might be of assistance to this research. An example of on-going LCA for a resurfacing job is presented, and some further work proposed.