Sustainable Road Design: Promoting Recycling and Non-Conventional Materials

Nicholas Thom,Andrew Dawson

doi:10.3390/su11216106

Abstract

Many factors impact on the sustainability of road maintenance, including the organization of road authorities, contract forms used, financing structure and, unfortunately, political interference and corruption. However, this paper reviews the opportunities to increase sustainability by utilizing less environmentally damaging material sources, and also the associated challenges. It is a field that has seen advances in recent decades, for example in the effectiveness of cold-mix asphalt binders. Nevertheless, the opportunities are not being taken up in many countries, and this reflects uncertainty in predicting performance. This paper reviews the different design methods available, developed in both temperate and tropical climates, and highlights the lack of agreement with regard to non-conventional materials. The different sources of uncertainty and risk are then discussed, together with ways of limiting them. It is found that, while advances in performance prediction are highly desirable, the key to encouraging recycling and the use of inexpensive but non-conventional materials lies in development of the right contractual arrangements, specifically partnering and risk/reward sharing. The paper concludes with a discussion on approaches to partnering in the construction industry and the prerequisite climate of trust without which innovation is almost inevitably stifled.

Highlights

The need to minimize use of scarce primary resources is becoming ever more urgent in most industries as humanity relentlessly exhausts this planet’s ability to satisfy its demands and carelessly discards waste to the detriment of the environment
In the UK, for example, roads consume some 25% of all materials extracted from the ground [1] and, while most of these sources are not in immediate danger of becoming exhausted, the impact on the environment is substantial
In relation to Malawi, Kamanga and Steyn [2] list material cost and/or shortage as a key reason for project delays. They suggest this is often because designs and specifications do not allow for the use of a possibly inferior but more readily available material, which would include recycled materials

Summary

Introduction

The need to minimize use of scarce primary resources is becoming ever more urgent in most industries as humanity relentlessly exhausts this planet’s ability to satisfy its demands and carelessly discards waste to the detriment of the environment. In the UK, for example, roads consume some 25% of all materials extracted from the ground [1] and, while most of these sources are not in immediate danger of becoming exhausted, the impact on the environment is substantial. In relation to Malawi, Kamanga and Steyn [2] list material cost and/or shortage as a key reason for project delays. They suggest this is often because designs and specifications do not allow for the use of a possibly inferior but more readily available material, which would include recycled materials. As reported by Oke et al [3] in the case of Nigeria, failed asphalt is routinely discarded rather than being recycled, this in itself represents a direct and negative environmental impact

Objectives

Methods

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Conclusion