This volume presents the proceedings of the International Conference on The Science and Engineering of Recycling for Environmental Protection (WASCON 2000), of which a number of themes have been identified. All are inter-related and inter-dependent in so far as potential users of secondary, recovered or recycled material have to be assured that the material is environmentally safe and stable. It is the environmental challenge that forms a leading theme for the conference, and the themes of quality assurance and quality control support this aspect. In terms of use of ''recovered'' materials, science and engineering play important and inter-dependent roles and this is reflected in themes which form the very core of the conference. Of no less importance is control of land contamination and how we propose to model for the long term impact of our aims. However dutiful and competent our ideas and studies, there has to be a measure of control and the role of legislation forms the final theme of WASCON 2000.The breadth of studies being undertaken world-wide and the innovative ideas that are expressed in papers submitted are worthy of this important subject. It is also interesting to note that papers were offered from 30 countries, a sign of the increasing awareness of the need to preserve our natural resources and utilize to the full those with which we are more familiar. This book will contribute to the understanding of and solution of environmental problems concerning the re-use of waste materials in construction.