This article discusses the use of alternative methods in road construction, with special reference to the European Union (EU) project ALT-MAT (ALTernative MATerials in Road Construction). The use of alternative materials will primarily enable reduction of the consumption of natural gravel, and reduce the volume of demolition materials deposited on waste tips. However, several questions have been raised about methods of correctly evaluating alternative materials and their properties. ALT-MAT projects generally aim to define methods for evaluating the suitability of alternative road construction materials in various geological environments and climatic conditions. Methodology studies include those on mechanical properties, performance requirements, leaching of various substances, and long-term stability. The emphasis is on assessing and evaluating various materials for use as unbound materials in roads, streets, etc. The projects's core is a literature study of political, technical, environmental, and economic prerequisites for using the materials. Specific studies include a test of a highway using a new form of blast furnace slag, and crushed concrete, sometimes mixed with brick, as an interesting alternative for use in roads, streets, cycle paths, and parking areas. ALT-MAT will issue its final report in late 1999.
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