The production of aggregates for construction is the largest of the extractive industries in Britain. Natural aggregates form the main component, by volume, in the manufacture of concrete but the part played by aggregates in the durability and performance aspects of concrete is still relatively little understood.
The paper summarizes the main physical and chemical considerations of aggregate in concrete, especially those leading to cracking and deterioration. It broadly considers the British specification of aggregates, which has largely been built up from decades of local experience, and emphasizes the need in many locations overseas for more specific requirements on use of aggregates in different climatic and geological settings. The strong influence on aggregate performance by the use of geologically weathered rock is little recognized even in good concrete practice and is highlighted in the paper. In conclusion, suggestions are given for all-purpose aggregate testing programmes.