This BRE Special Digest provides practical guidance on specifying concrete for use in natural ground and in brownfield locations. The procedures for ground assessment and concrete specification cover the fairly common occurrence of sulfates, sulfides and acids and also the more rarely occurring aggressive carbon dioxide found in some ground and surface waters, which affects concrete foundations and sub-structures. This edition has been revised to reflect thinking and changes to British Standards. It introduces the phenomenon of chemical attack of concrete in the ground, describes modes of chemical attack and discusses the mechanisms of the principal types, including sulfate and acid attack, and the action of aggressive carbon dioxide. It then gives guidance on assessing the chemical aggressiveness of the ground, and recommendations for specifying concrete for general cast-in-situ use in the ground. It also gives recommendations for specifying surface carbonated precast concrete for general use in the ground, and includes design guides for specification of specific precast concrete products, including pipeline systems, box culverts and segmental linings for tunnels and shafts. The guidance applies to both buildings and civil engineering construction.