Concrete and its reinforcement


Aggressive chemical environment for concrete classification (ACEC class)A system for the classification of aggressive ground conditions that are derived from
design sulfate class. It takes into account the site (natural or brownfield) and the mobility and pH of ground water. Brownfield, ‘mobile’ water and low pH (acidic) conditions may have adverse effects on buried concrete and hence result in a more severe ACEC class.
Additional protective measures (APM)These are defined as the extra measures that could be taken to protect concrete where the basic concrete specification might not give adequate resistance to chemical attack.
Design chemical class
(DC class)
This defines the qualities of concrete that are required to resist chemical attack. The DC class is derived from the ACEC class of the ground and other factors, including the type of concrete element and its required structural performance.
Design sulfate class
(DS class)
A site classification based on the determined sulfate (including potential sulfate) contents of the ground and/or ground water. It is also dependent on the type of site, presence or absence of magnesium ions, pyrite, and for pH less than 5.5, chloride and nitrate ions. Five levels of classification are given that are equivalent to those given in BRE Digest 363 (now superseded).
Enhanced concrete qualityAn incremental step in concrete quality that could be used as an Additional Protective Measure (APM). Each increment in concrete quality is counted as an extra APM.
Mobile ground waterSites where water is free to flow into an excavation to give a standing water level are affected by mobile ground water. The threshold ground permeability is greater than 10-6 m/s (i.e. 86 mm/day).
Static ground waterThe sites where the free flow of water is confined due to either permanently dry conditions or the soil is relatively impermeable (of permeability less than 10-6 m/s).
Total potential sulfate (TPS)The total potential sulfate content is the result of the combination of sulfates already present in the ground and that which may be added due to the oxidation of pyrite in the ground.