ABSTRACT

This chapter characterizes the different environmental exposures, or more correctly, the durability loading that is imposed on infrastructure. Built infrastructure coexists with an external environment that can have a diverse range of physical and chemical characteristic. The macro-environment affects large geographical regions and is applied to multiple built infrastructures that may be located in one or several countries. The macro-environment is difficult to change: the features that define the physical and human ­geography of a region are reasonably fixed. Within a meso-environment, exposure to rainfall can bring mixed fortunes: rainfall can contribute beneficial washing of corrosive salts from the surface, whereas pooled water and prolonged surface wetness can accelerate corrosion of unprotected metals. The meso-environment must consider the soil and groundwater chemical composition, permeability and the propensity toward corrosion and/or adverse chemical reaction with construction materials. The generation of acidic soil occurs from nearby coal or metalliferous mines where metal sulphides are oxidised, thereby, generating sulphuric acid.