Durability of concrete and cement composites

Conclusions Chemical degradation of concrete

This chapter has presented a fairly brief overview of some of the main areas of concrete durability that depend on the ability of the hardened cement matrix to resist common forms of chemical and microbiologically induced degradation. Constraints on the length of the chapter meant that it was not possible, however, to include a number of interesting topics that would have merited further detailed discussion.

In particular this is so in the case of concrete made with calcium aluminate cements (also known as high alumina cements). These cements have had a chequered history since their introduction in France a century ago where they were originally produced in response to the need for cements with high resistance to sulfate attack. The problems later encountered as a consequence of the gradual phase transformations (known as `conversion’) of the hydrated cement that can degrade its mechanical properties led to an effective ban on structural applications in the UK in the mid-1970s (Neville, 1975). Since then there has been a substantial amount of research into to the nature and properties of these materials and a reassessment by the UK Concrete Society of their potential for applications in construction (Cather et al., 1997). More recently, a number of reviews of calcium aluminate cements have been published (Scrivener and Capmas, 1998; Bensted, 2002d) and they were the topic of a fairly recent international conference (Mangabhai and Glasser, 2001).

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