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Chemicals harmful to concrete

What common chemicals are harmful to/attack concrete?

Answer

Commonly used chemicals will not seriously damage concrete unless they are left in contact for some time. To a greater or lesser extent, concrete is attacked by most acids, which may become more concentrated due to evaporation. This leads to an increased rate of attack. Details of the various potentially harmful materials and rate at which various acids attack concrete are given in Concrete Society Technical Report 54, Diagnosis of deterioration in concrete structures.

It is important to realise that many acids are the products of reactions of other substances which may, in themselves, be harmless to concrete or may only be present in low concentrations in these substances. For example, milk is not harmful, but sour milk contains lactic acid, which will attack concrete rapidly when concentrated. Examples of common substances with low concentrations of acids include beer (lactic or tannic acid), cider (acetic acid) and fruit juices (various acids). Finally petrochemical products (such as petroleum oil) can attack concrete.

Substances containing acids, or ones that can react to form acids, should not be left in contact with the concrete, but should be removed as soon as possible. The concrete surface should be washed with fresh water to remove traces of the material. Oils may require the use of a solvent to remove them.

The PCA publication ´Effects of substances on concrete and guide to protective treatments´ can be downloaded from the PCA catalogue

Acknowledgement: Concrete Information Ltd

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TR54 Diagnosis of deterioration in concrete structures- identification of defects, evaluation an