Unless you’re a Cornish structural engineer I bet you don’t know what mundic means.   It is a Cornish adjective that describes a kind of crumbling concrete.  I came across it here, a weekly column in the Guardian that shows interesting property for sale.  According to Wikipedia,

Mundic was used from the 1690s to describe a copper ore, which began to be smelted at Bristol and elsewhere in southwestern Britain. Smelting was carried out in cupolas, that is, reverberatory furnaces, using mineral coal …

The thing is, as every architect and engineer kno, concrete and copper cannot come in contact, because galvanic action occurs (a bad thing like rusting).  Nowadays “mundic” refers to what happens to Cornish stones that have been used as aggregate in concrete:

The mundic problem
The Cornish word mundic is now used to describe a cause of deterioration in concrete due to the decomposition of mineral constituents within the aggregate. A typical source of such aggregates is metalliferous [in this case, copper-] mine waste. Current professional guidance notes describe all of Cornwall and an area within 15km of Tavistock as being areas where routine testing for mundic is required. The notes go on to state that testing should be confined to buildings which contain concrete elements (blocks or insitu) and that were built in or prior to 1950. However, the notes contain advice that testing may be required where there are visual or other signs of mundic decay. Testing leads to a classification of A, A/B, B and C. A is sound and C is unsound. Classifications A/B, B & C may make properties un-mortgagable.

The next time you’re on a seven-hour flight, tell your neighbour all about the mundic problem; it may have consequences if they apply for a mortgage in Cornwall.

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