What is Mundic?
Cornwall and parts of Devon have witnessed centuries of mining activity. Widespread adoption of concrete blocks and mass concrete construction resulted in builders and blockmakers using mine waste as aggregate - it was cheap, often free, and readily available in the region. In some instances the minerals (including pyrite, or ‘mundic’) have caused the concrete to deteriorate due to chemical reactions within the aggregate. This has resulted, in some cases and with some types of aggregate, in the physical strength of the concrete being compromised. The sample below shows an extreme example of mine waste material; not all instances are this dramatic.
Mine waste was readily available across large parts of Cornwall and Devon. The very metals that were so prized and hard won from the ground proved to be a potential cause of concrete decay and structural failure. The scale of construction using these aggregates ran from entire estates down to batches of blocks and small extensions. Raw material and finished blocks were often stockpiled and occasionally turn up in properties outside of mining areas. It is generally accepted that particular attention must be paid to mass concrete and concrete block constructions dating from the turn of last century to around 1965.
Mortgage lenders require assurance that an asset will survive for the duration of the loan period, and home and property owners need to know that their asset is mortgageable. Research conducted by local surveyors working with the BRE lead to a series of tests to indentify and classify aggregate types in order to predict the potential behaviour of the concrete. These tests were formalised and issued by The Royal Institution of Chartered Surveyors (RICS) in the form of a Guidance Note. It is this guidance note that Chartered Surveyors use when assessing properties and making recommendations to lenders.The classification can involve up to three stages, all of which we carry out here at Wheal Jane.
