Guide To Mundic Testing

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The term Mundic has become used as the generic name in Cornwall, and parts of Devon, for concrete which is made with aggregates containing reactive minerals.

In particular the term relates to concrete where the aggregate used was a mining, or a processing waste. Such materials are frequently rich in sulphide minerals and in particular pyrite (frequently known as fools gold), from which the Cornish word Mundic is taken.

When incorporated into concrete these minerals have proved to be unstable and through a complex chemical and mechanical process will ultimately lead to the complete breakdown of the concrete.

Which Properties are at Risk?

During the early part of this century, builders and concrete manufacturers made extensive use of the readily available mine spoil tips in the production of concrete. These tips were widespread throughout the county, wherever mining activity had taken place, and of course comprise crushed, broken stone, diminishing to dust, all being of ideal size for use as an aggregate and binder in concrete.

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The unsatisfactory nature of these aggregates was not fully recognised until after the second world war when British Standards, and improved quality control gradually eliminated their use. Therefore it is generally considered that any property of concrete construction built prior to 1950 can be at risk, or may already show signs of deterioration.

However there are occasional exceptions and therefore the local knowledge of an experienced Chartered Surveyor, specialising in this sphere, is invaluable.

Who Requires a Mundic Screening Test?

Almost anyone owning, or wishing to purchase a property built during the at risk period will, at some point have need of a test.

In an advanced state of deterioration Mundic concrete becomes physically unsound and in many severe cases has lead to a need to demolish affected buildings.

In most instances Mundic materials cannot be identified visually insitu and the building may show no signs of distress whatsoever. For this reason a full concrete screening test is the only way of identifying that a property is unaffected.

Because of this anyone considering purchasing a property must have a test carried out in order to protect their investment. A cash purchaser should be mindful of the need for a satisfactory Classification for potential resale purposes. Any purchaser, or existing owner of a property considering a mortgage or remortgage, will be required by their bank or building society to have a test carried out prior to an offer of advance being made.

In most cases, anyone selling a property prior to the relevant date will find that a test carried out in advance is a useful marketing tool and can certainly save time at the contract stage.

What Does the Test Involve?

There are two main elements to a concrete screening test.

The first element is the site inspection and concrete sampling.

This involves a careful assessment by an experienced Chartered Surveyor of the structure of the building, together with its condition where relevant to this subject.

Following this, concrete samples are taken from positions considered appropriate.

In most instances the samples taken will be 50mm (2″) diameter cores drilled to a depth of about 75mm to 100mm, which will be carefully recorded, labelled and submitted to a laboratory for examination.

Before leaving the property all visible holes caused by the concrete sampling procedure will be repaired.

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