Mundic Test (Concrete Screening Test)
- Stage 1 analysis is a visual inspection and observation under low magnification. Further testing can be recommended at this stage, such as Total Sulphate Content and Dry Density. This is also carried out in house.
- Stage 2 analysis entails a detailed microscopic study of a thin section of concrete core. If the sample is classed as B, it may be suitable for further testing.
- Stage 3 analysis - wetting expansion - sees the sample placed in a controlled environment, formulated by the BRE to simulate aging.
As more and more properties were tested throughout the 1990’s it was noted that some Class B concretes had a much better structural ‘life’ than others. A test was devised to enable the release of some Class B properties back on to the mortgage market under an AB classification. In January of 2002 the RICS issued a supplement to the 2nd Edition of the Guidance Notes, detailing the new test procedures.
Stage 3 procedure.
In brief, the test takes four samples of Class B concrete from a property and places them in sealed containers to keep them in a humid and warm (100% RH, 38°C) environment for some 250 days. The core will expand during this time as it takes in moisture. This expansion is recorded every month by measuring the distance between paired studs, of which 6 are mounted on each core.
A fifth sample is set aside for petrographic analysis.
The expansion of the core is determined as a percentage of the stud distance and compared with set targets. If the average expansion of any one set of cores is less than 0.025%, and no single set of studs on a core exceeds 0.04% expansion, the concrete can be re-classified as Class AB.
The cores submitted for testing must all be of the same type of concrete. Properties with more than one type of Class B concrete will require a set of cores for each type of concrete. The five cores have very specific parameters:
- must be at least 70mm in length (excluding render)
- a nominal 75mm in diameter
- no mortar joints
- in good condition, i.e. not cracked
- must be passed by the petrographer as suitable for testing
We would recommend that, where possible, any render/plaster be removed from the subject wall prior to taking cores - this allows the surveyor to avoid mortar joints.
Please call for prices! ed are a combination of laboratory fees and the surveyor’s fees. Our laboratory charge is £750 (plus VAT) per set of four samples.
The costs for multiple sets of samples from the same property are negotiable. The laboratory charge covers set up, 7 day wetting expansion and the first 7 day measurements. As the test progresses, monthly fees apply.
Our laboratory uses a dedicated Weiss-Gallencamp Environmental Chamber, which is capable of the very high accuracy and reliability required for this kind of testing.
The report issued upon completion of the test includes graphs showing the performance of the cores against the recommended expansion levels, and is designed for ease of reference for lenders and conveyancing solicitors.
If you have any questions regarding mundic testing, please call.
The RICS Mundic Guidance Note supplement is available from the RICS, ISBN 1-84219-082-2.
