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Sulphate Attack in Hardcore

Alan Wood & Partners SULPHATE ATTACK IN HARDCORE Sulphate attack is a chemical reaction, affecting the concrete in the floor construction of properties. In the 1930s, suspended timber floors were the usual construction method in houses. After World War II, building materials were scarce and from the 1940s onwards, solid floors made up of hardcore covered by a concrete floor slab became the preferred method. Here we take a look at a history of national recommendations given for new construction in respect of sulphate bearing hardcore. During the present shortage of timber, the construction of ground floors of wood joists and boards is not allowed except on steeply sloping sites where the cost of a solid concrete floor would be prohibitive. 1951 HOUSING MANUAL This manual -Ministry of Works Housing Manual provided no recommendations for the appropriate materials to use in hardcore. No hardcore laid under such floor shall contain 1965 water-soluble sulphates or other deleterious matter in such quantities as to be liable to cause damage to any part of the floor. -Building Regulations - Feb 1966, Regulation C3 BUILDING REGULATIONS 1973 National House Building Council (NHBC) issued Practice Note 6, which provided advice for the private sector. Essentially, it banned solid floors with a hardcore measuring more than 600 mm deep. Instead it recommended the use of suspended floors. This helped avoid problems with compaction of fill, and the likelihood of attack from sulphate-bearing hardcore. NHBC In general, hardcore materials containing sulphates should be avoided Alternatively, a concrete quality should be chosen that will resist the effects of sulphates ... in accordance with the recommendations of Digest 250. If any sulphate is found or suspected in hardcore, a moisture barrier (such as a polythene sheet at least 0.2 mm thick should be placed between the hardcore and the concrete floor slab. 1983 DIGEST -Digest 276 In general, hardcore materials containing water T 2 soluble sulfates above Class 2 in Digest 363 should not be used beneath concrete ground floor slabs. DIGEST -Digest 276, re-issued with clarification Special Digest 1 (3rd edition) does not include a specific reference to concrete floor slabs supported by hardcore due to the comprehensive recommendations now included in UK Building Regulations. 2005 SPECIAL DIGEST Alan Wood & Partners have vast experience in concrete investigations, in particular sulphate attack mechanisms and scenarios. The company have many years experience of the recognition of symptoms and managing the necessary remedial works. Get in touch now to find out more. Alan Wood & Partners have seven offices across the Yorkshire and Lincolnshire region - Hull, Leeds, Lincoln, London, Scarborough, Sheffield and York. Established in Hull in the 1960's, Alan Wood & Partners provide a comprehensive range of engineering services to the construction industry. Alan Wood & Partners are proud to deliver outstanding customer care, delivered specialist teams, with the skills and experience required. Alan Wood & Partners

Sulphate Attack in Hardcore

shared by ObjectiveCreative on Sep 03
Sulphate attack is a chemical reaction, affecting the concrete in the floor construction of properties. In this infographic we take a look at a history of national recommendations given for new cons...


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