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Your Build - Spring 2018

Phase 1 35 Footings & Foundations Spring 2018 Comparison Study, which identified that constructing foundations using aircrete blocks is more cost-effective than dense aggregate alternatives. The Study, which used a typical three-bedroom semi-detached UK home, showed that changing the foundations to aircrete alone could reduce total build costs by almost 25%. This is achieved through aircrete’s naturally quicker build speed, which leads to reduced labour costs, while the solid construction means that fewer materials are needed. One often overlooked advantage of aircrete blocks is their width. Being available in sizes to suit the external cavity wall above ground, which is typically 300mm wide, a single block can easily replace two 100mm concrete blocks, giving aircrete twice the laying rate of the traditional alternative. In addition, Aircrete weighs only a third of the equivalent dense aggregate block. This significant weight reduction means that aircrete provides the additional benefit of being far easier to transport, manipulate, and lay on-site. Cutting aircrete blocks only requires the use of a hand saw, and the ability to manipulate on-site means that there is far less wastage. Enhanced freeze/thaw durability During the UK’s cold winter months, foundations are subjected to a continuous attack by the elements. The ongoing process of freezing and thawing that occurs in these icy conditions can lead to a multitude of problems for concrete foundations, such as spalling. Water naturally freezes and expands, which can lead to potential damage in several forms of concrete. Aircrete on the other hand, does not suffer from these problems, as it boasts enhanced freeze/thaw durability, giving it less chance of damage due to the density of the blocks. Sulphate attack is another serious issue to contend with as it can cause structural damage to the main walls of a home when the foundations are compromised. This occurs when natural sulphate in clay soils leach into the foundation material, causing certain types of material to expand. Certain types of concrete material are susceptible to attack from sulphate chemicals that exist in soil and groundwater. When used below the damp-proof course level, aircrete blocks have been shown to have superior resistance to sulphate attack, compared to other concrete materials. BBA testing and assessment shows that aircrete is suitable for use across all applications where high sulphate levels are likely to be encountered. Aircrete clearly has a number of advantages over dense aggregate that make it highly suitable for use below the damp-proof course level. As well as being fit-for-purpose when used in residential foundations, aircrete has proven itself to have significant structural, logistical and performancerelated benefits, whilst allowing cost savings, when compared to typical construction using aggregate blocks. www.hhcelcon.co.uk


Your Build - Spring 2018
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