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05 Apr 2023

Concrete site wastage rates significantly lower than first thought, research finds

The amount of concrete block and ready mixed concrete wastage on construction sites may not exceed 5% and 1-2% of the material developed to site, a new study has revealed.

The study by circular economy consultancy, Reusefully, was launched last year to help the masonry and ready mixed concrete sectors understand the levels of materials’ use and wastage on construction sites and what best measures need to be employed to limit wastage and encourage circular economy principles on construction sites.

Work by Government’s waste programme, WRAP, in the late 2000’s and early 2010’s offered the only reference to the nature and levels of site wastage for different materials and products used in construction. At the time, it was thought that ready mixed concrete wastage could amount to around 5%. There was a very wide variation in values quoted for the level of site wastage expected for concrete blocks (dense, lightweight and aerated). WRAP’s Net Waste Tool report gave all blocks and bricks a standard 20% wastage estimate.

Reusefully were able to carry out a wide-ranging literature review, looking at several studies, reports and papers, and assessing default wastage values used in a number of European construction embodied carbon databases, including INIES in France, Milieu database in the Netherlands, Boverket (Sweden) and Rakentamisen päästötietokanta (Finnish embodied carbon database). The project also included questionnaires followed by in-depth interviews with a wide range of contractors, developers and housebuilders.

Feedback from the five housebuilders involved, who included some of the largest housebuilders in the UK, repeatedly indicated that the amount of dense, aerated and lightweight block site wastage does not exceed 5%. The survey found that blocks with minor visual imperfections were usable by blockwork contractors and some projects would move unused product to other sites if surplus to requirements.

ON the other hand, interviews related to ready mixed concrete use on site suggested that waste rates have fallen significantly in the last 10 years due to more efficient production and better control over client ordering and usage. There will always be some use for ready mixed concrete around a site, leading to very small volumes of unused product overall. Those interviewed put it at around 1% to 2%.

The new published report will help improve data about construction and site wastage and should help update upfront carbon calculations as carried out currently under the RICS Whole Life Carbon PS and other publications.

Click here to download a copy of the report