Title: Fitness for Purpose of Residential Slab-On-Ground

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Publication: CIA

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Date: 2/13/2011

Abstract:
In Australia, concrete is widely used for residential ground floor construction. Cement Concrete & Aggregates Australia (CCAA) has undertaken a research project, conducted by CSIRO, to evaluate the fitness for purpose of concrete slab-on-ground built using current construction practices. The project involved a survey of 75 slabs during and after construction. For each slab, a two-stage inspection was carried out. The first focused on the ‘non-intrusive’ observation of construction practices and the second examined the early performance of the hardened concrete slabs. The majority of hardened concrete slabs were examined within one week of casting. Of all 75 sites inspected, thirty (40%) were conducted during the warmer months and forty five (60%) during the cooler months. The samplings were considered reasonably well spread throughout the year to pick up seasonal differences. All concrete slabs inspected were found to be structurally sound, flat and free from dusting. Current concreting practice is therefore delivering slabs which are fit-for purpose. The N20/20/80 concrete supplied was adjusted at the request of the concreting foreman, to give an estimated slump of at least 100 mm. It is therefore recommended that N20/20/100 concrete be specified and supplied for slab-on-ground construction. The 100mm slump concrete will satisfy the current concreting practice and eliminate uncontrolled water addition on site thus improving the in-situ quality of the concrete.