AS 2870-2011 Australian Standard for Site Classification and Residential Footing Design.
In Australia and New Zealand, many routine commercial and residential developments adopt standard footing and slab design solutions based on a calssification of expansive nature of the site in accordance with AS 2870 - 2011. This process is very efficient and, following an appropriate geotechnical site investigation to determine the correct Site Classification, facilitates the adoption of standard foundation systems for many projects.
AS 2870 designates a Site Classification that is appropriate to the site based on the predicted magnitude of movement at the ground surface, under normal conditions, due to potential volume change associated with seasonal variations in moisture content. AS 2870 then provides details and specifications of standard footings that are relevant for the designated site classification.
CMW routinely undertakes Site Classification assessments for large residential subdivisions and individual lot owners for use by structural engineers and project specific design of footings for non-standard structures.
The Site Classification is related to the clay content, plasticity and inherent reactivity of the soil. In order to assess a reliable Site Classification, CMW relies on a comprehensive geotechnical investigation, incorporating relevant laboratory testing, in conjunction with a sound understanding of the derivation of the shrink/swell properties of the soil.
Where relevant, once the appropriate Site Classification has been assessed, CMW can design the minimum thickness of sand pad, or alternative measures that may be required to reduce the severity of the Site Classification.
In providing a reliable assessment of the site in accordance with the AS 2870 Site Classification system, and determining minimum sand pad thickness, CMW can significantly reduce costs and time associated with bulk earthworks operations relating to sand pad construction and expensive construction of non-standard foundation solutions.