GFWAust carry out sand stabilisation with microfine cement or sodium silicate grouts. The grout fills the pore space between the sand particles. The best results are achieved with clean sand. In silty or clayey sand the pore space is already filled with silt or clay particles.

The grout spears are installed with a water flush - in dense sand or for deeper treatment greater than 3m the installation process can be assisted by the use of compressed air. The pore pressure in the ground is then allowed to stabilise prior to the grout injection.

With this process we are able to achieve grouted piers between 500 to 700mm diameter.

Sodium silicate will achieve strength of about 2MPa.

Microfine cement will achieve strengths of between 5 to 10 MPa after 28 days. However the grout strength continues up to 90 days and strengths of up to 15 MPa have been recorded with the addition of micro silica.

Stabilised sand can be used to strengthen the founding material beneath footings, transfer load bearing footings to a deeper depth, reduce settlement caused by vibrations such as sheet piling, reduce ground water dispersion in contaminated ground, or create retaining walls to ease excavation and stop sand rilling.

Projects have been carried out at Coogee, Bondi, Bellevue Hill, Brighton Le Sands, Tempe, Alexandria and Waterloo in Sydney as well as Umina on the Central Coast