Geo-Technical Contracting & Engineering
Precast piles are installed by means of a drop hammer mounted on a crane leader. Piles are driven to refusal or to a predetermined set in order to obtain the necessary load carrying capacities. The Company produces three standard precast piles which cater for loads of 1 000 kN, 1 500 kN and 2 000 kN. These piles are square in cross-section and measure 250 mm, 300 mm and 350 mm square respectively.
A steel joint is cast into the pile to enable standard lengths to be connected when driving to depths greater than 13 m. Where required, a rock shoe can be cast into the toe of the pile. The concrete has a minimum strength of 55 MPa at 28 days. The piles are cast in rigid tapered steel shutters from which they are lifted by their lifting lugs (located at fifth points), once a minimum strength of 25 MPa has been attained.
Reinforcement in the 1 000 kN, 1 500 kN and 2 000 kN piles consists of 4 x Y20 bars,
4 x Y20 and 4 x Y25 respectively, all spiral reinforcement is R6 at 150 cc excepting for 1 m from each end where the pitch is reduced to 75 mm.
Cover is usually 35 mm to main bars but can be increased to 50 mm where required. Interconnection of the piles is made by means of a patented dovetailed wedge system which is cast into the pile by means of 4 x Y20 mm diameter splice bars 800 mm long. Where necessary, i.e. in the event of a fluctuating water table, these joints can be coated with a protective epoxy coating.