Illovo 96 – Gauteng

The project involves the development of a 7 500 square metre A-grade office block, consisting of four levels of basement and ground, plus three levels of offices. The size of the plot is 3 500 square metres in an extremely tight site located on 15 Chaplin Road, Illovo, Sandton, Gauteng. GeoCiv Group is responsible for the major lateral support works and piling works within the four parking basements.
The piles are various diameters, ranging from 500mm to 1.2 metres — BIG piles, with heavy steel, to support massive loads. The concrete used in the piles amounts to about 700 cubic metres, with about 40 tons of rebar. The 13-metre-high basement’s retaining walls are made of wet Shotcrete. Previously, dry Shotcrete was used. This new wet Shotcrete is an innovation; it reduces wastage massively and also produces a more consistent mix and wall finish.
In the old conventional system, using dry Shotcrete (gunite), the process was to add the water at the nozzle, whereas wet Shotcrete is already mixed. By adding water at the nozzle, the emerging concrete spray can be inconsistent, dependent on the consistency/pressure of the water spray. Now we use ready-mix, which goes straight through the nozzle. This gives uniform quality and moisture consistency, which also reduce wastage considerably. Air entrainment in the mix ensures that when the mix leaves the nozzle and impacts with the wall, it stiffens, or firms within about 20 minutes.