CGH South Africa offers a Speed chassis / frame that protects against buoyancy due to ground water. The tank is strapped to the speed chassis by means of the steel retaining straps. The speed chassis offers reinforcing bar to allow the speed frame to be cast into a concrete foundation.
- Safety for transportation / loading
- Easier levelling within the excavation
- Time saving on construction site
- Concrete level indications provided
The frame for ‘SPEED CHASSIS’ comprises I-beam sections welded in the shape of the letter ‘K’. The frame with the tank is put in an excavation and levelled. The frame is embedded in concrete to form a foundation block. For setting the tank, a foundation block with a constant thickness of 300 mm and horizontal dimensions equalling the tank diameter x tank length has been provided.
Remarks and recommendations for excavation works
Soil survey has to be carried out when developing a building project for a given location.
When backfilling the foundations, soil from the excavation should be used and laid in layers with a thickness of approx. 0.3 m, while ensuring thorough compaction.
Assumptions for calculations
There is a load-bearing soil beneath the foundation.
The tank will be poured with non-cohesive soil, placed and thickened with layers, γ =18 kN/m3.
The concrete density in the foundation slab of γ =22 kN/m3 was taken for the calculation of tank buoyancy.
Tank weights as per technical sheets of CGH SA were taken for the calculations.
Tank clamping depth – 0.8 m (backfill layer above the tank).
The XC2 exposure class of the foundation slab was assumed, C16/20 (B20) concrete was taken for this expansion category. If there is water in the ground more aggressive for concrete than for the XC2 category, the composition and brand of a concrete mix has to be modified accordingly.
hw – water level below ground
Notes for concrete works
Due to shrinkage stresses in concrete, proper care of concrete on the construction site is very important. The concrete care method should be determined before any concrete works.
A concrete mix should be applied and thickened in such a way to avoid its segregation. Thickening should be carried out continuously when laying is part of concrete.