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Ground Movement - Cell Core

Cell Core

Cellcore is designed to support the weight of a given thickness of concrete plus a live load allowance of 1.5 kN/m2, without creep compression during the 16 hour curing period. The total of these is defined as the SAFE LOAD and is expressed in kN/m2. When ground movement occurs, the Cellcore honeycomb will compress and buckle when a pre-determined load is reached. Defined as the FAIL LOAD, in kN/m2, it is the maximum load that will be transmitted to the foundations.

The variables which determine the performance of Cellcore are the ‘leg depth’ of the panel (selected to accommodate the predicted amount of ground movement at the Fail Load), and the compressive strength of the legs which is defined by the density or the thickness of the polystyrene honeycomb. This flexibility of product design allows selection of the optimum grade of Cellcore to suit the designer’s particular requirements.

Cellcore is manufactured with two different tops:
TYPE CC for use beneath piled beams and pile caps, incorporates a heavy-duty polypropylene top. In certain circumstances a protection layer of concrete blinding may be required.

TYPE CP for use beneath suitably reinforced concrete slabs. It includes a 50mm thick polystyrene top, protected by a 2mm thick polypropylene sheet that provides a high degree of insulation. This can be improved by increasing the thickness of the top.

Unlike other anti-heave products, Cellcore does not rely on material degradation for the system to become effective. Once the Cellcore panels are laid and the joints sealed, the surface is ready to receive the reinforcement and the concrete. Cellcore is unaffected by water so, in wet weather or when foundations are below the
water table, work can continue without reducing its effectiveness.

On sites where water pressure is a potential problem or the water table is expected to rise, special grades of Cellcore are available with drainage apertures. To assist specifiers, the tables below detail the standard Cellcore range.

Standard Grades of Cellcore
Concrete Depth and Load characteristics
Cellcore Grade Maximum Concrete
*thickness
Cellcore Type Safe Load kN/m2 Fail Load kN/m2
8/12 270mm CP 8 12
10/15 350mm CC CP 10 15
15/22 550mm CC CP 15 22
20/30 770mm CC CP 20 30
*Allows for 1.5kNm2 Live Load
When concrete thickness exceeds 770mm please contact Cordek
Proven Cellcore Grades are available for concrete thickness up to 2,000mm
For depths in excess of this thickness please contact our Technical Services Department
 
Sizes
Standard Panel: 2.44m x 1.22m
Beams: Manufactured to width in 2.44m lengths
For non standard sizes please contact Cordek

Standard Depths for Cellcore
Compression characteristics
Cellcore Type
Compression at Fail Load mm
Type CC depth mm
Type CP* Depth mm
100
150
55
175
225
100
250
300
150
300
350
200
The depth of Cellcore selected will depend on th epredicted measure of ground movement at the Fail Load
Selection of Cellcore
Ground movement and void characteristics
Results of
Soil Analysis
NHBC Category
Predicted Ground Movement, or BRE/NHBC requirement
Depth of Cellcore required to achieve 'Equivalent Void'
Plasticity Index
Shrinkage Potential
Void dimension (mm)
Type CC
Type CP
10-20
Low
50
100mm
150mm
20-40
Medium
100
175mm
225mm
40-60
High
150
250mm
300mm
Above 60
Very High
200
300mm
350mm
This category is applicable when potential ground movement exceeds the NHBC range