FurseCEM Earthing Conductive Aggregate Concrete
Published 12 Nov 2018
uploaded by Chris Dodds - Thorne & Derrick Sales & Marketing Manager
FurseCEM is an earthing conductive aggregate concrete, manufactured by Furse, offers a convenient and permanent solution to earthing problems by obtaining a reliable earth resistance even in installations that require a very low resistance regardless of ground conditions – this includes low LV, medium MV and high HV substations.
A conductive concrete is formed when FurseCEM is added in place of sand and aggregate. This electrically conductive medium has many applications in the electrical/construction industry including RF and microwave screening, static control and of course earthing for which it was specifically developed.
When used as a backfill for an earth electrode or earth rods, FurseCEM impregnated concrete greatly increases the electrodes’ surface area. For example, increasing the effective diameter of a copper earth rod from typically 15mm to 200mm, could lower its resistance to earth by as much as 50% (see graph below).
FurseCEM Features & Benefits
- Permanent earth reading – resistivity that will remain constant over the life of the installation without the requirement for maintenance
- Constant volume – regardless of water content, FurseCEM will not shrink or expand, thus maintaining constant contact between the earth electrode and the soil
- Cost effective – reduces drilling, saves on earthing materials, and requires no expensive maintenance
- Non leaching – FurseCEM is a conductive concrete and therefore cannot be washed away
- Chemically inert – completely non-corrosive, and will not in any way damage earth electrodes, steelwork or concrete
- Fast drying properties – allows for quick and easy installation
- Mechanical strength – provides high compressive strength where required
- Long shelf life – can be stored for long periods without deterioration
- Versatile installation – suitable for use in boreholes and trenches
Earthing Conductive Aggregate Concrete
FurseCEM Part Numbers
FurseCEM should be mixed in a 3:1 ratio by weight (not volume).
|Description||Sack Weight||Part Number|
|FurseCEM (supplied with cement)||25kg||CM030|
FurseCEM versus other methods of earth improvement
Chemical solutions — such as copper sulphate, sodium carbonate, calcium sulphate and sodium chloride (table salt) mixed with charcoal are sometimes poured into the ground to improve earth readings, but these have the disadvantages of:
- being required in large quantities to make a difference
- requiring constant moisture to remain effective
- drying out if moisture is not present
- eventually leaching out of the soil, returning the earth to its former high value, unless regularly and expensively maintained
- causing corrosion of the earth electrode system and deterioration of concrete (particularly relevant to transmission towers).
Chemical earth rods — perforated metal tubes packed with a with a chemical compound are also sometimes used but these:
- are costly
- are subject to leaching or washing away of the chemicals unless maintained
Bentonite — and certain other compounds intended to absorb and retain moisture in and around an earth electrode.
- rely on constant moisture to maintain volume and hence work effectively
- without moisture, drying and shrinkage occur, causing loss of contact with the surrounding soil and a deterioration in the earth reading
- regular checking and/or maintenance may be required
FurseCEM is a non-corrosive permanent solution to earthing problems, providing a fixed earth reading that will not very significantly regardless of seasonal factors, and without maintenance.
SUBSTATION EARTHING & MV HV CABLE JOINTING