Certain ground conditions make obtaining a very low earth resistance difficult, which is required for some installations.
For such cases, CM040 FurseCEM provides a convenient and permanent solution.
Conductive concrete is formed by adding FurseCEM to cement in place of sand and aggregate. This electrically conductive concrete can be used in many earthing applications, but it is primarily used in power generation and distribution, rail, underground and transport networks, telecommunication sites, and defence facilities.
When used as a backfill for an earth electrode, FurseCEM will reduce its resistance to the earth by greatly increasing the electrode’s surface area and improving its contact with the surrounding soil. For example, increasing a rod’s effective diameter from 15 mm to 200 mm could lower its resistance to earth by as much as 50%.
Features & Benefits
- Tested to industry standard. Fully compliant with IEC 62561-7 lightning protection systems components (LPSC) – Part 7: requirement for earth-enhancing compounds.
- Permanent earth reading. Resistivity will remain constant over the life of the installation with no maintenance needed.
- Constant volume. 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.
- Environmentally friendly. Chemically inert and completely non-corrosive in both aggressive and non-aggressive environments.
- Mechanical strength. Provides high compressive strength where required and will not in any way damage earth electrodes, steelwork or concrete.
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’s resistivity 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 chemical compound are also sometimes used, but these:
- Are costly
- Are subject to leaching or washing away of the chemicals unless maintained
FurseCEM is a non-corrosive permanent solution to earthing problems, providing a stable and maintenance-free earth that will not vary significantly regardless of seasonal factors.
Mixing Procedure
The FurseCEM to cement/water ratio necessary for a particular application will depend on the workability and compressive strength required of the conductive concrete.
A typical specification would be 3:1 by weight, e.g., to mix 1 m³ of conductive backfill, mix 975 kg of FurseCEM to 325 kg of cement and 250/300 litres of water. The mixing and placing of the concrete conform to normal practices.
