Grouting is an engineering and art combined to fill up voids or cavities in the rock or soil masses with a fluid that will increase the overall strength and/ or impermeability of mass.

In many cases rock deposits contain cavities, slips, seams, breaks etc. which make them unsuitable for dams, reservoirs, building, bridge piers, tunnel etc.

In such cases it becomes necessary to adopt corrective steps to make the foundation suitable for intended use. If correction is impossible or too expensive, then it is necessary to abandon the site.

The operation to correct the foundation conditions is known as pressure or foundation grouting.

The foundation under or adjacent to a structure is grouted with an objective

1. To solidify and strengthen the formation in order to increase its capacity to support a load

2. To reduce or eliminate the flow of water under a dam or into a tunnel

3. To reduce the hydrostatic uplift under a dam.

Materials used for grouting are:

1. Cement and water

2. Cement, rock flour and water

3. Cement, clay and water

4. Cement, clay, sand and water

5. Asphalt

6. Clay and water

7. Chemicals.

Grouting equipments include:

1. Air compressors

2. Grout mixers

3. Agitator type reservoir tanks

4. Grout pumps

5. Grout discharge pipe or hose, valves, pressure gauges.