Various methods of damp proofing are as given below:
➞Providing D.P.C. course➞ Providing cavity walls
➞ Surface treatment
➞ Integral treatment
➞ Guniting and
➞ Pressure grouting.
➤Providing damp proof course: It consists of providing a damp proof course between the
source of dampness and building component. The DPC may be with any water repellantmaterial like bitumen, mastic asphalt, cement concrete, metal or plastic sheets. DPC should
cover full width of wall. It should be laid on levelled surface of mortar. Joints should be
minimum and should not be at critical points. When horizontal DPC on roof is continued on
vertical face of parapet wall, the junction should be filled with about 75 mm fillet of cement
concrete.
➤ Providing cavity wall: Cavity wall may be constructed to protect foundation masonry and
the wall. The cavity prevents moisture travelling from outer to inner wall.
➤ Surface treatment: If moisture is only superficial and not under pressure this method is
useful. It consists of application of layer of water repellant compounds on the surface. Some
of the water proofing agents used for such treatment are silicates of sodium or potassium and
sulphates of aluminium, zinc and magnesium.
➤ Integral treatment: It consists in mixing commercially available compounds in water before
concrete is wet mixed. These compounds are made from chalk, talc, flutter earth or chemical
compounds like calcium chloride, aluminium sulphate, calcium chloride etc. Some compounds
contain compounds like soap, petroleum oils, fatty acids etc.
➤Guniting: In this method a mixture of cement and water is forced by cement gun on the
surface to be made water proof. Later 1 : 3 or 1 : 4 cement mortar is applied to the surface
with pressure using compressed air. Thus an impervious layer of mortar is provided.
➤Pressure grouting: This is the method used to seal cracks in the concrete surfaces. In this
method cement grout is forced under pressure.
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