🕑 Reading time: 1 minute
Polyethylene Films are used for waterproofing in Walls or base of Structures. Water proof treatment is applied as outlined and as per sequence given below:
a) The concrete surface is made smooth with 12 mm cement plaster 1:6
ii) Apply hot bitumen 80/100 grade (IS:73-1961) at the rate of 1.0 Kg./Sq.m minimum.
iii) Lay black polyethylene film 250 micron (IS:2508-1977) with cut back bitumen adhesive in overlaps over hot bitumen surface, gently pressed, taking care not to puncture the film. Alternatively, the overlaps is heat sealed by an electric iron having three parallel sealing bars. A long piece of plywood is to be heat sealed.
On the plywood a rubber gasket is laid to provide a cushion for better welding of the film. On the rubber padding, a cellophane tape is to be spread and on this the LDPE film, with 100 mm overlap film another cellophane tape is stretched. On the overlapped film another cellophane tape is placed to prevent the heat sealer from sticking to the LDPE film. After this, the electric iron is to be pressed on the overlap joint for sufficient time so as to allow perfect welding. The operation is to be repeated for subsequent lengths of joints. After heat sealing, the cellophane tape is to the removed and the joints are to be tested for leaks.
iv) Lay 100g brown craft paper laminated with a layer of straight run bitumen.
v) Lay hot bitumen 80/100 grade (IS:73-1961) at 1.0 Kg/Sq.M minimum.
vi) Lay 250 micron polyethylene film as second layer similar to (iii) above.
vii) Lay second layer of 100 gm. brown craft paper laminated similar to (iv) above.
viii) Apply hot bitumen (straight run grade) to IS:73-1961 at 1.0 kg/sq.m dusted with fine sand.
ix) Protecting with a layer of 75 mm plain cement concrete M-100, or a layer of brick laid in cement mortar 1:6. In case of wall apply a 12mm thick plaster as shown on the drawing or a protective brick wall in 1:6 cement mortar as shown on the drawing.