Surface Preparation:
Surfaces to be waterproofed must be sound, clean, free of dust, paint, curing agents, loose plaster debris etc. Honeycombs should be opened up to ensure uninterrupted and even coating of waterproofing application. An existing waterproofing membrane/ coating to be removed completely. All final cleaning will be carried out with pressurized water. Apart from cleaning this will ensure that all pores, capillaries, pores and voids etc will be filed with water which is essential prior to treatment with Koster NB cement based crystalline waterproofing systems.

All static cracks wider than 1 mm. in the substrate must be opened up to 12 mm X 12 mm. and treated with a mix of cement/sand mix with Koster SB Bonding emulsion and water at least 24 hours to application.

Fillets:
Similarly at all the junctions of the parapet wall and the slab, the fillets must be built up with a mix of cement/sand/quartz sand mix with Koster S B Bonding emulsion and water at least 24 hours prior to the application.

Down take / Pipe Insertions:
Pipe inserts must be installed prior to the application of the NB\NB Elastic waterproofing system. At the opening in the slab around the pipe the substrate should be similarly opened up by cutting back around the pipes to give sufficient depth and cleaned thoroughly. This must be then built up with a mix of cement/sand mix with Koster S B Bonding emulsion and water at least 24 hours prior to application.

Construction Joints:
Finally dampen all the surface areas thoroughly with clean water using high pressure water, as this is necessary prior to the application of the NB system. The dampness in the substrate will ensure that the chemical reaction between the NB system and the chemicals in the concrete substrate takes place completely. However the application of the NB system should not be made over standing or running water.

MIXING AND APPLICATION:

Materials:
NB cement based crystalline waterproofing system
NB Elastic cement based crystalline waterproofing system
SB Bonding Emulsion liquid
Water
Brushes

Mixing:
To one bag of NB I (25 kg), add 7 - 8 liters of water premixed with 10 % SB Bonding Emulsion. Mix thoroughly to a slurry consistency. The system is now ready for application.
The two components of the NB Elastic system must be mixed together. Mix thoroughly to a slurry consistency. The system is now ready for application.

Application:
The NB system is brush applied, on to the already damped surface. The brush on is done in 3 coats. The coverage is 0.75 kg per sq. meter per coat and each coat is done perpendicular to each other. After the 1st coat there should be a gap of 12 – 24 hours before the 2nd coat is applied. Prior to the 2nd coat application the 1st coat surface should be dampened to ensure that the chemical reaction is complete on the underside. No water curing is required. Similar procedure must be followed for the 3rd coat. The finished surface should be left exposed for 48 hours for positive side treatment and 4 days for negative side after which further roof build up works can be carried out.

If the basement is of two levels then the negative side waterproofing on the vertical walls would extend 300 mm onto the underside of the upper slab. This will ensure that all the weak points are covered completely and the basement walls are completely watertight.

For all the pipe insertions, the NB Elastic system should be applied right around and onto the pipe section to make it completely watertight as 4th coat. The NB elastic properties of the system will eliminate the possibilities of cracks developing at these junctions.

For the expansion joints care must be taken to complete the application of the NB system right into in insides of the expansion joint first. Once this is complete and cured then a backing of thermocole is provided as a filler material and the final 25-mm must be filled with Polyurethane sealant. This will help to take care of the high expansion/contractions of the substrate at these points. This treatment is carried out at additional cost.

All vertical and horizontal watas must be built up and then treated with the NB and then the NB elastic system as given above.

Limitation:
The NB system cannot be applied on running or standing water.
The NB system must be protected from acid or sulphurous attack in concentrations exceeding that in Portland Cement Type I/II
The NB system once installed must be protected from damage by other agencies working in the installed area. Further if applied on the positive side protection must be provided against mechanical damage.

SCREED :
The NB system once installed must be protected by a protective screed from damage by other agencies working in the installed area. Screed of Cement sand mortar of 1:4 proportion of 20mm thickness.