Water Proofing Methods

Er R. Madhusudan Raj, Manager Projects, Techny Chemy

Waterproofing is the process of making a structure waterproof or water resistant so that it stays unaffected to the exposure of water, wet environment and other similar conditions. There is a wide difference between waterproof and damp proof. Water proof is the resistance to the penetration of water in liquid state whereas damp proof is the resistance to moisture, humidity or dampness.

One of the main requirements of a building is that it should be dry. Water proofing can be defined in a very simple way. "It’s a process which does not allows external water to penetrate dry areas of a building and water to move out of wet areas of the building.” Water leakage not only affects the life of the building but also creates unhygienic conditions inside the building.

Implications of Water Leakage

• Peeling of plaster or paints and formation of efflorescence
• Corrosion of reinforcement which leads to spalling of concrete
• Decay caused may lead to warping, buckling and rotting of timber in the building
• Deterioration of electrical fittings
• Growth of termites

Sources of Seepage

• Capillary pores/differential shrinkage
• Construction joints/honeycombs
• Failure of water bars
• Expansion joints
• Form & Tie Rod holes
• Inadequate drainage
• Rise in water table

Capillaries / Differential Shrinkage
Cause:

• Time lag between mixing and pouring, work stoppages
• Extreme climatic conditions – microcracks

Solutions:

• Continuous capillaries are disrupted by chemical admixture – TEC MIX 150
• Surface applied coatings to bridge hairline cracks - TEC WAVE 2000

Construction Joints / Honeycombs
Cause:

• Excessive water
• Poor shuttering
• Construction practice – walls / columns cast in lifts

Solution:

• Polymer mortar for V groove
• Injection grouting

Failure of Water Bars
Cause:

• Thrust during pouring
• Displacement during application of needle vibrator
• Leakage

Solution:

• Epoxy bonding agent (TEC BOND EPO) -Structural bonding of old concrete with new 2 – component system – easy to apply
• Allows 45 – 60 minutes for placing concrete

Techniques and Requirements of Water Proofing

There is a misconception that water proofing can be done with a single product. Failure in water proofing jobs is caused because of this misconception. Waterproofing is a system that has various requirements.

Study the Problem

• Inspect the inside of the structure and pinpoint the exact location of interior leakage
• Study the original plans and specifications
• Determine what type of waterproofing system was used in the original construction
• Excavation and inspection must be done in order to reliably understand the nature of the problem

Requirements of Water Proofing Treatment

• Impermeability to prevent passage of water
• Minimize water absorption by substrate
• Good bonding with substrate
• Elasticity to resist cracking
• Easy to apply
• Compatibility with substrate
• Resistance to UV attack
• Resistance to service temperature differentials
• Resistance to water
• Long life and durability
• Economy

Techniques of Water Proofing

• Guniting
• Grouting
• Bituminous system
• Integral water proofers
• Silicone coatings
• Water based coatings
• Polymer modified cementitious coatings
• Epoxy coatings and modified epoxy coatings
• Polyurethane coatings
• Polymer based spray applied membrane
• Polyurea

Areas of Application of Water Proofing
Positive Side Water Proofing:

• Positive side is same side of the structure as the source of the water
• Designed to stop water before it has a chance to enter the structure and cause structural damage
• Typically, the most effective solution

Negative Side Water Proofing:

• Negative side is opposite the water pressure side of the structure

POSITIVE SIDE	NEGATIVE SIDE
Split Slabs Bathrooms, Kitchens Laboratories, Mechanical rooms Fountains Planters Foundation walls Plaza decks, Parking decks, Bridge decks Tunnels Balconies Roofing	Elevator pits Soil retention systems Cut and cover tunnels Under slab Underpinning

Waterproofing Solutions
Surface Preparation: For a successful water proofing job execution, preparation of the surface plays a vital role.

• Surface must be structurally sound
• Treat cracks and movement joints
• Clean and free from any contaminant materials
• Repair any holes/voids in the substrate
• Remove any protrusions and sharp edges
• Concrete should be aged for 28 days and screeds should be aged for 7 days
• Cementitious surfaces can develop plastic shrinkage cracks during initial curing, which must be totally formed before the membrane is applied.
• Ensure substrate is dry (5% moisture or less)
• High substrate moisture content will form blisters in the membrane during curing.

Range of Products

Building friendly and user-friendly coating systems that are tailormade for specific areas of application.

• Waterproofing membrane coating
• High flexibility membrane
• Crystallization type coating
• Solvent-free food grade epoxy coatings
• Water thinnable epoxy coating
• Modified bitumen based coating

Specifications for Water Proofing
Sunken Portions: In a building the main problematic area is the sunken portions. Specifications for solving leakage problem arising in sunken portions are given below.

• Water should be stagnated in the sunken portion for a minimum period of 72 hours to identify seepage points.
• Pockets should be drilled at these points, weak concrete junctions and honeycombs and PVC nozzles fixed using instant plug- TECR STOP.
• Dressing the concrete joints and honeycombs and patching with modified cement mortar prepared using TECR BOND SBR.
• Neat cement slurry admixed with TECR SWELL (@225 gms per bag of cement) shall be grouted under pressure through the nipples provided using a hand operated grouting pump.
• The floor and wall surface should be cleaned and be free of dust and loose particles.
• Over the walls and floor two coats of TECR WAVE 2000- flexible membrane waterproofing coating is to be applied strictly following mix and application instructions for the product.
• The concrete surface should be wetted but free of water puddles prior to application of TECR WAVE 2000.
• While the second coat of TECR WAVE 2000 is still tacky, cement plastering in CM 1:4 admixed with TECR MIX 100 liquid (@250ml per bag of cement) should be carried out and finished neatly.
• Pipe and trap joints should be sealed with an appropriate sealing system depending on site conditions.
• The treated area should be cured adequately for a minimum period of 7 days.

It is always better to prevent than cure. Many people are ready to spend lakhs on interiors but neglect spending a few thousands on waterproofing. It is better to undertake water proofing to prevent problems in future.