Waterproofing Types and Solutions

Waterproofing: The need and importance:

Waterproofing is a very common word used in day to day life. Most of us know & understand the pain of leaking roofs, walls & bathrooms. The damage done by such leakage is not only limited to aesthetics but many times compromises the safety of users & inhabitants. Dampness on interiors may lead to many issues like fungus growth, foul order & spalling of plasterwork. Water ingress may result in damage to electrical fittings, potentially exposing people to various hazards such as fire and electrical shock.

Concrete is the main building material used in all civil construction & as everyone knows concrete always shrinks. Why does concrete require protection? The simple reasons are the porosity, cracks & potential to react with atmospheric gases such as CO_2.Apart from that, the structures have various joints & connections which need to be considered & given extra protection.

Waterproofing types and importance

Some important areas for providing waterproofing are Basements, Exterior Walls and Roofs.

Integral approach:

It is very clear that waterproofing is not just about a single system or section of construction. Careful analyses need to be done to understand & design a waterproofing system, which will take care of the entire building envelope. The integral approach considers all materials, section & factors such as the environment, final use, and critical areas. This approach begins at the stage of conceptualization of a project. There are various places and sources from where water can enter a structure. This could be groundwater (which depends on the water table), rainwater & water associated with damp areas & plumbing works. Various products & systems such as sheet membranes, liquid waterproof coating, crystalline systems, water repellants, and integral waterproofing agents are available in the market.

Types of system available:

Numbers of systems are available for waterproofing of the complete building envelope as well as infrastructure. Each system has its own advantages & disadvantages. Table 1, shows some of these systems.

Table 1

Type	Products	Uses	Chembond Products
Sheet Membranes	APP/SBS modified Bitumen Membranes, TPO, HDPE, PVC and EPDM membranes.	Roofs, Basements, Water Tanks, Roof / Terrace Gardens, Lakes, Swimming pools and Underground Structures.	KEM Hydroshield BAP 3000/4000, KEM Hydroshield SBS 3000/4000, KEM Hydroshield TPO and KEM Hydroshield HDPE
Integral Waterproofing	Liquid and Powder admixtures added to concrete and mortar.	All concrete structures and external plasters.	KEM Proof IWC KEM Proof IWP
Crystalline Compounds	Cement based brush applied or dry shake products as well as concrete additives.	Basements, water retaining structures	KEM Proof CWC, KEM Proof CWC – Additive
Cementitious Coatings	One or two component polymer modified cement based products.	Terraces, Damp Areas, Sunken Portions, Basements	KEM Brush Coat
Polyurethane Membranes	One or two Component PU based Coatings applied at 1-2 mm thickness.	Terraces, Balconies, Parking Decks, Basements, Water Tanks, Sunken Portions	KEM Proof PUWC
Water Based Elastomeric Coatings	Single Pack Acrylic or SBR based coatings.	Roofs, Balconies, Sunken Portions, Exterior Walls.	KEM Proof 86, KEM Proof 87 , KEM Proof EWC – White and KEM Hydroshield AE 500.
Epoxy Based Coatings	Two or three pack solvent or water-based products.	Water tanks, covered roofs, internal and external areas where seepage is expected.	KEM Dampseal KEM Proof EWB

Liquid applied to waterproof

The term means, any system applied in the liquid state and then transforms to solid state or integrates itself to effectively waterproof the application area. This mainly includes Flexible cementitious slurries, acrylic, EVA or SBR based elastomeric coatings, Polyurea, polyaspartic, Polyurethane, Hybrids, thermoplastic acrylates, epoxy based coatings, and membranes, etc. Crystalline and penetrating treatments are also applied in liquid form but their action is not through sealing but through the penetration into the concrete and reaction with hydration products.

Effectiveness of each system depends on application methods, substrate conditions, exposure/usage conditions, thickness applied and subsequent maintenance. Differentiation can be made depending on the following factors,

Whether applied Internally or Externally
Covered or Exposed
Contact of water is continuous or intermittent
Trafficked or Non-Trafficked
Exposure to other chemicals except for water and CO₂
Access to the area in the future, if reapplication or repair is necessary
Underground (Below Grade) or above ground (Above Grade)
Expected Movements
Primary or Secondary system
Other specific requirements as per user need or Exposure conditions.

Some standards & specifications:

Some of the standards used to test & evaluate the performance of waterproofing systems are mentioned in table 2

Table 2

Standards	Typical Application	Typical Products
ASTM C 836	Elastomeric Waterproofing coatings with Separate wearing course	PU, Acrylic and SBR based coatings. Both water based and solvent based.
ASTM C 898	Guide for the application of products meeting ASTM C 836.	PU, Acrylic and SBR based coatings. Both water based and solvent based.
DIN 1048 Water Permeability	Water permeability of treated and untreated concrete samples.	Integral waterproofers and coated concrete specimens.
IS 2645	Specifications for Integral Cement Water Proofing Compounds	Integral Water Proofing Admixtures
Taywood Method	Testing of CO₂ diffusion rates ( R and Sc values)	Anti Carbonation Coatings.
ASTM D 6222 and ASTM D 6509		APP Modified Bitumen membranes Polyester reinforcement and Glass fiber reinforcement respectively.
ASTM D7311 / D7311M	Standard Specification for Liquid-Applied, Single-Pack, Moisture-Triggered, Aliphatic Polyurethane Roofing Membrane	The moisture-curing Aliphatic PU based single component roofing membranes.
ASTM C 957	Elastomeric Waterproofing coatings with Integral wearing surface.	Both one and two component PU, Polyurea / polyaspartic and epoxy based products.

There are more standards and a lot of effective test methods to verify and ensure that the waterproofing product being used would serve its purpose and last for the specified lifetime.

For elastomeric coatings following properties assume utmost importance,

Tensile Strength, Elongation and recovery after extension. (ASTM D 638)
Crack Bridging ability (ASTM C 1305)
Tear Strength (ASTM D 624)
Adhesion in wet and dry conditions (ASTM D 7234, 719 and 794)
Water Vapor Permeability (ASTM E 96)
UV Resistance (ASTM D 4587, 5894, 6695)

Application Procedures

As for any coating or liquid applied system, surface preparation holds the key. Proper surface preparation will ensure good adhesion, uniformity of coating thickness, proper curing or drying, as well as the development of performance properties such as tensile, tear strength and hardness.

Some systems require a primer, some are self-priming. Whether to use the primer or not always remains a tricky question. As a general rule, all smooth surfaces such as glass and metal require a primer. Surface with poor strength and high porosity would also need priming/sealing. Various primer systems including epoxy, moisture curing PU, silane / Siloxane based primers and latex-based products are widely available in the market. Proper primer shall be decided from the manufacturer’s literature and project specifications.

Application methods may vary from brush application to multicomponent spraying. Uniformity and proper thickness will only be achieved, with the use of suitable equipment and method. After application, care has to be taken to protect the application area, until the applied product dries completely. In traffic areas, the traffic shall only be allowed after the applied product cures to attain minimum performance criteria.

Summary

We have covered the importance of waterproofing and integral approach for achieving the desired performance. We have also discussed some prevalent systems, standards, and test methods as well as a quick look at application procedures. We have tried to cover some important aspects, keeping in view, the general requirements of construction industry professionals. For specific queries and suggestions, you may contact us at eshop@chembondindia.com

Swapnil Deshmukh

Sr. Marketing Manager

Chembond Chemicals Limited

EL 71, MIDC Mahape, Navi Mumbai.

Tel: 02262643116