Monday, July 24, 2017

FEATURE: WATERPROOFING

Securing structures

With rapid growth in the construction sector there is an urgent requirement for new technologies to be adopted to make structures waterproof. Construction Opportunities attempts an overview of the sector.

 

India’s waterproofing industry has come a long way from the time it was intended purely as a means of protection of building structures – basements, decks, flat roofs etc – from damage caused by rain water. Over the years with the emphasis increasing on structural integrity of building and measurement of water tightness there has been a increase in sophistication both in the quality of materials employed and in the manner of their usage.
A sea change is discernable in the past decade with the arrival of several players in the waterproofing market armed with both imported and indigenous technologies.
Quality conscious customers are always on the lookout for a Total Solutions Provider for long lasting results. While there are unfortunately a few fly by night operators who make tall claims offering quick fixes with low quality solutions which do not perform as promised, there are waterproofing manufacturers and service players with both the intention and the capabilities to serve quality clients. “This necessarily requires knowledge and technology to match the explicit and implicit needs related to waterproofing of concrete structures”, avers P. Srinivasa Reddy, Chief Executive Officer, Rehab Technologies.

 

Conformity to specifications  
At present depending on the applications to be used like terrace, basement, kitchen, bathroom, swimming pool etc there are various types of products available in the market.
“The underlying fact, common for all applications that is the product should conform to the minimum criteria for water proofing,” points out Sumon Chakravarty, Head Technical and R&D (Building Products Division), UltraTech.
There are specifications for water proofing which have been in place for decades laying the foundation for proper and durable waterproofing work. The specifications as laid down in the globally followed EN and DIN standards,  categorises products as "Waterproofing" only if the products conform to Nil water penetration at 1.5 Bar pressure in water impermeability test (as stated in EN 14891 and DIN 1048 part 5), informs Dr Chakravarty.
In India, in the absence of similar criteria, it leads to the usage of products with disastrous effects. The lack of proper standards of waterproofing have also led to products of questionable types and quality being promoted. Many a time, such products have been at complete variance with the minimum requirements of quality waterproofing work.

MODERN TECHNIQUES IN WATER PROOFING

Modern technique relies basically on two main waterproofing systems, which are fool proof and simple. They are as follows:
•    Crystalline waterproofing system
•    Flexible membrane water proofing system
 
Crystalline Waterproofing System
This system involves blocking the water bearing capillaries with insoluble crystals. This method is used for waterproofing water-retaining    structures like overhead/underground water tanks, sunk slabs of bathrooms and toilets, swimming pools, basements, terrace gardens etc.
Flexible Membrane Waterproofing System    
The main product used in this system comprises two components: one liquid and the other, a powder packed roughly in the proportion of 1:4 by weight. The liquid component is an acrylic emulsion and the powder component is a polymer-modified cement with film forming chemicals and fillers. Some manufacturers add reinforcing fibres to make the product extra effective.
(Source: PERMA CONSTRUCTION AIDS PVT LTD)

 

Waterproofing treatments and failures
The waterproofing systems or treatments, provided on the surface of structures can do much more than preventing an inconvenience or architectural nuisance. Such treatments, if effective, can make structures durable. That, however, requires that treatments are not only effective in preventing the ingress of water into the structure, but also that the treatments are durable. Many different materials and systems have been tried for waterproofing of structures.  According to a research paper by Anil K Kar, Chairman, Engineering Services International, most of the treatments fail to achieve the desired results even in the short term.
“Failure of waterproofing treatments is due to the application of wrong concepts all around. Awareness of the same at all level needs to be increased in order to get the desired results which would help to increase construction quality and durability of structures. This should help in good construction practices,” says Kar.
“Presently 90 per cent failures in waterproofing occur mainly due to lack of knowledge on right accessories,” declares Sanjay Bahadur, CEO, Global Construction Chemicals, Pidilite. “In India people have to use correct accessories for waterproofing which is presently very much missing. We can succeed only when we use right material with right product.”  
Much of the waterproofing problems in the Indian environment stem from access of chemicals to people who do not know the correct purpose of their use. Further, the waterproofing work is executed by contractors masquerading as authorised or approved applicators leading to severe deficiencies in the quality of work.

 

Appropriate technologies and solutions
Since waterproofing is an activity related to structures being leak proof – and involves understanding of products, tools, methods and treatment systems – it is paramount for the practitioners to have knowledge of civil engineering. Oftentimes chemists who develop materials which we dub as construction chemicals tend to ignore fine structural engineering requirements. The challenges also stem from each work site having its own unique character requiring improvisations or modifications to implementation procedure on the part of the user to make the waterproofing operation successful. Very  often a standalone treatment is required. A different chemical or system may need to be employed and an inability to anticipate this requirement could contribute to failure. In the light of extensive usage of chemical based treatments in projects that cost millions it is important to have knowledge of appropriate processes and solutions that are specific to the project.  

 

Chemical Resistance/Acid rains/sea shore environment

Comparision of Water proofing systems

Requirements of a good water proofing system

Bituminious roofing felts

PVC/EPDM TPO membrane

 Acrylic based system

Polymer modified cementetious system

Polyurethane liquid applied membrane
Bonding Poor Poor Good Fair Excellent
Breathebility Very Poor Poor Good Good Good
Elasticity Good Good Good Fair Excellent
Tear Strength Excellent Excellent Poor Poor Excellent
Puncture resistance Poor Excellent Fair Poor Excellent
Abrasion Resistance Poor Good Poor Poor Excellent
U V stability Poor Excellent Excellent Poor Excellent
Degradation due to stagnant water No effect No effect Easily disintegrates Easily disintegrates No effect
Overlap joint strength Poor Good if special equipment used Seamless as liquid applied Seamless as liquid applied Seamless as liquid applied
Crack bridging capacity Good Good Poor Poor Good
Thickness Uniform Uniform Not uniform Not uniform Uniform
Trafficability Not suitable Suitable Suitable Not suitable Suitable
Ease of Application Requires special equipment for overlaps jointing and mechanical fixing in vertical applications Requires special equipment for overlap joints Can be applied with rollers.

Can be applied with rollers.

Can be applied with rollers.
  The joints have to be tested. The jointing has to be tested with vaccumized equipment Seamless as liquid applied. Seamless as liquid applied. Seamless as liquid applied.
Areas of Application limited limited limited limited Can be applied on any substrate including glass
Service temperature + 10°c to + 38°c -20°c to +90°c - 4°c to 80°c NA -30°c to + 90°c
Chemical Resistance/Acid rains/sea shore environment Poor Poor Poor Poor Excellent
Source: Maris Polymers India

 

Road ahead
The market for construction chemicals for water proofing in India has a huge growth potential owing to the construction and manufacturing boom. With growth primarily driven by increasing construction activities in both new construction and repairs and rehabilitation technologies, demand for construction chemicals is expected to increase. There will be a shift in demand towards products offering
better performance. That said, however, there is an urgent need for construction chemical manufacturers to promote technologies suitable to the national economy – which take into account factors such as affordability, environment, weather and climatic conditions. Now is the time for the sector’s emphasis to shift to development of indigenous skills, knowledge and processes rather than import of knowhow.




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