WATERPROOFING a surface is an engineering by itself it cannot be done by reading MSDS.
Leakage is always typical by nature thou it ends up permeation of water or any liquid or gas thru or between surfaces. if we take leakage of water as case study in construction industry it is at-least in India considered that waterproofing is C grade activity and most of the contractors over look or never carry out this activity. This could be due to negligence or to save money or due to overconfidence. what ever may be the reason leaks have made all of us to invite ourselves to LEAK-AGE
The typical areas of leakage is not necessarily roof top it can be sunken portion or roof top garden or in general water holding body or water running body. Source for water penetration can be the tile itself which is least suspected area. The water penetration thru tile is immanent as we get imitated tiles which are either cheap or ready to cheat. Some tile a particular grade of natural stones which absorb water is used to give natural ambiance inside toilet/washroom.
In general if we are to talk about leakage we can classify it as sweating, dropping, dripping, flowing, oozing. sweating or scaring takes place as initial symptom and is followed by other process oozing takes place mostly in case where water table is high. For thumb rule one can consider water can come out any where in the vicinity of 21 meters from source of inlet in normal course and can be more if it gets support or guide to flow further. Under pressure it can leak any where to a height of 4 feet from surface of travel.
There are different situation we come across as a user/client, consultant, promoter(trader/manufacturer) As a client there is general notion that he knows every thing which to some extent is true as he would have googled information or by hear and say so they get carried out by jargon and make them prey. As promoter he always like to confuse or corrupt in most of the cases instead of convincing which demands some information about the products which invariably they will not have. but most of them will be successful in promoting products since contact is known to them or to consultants.
In rare situation the products is selected based on performance and most of the cases they will have to undergo more than required tests and humiliation as there will be dedicated system which tries to fail the product or system. But once we are successful it is easy to get repete orders as products will speak by itself.
Identification of source product selection and surface preparation will do 85% of the waterproofing job rest lies in application. Grouting has been considered as all time solution which is not especially on old surfaces and lean structures which due to vibration while grouting will weaken the structure and either drifts the leak point or give temporary relief. Grouting can be solution for multi layered structures and not every where. It is sure shot answer for most of ingress of water from subsoil.
There are situation where both consultants and owners get carried away by jargon's and solution providers are put into embarrassing situation where they will be made to adopt process and products that just camouflage the problems and not solve them. There can be a situation where slab is cracked due to exothermic reaction and is growing due to non-quenching activity but contractors are asked to waterproof with out being allowed to understand and salvage the problem. coatings under such situations can camouflage problems but once it get punctured the leak persists. This has become common in most of the case and may be this is why one of the magazine in recent past had mentioned 95% buildings are leaking in India. This may not be a fact but definitely expresses gravity of situation. Minor cracks can be covered using resins of epoxy or pu or even sodium silicate mixed with chalk powder instead of grouting any where everywhere. Pressure grouting can be more trouble creator due to withering action than problem solver.
Leakages are of different form it starts from scar, wetness, sweating, dripping and flowing.
scar can be misleading as due to urgency if wall putty is applied over wet surface then it looks like leakage but it is not. Under such situation blow torch is used to dry the surface that can be devastating as it will dehydrate wall plaster also and lead to cracking. Right thing is to wait for surface to dry and then apply putty and paint if damage is done then allow it to loose the sheen due to natural heat and light (including lights normally used in the premises). If scar is due to water presence then it will slowly expand or diminish and wetness improve leading to sweating, dripping and flowing some time even oozing or spring.
If the water leakage is due to surface cracks in tiles etc then impregnation is best way as impregnate will get into surface and arrest the leak. Impregnation is nothing but grouting by gravity where liquid will displace air and vick inside even to come out of mother surface be it a slab. Vicking is possible even in lateral movement and downwards. Lateral movement will not be for a distance but downwards can be more than 32 inches ie where ever water travels this will go along with water and seal from reverse once liquid content gets decimated by either getting absorbed by concrete or available material. Once this happens it will also augment the strength of surface as it would have filled the voids. The water collected before will exit down ward over a period of time say 4-6 weeks depending on water collected earlier over a period of time.
The advantage of this process is one can work on wet surface and on tiled surface or claded surface there by saving time and money and still get the result. This can also be used where water is coming out in pressure say close to 20 liters per hour. Application process for such situation will vary depending on site condition.
The limitation of this product is it can be used only where cement is used be it a white or grey cement ppc or opc. advantage is one product by varying proportion and consistency can be used on all WATER RUNNING AND WATER HOLDING BODIES AS INTEGRALS, COATING, LAMINATE, IMPREGNATE. THIS HAS HEAT AND U V RESISTANCE PROPERTY ALSO APART FROM CRACK RESISTANCE. WATERSHIELD IS ONE SUCH PRODUCT WHICH IS UNIQUE TILL NOW.
Impregnates can be used to waterproof the cement blocks to avoid leakage and also plastering in appropriate places say Deccan Plato.
COATINGS: coatings are good on porous surface and when surface is properly prepared.
This when applied over non traffic areas will be in stay put condition and will not allow leakages. There are exceptional coatings like epoxy, polyurethane, polyurea which can even take heavy traffic and still not leak. It is not that all epoxy or pu or polyurea are good for waterproofing for some lower derivatives are also available in market which sounds economical but not effective as it is supposed to be. Also if coating gets damaged then the leak starts as they form top layers and not integrate deep into structure.
Superior grades which has higher face value defies all above statements and can be even used under water in presence of water say in dam like situation and leaks can be arrested effectively.
There are coatings which can be used as grouts, coats or sprays depending on surface and site situation.
The coatings have different bases like cementetious, lime, acrylic, silicone, epoxy, polyurethane, polyurea.
Cementetious and lime coatings are time tested and long lasting. These are effective and economical. Acrylic are brittle in nature and silicone has low peel strength. Depending on surface and end requirement it is commonly used for waterproofing.
Epoxy is solvent based or solventless and bitumen based. Each one has its own advantage when it comes to eco-friendly concept solventless epoxy is best that apart solventless will have no smell and also air pockets as there is zero or less voc.
Epoxy can be used on surfaces which are hard and clean free from dirt grease water and foreign materials. It needs 72 hours for chemical curing and 14 hours for traffic movement. There are three stages of curing tack dry, green stage and grey stage which is final. There are advanced epoxies which can be used under water or quick setting like touch dry etc but we are talking about general epoxies which are used for waterproofing conventionally. Epoxies can be used on surfaces like wood, concrete steel and glass structures apart from metal shingles etc.,. It can be used on flooring's where there will be traffic too.