Concrete comprise the largest of all man made construction material of our time.
Its plasticity, workability, ease to place, to cast and compact while wet and strong and durable when hardened, make it one of the unique material. Generally strength of concrete is considered as the most important criteria among other properties
But when taking the account of durability, resistance to water permeability is also considered as an essential requirement for which it is designed to withstand the environmental condition for over period of time without any deterioration.
Waterproofing or damp–proofing is carried out to prevent or to seal unwanted water containing deleterious salts and chemicals to enter in the structure, resulting reinforcement corrosion and other destructive activities.
What is water proofing ?
- Building waterproofing is a process which is designed to prevent water from penetrating a building.
- Usually extensive waterproofing measures are added to a building at the time of construction, to provide moisture control from the start.
- Waterproofing may also be done after a building is built, to address problems as they emerge or as part of a building retrofit
WATER PROOFING vs DAMP PROOFING
- Often the terms waterproofing and damp-proofing are incorrectly interchanged. According to astm definitions:
- Waterproofing is the treatment of a surface to prevent the passage of liquid water in the presence of hydrostatic pressure.
- Damp-proofing is the treatment of a surface to retard the absorption of moisture in the absence of hydrostatic pressure.
- Virtually all building envelopes encounter hydrostatic pressure from water during their lifetime.
- Therefore, the use of a quality waterproofing system is essential to preserve the water-tightness of the building envelope.
Rising water table creates hydrostatic pressure against your foundation
What is hydrostatic pressure?
Hydrostatic pressure is the force exerted at a given depth by the weight of the overlying column of water. This pressure acts with equal magnitude in all directions.
How water can penetrate concrete structures?
- Hydrostatic pressure
- Concrete cracks
- Capillary action
- Vapor transmission
|Causes of leakages
- Defective structural design
- Use of poor quality construction material
- Porous structures
- Improper methodology of construction
- Improper slopes on top surfaces.
|Sources of leakages
- Subsoil water rising by capillary action.
- Cracks in external plaster
- Vegetation growth
- Separation gaps between partition wall and beams and the columns.
- From expansion joints
| Foundation/soil settlement.
|| Construction joints
|| Concrete shrinkage
Permeability of concreate
- Well-graded sands containing considerable graded fine material are preferable for making impermeable concrete.
- The consistency of the concrete mixture should be wet enough so that it can be puddled, mixture should be well spaded against the forms to avoid the formation of pockets on the surface.
- Care should be taken not to over trowel.
- The use of excessive water, causes shrinkage cracks and formation of laitance-seams.
- Defective workmanship can result in improper proportioning, lack of thorough mixing etc.
Portland cement mortar and concrete can be made practically waterproof or impermeable without the use of any integral waterproofing materials; But in order to obtain it considerable care should be exercised in selecting good materials.
Signs of water leakages
Cracked walls should be inspected to determine the exact cause.
Mold and mildew fungus that grows in damp and dark areas, and cause discoloration, or musty odors.
White substance on basement walls this is a chemical breakdown of the bonding agent that holds your walls together.
Peeling paint peeling paint is a sign that you have moisture problems and waterproofing issues.
Rust on appliances or furniture Like furnaces. Rust is caused by a wet environment and is the sign of waterproofing issues.
Damp spots on walls Water has absorbed through your walls.
Moldy odors This is the result of the decay process from mold, and dry rot.
Dry rot Black fungus grows mostly on walls or wooden surfaces, causing wood to decay.
Where to apply water proofing?
- Positive side waterproofing
- Negative side waterproofing
- Blind side waterproofing interior
- Interior applications
- Exterior applications
1. Positive side waterproofing
- 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
2. Negative side waterproofing
- Interior side opposite the water pressure side of the structure.
3. Blind side waterproofing interior
- Positive side applied prior to installing the structural walls or slabs.
- Typically inaccessible once the structure is complete.
|Positive side waterproofing
- Split slabs
- Mechanical rooms
|Negative side waterproofing
|Positive side waterproofing
- Foundation walls
- Plaza decks
- Parking decks
- Party walls
- Bridge decks
|Blind side waterproofing
- Soil retention systems
- Party walls
- Cut and cover tunnels
- Under slab
- Elevator pits
What is a quality waterproofing system?
- A waterproofing system which prevents the passage of liquid water in the presence of hydrostatic pressure.
- Protection as necessary.
- A drainage system that reduces hydrostatic pressure.
- Accessory products which complement, attach and detail the waterproofing and drainage.
Materials used for water proofing
- It should be impervious.
- It should be strong and durable be capable of withstanding both dead as well as live loads without damage.
- It should be dimensionally stable.
- It should be free from deliquescent salts like sulphates, chlorides and nitrates.
- Full adhesion to substrate: to prevent lateral migration of water between the waterprofing material and substrate.
- Factory controlled uniform thickness: variance in thickness may lead to variable peformance.
- Flexibility over cracks: able to widtstand substrate movement.
Advantages waterproofing system?
- Waterproofing protects the structure
- The damage to buildings imposed by water is a threat to life and property particularly in the regions bearing the risk of earthquakes.
- Water leaking into the building’s reinforcement in any form will lead to the loss of quality of equipment by means of freezing or chemical reactions.
- Loss of quality of the reinforcement will result in impaired resistance and longevity.
2.Waterproofing brings convenience
- Passing through the pores of the construction elements, soil moisture and pressurized water cause formation of mildew, black spots and fungal organisms on the interior surface.
- As a consequence, it leads to the decay of natural interior surface materials such as wood, flaking of plaster and rusting of the iron curtain walls, thereby leading to the disruption of our convenience.
- Moisture and the associated mildew generates bad odor in the environment. This is an undesirable effect on the inhabitants.
- Waterproofing not only prevents moisture, but also eliminates bad odor which is a negative impact on human comfort.
- Waterproofing saves cost
- Nowadays, the structures which gain increasing economic value must be long lasting. Currently, the average life of a given structure is approx. 50 years.
- The negative effects of water reduce the longevity of the structures, thereby leading to financial loss.
- Waterproofing will also eliminate losses of this kind. The costs of waterproofing at the construction stage are estimated as 3 percent of the building’s value.
- Robustness of the buildings is the most important aspect to be taken into consideration. Accordingly, the benefits offered by waterproofing are far more important than the cost
Types of water proofing :
- Sheet membrane system
- Sheet membrane waterproofing systems are designed for above and below grade use as well as horizontal and vertical applications.
- Sheet membranes can be installed utilizing one or more layers depending upon the system specified.
- An advantage that sheet membrane offers over fluid applied is that it gives a guaranteed membrane thickness that does not rely on the installation process.
- Bonded sheet membranes are generally cold-applied or heat-bonded to the finished structural walls. Both are modified bitumen on a range of carrier films.
- They are applied externally.
- They are attached to the enabling works (reverse tanking) but subsequently fully bonded, by means of a specifically formulated pressure-sensitive adhesive, to the poured concrete.
- Design considerations:
1.Flexible and able to adapt to minor movement and shrinkage within the substrate.
2.They are of consistent thickness and quality.
3.May provide protection against aggressive soils and groundwater when applied externally.
4.Require good surface preparation.
5.Substrate must be free from surface water for bonding to occur.
6.Generally, suitable only for uncomplicated foundation systems such as plain rafts.
- Easy installation
- Time saving
- Bonding has to be strong
- Joints should overlap
- Trained labour required
- Asphalt based
- Thermo fusible
- Problem in vertical application
- Bitumen based
|CONTROLLED, GUARANTEED THICKNESS
|NO MIXING OR SPECIALIST EQUIPMENT
|Sheet membrane waterproofing for basement in London
||Self adhesive bitumen she
|It takes two people, one on top to smooth it out and stick it down, the other on the bottom to pull off the paper.
|| Melbourne torch on waterproofing membrane system
- Liquid applieds system
- Fluid-applied waterproof products are liquid coatings containing a base of urethanes, rubbers, plastics, vinyls, polymeric asphalts, or combinations thereof, which are applied to the surface usually by spraying or rolling.
- The fluid-applied membranes are easy to apply, conform to the surface texture and irregularities of the concrete and do not have seams.
- You apply a liquid membrane by spray, roller, or trowel.
- They can be applied both externally and internally.
- In the latter case, the loading coat must be strong enough to resist hydrostatic pressure.
Gray waterproofing membrane that can be sprayed or rolled on. Waterproof protection above and below grade.
- Being jointless, they maintain continuity of membrane.
- May be applied to difficult substrate profiles.
- Elastic and flexible, thus accommodating minor movement and shrinkage within the structure.
- Can protect the structure against aggressive soils and groundwater when applied externally.
- Have high substrate adhesion and chemical resistance.
- When applied internally, must beRestrained by a loading coat.
- Substrate must be free from surface water for bonding to occur.
- Requires good surface preparation.
- Careful application needed to achieve correct thickness of dried film.
|GOOD FOR COMPLEX GEOMETRIES
|QUICK COVERAGE WITH SPRAY APPLICATION
||MIXING AND SPRAY EQUIPMENT
|MINIMAL SUBSTRATE PREPARATION
||INCONSISTENCY IN COVERAGE
|LOW IN-PLACE COST
- Fluid-applied membrane applications require that the termination of the membrane be carefully completed to prevent disbonding at the edge and potential water infiltration.
- Blistering will occur if materials are applied to wet substrates or if water finds its way behind the membrane since they are non-breathable coatings.
- Cementitious waterproofing system :
- Cementitious products are probably the easiest waterproofing materials to use.
- They’re readily available from suppliers of masonry products, and they’re easy to mix and apply.
- The chief disadvantage is that cementitious products have no give to them probably because cement just doesn’t stretch to any degree worth mentioning. They will stand up fine to a head of water, but will tolerate almost no joint or crack movement.
Cementitious waterproofing applications:
- Water treatment plants
- Sewage treatment plants
- Railway & subway systems
- Marine cargo ports & docks
- River locks/channels & concrete dykes
- Parking structures & lots
Features and benefits:
- Designed for negative water pressure
- Eliminates water migration vertically
- Good as solution to complex details
- Ideal as remedial solution
- Provides excellent impermeable coating
- Heavy duty waterproof coating
- Good adhesion with cementitious surfaces
- Applied for positive & negative sides of waterproofing
- Easily brush applied
- Flexible enough to take care of minor cracks in concrete & plaster
- Durable & economical
- Application tools easily washed in water
- Available in pre-packed, ready-to-use containers
Precautions and limitations:
- Must be protected from foot traffic & other physical abuse.
- Do not pond with water immediately after the 2nd coat. Allow it air to cure for atleast 72 hours.
- Pre-wetting of the substrate is essential before coating.
- Film thickness of 1 to 1.2 mm must be achieved in 2 coats. For a critical areas 1.5 mm thick film is recommended to be achieved in 3 coats.
- Must be applied on totally cured surface.
- Do not undertake application in hot sun (above 300c) and below 100c.
- Do not dilute product with water at site.
- Drainage board
| Dimpled drain boards create a 1-inch air space next to the concrete foundation
||Drainage sheets come with an integral termination strip.
- Another approach to waterproofing with applied sheet materials is to use drainage boards, with or without waterproofing on the concrete wall.
- Waterproofing membranes are a critical component for keeping basements dry.
- These dimpled plastic sheets are available from several manufacturers and come in various length rolls, ranging from 4 feet to 9 feet 9 inches tall.
- The dimpled side is placed toward the foundation and holds the sheet about ½ inch from the wall.
- A termination strip is attached to the wall at the top. The plastic serves as a waterproofing membrane, keeping water from penetrating to the surface of the wall, and as protection for the membrane on the wall during backfilling. Any water that may get through (by condensation or leakage) can trickle down to the foundation drains through the space formed by the dimples.
||Some dimple drain products utilize a fastening strip at the upper termination to prevent water from getting behind the membrane at grade.
- Some drainage boards incorporate solid materials that are porous enough to allow water to flow down while supplying some insulating value to the wall. Still others uses twisted or deformed wire covered with a filter fabric to provide the drainage space.
- Some other are made from fiberglass and resin. Others are made from expanded polystyrene (eps) foam, flexible closed-cell foam, and even mineral wool. Panels are usually available with a geotextile face on one side.
- Bentonite waterproofing system :
- Bentonite is a type of clay having the unusual characteristics of cohesion, binding, sealing, and thickening.
- When installed as a waterproofing membrane, it becomes hydrated with the moisture that is naturally present in the soil and forms an impermeable barrier that absorbs and expels
- It can expand and contract and is capable of absorbing seven to 10 times its own weight in water, swelling up to 18 times its dry
- To function properly as a waterproofing barrier, it is extremely important that this barrier remain under a constant minimum pressure of 30 to 60 pounds per square
- Bentonite has enjoyed a steady upsurge in popularity over the past several
- When it reaches its maximum volume, it stays in these areas permanently to seal against
- With other products, you can inspect the finished waterproofing application and confirm the integrity of the seal before backfilling. With bentonite panels, the seal doesn’t form until the foundation is backfilled and water reaches the panel.
- Bentonite can be used under structural or non-structural concrete floor slabs,
- On below-grade foundation walls,
- Between slab applications,
- Under slab applications,
- For zero property line construction, and
- Along tunnels and subway walls.
- Prevents tracking of water between membrane and concrete surfaces.
- Resistance to hydrostatic water head of 46m.
- Over 100 years of life expectation.
- High puncture resistance.
- Non-toxic and environmentally
- Quick and easy installation over green concrete
- Does not require priming and heat
- Installation temperature -30°c to +55°c.
2.Bentonite hydrates preventing further water penetration
3.No tracking of water between membrane and concrete
What are the problems with bentonite waterproofing?
Before agreeing to have your foundation treated with bentonite, it’s important to know about certain limitations and disadvantages.
- Like any exterior coating, bentonite can only provide effective protection against water intrusion if the application is perfectly done. Small gaps, missed spots and thin coverage are application errors that will allow ground water to enter the basement.
- This is especially true when bentonite is injected into the soil rather than applied in sheet form.
- For full coverage with bentonite, your foundation must be completely excavated.
- Bringing heavy equipment onto your property can be destructive to your yard and landscaping; it also turns your property into a major construction site.
- Care must be taken not to damage the foundation during the excavation process.
Water leakage from inside the foundation.
- Bentonite applied to foundation walls can’t prevent water from entering your basement along the most common leak area: the crack between the basement slab floor and the basement wall. During wet weather, high hydrostatic pressure can easily force water up through cracks in the basement floor and along the floor- to-wall joint.
- Interior drain and sump pump systems are better able to provide waterproofing
Protection because they alleviate water pressure rather than causing it to increase.
Also known as…
Bentonite waterproofing goes by other names, like “hydroclay” “sodium bentonite“ and “granular bentonite.”
1.Compacted and level soil
2.Concrete blinding layer
4.Optional concrete protection layer, for load distribution
5.Reinforced concrete base
Expensive and extensive. Installing a bentonite waterproofing system on an existing house usually calls for complete excavation of the foundation. Interior drain and sump pump systems are more affordable and also more effective.
DETAILS OF WATERPROOFING OPTIONS AND FORMS OF CONSTRUCTION
Waterproofing las vegas mccarran international
Airport’s new terminal 3
The station and the tunnel comprise the “early site package” of the terminal 3 project and represent about 600,000 square feet of excavation and construction, requiring 275,000 sq. Ft. Of preprufe and 370,000 sq. Ft. Of bituthene waterproofing membrane along with hydroduct drainage composite.
Precautions to be taken by the client and consultant
- Selection of an effective waterproofing system for a structure taking all the performance criteria of the structure into account and also taking into the consideration, the performance of the materials in the system is of prime importance for any success of the waterproofing
- Waterproofing jobs awarded to waterproofing contractors purely on economical price considerations often
- It is always advisable to involve the architect or the structural engineer in selection of a system and requisite performance guarantees should be taken from the
- It is better to avoid bargaining for the job value out of contractor’s This could result in stretching the product beyond the coverage specified by the manufacturer or substitution of cheaper material in the system to cover the cost.
- Always supervise the job and the incoming materials for the intact tamperproof seals and
- Use the services of an engineer or architect in selection of That too only procured from well know manufacturing firm.
Failure of waterproofing systems
- Especially in large buildings, waterproofing systems fail if the control joints are not in position or not properly executed and maintained. This failure occurs even after one complete year when the structure has passed through one complete summer and the winter cycle. One can’t repair this type of failures. It needs a different type of approach involving provision of crack inducer joints and then tackling the waterproofing in movement restricted bays.
- Application of a waterproofing product in non-specified areas, such as using a crystalline waterproofing system in waterproofing the terrace or using a flexible membrane system in the water tank results in failures even though the products themselves may be genuine.
- Stretching the coverage of the products beyond the specified limits by the manufacturer results in inefficiency of the product and hence a failure.
- Generally, architects in india, do not specify in depth waterproofing details and leave this aspect generally to ignorant client to chose whatever system he likes, and many structural designers give least importance to the control joints. As a result of this, many systems have failed in several prestigious buildings and the blame went to waterproofing contractors or the product manufacturer.
- There is a need for the architects and the structural designers to understand the various systems available and specify them clearly and in sufficient detail, taking into consideration the in-service conditions of the structure.
- The client should also insist on the architect to provide waterproofing design details in advance so that no ambiguity remains till the end. This would give enough time in selecting the specified material.