Integral waterproofing
Integral waterproofing for: below ground, water tanks, industrial wastewater
Below ground areas are are the part of a building that most often have leaks and this is why good quality integral waterproofing (i.e. putting admixtures into the concrete prior to pouring) has become the largest growth area in the worldwide market. It is also commonly known that leaks in below-ground situations are much harder to fix than leaks above the ground in any structure.
Although membranes have been used below ground for many years there were many issues with them tearing, puncturing, debonding et cetera.
Not only is integral waterproofing used for below ground applications but it is also used for water tanks regardless of whether these are below ground or above ground. The rationale for this is that the chemistry of most admixtures mean they don’t handle thermal stress well and therefore should be used in areas of low thermal stress. This means areas such as basements, water tanks and other below ground applications.
The future of below ground waterproofing
There was a massive advance in technology in the mid-1950’s with the development of crystalline (also known as crystal growth and capillary). Although originally applied as a surface coating it was soon realised that it was far more effective to be added to the concrete as an admixture and the concept of water resistant admixtures was born. Today these admixtures are a standard and increasingly common form of waterproofing around the world.
Integral is a slightly generic term which refers to a whole variety of admixtures put into the concrete during mixing.
Thus crystal growth is technically just one form of integral but in many parts of the world it is just known as integral. There are several different water resistant concrete admixtures put into concrete (beton) but integral has been by far the most successful and is now used throughout the world, in both hot and cold climates.
Today this market is growing massively and in 2026 the world market is estimated to be in excess of 5 billion USD.
Concrete admixtures added to the mix
Integral is a generic word for any type of admixture that is added to the concrete.
Stearates and crystal growth (crystalline) are the two most common forms of concrete admixtures for waterproofing. Another important difference between stearates (commonly called pore blockers) and crystalline is that crystal growth products have the ability to seal static cracks which may occur in the future whilst stearates don’t. This is very important. Because this type of product remains reactive in the structure for the lifetime of the building, it can seal cracks that may develop In subsequent years. This means it protects the building for many years longer than would otherwise be the case.
Siloxanes and silanes and various other pore blockers do not have this ability and therefore the structure develops any cracks there will be leaks in the building. This may cause issues such as unhappy clients and a lot of rectification to be done, usually at great cost as well as a great deal of inconvenience to all concerned.
Resisting Hydrostatic Pressure
Obviously for below ground applications – and also for water tanks – it is important that whichever products are used are able to resist hydrostatic pressure. Fifferent forms of integral and different admixtures have different abilities to withstand the effects of hydrostatic pressure. Stearates for example will resist virtually no hydrostatic pressure whereas crystalline will resist a lot of hydrostatic pressure. The majority of these products are tested to about five bars of pressure under an International standard but CWS Admix has been successfully tested to 14 bars of hydrostatic pressure.
Many hydrophobic waterproofing products that have been around for many years are stearates: essentially a fat that reacts with calcium hydroxide and gradually blocks the pores within the concrete. These products do not withstand hydrostatic pressure to any extent and will break down under ponding water.
The benefits
Originally membranes were the most common form of waterproofing for below ground structures. Membranes are still widely used but are losing market share because they have many disadvantages when compared to integral. Membranes must be put down in very strict conditions with a very limited amount of moisture in the concrete or issues like delamination and bubbling will occur. This shortens the lifespan. Likewise sharp objects or people walking on membranes cause them to deteriorate even though that deterioration may not be seen for several years.
Of course most of these are construction issues but that is the reality of building new structures.
Integral on the other hand does not suffer any of these issues. Admixtures are placed directly into the concrete and when it is poured the products have spread through the mix and protect both positive and negative sides.
This gives a massive advantage in terms of speed of application. This building is protected as soon as the pour has finished – albeit with the understanding that it will take the admixture some time to reach its full potential.
Other advantages include the fact that there might be irregular shapes in the building’s design and this is easily catered to by admixtures. Likewise it means that the building can be constructed to the edge of the site because there is no requirement to be able to access the outside of the building. This might not sound much initially but if it means an increase in the building footprint that is a massive investment boost to the owner.
One other issue that happens often with membranes is that during backfilling operations they are damaged and basically for the rest of their life span will not do the job they were designed to do.
Most of these products – but not all – are very friendly to the environment and this is an important consideration these days.
Generally speaking this type of product is used for below ground applications and water tanks. For above ground applications more flexible products are needed that can adjust to the thermal stress involved on a rooftop. For this type of application we recommend you look at a more flexible products such as CWS100.
Common applications include the following:
Tunnels
Below ground car parks
Ground slabs
Potable water tanks
Elevator pits
Foundation walls
Footings
Industrial wastewater
Core filled block work
Basement waterproofing
How do these admixtures affect concrete?
The answer to this depends on the exact product and brand in question. In general, the majority of these products are crystalline and it has three common effects on the concrete:
It retards the concrete set slightly
It generally increases the slump
Normally it has little or no effect on concrete strength
One very positive outcome is that the durability of the structure is dramatically improved, a key determinant in increasing life span.
CWS Admix
CWS Admix is manufactured and supplied by Concrete Waterproofing Systems.
This is a crystalline admixture which was developed nearly 50 years ago and has been used in applications all around the world ever since.
CWS Admix has the ability to seal static cracks in a slab should they develop at some future stage.
CWS Admix has proven to be superb under hydrostatic pressure and has been tested at 14 bars of hydrostatic pressure which is roughly the equivalent of a 40 story building. We are not aware of any other such product that has testing even near this standard. Most such products in the market have testing to only five bars of pressure…… way, way less than the performance of CWS Admix. Thus it is great to use for below ground protection, water tanks and tunnels.
One of the further advantages of CWS Admix is that it is dosed at a fixed rate of 0.8kg/m3 regardless of cement content. Quite often, during the final refining of the mix design, the actual mix is changed numerous times. This has resulted in companies mismanaging the exact quantity of admixture that will be added to the mix because, each time the cement content is changed, so does the amount of admixture. This does not occur with CWS Admix, whose dosage is constant. Simplicity is a key in construction.
Environmentally friendly
CWS Admix is extremely friendly to the environment. It contains no volatile organic chemicals (VOC’s) and has been tested under international standards to be safe for drinking water.
Please talk to us about how CWS Admix can help you protect your newest project. To learn more please email us.