Technologies used for Active and Static Waterbars.
Technologies
Active Waterbars
Bentonite
Bentonite is a naturally absorbent clay. Of the two types of bentonite clay, it is sodium bentonite that has the natural ability to absorb large quantities of water which can increase its volume by up to a factor of eight. It is this property that makes it an excellent joint sealing material within concrete as it provides a self-sealing, low permeability barrier.
When mixed with butyl rubber, the clay takes on the ability to hold its form and slow the process of washout. The butyl rubber aids the holding of the form once swollen. However, during continuous wet and dry cycles*, the active waterbar will reduce in size during the dry cycle (though not to its original size), and then swell again when water is reintroduced.
Synthetic Rubber
Synthetic rubbers are a mix of polymers (normally a combination of a plastic and a rubber) that contain thermoplastic and elastomeric properties.
Synthetic rubbers show advantages typical of both plastic and rubber-based materials. The benefit of using synthetic rubber is its
ability to elongate and return to its near original shape thus creating a more durable and versatile material.
The combination of this technology with hydrophilic elements, gives the ability to create products with differing swelling properties.
Material Comparison
The big differences between synthetic rubber and sodium bentonite are:
- When water is no longer present synthetic rubber shrinks back to near its original size.
- With synthetic rubber the wet / dry cycle* is a process of expansion and contraction that can be repeated many times.
- Synthetic rubber has structural integrity which cannot wash out.
- Weight - Synthetic is significantly lighter than a bentonite based active waterbar.
- Flexibility - Synthetic rubber is more flexible than sodium bentonite.
- Bentonite cannot tear.
- Bentonite can become fibrous and fill minor cracks adjacent to the installation.
- Bentonite can withstand more robust installations of concrete.
| Bentonite / Clay Mix | Synthetic Rubber | |
| Sealing Force / Expansion | At a size of 20 mm × 25 mm the sealing force is up to 1.25 tonne per metre | At a size of 20 mm × 5 mm the sealing force is greater than 2.60 tonne per metre |
| Wet / dry cycles | The mix is the highest quality of bentonite waterbars on the market. This is reflected in the fact that it can easily withstand 3 full wet / dry cycles without loss of important properties. However, as with any bentonite based waterbar, at a certain point, washing out will be initiated. There is a benefit of this phenomenon though in that minor concrete voids can be filled up with the bentonite. | The synthetic rubber is a high quality, durable product. After >35 wet / dry cycles the material has been proven to keep its expansion potential. |
| Weight | 17 % heavier than synthetic rubber @ equal size. 586 % heavier than synthetic rubber @ actual size. | 15 % lighter than bentonite mix @ equal size. 83 % lighter than bentonite mix @ actual size. |
| Mechanical properties | The bentonite mix is butyl rubber based, and therefore has a low-level of, in relative terms, tensile properties and longitudinal tear strength. Due to the consistency of the bentonite mix, the bar will not crack or split during the nailing process. | The synthetic rubber has a high-level of, in relative terms, tensile properties and tear strength. Due to the constancy of synthetic rubber the bar is likely to crack or split if punctured. Therefore, if nailing is required a containment such as Fixing Wire, must be used. |
| History | Bentonite based sealing profiles are well-known and have been widely used in the construction industry for more than 20 years. | Synthetic rubber is a new innovation, proving an excellent alternative to bentonite. |
Static Waterbars
Static waterbars are, in simple form, a solid physical barrier placed at the joint line to produce a tortuous path for the water to navigate.
Manorteq Static waterbars have this technology as the primary barrier, but also have a secondary line of defence incorporated into them. This secondary barrier is either the HydroBar Original
technology which swells to seal; or a bitumen layer which adheres to the concrete creating an impermeable barrier.
All the Manorteq Static waterbars are made of galvanized steel. Whichever options your project requires the steel waterbar is protected from corrosion.
Why Static waterbars instead of Active?
Is there a simple answer to this question? There are reasons to use Static waterbars, and reasons to use Active. In fact, it is not unusual to find construction sites using both types of system where demands of the of the site and the construction methods so require.
That said, Static waterbars are much more robust than any Active waterbar and can be left in situ for significant amounts of time prior to the subsequent pour. There are many additional non-waterproof benefits to Manorteq Static waterbars. Please consult your Manorteq representative for further information.