Project: Potable Water Facility, Tullamore, City of Brampton, Ontario. 2013
Designer: AECOM, Mississauga, Ontario
Owner: City of Brampton, Region of Peel
Installer: Tarpon Construction
Gemite products: Cem-Kote Flex ST, Reinforcing Fabric HD, Fibre-Patch OV, Gem-Plast TC
Objective: waterproofing of new concrete tanks in a water treatment facility. The project started in 2013 and was finished the same year. The interior of the tank is shown in Figure 1. The waterproofing system consisted of Cem-Kote Flex ST reinforced with the Reinforcing Fabric HD applied over the cracks only. A typical leaking crack is shown in Figure 2. The cracks were urethane injected to stop the active water leaks prior to application of Cem-Kote Flex ST and a strip of Reinforcing Fabric HD. The “bug holes” were repaired with Gem-Plast TC as shown in Figure 3. Cem-Kote Flex ST was spray applied on the walls in two coats and each coat was brushed to achieve membrane continuity in a minimum thickness of 1.6mm (63 mils).
Cem-Kote Flex ST has been used in potable water concrete tanks for over 23 years, with no single bond failure. The key advantages of the Cem-Kote Flex ST system over polymer coatings are as follows:
- Flexibility – with the Reinforcing Fabric NW used over drying shrinkage cracks and its inherent flexibility Cem-Kote Flex ST provides excellent crack bridging, much better than epoxy, vinyl-esters or flexibilized epoxies.
- Moisture – application of Cem-Kote Flex ST does not require drying of the concrete prior to application or low humidity in the tanks. Cem-Kote Flex ST is completely insensitive to moisture in concrete, surface moisture and high humidity environments.
- Water insensitivity – polymer membranes are very sensitive to moisture in concrete, surfacemoisture and high relative humidity. Most of the polymer membranes specifications call for drying the concrete to a depth of 1 inch, or application of an additional low moisture content render, prior to application.. These procedures, drying or application of a render, are very expensive. For example, drying this type of tank would require approximately 1-2 weeks, with the cost of heating fuel up to 1200 $ per day.
- Outside moisture – Cem-Kote Flex ST membrane also resists water penetrating from the outside, from the negative side. It has been extensively used for both positive and negative side waterproofing. Cem-Kote Flex ST membrane is insensitive to any moisture which can be present at the concrete/membrane interface, either due to water vapor condensation or penetration through cracks in the concrete. High capillary pressures which develop at the interface may cause debonding of the polymer membranes but will not de-bond cement based material due to its inherent gel porosity.
- Breathable – Cem-Kote Flex ST is “breathable” and can release the water vapour from the substrate concrete. Polymer membranes act as vapour barriers, resulting in the de-bonding problems associated with this property.
- Ease of Application – Cem-Kote Flex ST is a waterborne material so does not present the application difficulties of “sticky” polymer resin coatings. Tools and equipment are easy to clean with water whilst expensive organic solvents must be used when cleaning polymer coatings. .Cem-Kote Flex ST is easily and quickly applied by spraying, unlike polymer coatings.
- Robust – Cem-Kote Flex ST is a very “robust” product in application allowing large variations in moisture content and relative humidity. Its “application window” is very wide and tolerant to varying conditions compared to the very narrow “window” required for application of polymer coatings. Therefore the application of polymer coatings is more risky than applications of Cem-Kote Flex ST.
- Low cost – Cem-Kote Flex ST is considerably less expensive – only 25% of the average applied cost of polymer coatings, mainly due to the application reasons explained above.