Waterproofing and bonding admixture for cement based screeds
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Bondex is a styrene butadiene co-polymer admixture designed to increase the bond strength when used in cementitious mixes, at the same time improving resistance to water, chemicals and freeze/thaw cycles due to reduced permeability. Bondex enhances the flexural and tensile properties of the mix enabling thin sections to be applied.
Bondex is a versatile product ideal for use both as a primer for cementitious screed and repairs, and as an admixture for floor screeds, renders and repair mortars. It is suitable for interior and exterior use.
Suitable substrates: The use of Bondex gives sand/cement mixes high bond strength to concrete, masonry and reinforcing steel.
Colour: Bondex is milky white in appearance and translucent once cured.
Packaging: Bondex is supplied in 5L units or 25L drums.
Curing time: Will support light traffic after approximately 48 hours, depending on temperature. Full strength is achieved within 28 days.
At higher temperatures, the curing process should be retarded by waterspray and covering with polythene sheeting, damp sand or wet hessian for 24 hours.
Application temperature: Bondex mixes should not be applied below 5°C.
Coverage:
The coverage per 5L unit of Bondex when mixed with 25kg cement and 75kg sharp sand is approximately 9.5m2 at 6mm nominal thickness.
Please consult the technical data sheet for full technical product data.
Surface Preparation
Thorough substrate preparation is essential.
Recommended methods are:
For floor screeds – remove all weak or loose material and provide a mechanical key to smooth concrete by means of scabbling or shot-blasting. If this is not possible, chemically etch the floor with Polycote Etch IT followed by thorough rinsing.
The abrasive effect of jet washing can assist in preparation and is recommended where appropriate. Ensure the surface is clean and free of loose material, oil or grease. Degrease if necessary using Polycote Degrease IT followed by thorough rinsing.
For patch repairs – concrete repairs should be prepared with squared off edges having a 6mm vertical lip.
Remove all loose material – wire brushing is advisable.
Remove any oil contamination from the surface using a gas torch and/or Polycote Degrease IT.
Expose any reinforcing steel and clean any rust back to bright metal, then prime with Bondex.
For porous surface prime with neat Bondex.
Mixing (Bondex Sand & Cement Mixes)
The standard mixing ratio for screeds or patch repairs is 25kgs cement and 75kgs sharp sand per 5L unit of Bondex. Water may be added to the mix to achieve the desired consistency.
Having primed the area, place the Bondex/Sand/Cement mix by trowel before the primer has dried.
Allow INITIAL cure before finishing the surface with a steel trowel – if this is attempted too early, surface crazing may occur.
Application Temperature
Bondex mixes should not be applied below 5°C.
Application Thickness
The recommended thickness range for Bondex-based sand/cement is 6mm minimum to 40mm maximum in one layer.
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