Bondex

Bondex is a highly specialised styrene butadiene co-polymer admixture, designed to increase the bond strength in cementitious mixes used in floor screeds and patch repairs. This will also dramatically improve resistance to water, chemicals and freeze thaw cycles due to reduced permeability. Furthermore Bondex enhances the flexural and tensile properties of the mix enabling the screed / repairs to be laid in much thinner layers down to only 6mm.

Dramatically increases compressive strength
Simply mix with sand and cement
Tenacious adhesion
Screed may be laid as thin as 6 – 7mm
Coverage: 5L mixed with 25kg cement & 75kgs sharp sand = 9.5m² at 6mm thick

Full compressive strength:31.2N/mm²
Full tensile strength:3.9N/mm²
Full flexural strength:10.6N/mm²
Mixing ratios:For general repairs, use a 3:1 sharp sand/cement mix. 5L of Bondex / 75kgs Sand / 25kgs Cement will cover 9.5 sq.m. @ 6mm thick
Mixing ratios:For thin/slurry repairs, use a 1:1 kiln dried sand/cement mix. 5L of Bondex / 5kgs Sand / 5kgs Cement will cover 4sq.m. @ 2mm thick
Number of parts supplied:1
Priming required:For very porous surfaces or feather edging, prime with either neat Bondex or 1:1 Bondex/Cement

Please consult the technical data sheet for full technical product data.

Preparation:
Thorough substrate preparation is essential.
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.
Ensure the surface is clean and free of and oil or grease. Degrease if necessary using Polycote Degrease IT followed again by a thorough rinsing to neutralise.
For patch repairs it is always better to square off edges to ensure at least a 4-6mm lip. Should this not be possible (or would rather be avoided) then mix the Bondex with a stronger and wetter mix (more Bondex) and use this for the edge work.
Expose any reinforcing steel and clean any rust back to bright metal, then prime with Bondex.

Priming:
First of all, it is advisable to dampen the surface with water to reduce suction.
Add 2 parts ordinary Portland Cement to 1 part Bondex and apply by brush to prime the surface. The sand/cement mix must be placed whilst the primer is still TACKY and it is very important to note that this priming mixture WILL cure quickly. Should the cement/Bondex primer become dry before material is placed, then you must re-prime the area!
The coverage of cement/Bondex primer mixed 2:1 is 2-3m² per litre depending on surface texture and porosity.

Application:
It is strongly advised that this general screed mix is indeed mixed and ready to lay BEFORE the primer is mixed and applied, due to the aforementioned point that the primer will cure fast and the importance of laying on the primer whilst it is still wet! So, having primed the area, place the Bondex/Sand/Cement mix by trowel. Allow an INITIAL cure before finishing the surface with a steel trowel. If this is attempted too early, surface crazing may occur and whilst this should not be any real detriment to the product, it does not make for which should a nice aesthetically pleasing finish.
TIP:
Bondex is a great product and can turn a sand and cement mix into a granite hard finish. Should you wish to apply VERY thin screeds over areas such as damaged / spalling concrete or asphalt, even in areas taking heavy traffic such as grain stores, use kiln dried sand – commonly known as block paving / silver sand. Using a sand/cement mix ratio of 2:1 or even a 1:1 mix this with neat Bondex into a wet slurry. (Obviously you have dampened the area first to remove the immediate suction)!! This can then be poured onto the affected area and with a steel trowel or wooden ‘straight edge’ this can then be leveled out to fill in the small indentations. If you are really concerned and/or have heavy traffic /digger buckets going over the area, then paint the Bondex neat over the top particularly around the edges. Please note that this is a ‘trick of the trade’ and one that you will not normally read in a set of instructions!!!