ProJoint RapidFlow FAQs

An easy-to-apply permeable paving grout for porcelain and natural stone

Learn all about Projoint RapidFlow paving grout, an easy-to-apply permeable brush-in grout formulated specially for porcelain paving, but equally suited for natural stone paving.

Buy ProJoint RapidFlow grout

General info

What are the benefits of usuing ProJoint RapidFlow grout?

ProJoint RapidFlow brush-in grout from Nexus offers a quick and easy solution for filling joints on porcelain paving and patios. The grout is resin-based and comes premixed with sand as an easy-to-apply brush-in grout.

Benefits of ProJoint RapidFlow:

Specially formulated for porcelain paving, but equally suited for natural stone
Professional strength in contractor-sized tubs of 12.5kg
Ideal for joints of 3mm upwards
Quick and easy to apply formula
No mixing required – pre-mixed and ready to use
Less wastage on smaller projects – each tub includes two vacuum-sealed bags of formula
For permeable, free-draining patio projects
Suitable for patios, paths and other areas for pedestrian traffic
Weed free and frost-resistant formula
Cement-free and non hazardous
Available in five colours: Neutral, Light Grey, Mid Grey, Basalt and Black

This brush-in grout includes two vacuum-sealed bags inside the tub for easy handling and less wastage.

What grout colours are available?

ProJoint RapidFlow is available in five colours: Neutral (Buff), Light Grey, Mid Grey, Basalt and Black.

Please note that sand is a natural product and some minimal colour variances may occur. Get in touch if you would like to see a colour sample.

Nexus ProJoint RapidFlow Colours

What types of stone can ProJoint RapidFlow be used with?

While ProJoint RapidFlow is specially formulated for porcelain paving, it still works brilliantly with natural stone pavers, making it a versatile choice for a variety of paving jobs.

Is ProJoint RapidFlow permeable?

Yes, ProJoint RapidFlow is a permeable grout that allows water to freely drain through the joints. This helps to prevent water build-up and puddling on the surface of your paving.

As RapidFlow grout cures when it dries out, the bedding mortar must also be permeable so that water can freely drain through. If water stagnates in the joints, it can soften the binder and encourage algae growth.

Use a permeable bedding mortar such as Perma-Bed or a 5:1 ratio (or above) of sand and cement.

What are the minimum joint sizes for ProJoint RapidFlow?

Joint sizes must be a minimum of 3mm wide.

Can I pressure wash after applying ProJoint RapidFlow?

Yes, but only once the joints have fully cured after 30 days.

When pressure-washing, use a fan nozzle and keep the nozzle itself at a safe distance to avoid causing any damage.

What's the best way of maintaining the joints?

Once you’ve installed ProJoint RapidFlow, keeping the joints clean is simple.

Regularly sweep the area to remove debris, dirt and leaves, and stopping weeds from taking root.

If the paving looks like it needs a deeper clean, Remove-It Black Spot and Algae Remover will easily blast through any dirt or algae.

How many tubs do I need?

How much coverage you get out of each tub of ProJoint RapidFlow depends on the size of the joints and paving slabs.

Use this table as a guide for estimating how many 12.5kg tubs of RapidFlow you need. Feel free to drop us a line if you need any extra help.

Joint size (width x depth)	600mm x 600mm slabs	600mm x 900mm slabs	600mm x 1200mm slabs
3mm x 20mm	34.8m2	41.8m2	46.5m2
5mm x 20mm	20.8m2	25m2	27.8m2
7mm x 20mm	14.9m2	17.9m2	20m2

Before use

Do I need to seal the paving?

When working with ProJoint RapidFlow, it is recommended that you use a pre-grout sealant, such as ProJoint Pre-Grout Sealer, when working with sensitive, sawn or highly textured paving.

Apply this sealant to the paving before applying the grout.

Should I do a patch test first?

ProJoint RapidFlow may temporarily highlight and enhance the natural surface colours and textures of paving. This can be more noticeable on grey paving, including granite. You may want to do a small test area before use.

Please note, these highlights are temporary, and will disappear with weathering and foot traffic. When applying the mixture, spread it evenly across the pavers to make sure any of these changes are consistent.

Get in touch if you have any concerns.

How do I prepare the area for grouting?

Before applying ProJoint Rapidflow, you must ensure that:

The paving surfaces are clean.
Joints are cleaned out to a depth of 20mm, with a minimum joint width of 3mm.
Paving is firmly bedded and stable, and laid on a permeable bedding mortar. ProJoint RapidFlow cures when it dries out so water must have an escape route. We also recommend using a quality paving primer.

In what weather conditions can I apply ProJoint RapidFlow?

ProJoint RapidFlow can be applied at temperatures from 3ºC and rising, and up to 25ºC.

You can even apply the grout in light rain. However, you do need to avoid heavy rain or freezing conditions – these types of conditions can affect the curing process.

How to apply ProJoint RapidFlow

What tools or equipment do I need?

When applying ProJoint Titan, you will need:

Hosepipe (with misting nozzle) and access to clean water
A rubber squeegee or long-handled broom
A long-handled broom with soft bristles
Finishing bar or trowel (optional)

How do I apply ProJoint RapidFlow?

Once the area is prepared and ready for grouting, here’s how to apply ProJoint RapidFlow:

First, liberally soak the paved area with clean water.
Open the tub and one of the vacuum-sealed bags and empty the mix onto the paving surface.
Quickly work the formula into the paving joints using a brush or squeegee.
Mist the surfaces and the joints with a soft spray of water, flushing the grout down into the joints.
Top-up any low joints, repeating the misting process if necessary.
Once the water has drained away, sweep the paving with a fresh soft-bristled brush at a 45º angle to the joints, removing any excess grout.
Finally, once excess grout has been removed from the surfaces, you can use a finishing bar or trowel to ‘strike off’ the joints for a traditional finish (optional).

Always read the full instructions provided with the tub before application.

How long does the grout take to cure?

It really depends on the outdoor temperature and weather conditions at the time.

Typically, ProJoint RapidFlow cures enough so you can walk on the area after 12 hours. Be aware that cold and wet conditions will delay the curing process.

You can expect the paving to be fully cured after 30 days.

Storage instructions

What is the shelf life of ProJoint RapidFlow?

ProJoint RapidFlow should be used within 12 months from the date of manufacture. Tubs must be stored in a cool and dry environment that is free from frost, between temperatures of between 5ºC and 30ºC.

Can any leftovers be stored and reused?

A great bonus of using ProJoint RapidFlow is that the formula comes divided into two vacuum-sealed bags for less wastage on smaller projects.

Plus, if you do still have leftovers on completing the job, the grout can be stored and reused for a later date. Just return any unused formula to the tub, submerge it in clean water and replace the lid. You’ll need to use this leftover formula within a month.