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Cleaning Concrete and Asphalt Paths and Driveways

How To Clean Concrete and Asphalt Paths and Driveways with Bio-Shield®
Including cleaning of:

Smooth or Exposed Aggregate Concrete.

Concrete Paving and Cobblestones

Concrete Block Walls

Unpainted Concrete Plaster


Should I water blast clean or use Bio-Shield to clean Concrete or Asphalt?
Water blasting concrete to remove fungal, moss and lichen growths will damage the surface by stripping away the cement and sand, leaving a rougher and more porous surface. 
Water blasting asphalt is even more destructive leaving deep gouges in the surface.
This is a time consuming, expensive, and ultimately futile way to clean these surfaces: if they are not sterilised in conjunction with water blasting, the spores within the concrete and asphalt will quickly regrow and discolour the surface again.

The best method for cleaning and maintaining concrete and asphalt are exterior cleaning solutions like Bio-Shield®.

A simple application will kill and remove the growths and keep the surface clean for extended periods. 
Regular lighter applications of Bio-Shield at the first sign of re-growths will effect a rapid clean up and keep the surface clean again for an extended period.

Why choose Bio-Shield® for your DIY Concrete and Asphalt Cleaning?
Bio-Shield® has been developed through 30 years of use in a demanding commercial environment so it works extremely well.
Bio-Shield® is a high quality product, and contains no bleach.
The high concentration of active ingredients in Bio-Shield® when compared to other outdoor cleaners means it will cost less per diluted litre and cover more area at a lower cost.

DIY Application or use our Professional Application Service for your Concrete Cleaning.
If you don't want to do DIY application we offer a professional Bio-Shield Application Service for domestic, commercial and industrial concrete and asphalt.
Prices are very competitive - substantially less than the cost of water blasting. The benefits of using Bio-Shield to clean concrete is lower initial cost to clean and a treated surface will stay clean for longer than water blasting alone. Please contact us for a quote to clean your concrete.

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How to clean Concrete and Asphalt - Bio-Shield® Application Instructions

For a successful DIY job, preparation is the key. Following these simple steps will ensure a professional looking finish and long lasting protection against fungal and moss regrowth.

Remove loose debris, tree leaves, dirt etc, from the surface.
The concrete surface can be either dry or damp. Asphalt is better treated when dry to maximise absorption of the Bio-Shield by the lichen growths.

Check the weather forecast, or rain radar - brief showers after application on a porous surface will assist the action of Bio-Shield®
Air temperature above 10 degrees C° will help to accelerate bio-cidal action.
Premix the Bio-Shield® 1 part to 20 parts water in the sprayer or a larger bucket.
Spread rate for diluted Bio-Shield on concrete will be 3 to 5 m2 per litre depending on the condition of the surface.
Spread rate for diluted Bio-Shield on asphalt will be 3 to 4 m2 per litre depending on the condition of the surface and how much lichen is present.

Bio-Shield Mixing Ratios
Clean Water Bio-Shield Concentrate Diluted Bio-Shield
1 Litre 50 ml 1.05 Litres
 10 Litres 500 ml 10.5 Litres
15 Litres 750 ml 15.75 Litres
20 Litres 1 Litre 21 Litres

If you have a respirator, now is the time to put it on, along with a pair of gloves and soft soled shoes and/or a pair of long pants.  If you don't have a respirator, try to stay upwind during application. Evaporation of the solution on a warmer day will generate vapour that should be avoided where possible.

Application is best done on an overcast day at any time of the year, or early morning and late afternoon in summer if a warm sunny day is forecast. This slows evaporation and speeds the treatment process.

Fill your sprayer with the premixed Bio-Shield® solution and pump it up to pressure.
Dividing the area to be treated into sections makes application easier.
Begin application to the surface in slow, even strokes. Allow the following stroke to overlap the previous stroke by 50% to ensure even and complete coverage.

Any moss growth growing in the joins or cracks will need to be saturated with Bio-Shield® to ensure penetration to the deep roots and achieve a good kill.  I do this by placing the nozzle of the sprayer directly into the moss and injecting it into the clump.

When you have finished treating the section, look back over it and respray any patches that have dried out.  This drying out can be caused from the application not saturating the surface.
Aim for the surface to stay wet for 5 to 10 minutes after application.

If you have achieved correct coverage the runoff should have an orange-brown colour - this is a good sign and indicates that the Bio-Shield® has penetrated the cell walls of the fungal growths and that their death is unavoidable.
Avoid too much over-spray on plants, if in doubt flush the plants with clean water.


Any leftover Bio-Shield® solution will keep indefinitely and can be kept aside to use as a spot spray to touch up any areas that need it.
Over the next few days the orange-brown colour will fade and the moss growths will begin to turn brown as they die off.
2 to 3 weeks after application the moss growths should be entirely brown and any lichen present will have undergone a slight color change. The black fungal growths will not change color, but will simply fade away.
If there are any green patches in the moss growths, the Bio-Shield® was applied too lightly to saturate the growth to the roots.  Spot spray these areas with the leftover Bio-Shield®.

The treated surface may clean up over the next few months providing it is exposed to rainfall; however it would not be unusual for a  very dirty surface to take up to 12 months to fully clean up.
The more rain the surface receives, the faster it will clean up.
It is best to reapply Bio-Shield® at the first signs of re-growth. Typically this will be every 1 to 2 years.
Best practice would be to re-treat just as the growths become visible again.
Application will be easier, faster and use less diluted solution; any new growths will die off and the surface will clean up quickly.

Once the surface is clean Bio-Shield® will give optimal results with regular removal treatments.  This will prevent the build up of moss, fungal and lichen growths.
Discounts, special offers, new arrivals
Bio-Shield is a New Zealand owned company based in Auckland.
I have personally developed and used Bio-Shield for over 38 years to successfully remove moss, algae and lichen from just about every exterior surface on domestic, commercial and industrial properties. 
The same high quality product is now available for DIY and commercial use on homes and businesses throughout New Zealand.
We are committed to supplying our customers the best outdoor cleaning product and services at the best price, complimented with the best technical advice in New Zealand.

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NZ :   0800 800 127 
AU :  1800 236 810
FAQs - Ask Andy®
Instructions For Use