Concrete sealing – what’s it all about?

Concrete, Concrete Pour, Concrete Pump, Order Concrete

The application of sealer to concrete has a number of benefits, it helps to prevent and minimise staining, and makes it easier to care for and clean your concrete. If concrete is left unsealed, it is more porous and may stain more easily.

Sealing, or resealing your concrete is a straight forward job, and can easily be done yourself.

What are the benefits of sealing?

Sealer allows improved cleanability of the surface. Staining is reduced, and any stains that do occur are more easily removed or fixed. When the correct sealer is used on new surfaces it may also aid curing the concrete. Decorative concrete should always be sealed on the day it is placed as it helps cure and protect the surface.

Can home owners seal their own concrete?

Yes, as long as they follow the manufacturer’s instructions.

What is the coverage rate of sealer?

Normal coverage is 3-5m2 for 1 litre of sealer.

What happens if the concrete is not sealed?

Unsealed decorative concrete surfaces will still be serviceable but may stain more easily. Sealer stains less readily than concrete and if it does stain it is a lot easier to clean or fix than unsealed concrete.

When should I reseal?

Resealing may be necessary when signs of wear or weathering become apparent (this may include flaking, peeling or “patchiness”). The most common sign of wear or weathering is when the pavement appears “faded” but darkens when wet.

How long will the sealer take to cure?

Curing times are dependent on ambient conditions. Under normal conditions sealer may take up to 1 week (7 days) to fully cure. Under milder conditions it can take longer. Exact curing times will vary from job to job. Driving on uncured sealer may reduce its lifetime.

Why does the concrete appear faded but darkens when wet?

The concrete may need resealing. If sufficient sealer is present (i.e. has been recently sealed/resealed) it may need a light solvent scrub. It is important to note that there may be a change in colour shade as the concrete cures.

I have seen small bubbles on the surface of the sealer, how are they caused?

Small bubbles may form if the sealer is applied thickly or if a roller is pressed too hard during application. A light scrub with solvent will reduce the amount of bubbles on the surface of the sealer. This should not be confused with sealer blistering which occurs when the sealer surface “skins” before the bottom of the sealer has cured. The solvent in the uncured bottom layer sealer may be trapped between the concrete and the “skin”, causing blisters. This is often caused by applying sealer too thick or applying a second coat before the first has sufficiently cured on temperature. High temperatures or wind will also cause sealer to blister.

There are lots of fine cracks in the sealer

If the sealer dries too quickly, fine plastic shrinkage cracks can form (also called “crazy” cracks). Accelerated drying can be caused by wind as well as heat. A light solvent scrub may reduce the effect when it is confined to the sealer.

What if there is peeling/flaking sealer present?

Old sealer may start to peel at the end of its service life or may be a result of excessive wear. Adhesion may also be compromised by blisters/moisture in the sealer left for prolonged periods or by rising damp. Smooth surfaces (such as a steel trowel finish) may peel if not acid etched before sealing. Peeling sealer will need to be removed before any resealing is undertaken.

What if a client insists on sealing a medium/steep slope or smooth surface?

The manufacturer does not advise sealing a sloped or smooth concrete. If the home owner insists, then the minimum amount of Concrete Sealer should be used. The use of Slip Resistant Powder is also suggested. Slip Resistant Powder is mixed into the sealer before application or fine glass is cast on top during application.

What influences the expected service life of sealer?

The type and frequency of traffic, along with the weather conditions all play a part in how long the sealer may last. Furthermore, traffic over excess dirt, friction (e.g. from tyres), and other excessive wear and tear (e.g.heavy traffic) may reduce the life of the sealer. Regular maintenance can help extend the useful service life of sealer.

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