Concrete En-Counter (Nat)

Concrete is one of the easiest products to customise, it can be ground, polished, stamped, or stained, you can have glass, marble chips or other objects embedded in it. You can mould and sculpt it to create your own exclusive design and turn a rudimentary kitchen bench top into a distinctive piece of art.

In saying that, being situated in the busiest room of the house, the kitchen bench needs to be up to the task of handling bumps, spills and scratches, in this respect the durability of concrete is an inherent advantage. Like its counterpart’s granite and marble, concrete can offer certain resistance to the everyday wear and tear of the kitchen environment.

Design & Styles

The versatility of concrete opens the door to creativity, which give home owners, designers and builders the opportunity to form completely unique and personal designs. There are a range of finishes available with concrete, which include:

Embedding

Embedding objects in a concrete bench is one of the more personalised options. Examples of objects that people have embedded in their concrete benchtops range from shells collected from a favourite beach holiday spot, to MTV’s countertops in the New York office being permeated with bits of CD’s.

Stamping

Stamping is a process where patterns and textures are impressed onto the concrete before it is fully dry. Various effects and patterns can be created through stamping especially when used in conjunction with colours.

Polishing

There is nothing quite as elegant as a polished concrete finish. Polished concrete is a generic term which covers a range of finishing methods, such as steel trowelling, burnishing and honing. Trowelling will give the most basic flat, smooth finish. Burnishing is produced by steel trowelling the surface until the concrete surface takes on a polished or glossy appearance, and is usually specified where a surface free of trowelling marks is wanted. A honed finish is particular good for exposing the aggregates within the concrete or any decorative inserts.

Comparison and Maintenance

While concrete is a heat-resistant material, like granite it is subject to thermal shock. If a hot object is placed directly onto the surface, such as a saucepan or baking dish, flaking or chipping of the concrete can occur. Excessive heat could also damage the concrete sealer. On any material it is always recommended to use a trivet to protect the bench top surface from hot pots and pans.

Just like marble and granite, concrete should not be used as a cutting surface, as it will probably result in scratches in the finish of your counter and a set of blunt knives.  Like most stone products, concrete corners can chip if struck by a hard object, placing silicone in the inside corners of the mould will ease the edges and prevent chipping.

Concrete (again like marble) has a certain amount of porosity, and as such is vulnerable to acidic liquids such as red wine, lemon juice and balsamic vinegar, which unless cleaned up straight away can cause surface stains. But for severe staining the concrete surface may be repolished with a mechanical trowel to restore a benchtop to its original finish.

Construction mixes and techniques

Concrete like most other materials will slightly change in volume as it dries out, so hairline cracks in the concrete surface can occur. These are not structural failures and in a lot of applications the hairline cracks work well with the characteristic of the concrete finish. But a concrete mix with maximum resistance to cracking is possible to achieve through admixtures such as superplasticizers, water reducers, shrinkage-compensating agents and polymer resins. These are available from specialist manufacturers.

Concrete benchtops should have a high strength level, with the concrete mix having a compressive strength of 40-Mpa minimum, thus the water to cement ratio should kept to a minimum. It’s a good idea for builders to produce a test sample and a trial batch to finalise mix specifications.

You will find that most concrete benches and benchtops are precast, this gives the builder / designer more ability to fine tune it and remove any imperfections. But due to site access, the bench design and the builder / designers personal preference, in-situ fabrication maybe the only practical option.

When it comes to sealing a concrete benchtop, it is hard to have both perfect aesthetics and perfect stain protection. Topical sealers are an effective stain barrier but can give an artificial look to the finish. Penetrating sealers will give off a low sheen finish that will enhance the concrete finish, but several coats may be needed to make it an effective against stains. But like all exposed surfaces, maintenance is the key to ensuring the long aesthetic and functional life of your kitchen benchtop.

When sealing a concrete kitchen benchtop, you should also take note of the toxicity of the sealer, as it might not be suitable for food preparation areas.

So always consult your builder or designer on specified finishes or designs to see if the application is right for your project.

For further information HIA members can contact HIA’s Building Services staff on 1300 650 620 or hia_technical@hia.com.au.   

If you would like to become a HIA member, contact 1300 650 620 or enquiry@hia.com.au

This information sheet was prepared based on the following references:

• Carol Brzozowski (2006), The Personalized Countertop, published in Precast Solutions
• Cheng Concrete Concrete Benchtop Facts www.concreteexchange.com
• Freya Lombardo (2003) Specifying Concrete Benchtops, published in Cement & Concrete Aggregates Association Mix 11.