What is Plain Concrete?
Plain concrete is a hardwearing product, ideal for structural and non-structural building works, from residential homes to high rise buildings. Concrete is made up from materials such as cement, gravel, sand, fly ash, and water. It may also have certain chemical admixtures, when added, may speed up or slow down drying time of concrete. When the cement mixes with the water, a chemical reaction begins to take place – this is known as hydration. Long strong short, the cement acts like glue that holds the sand and aggregate together.
Traditionally plain concrete is just concrete on its own, with no reinforcement. Today, we refer to reinforced concrete as plain concrete – the ‘plain’ part refers to the fact it has no colour or decorative aspect to it. Plain concrete is very strong, and can withstand high compression pressure. With correct steel reinforcement, it has the ability to withstand high tension (stretching). Plain concrete also comes in different strengths, this is based on the cement to water ratio.
What is Coloured Concrete?
Coloured concrete provides a classy and cost effective alternative to plain concrete – ideal for driveways, patio area, pool surrounds, and pathways etc.
There are ways to colour concrete, the first and best way is to use a coloured oxide. This is also referred to as full depth coloured concrete – as the colour oxide is mixed with the concrete while still in the truck, so it mixes the thoroughly through the mix.
Colour concrete done using oxide is ideal because as the concrete wears out, the colour will stay consistent as it is thoroughly mixed through the slab. Most important thing to remember is different concrete loads must have the same concrete to oxide ratio to keep the concrete colour consistent. Generally it works by – e.g. 10 kg bag of oxide per 1 cubic metre of concrete.
The second method for colouring concrete is by using a colour hardener, this is done by throwing the colour on top of wet concrete once it has been levelled. The next step is to trowel the colour into the concrete. This is a very messy and labour intensive approach to coloured concrete. There are no real benefits to colouring your concrete this way, except it is cheaper in materials, the colour is generally inconsistent due to the method of application. It generally wears out over time, making the plain concrete below visible, which is undesirable. This method is outdated and not favoured by concrete professionals who would not compromise quality for cost.
At Base Concrete Brisbane, we believe coloured concrete should be done using a full depth colour oxide. When coloured concrete is done right it looks great and lasts for a very long time – definitely value for money for the result!
What is Exposed Aggregate?
Exposed aggregate can give your home or office a modern and natural look. There are a large range of exposed aggregate mixes to choose from – with a variety of different colours and textured stones available. You can also mix a colour oxide (coloured concrete) into your exposed aggregate mix, so rather than having just a plain grey concrete behind your exposed aggregate stone, you may mix full colour oxide to your mix to enhance the look (see coloured concrete).
Exposed aggregate has the same properties as plain concrete, with the difference being the different coloured and textured stones in the mix, where plain concrete generally has just standard black gravels. Exposed aggregate is placed and finished the same way as plain concrete until the final finishing stage, at which point the top of the exposed aggregate concrete is sprayed with a retarding agent that slows the layer of slurry at the top from setting. The top layer is later hosed off, which then exposes the top layer of aggregate, giving you exposed aggregate. 48 hours after exposed aggregate has been completed it needs to be acid etched, which removes the dusty film that settles back over the slab after being hosed off.
Exposed aggregate can look great and add value to your property. With so many colours and textures to choose from, be sure to take your time and select something that matches with the surrounds.
When deciding on exposed aggregate, things to watch out for is that it can be very slippery on a slope in the wet. So if you have a steep driveway it might pay to explore other options such as coloured concrete or you may want to park on the street on rainy days. Poor surrounds can look great in exposed aggregate, just watch out for texture as it can be harsh on small feet.