In 1824, Joseph Aspdin patented Portland cement in England and the rest is history! Concrete has risen to be the most plentiful man-made material on earth, carrying its strength on the inside and its beauty on the outside.Greater flexibility equals greater demand But, Portland, we have a problem – there continues to be a ‘once in a lifetime’ surge in demand for concrete across many parts of Australia. Demand has been fuelled by massive infrastructure projects and the continued growth in residential building. In some areas, it can be hard to get concrete as batching plants become stretched!
Concrete has always been able to compete on price, durability and speed of application with the landscapers ‘bread and butter’ surfaces (crushed gravel, paving). Yet, in the last few decades, we’ve advanced from just exposed aggregate to new concrete finishes that provide so many choices in pattern and colour. New products and methods have meant that concrete has gained even greater popularity as a hard traffic surface in both the domestic and commercial market.
The continued rise of concrete has led to the establishment of ‘decorative concrete supply companies’ in the cities and major towns – businesses that specialise in concrete colours, hardeners and sealers. Many even hire out equipment such as stamps and machinery, making it easier for the landscaper to offer innovative concrete solutions.
Concrete can be stamped to give texture, stenciled for a three-dimensional effect, coloured rather than grey, or resurfaced as a budget alternative – even the characteristics of the batch can be altered to fit the job.
Stamped concrete, also known as textured or imprinted concrete continues to grow in popularity, particularly for driveways, but also in the construction of paths, pool decks and courtyards.
Some of the newest finishes on the market use various coloured surface hardeners, sealers and release agents in conjunction with specially designed mats to produce either a slate or timber look.
Firstly, the concrete is poured. Colour is achieved by using either an integrated colour within the batch or by broadcasting a colour hardener directly onto the pour and floating it in.
A powdered colour release agent is then applied to prevent the mats or stamps from sticking as they are placed onto the concrete. Choosing a release agent with a darker tone than the colouring agent helps to provide depth to the finished surface. After 24 hours, excess release agent is removed with a high pressure washer before the application of a clear sealer.
With stencilled concrete the appearance of brick or stone can be achieved the same as stamping, but, with the extra advantage of being able to create contrasting grout lines. Designs can also be placed on the surface using customised stencils – anything from a star compass to a cobbled rosette or even a company logo.
A concrete stencil is laid over the surface of the wet (coloured) concrete. Colour hardener – in another colour – is spread over the entire surface and when removed, a grouted paving pattern is achieved. Finally, after washing down, a concrete sealer is applied.
The easiest and fastest way to colour concrete is to use integral colour added to the batch before the pour. The colour is thoroughly mixed through the whole work so there is no danger of it being chipped, cracked or worn off. Using integral colours allows the contractor to begin finishing sooner and with less issues concerning surface crusting.
Concrete continues to get a bad rap from some for its poor environmental credentials. Being able to repair rather than replace an existing surface ticks all the right boxes by transforming old, dull, grey concrete into a new, high class surface at a fraction of the cost of new concrete, pavers or tiles.
The process is quite similar to stencilling, starting with the towelling down of a base coat that smooth’s and primes the surface as well as forming the grout colour. After stencilling and clean-up, the job is finished with the application of a sealer.
If the concrete is in good condition, another solution is the application of a stain, which will not change the original textured finish.
Most sealers remain solvent based although some water-based products are now on the market. Penetrating sealers provide surface protection without changing the surfaces appearance, which is handy on a driveway where the surface needs to be protected but a more natural, non-sheen look is required. Conversely, film forming sealers form a protective film on the concrete’s surface enhancing the colour or providing a wet look. Some sealers can make the surface slippery, particularly on a sloping path or driveway and may require the use of a slip-reducing additive. It’s also essential that the right sealer for the job is selected because certain sealers can react with the colouring agent or colouring overlay causing blistering, bubbling or colour bleeding.
Although fly ash has been used for decades as a ‘green’ ad mixture, there are now a multitude of products that can be added to the batch. In large commercial construction projects, products that inhibit the possible corrosion of reinforcement bars as well as those that increase the compressive and bending strength of concrete are common. In the landscape industry, super plasticizers – polymers that provide a fast-flowing concrete with a standard water content as well as admixtures that prevent efflorescence and set accelerators (in the southern states) and set reducers (in the north) – continue to be specified.
Advances in concrete continue to lead to better texture and colouring. New products and methods are making decorating with concrete easier and more beautiful, increasing the landscaper’s construction options. Finished concrete certainly isn’t… finished!