Exposed aggregate concrete can be used in various ways, such as in; driveways, pool surrounds, internal floors, and outdoor entertainment areas, the possibilities are endless.
Cement is a type of binder, a substance that sets and hardens when added with water, or any other inert durable materials like stone and sand. Its chemical compound allows it to set as hard as rock and can withstand impacts, heat, abrasion, and weathering.
Cement is primarily made by heating limestone to very high temperatures to create a material called clinker. The clinker is then ground with a small amount of gypsum into a powder to make ‘Portland Cement’, the most commonly used type of cement. Portland cement is a basic ingredient of concrete, mortar and most non-specialty grout. The most common use for Portland cement is in the production of concrete.
Concrete and cement are usually contrasted together as being similar products. However, cement is actually an ingredient of concrete. Cement is an additive that provides the basis for the glue that holds concrete together. Concrete is a mixture of aggregates (stones) and sand, along with water and cement. The process of mixing these materials is called hydration, where the cement and a portion of water undergo a chemical reaction and harden.
This means that concrete “sets” or “hardens” as a result of the chemical reaction – and does not simply dry out. Other special additives can then be added to alter texture, pigmentation, and other properties.
Due to concrete’s versatile nature, it can be used in multiple situations and perform various jobs. Buildings, bridges, slabs, piping, inside and outside flooring, streets, driveways, are some instances where concrete may be applied.
For more decorative touches, colouring, sealing, and finishing can be applied to exposed or polished concrete, perfect for creating a custom look for homes, or businesses.
Concrete changes volume when it dries out, this is because of its chemical compound. It cracks due to tensile stress, which is when the concrete expands. The pressure that builds up as a result of this change in volume can cause the concrete to move outward and inwards.
Measures are implemented to reduce the concrete’s ability to crack, such as putting in joints to allow for neat, straight line cracks. These joints also allow the concrete to move when its volume is changed due to expansion and shrinkage. One of the biggest factors that affect concrete is the weather. The risk of cracking is much higher on warm, dry days with low humidity and strong wind.
Metro Mix gives you the ability to design your own custom exposed aggregate mixes, with aggregates of your choice, you also have the choice to change the colour of the cement base. The only part you need to worry about is finding the perfect match, and you can leave the technical stuff to us.
Options available to you:
• A choice from Melbourne’s largest range of exposed aggregate concrete mixes on display at Metro Mix’s showroom
• The large range of aggregates (stone) available to create your custom mix
• The option to alter the colour of the cement base using quality oxide products
Polishing concrete involves grinding concrete that has been treated with a chemical densifier that removes blemishes, and increases density. Polishing the concrete with specialised tools, fitted with diamond padding, then smooths out any peaks and valleys that may be showing. This then exposes the aggregate that has been added to the mix, creating a flat and shined surface. The resulting texture is called: Polished Concrete. There are quite a few choices of polished concrete finishes e.g. Hiperfloor, full grind and seal, light grinds (to achieve a hit-and-miss with the exposure of the aggregates, usually referred to as salt & pepper), natural concrete finishes and more. There is also a range of different sealers e.g. high gloss and satin (low sheen). Each different choice of finish is carried out in a similar but has slight changes in the process.
There are many benefits from polishing concrete besides a great looking floor.
• Polished concrete makes use of the materials already present, eliminating the need to install extra floor coverings such as floorboards and carpet
• Polished concrete is low maintenance, and is far more durable than any other flooring applications which means less maintenance
• Accompanied with special sealers provided by Metro Mix, polished concrete can be virtually impenetrable making it easy to clean and keeps it looking great
• Concrete’s chemical compound reduces dust mite and allergen problems, as well preventing any mould growth
After the concrete has been placed, a surface retarder is then applied to delay the top layer of cement from setting. This gives the concreter the flexibility to remove the excess concrete and expose the decorative aggregates (stone) that was used in the mix.
The retarder is applied once the concrete has been screed and finished and has reached a certain point of the curing stage. This prevents just the top layer of the concrete from setting, which then can be removed in a number of ways, often using a pressure cleaner.
Exposed Aggregate concrete is placed (min thickness usually 100mm, for driveways).
Once the exposed aggregate is on the ground the concreter screeds the concrete, forming the area’s levels and run offs.
A bull float is then used to smooth out all screed lines and flatten the surface.
As the exposed aggregate mix begins to set, they will edge all necessary areas and hand or stick trowel the entire surface to once again smooth out all imperfections, this also helps to flatten out all aggregate below giving it a very even and consistent look once washed off.
Once the exposed aggregate has been finished and the bleed water has begun to dry up, they will spray on a surface retarder which is designed to keep the very top layer of the concrete moist. These retarders are coloured to enable the concreter to see where it has been applied.
In some applications, including hotter days and the wetter months they may cover the exposed aggregate with polythene to protect it from the elements.
The concreter will return the following day to expose the area (we do not recommend same day wash off).
The washing process is a crucial part of a quality exposed aggregate job, the concreter must be careful and just wash off enough of the slurry to expose the aggregate and achieved an even smooth finish.
– If too much slurry is washed away this is known as over exposure which can make the mix look different as the majority of the slurry is removed from in between the aggregates.
– On the other hand, if not enough of the slurry is washed off this is known as under exposure which can also make the mix look different as there will be more slurry which will give it the appearance that there is less aggregate, but really the aggregate is still there but just deeper under the surface.
Once exposed the concreter will then acid wash the surface (sometimes same day or next day) using a mix of hydrochloric acid and water, this helps clean all residue including excess slurry and other contaminants, this process can also be used to even out inconsistencies in the exposure.
If the area is big enough the concreter will saw cut, expansion cuts to help minimise and control cracking. They will wash area after cutting (they may acid wash after saw cuts).
Once the concrete surface has dried out to a suitable level, the concreter will apply a surface sealer (usually 2 coats) this not only protects the concrete but increases colour and enhancement of the exposed aggregate.
As well as its visual appeal, Polished Concrete is extremely easy to maintain and keep clean. A simple dust and mop with warm water and it’s looking as good as the day it was polished.
With our large selection of Polished Concrete mixes and abundant choice of aggregates allows our customers imagination to run riot.
While retaining its matchless durability and resistance to wear for which Polished Concrete is so highly prized, it can be easily sculpted to create shapes and structures that would be impossible to achieve with any other material.
At Metro Mix Concrete we invite customers, designers and architects to visit our showroom at 42 – 46 Cahill Street,
Dandenong South, Victoria, 3175 to view our comprehensive display of polished concrete samples, as well as our newly finished Polished Concrete floors with in slab heating.
Our highly-trained sales staff will be more than happy to run you through our range and discuss your ideas with you. With our unrivalled depth of experience in creating custom polished concrete mixes, were sure to come up with a perfect solution for your next project
So, for Polished Concrete Melbourne, contact Metro Mix Concrete today on 1300 Metro Mix or email us here for a prompt response
Speak to us today about having your very own custom designed polished concrete sample created by our creative design team and visit our showroom to see our life-size polished concrete office display, finished in all your different polished finishes.
Designed for external uses such as alfresco areas, pool surrounds, driveways and more Pavilion finish concrete offers you the smooth profile of Polished Concrete with the enhanced grip factor similar to exposed aggregate. This is achieved by simply grinding back the concrete as they would when polishing, then etching the surface to your desired grip level and coating with a satin or gloss sealer.
Looking for that Polished Concrete finish but concerned about the slip factor?? Then look no further with our Pavilion Finish Range of Polished Concrete.