FAQs

It is important that the area where you are going to install your Geostone concrete has been properly compacted. The process of compacting pushes the soil particles together to create a more stable subbase. Be especially aware that areas that have been excavated alongside buildings, retaining walls and pipework are often poorly compacted and will require special attention. We recommend contracting a professional to assess the compaction of your project. Aside from issuing a compaction certificate, you’ll have peace of mind that your site is well prepared and ready to go.

Once the area has been compacted, it needs to be well watered prior to your installer coming on site (unless you are using plastic or ‘poly’ beneath your concrete or otherwise advised by your installer).

You can read more on preparation in our Best Practice Placement Guide.

It is quite common (and recommended) for concrete projects to be engineer designed. You may wish to consult with a structural engineer at the outset to specify and design your project, this is particularly vital for internal flooring and commercial projects.

Please consult with your structural engineer or builder.

We recommend that control joints be cut to a minimum of 25% of the concrete depth in order to be effective.

You can read more on control joints in our Best Practice Placement Guide.

We recommend that control joints be cut by trowel or jointing tool whilst the concrete is ‘plastic’, or by saw no later than 18 hours after the concrete is laid. While control joints can be cut by saw, this can introduce unwanted moisture into your concrete which can later produce a milky colour on sealed concrete. Saw cut joints may also introduce foreign material such as sand which can allow weeds to grow causing the edges of the concrete to crack. Commercial coloured seals are available to cover saw cut joints and prevent these issues. Alternatively, your installer may supply one of several commercial jointing products.

You can read more on control joints in our Best Practice Placement Guide.

Control joints should be planned at the outset and placed at aesthetically appropriate areas. For Geostone projects that are 100mm deep, we recommend that control joints be spaced no further than 2.5 metres apart. When planning your project with your installer, you should aim to achieve square rather than elongated shapes with your control joints. It is important that the reinforcing mesh also be cut at the points where control joints will be placed in order to enhance their effectiveness.

You can read more on control joints in our Best Practice Placement Guide.

Control joints are placed in the concrete to encourage any cracking that may occur to happen in predetermined locations, allowing the customer to control to an extent where the cracking happens and reduce cracking as much as possible given the terrain.

For decorative concrete, we recommend your installer use the membrane method of curing by applying a single coat of solvent-diluted acrylic sealer (sometimes referred to as ‘same day’ sealer). Normal pond curing (where sand and clay are used to create ‘ponds’ which are filled with water) is not recommended as the sand and clay can cause staining of the concrete and affect the appearance of your Geostone concrete.

The curing process protects fresh concrete from rapid moisture loss and extreme temperatures; this both reduces the risk of cracking and increases the strength of the concrete.

Using a water vapour barrier, such as plastic or ‘poly’ under the concrete can help prevent cracking as it reduces movement and friction between the concrete and the ground below. Additionally, it will also help to protect your concrete from possible discolouration caused by underground water, dampness or water logging. Talk to your installer to see if this solution is suitable for your Geostone project.

Where possible, it is better to avoid pouring on days of high temperature or high wind as your concrete may dry too quickly which can lead to cracking. If it is critical to pour on such days, it is essential that the necessary steps are taken to prevent rapid drying. Discuss with your installer what steps will be taken to prevent rapid drying on your Geostone project.
On page 3 of our Best Practice Placement Guide linked below, you can read more on how to avoid the risk of cracking when pouring on hot windy days.

As concrete is highly alkaline, the steel will not rust provided that it is fully encased by the concrete. The reinforcing mesh should be placed a minimum of 25mm away from the concrete surface to ensure it won’t come into contact with the atmosphere.

You can read more on the risk of rusting in our Best Practice Placement Guide on page 2, linked below.

In the first instance, always consult with your engineer, architect or designer. We recommend for external areas, SL62 (or higher), and for internal polished or floating slabs, SL82 (or higher).

You can read more on reinforcement in our Best Practice Placement Guide.

Your installer must use commercial bar chairs designed to hold the steel reinforcement above the ground when placing the steel mesh. This is essential as it ensures the steel reinforcement is installed in the upper part of the concrete where it is most effective.

You can read more on reinforcement in our Best Practice Placement Guide.

It is essential to use steel reinforcement to provide additional strength and to assist in the control of natural movement which can lead to cracking.

You can read more on reinforcement in our Best Practice Placement Guide.

The level of exposure can be controlled; light exposure reveals a few stones in the surface while heavy exposure creates a more coarse effect with more stones protruding from the surface. Make sure you discuss the options with your installer before starting your Geostone project.

Only commercially available retarders (a chemical used to prevent the top layer of concrete from hardening) should be used when exposing the stone in your Geostone project. Sugar should never be used as a retarder as it has been our experience that it will not achieve a consistent result. Your installer should include the cost of retarders in their quote.

We recommend avoiding adding water to the mix as this will affect the colour, finish and strength of your concrete.

To protect your Geostone concrete, it is recommended to seal the decorative concrete surfaces. Read more on sealing here. Decorative concrete is quite easy to look after. Click here to read more tips for cleaning decorative concrete.

We recommend resealing your Geostone concrete every 2 years to keep it looking the way you want it to. Keep in mind this depends on the amount of traffic and resulting abrasion on the concrete surface.

As concrete is a porous material it can absorb contaminants which can lead to staining if not treated. Not all installers include sealing as a standard so make sure you ask your installer about sealing at the outset of your project.
Click here to read more on sealing your decorative concrete.

The process of exposing aggregate and grinding polished or honed concrete floors produces sensitive waste materials such as cement slurries, care should be taken to retain all waste on site and then dispose of it in a responsible manner. Contact your local council for more information.

For further information please refer to our Best Practice Placement Guide or contact your local Geostone representative.