Having checked the weather forecast is favourable, all systems are go and so begins the main stage of all DCS printed concrete installations.
We arrive on site about an hour before the concrete is due. In this time we get all tools and equipment ready, protect walls and adjacent structures from splashes and contamination, get all materials ready for use and organise the site in anticipation of concrete arrival.
The correct concrete mix, in accordance with the Concrete Society specifications and guidelines, is delivered to site in ready-mixed lorries. The concrete is unloaded quickly, using wheelbarrows or concrete pumps as needed, and placed evenly throughout the area to be paved. It is then raked to the correct levels and screeded ensuring the levels and falls are correct. Large magnesium floats are then used to trowel the surface of the concrete, creating a flat, floated, soft, wet, grey concrete slab.
At this point, with a normal concrete slab, work would finish. However, with us the real work is only just beginning.
After floating, the concrete is coloured with the chosen pigment. This is a powdered dry shake material called colour surface hardener (CSH). It is cast by hand over the surface of the concrete at a rate of about 2 kgs per m² and allowed to hydrate before being floated into the concrete.
The coloured concrete is dyed again using the same material, allowed to hydrate and floated again to ensure that the area is not patchy and a durable and uniform colour surface is achieved. Dependent on site conditions a third application of CSH may be applied.
Once the correct consistency of colour is achieved, the coloured concrete is ‘closed’ using large steel trowels. This achieves a smooth surface, free of any marks.
A coloured release agent is then applied to the soft, wet, coloured concrete. This prevents the imprinting mats from sticking to the concrete, ensuring a crisp, clean print. It also imparts a secondary, two tone effect to the surface of the paving, creating the rich natural stone effects achieved with this method.
The concrete is then imprinted with the chosen pattern while the site is cleaned.