thisplace.com.au - Concrete Tips

To most people in the building industry quality can be a very subjective issue and is measured by degree dependent upon individual experience, product knowledge and practical trade skills. When the talk turns to concrete one thing is sure - everyone is an expert!

What is quality concrete?

Quality concrete, quite simply, is the hardened product in place having the desired appearance and strength which has minimal flaws and possesses the properties desired of concrete: Appropriate strength Hard-wearing surface Uniform appearance with a low incidence of blemishes including cracking Proper jointing.

How is quality concrete achieved?

Quality concrete is achieved through specifying the appropriate concrete quality followed by the adoption of best practices in transporting, placing, compacting and curing.

Defects & Causes in Stamped & Stencilled Concrete

Fading of the colour finish to stamped concrete - possible causes

One application of the base colour hardener with the release coat as a second coat Colour hardener not sufficiently worked into concrete matrix Insufficient colour application rates - minimum 2kg m2

Surface colour peeling or wearing away - Possible Causes

Inadequate washing off of the release coat resulting in delaminating from the concrete surface Colour was applied to setting surface and colour not sufficiently worked into the surface matrix. Adequate bond was not attained. Colour worked into the concrete while bleed water was present, result diluted surface matrix offering minimal abrasion resistance. Base colour hardener applied to wet areas attempting to soak up bleed water, result dries out and crusts. Rain affected surface, result wide spread damage over extended period.

Colour variation and inconsistency of colour - Possible Causes

Changes in water/cement ratio, caused by addition of water to concrete on site. Using two different concrete suppliers with variable mix designs. Two or more different concrete strengths, resulting in differing surface colour. Blending two products manufactured by different companies when hand blending on site, not taking into account different minimum colour percentages. Inconsistent curing resulting in mottled surface finish.

Surface sealers bubbling, flaking or inconsistent - Possible Causes

Sealer applied to damp surface, resulting in sealer not bonding adequately. Moisture still rising through concrete, resulting in white bloom. Surface not cleaned down sufficiently to remove residues, causing affects on the sealer surface. Grit is applied to sealer too late and re-coated without removing excess. Touch-ups done while film is tacky.

Most problems arising with coloured concrete flatwork can be overcome by attention to best practices in all stages of the process: ordering, transporting, placing, compacting and curing. The two main processes available for colouring are: Dry shake toppings which must be worked into the freshly placed and screeded concrete surface. The use of an integral colour which is added at the concrete batching stage. Attention to detail and understanding the use of products will minimise potential problems with the finished product.