Products and Services

Acid Etched

This finish is produced by applying (usually by brush) a diluted solution of hydrochloric acid to the required surfaces. In some instances, it may be appropriate to apply the solution in a gel form or to even ‘dip’ the element into an ‘acid bath’. In all cases, the surfaces are thoroughly rinsed with clean water to further dilute the ‘run-off’ and to ensure no acidic residue is left.

Acid etching removes the surface laitance of the concrete and leaves a fine granular texture. The degree of texture can be varied by the length of time the solution is left before rinsing off, the strength of the solution or the number of applications.

Faced

Decomo can produce elements faced with inlays of bricks, natural stone, terracotta or tiles/ceramics.

The inlays are placed ‘face outwards’ against the requisite mould surfaces and when positioned in a vertical plane will be secured through the formwork to ensure there is no movement or displacement when pouring the backing concrete. Where appropriate, ‘keys’ will either be pre-formed or cut into the rear face of the inlays or stainless steel pins may also be used.

The joints between the various forms of inlay will, generally, be post pointed with selected mortars following demoulding and any other form of finishing required.

Gritblasting

Using a high-pressured air supply to blast the required surfaces with either sand or grit particles, the surface laitance of the concrete is removed to expose the fine and/or coarse aggregates depending upon the extent of blasting.

As this is an ‘abrasive’ finishing technique, even a light blasting will still provide a rougher texture of finish than acid etching.

Polished/Honed

Polishing (or honing) is carried out using our ‘state of the art’ polishing machines, Whether flat panels, circular columns or, simply, irregular or intricate shapes and configurations, Decomo has the right equipment for any application.

The polishing is carried out in stages with the first ‘pass’ of the polishing head, with an ‘aggressive’ diamond tipped pad fitted, removing approximately 3mm from the surface and, essentially, cutting through the aggregates. An allowance for this ‘removal’ is made when dimensioning Production Drawings for the elements.

Subsequent ‘passes’ are made using ever finer polishing pads until the required level of sheen is achieved. A polish, similar to that used on marble, may also be applied.

For honed finishes, the number of passes are limited with the final finish remaining matt with some coarseness to the texture still being discernable.

Structured

A structured appearance may be formed by creating a ‘negative relief’ pattern on the requisite surfaces of the mould or formwork or by utilising a patterned mould liner. These liners are, generally, in the form of rubber mats incorporating either ‘off the shelf’ or custom designs and will, usually, be procured from specialist suppliers of the likes of www.reckli.net.

Retarded

Retarders may be applied to the mould or formwork from which an element is to be cast or may, equally, be applied, directly, onto the required surfaces of the fresh concrete.

In both situations, these surface retarders, which are also often referred to as “deactivators”, chemically delay the set of the concrete, to a controlled depth, by slowing or stopping the hydration process. The remaining depth of concrete will cure and harden normally without affecting the setting time or strength gain.

The un-hardened cement/sand matrix is removed from the surfaces by washing away with pressured water, leaving the coarser aggregates exposed.

The depth of retardation and, hence, the degree of aggregate exposure is controlled by selecting the appropriate strength of retarder.