EXISTING STRUCTURES

Grouting against existing concrete or masonry

AKS may be installed to existing concrete or brick structures. An important advantage over other lining and coating systems is that the underlying surface does not need to be dry before it can be lined.

> Ensure that the walls are clean and free of any loose or flaky material. Sand blasting or a high-pressure water gun should be adequate.

> Position the AKS lining with the anchor knob surface against the wall and trim the AKS to ensure a neat fit into corners. The joints between the AKS sheets need to be tight and well-sealed using tape or the H-Profile and vertical edges of the sheets can be temporarily sealed using foam gasket strip supported by a strip of timber, temporarily nailed to the existing surface.

> The AKS being grouted against vertical surfaces must be fully supported by temporary formwork to carry the load of the wet grout. This will ensure that a neat and even finished surface is achieved.

> In the corners and at the junction with the floor, it will be necessary to create a watertight seal.

• This can be done using strips of closed cell secured between the existing surface and the back of the AKS liner.
• It may be necessary to remove one row along the edge of the AKS to provide space for the foam strip. The knob removal method is discussed later.
• The foam strip should be at least so that it is thicker than the length of the knobs and is compressed between the AKS and the wall surface. A timber strip may be necessary to support the temporary gasket. It should be fixed to the wall using concrete nails with heads left protruding for easy removal after grout has set.

> Leave the top edge of the sheet open for pouring grout.

> The sheet must be adequately supported to prevent buckling as a fluid grout is poured into the 12mm wide space formed by the knobs resting against the existing surface.

> Pour the grout into the gap between the sheet and the wall and tap or vibrate the sheets and support framework lightly to expel any air.

> Once the grout has set, remove the bracing, supports and temporary gaskets.

> Subsequent sheets are linked to previous panels using the H-Profile positioned where temporary gaskets have been removed.

The properties of the special grout are:

> Liquid consistency
> Low shrinkage
> High "wet to dry" adhesion (achieved with an incorporated cement modifier)
> High strength
> Quick setting

A typical example of a proven grout is "Superflow Bedding Grout" with " Supercrete Latex" - this is a  typical cable grout.

Care should be taken with the following:

When the AKS panels are positioned, joints between the sheets should be fitted with the H-Profile or taped on the anchor knob side prior to placing the sheets. The gaps between sheets should not exceed 3,0mm.

The existing concrete must be properly wetted (to the specifications of the grout manufacturer) to eliminate "suck". Ensure all free edges (sides and bottom) are closed off with an approved material, such as foamed polyethylene, to prevent leakage of the grout. This is normally supported with a temporary wood strip fixed to the existing surface along the edge of the AKS liner.

Grout must be freshly mixed and fluid enough to flow past the anchor knobs with ease. The pour should be controlled to allow trapped air to escape. This can be aided by tapping on the formwork/bracing.

Specific advice on the use of pouring and air release tubes is available on request.