How To Use


The manufacturing process of a precast element produced using a graphic concrete membrane is basically the same as a traditionally exposed fine aggregate surface.

The process can be summarised as follows: 

  1. Positioning the graphic concrete membrane
  2. Casting the concrete
  3. Stripping the formwork
  4. Lifting the concrete element
  5. Removing the graphic concrete membrane
  6. High pressure washing

Guidelines for using graphic concrete
 technology


Storage and handling of membranes

The graphic concrete membrane must be stored in a dry, warm space and must be protected from direct sunlight. It is recommended to store the roll on a mobile rack (complete with a cover or tarp), so that the membrane can be free of dust and dirt, moved around the yard (from bed to bed) and easily unrolled as required. Ensure that the membrane is handled carefully so there are no creases or wrinkles - these can be reflected into the cast panel. Do not allow the membrane to become dirty, wet or fouled by oil. If a membrane needs to be trimmed to size, it recommended this is done on the same day as casting. Do not allow any debris or particles to stick to the membrane when in position. Remove particles by sweeping, or blow them off with compressed air.

Preliminary tests and trials

It is recommended that a precast yard performs preliminary tests before starting production using graphic concrete™ technology. The preliminary tests not only produces a pre-production cast sample which can be used for client sign-off, but product trials also facilitate quality results and improves production efficiencies.

Bed preparation

The graphic concrete membrane should be used on a steel bed that is both smooth and clean. Even the smallest of irregularities in the casting bed surface, (for example like hammer marks or grind marks) will be imprinted on the concrete surface. Any debris (dust or other contaminants) should be removed from the casting surface with compressed air or a vacuum. Contaminants will be reflected in the cast panel, so it is important to ensure there are no particles between the bed and the membrane, as well as any particles sitting on the membrane itself.

Spreading the membrane on the casting bed

Once the precast bed is clean, unroll the membrane and place it in the correct position on the bed. Check the pattern orientation is correct, and also check the membrane has not been damaged or is not defective in any way. The membrane can be pulled at the ends to ensure it is set tight on the bed. Once in position, the formwork can be put in place and the magnets engaged. When setting up the formwork, the sideform is loosely placed in position on the membrane. When the correct dimensions are achieved, the magnets are engaged, locking the formwork into position. If required, the excess membrane can be trimmed from around and underneath the magnets.

Casting the concrete element

When pouring, consideration should be taken to ensure the membrane has not slipped or moved during the concrete delivery process.  Where possible, concrete should be delivered into the panel from the lowest possible height. Pouring concrete from a great height is likely to either shift or move the membrane, and may also cause damage to the membrane. The concrete element can then be vibrated in the normal manner. If using a poker vibrator, do not allow it penetrate the bottom of the mould as this will damage the membrane. The panel can be screeded and trowelled in the usual way. 

Removing the graphic concrete membrane

For best results, the membrane should be stripped from the cast element and pressure washed as soon as it is lifted from the casting bed. 

A membrane should not remain in contact with the panel surface for more than 24 hours. The best practice is to lift the panel and move it to a designated area where the membrane can be stripped and pressure washed. The membrane is simply peeled from the cast panel by starting in a corner and working towards the middle.

Using a pressure washer spray the panel washing away the unset or unhardened concrete. Whilst there is no special requirement in pressure washing, consideration should be given to keep the time between casting and washing the same throughout the project to achieve a consistent finish across a number of cast elements. When washing is complete, the panel can be stored for curing and drying. 

 

Downloads for Panel Precasters


Basic Requirements for using Graphic Concrete in a precast yard.
How to Use GC Technology in a Precast Yard (non-vacuum beds).
Necessary Tools and Equipment 
Graphic Concrete Mixes or Recipes 
Product Properties Data Sheet
Instructions for Casting Graphic Concrete Samples
Summary of the Production Instructions 


For more information, download the graphic concrete Q&A







Preparing samples.

 
Precast beds must be clean.

 
Remove any debris from the membrane.



Concrete is carefully poured.


graphic concrete™ membrane is stripped.

 
The cast element is high-pressure cleaned.