Planning
Before proceeding with the installation, careful consideration should determine the best way of installing the Altro system. Efforts should be made to minimise day joints and optimise the open time of the product (i.e. minimise the distance between mixing and laying). It is best to also consider the effect of external influences on the final installation (i.e. direction of light from windows etc.). Time spent at this stage will be invaluable towards the success of your installation.
The Altro Crete cove variant is designed to be laid at the required thickness at the floor to wall junction to be uniform with the installed Altro Crete flooring variant but is not designed to be applied thicker than 4mm on the upstand section. Often for cosmetic reasons coves are continued 100mm up the wall but there is no upper limit to the application height of the Altro Crete cove when applied at 4mm on the vertical. Some applications may make use of metal floor trims to ensure a neat transition from the floor to coving material. This should not be used in lieu of a mechanical rebate.
Altro recommend that stainless steel mixing, laying and application tools are used in this process. Metal transfer from mild steel tools may result in discolouration of the screed which will be unacceptable to your customer. This will be particularly noticeable with pale colours, please contact Altro for further guidance.
Rebates and anchor points should be cut into the substrate prior to application of the primer.
Application
The following application guide is based on laboratory and simulated site conditions. However, when installations conditions differ appreciably from those detailed by Altro, the performance characteristics of both mixing and laying may not be as expected. To achieve the best results at all times please endeavour to establish the correct conditions which in turn will allow the materials to be laid effectively, and meet your customer’s expectations.
Installation conditions
Apply in well ventilated areas. Both the slab and air temperature should be between 10°C and 25°C. It is not advisable to mix and lay polyurethane resin products outside of this range. Ambient conditions should be maintained at least 3°C above dew point or below 75% R.H. during the initial stages of cure. At site temperatures below 10°C cure times will be substantially increased unless some form of external heating is used. It must be recognised that the concrete slab temperature will generally be lower than the air temperature, often as much as 10°C, and this will govern the rate of cure. As the resin flooring cures, in condensing conditions moisture vapour may condense onto the surface and cause ‘blooming’, a permanent clouding of the surface.
Cold, wet or humid conditions, and limited air flow, can result in condensation on the part cured floor. The workability, open-time, cure development and return to traffic will be significantly affected by ambient conditions.
Mixing equipment
* All tool number references relate to Refina Ltd 01202 632 270
- Slow speed drill (200-500rpm) *
- Mixing paddle, such as MR2 60B *
- Stainless mixing vessel *
Cutting rebates
Prior to priming a mechanical rebate should be formed at the floor to cove detail to avoid weakness at the most vulnerable zones, evenly distributing loads and stresses, preventing ingress of aggressive media to the subfloor and bond line and provide a neat finish to the flooring. This is normally formed by casting a chase when the concrete is laid or by cutting using a wet cut concrete saw.
The preferred dimensions of the rebate are twice the thickness of the screed in depth and twice the thickness of the screed in width.
Please refer to the Altro design and detailing diagrams.
Priming the substrate
In order to achieve a uniform finish, prevent bubbles and maximise substrate adhesion, primer should be used. An Altro primer should be selected which is suited to the installation, and appropriate for the nature and moisture content of the substrate (seek further guidance from Altro).
The appropriate Altro primer should be applied in accordance with the product data sheet. Ensure that the substrate is well sealed and that all hungry areas are addressed before proceeding to install the system.
Both the floor and the upstand should be primed. While the primer is still wet broadcast kiln dried aggregate, (nominal 1mm) into the primer on the floor and upstand.
If the overcoating time period for the primer is exceeded, the surface should be lightly abraded and vacuumed before further coats are applied.
A second ‘tack’ primer coat is applied as part of the product installation.
Product installation
Approximately 10 minutes prior to the application of the Altro Crete cove a ‘tack’ primer will need to be applied to the upstands to aid the application of the cove. Only apply the ‘tack’ primer to areas that the cove can be applied within a 10-40 minute window while the ‘tack’ primer is still live. Using a slow speed drill and paddle thoroughly mix together the Altro Prime standard base and hardener. To this add Altro TX until the mixture becomes paste like in consistency. (Approximately 0.5 litres of Altro TX per 1kg of Altro Prime standard.) Using a paint brush or similar apply the ‘tack’ primer to the upstands. Remember to always use the correct PPE.
Using a drill and paddle pre-mix the Altro Crete cove base, hardener and colour pack in a suitable container for 30 seconds prior to transferring into an appropriately sized mixing vessel. While mixing add the Altro Crete Cove aggregate into the vessel and mix for a further 2 minutes.
Using a flat stainless steel trowel apply the mixed material to the upstand at a depth of 3-4mm. Excess material will make the application harder and more likely to slump.
Again using the flat trowel, apply the material to the floor section before dropping in some material into the floor/wall junction to form the fillet of the cove. Use a rounded coving trowel to finish the material and to give a completed cove. Ensure the material is well closed and uniform.
Joints
The spacing of movement joints must be determined by the design of the subfloor. All live movement joints in the subfloor must be continued through the resin flooring. In all instances the type and positioning of movement joints should be agreed at the design stage between all parties concerned. Please refer to Altro or FeRFA’s Guide to the Specification and Application of Synthetic Resin Systems for further guidance.
All joints should be filled with Altro Expand flexible jointing compound. Please see Altro Expand data sheet for further information.