Introduction
ARDEX Technical Services have received many reports of problems over the years that can be explained simply by the fact that the weather was cold at the time of application. This short article looks at the common problems encountered and the simplest solutions.
The Major Problems
Cement Based Tile Adhesives – Slow Curing
Tile adhesives containing cement must chemically react in order to cure. In cold temperatures, chemical reactions slow down. This means that initial set times, final set times and the time before you can safely walk on a tile without dislodging it, are extended. Typically the product datasheets quote 23°C for their “walk-on times” so keep in mind if the temperature where you are working is only 10°C you can’t expect a 6 hour walk-on time if this is what a datasheet states for a particular product.
Levelling Compounds – Slow Curing
Floor levelling compounds also rely on cement to chemically react and this reaction is slowed in winter. The Technical Datasheets typically quote application properties at 23°C. The initial cure and subsequent final cure are much slower when the temperature drops below 10°C than what they are at 23°C. At temperatures below 5°C, the reactions can halt altogether. It is possible to apply a compound with a quoted walk-on time of 3 hours and have it still wet on the surface at 3 hours if the temperature is only 5°C for example. Figure 1 shows a levelling compound that due to a very low ambient temperature (around 5°C) took so long to dry that strange surface effects and settling can be observed.
Below 0°C, the water in the material freezes which can produce ice crystals which can permanently damage the compound. Refer to AS1884-2012 regarding conditioning required.
Figure 1 – Settling, a weak surface and a strange appearance due to low temperature curing of a leveller
Efflorescence in grout
Due to increased water residence times, as a result of slowed evaporation in winter, efflorescence can also be increased in cement based grouts. Efflorescence is a deposit of water soluble salts from the cementitious components which are drawn out by the water and then deposit at the surface when the water evaporates. Premature sealing can exacerbate this effect.
Epoxy – Slow Curing
Epoxy based grouts, adhesives, membranes and sealers cure by a chemical reaction between two components and this reaction is slowed or halted by cold conditions. The viscosity of the resins can also increase making effective mixing difficult. Water based epoxies can display increased drying times and apparent stickiness due to decreased rates of water evaporation.
Mastic Adhesive and Membranes – Slow Curing
Water based membranes and mastic adhesives cure by drying. That is, the water must physically come out of the product for it to cure. In winter, decreased rates of drying are common due to slow evaporation of the water. They can also become thicker in cold conditions.
Freezing of Mastic Adhesives and Additives
Mastic tile adhesives, water based membranes and latex additives can freeze which both makes the products not able to be laid, but may also cause the polymer/water suspensions to be permanently damaged, rendering the product unusable. Water based product must not be allowed to freeze.
The Solutions
There are a number of simple procedures which can be observed to avoid the worst of the cold weather problems. Below is a list of things to do and to not do.
Do….
- Where the work area is indoors, and air conditioning is available, it should be turned on to bring the substrate up to above 10°C.
- Use rapid set adhesives to reduce cure times.
- Where the product data sheet allows reduced water additions, use the lowest level consistent with the quoted minimum and workability.
- During the installation, factor increased drying times between each step in the job.
- Increase the amount of ventilation by the use of fans which will raise the rate of evaporation. This is useful for slow drying membranes and mastic materials. However the air must not be supplied by a heater as this can cause cracking and should only be used on floor levellers after the material has hard cured.
- If the daytime temperature is acceptable, but may drop significantly at night, only use products until around midday to allow the material to form an initial set prior to the onset of cold temperatures at night.
Do not….
- Store materials outside or where they may drop below 0°C.
- Work in the coldest part of the day in an uncontrolled environment.
- Work when the temperature is below 5°C (where possible minimise working below 10°C.)
For further advice on particular conditions, sites or applications contact ARDEX Technical Services on 1800-224-070 (freecall), or the relevant ARDEX Sales Representative for the product in your state.