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Why apply a levelling compound to a concrete beam structure? |
To minimise risks of alkaline breakdown of adhesives and coverings. |
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When is the earliest time for applying levelling to a concrete structure? |
For = 95% RH (CM < 3%), the earliest is 28 days after casting of the concrete – see Section Concrete with levelling compound'. |
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When should levelling be applied to concrete to achieve the shortest drying time? |
For a levelling-material thickness of about 10mm the timing is unimportant.
For thicker layers it can be advisable to carry out a drying calculation depending on the choice of concrete quality. See Section Concrete with levelling compound'. |
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Do levelling compounds prolong the drying time of concrete? |
Thick layers have the effect of increasing the thickness of the concrete. The effect depends on the choice of concrete quality. See Section 'Concrete with levelling compound.
No effect on high-performance concrete. |
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When can an adhesive floor-covering or a sealing layer be applied to the levelling material? |
For normal drying levelling products, follow the directions of the manufacturer of the adhesive, covering or coating regarding humidity criteria.
For self-drying levelling products, early covering requires the levelling material to have achieved sufficient surface dryness and sufficient 'grab' on to the concrete surface to achieve a satisfactory pull-off strength. This requires the underlying concrete to meet requirements regarding RH or CM. |
| Must a cement levelling compound be stripped from the concrete structure to allow moisture damage to dry out? |
No cement-based levelling compounds have very similar water vapour permeability to concrete. Reducing the thickness of the construction by stripping off the levelling layer does not shorten drying time at all. |
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Does the primer hinder drying of the concrete structure? |
No. maxit Floor 4716 allows free diffusion. |
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When does the levelling compound act as a protective layer? |
Where there is highly alkaline construction moisture and thickness is greater than 5mm – see Section 'When can adhesives be applied to floor-coverings?'. |
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When can parquet be laid on the levelling compound? |
Floating parquet: National requirements.
Glued parquet: National requirements or follow the adhesive supplier's instructions. Possibly use MS 'Casco Flexible' polymeric adhesive, that requires 85% RH (CM < 2%). |
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What happens if it is not possible to keep the building warm? |
Drying times are extended – see Section 'Drying' |
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Are levelling compounds more impermeable than concrete? |
Levelling compounds have a water vapour permeability of around 07*10-6 m2/s, that is comparable with a normal concrete. The value varies with the moisture content of the levelling material (it is lower when the moisture content is low and vice versa). |
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Are levelling compounds more porous to damp than concrete? |
maxit's levelling compounds are formulated to give similar damp-resistance to concrete. With RH levels continuously above 95% (CM 3%), strength falls off rather more than for concrete. |
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Do cement-based levelling compounds and concrete dry out in the same way? |
In the early phase additives in the levelling compound reduce the rate at that it releases moisture, but the difference is marginal in later phases – as confirmed by practical measurements. With thick layers it may be advisable to apply self-drying material underneath. |
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