Applying one-coat mortar to aerated concrete

The block of aerated concrete is a lightweight building material intended both for individual and collective homes. As this substrate has very particular characteristics, a series of precautions have to be taken when applying a one-coat render.

It is a solid material, low density, low unit weight and excellent thermal insulation capacity.

Its high porosity can cause the dehydration or rapid absorption of the kneading water of the monolayer mortar.

As a consequence, the correct performance of the mechanical performance of the coating is prevented.

Solution

PREPARING THE SUPPORT

Apply a primer made with PROPAM® LATEX (diluted with water), or PROPAM® PRIMER SOL (undiluted) in order to prevent it from rapidly absorbing water from the monolayer mortar.

Primer with PROPAM® LATEX: Dilute 1 volume of PROPAM® LATEX with 4 volumes of water, remove until obtaining a homogeneous mixture and apply on the support with brush or roller.
Primer with PROPAM® PRIMER SOL: Apply this primer directly to the support with a brush or roller (no dilution required).

APPLICATION

Use REVAT® SUPRA, REVAT® RASPADO or REVAT® PIEDRA, mortars with low modulus of elasticity.

Knead the monolayer mortar and then apply it manually with trowel or with a spraying machine on the previous primer (still fresh).

Carry out the finish.

Recommendations

It is not advisable to apply monolayers of dark colors, in particular in facades that, due to their orientation and geographical location of the work, are very exposed to the sun. In these cases, due to the low heat dissipation offered by the cellular concrete support (due to its high thermal insulation performance), retraction cracks can occur due to the accumulation of heat in the mortar.
To minimize the stresses produced by thermal expansion, it is advisable to apply fiberglass mesh centered on the thickness of the coating.
Placing fiberglass meshREVAT® 110 in the joints of the blocks with other materials (pillars, slabs, lintels, etc.).