Repairing of severe masonry cracks (cracks width > 1 cm) – Disorganised masonry

RELATED MATERIALS

DUROCRET Polymer-modified cement mortar

RAPICRET Fast-setting patching mortar

UNICRET Mortar for rendering and masonry

UNICRET-FAST Fast-setting, white repairing mortar

ADIPLAST Polymer latex for multiple improvements of mortars

FIBERGLASS MESH Fiberglass mesh for render reinforcing

I. NATURE OF THE PROBLEM – REQUIREMENTS

Severe cracking (cracks wider than 1 cm) and disruption of non-supporting masonry walls causes strength problems as well as being unsightly.

II. SOLUTION

The materials used to repair such cracks must have the following properties:

• Efficient bonding to bricks.
• Sufficient workability, to facilitate the filling of cracks.
• Low shrinkage during setting, so that they do not crack as they harden.

a) Repair of cracks

Suitable materials:

• DUROCRET, polymer modified cement mortar, or
• RAPICRET, fast setting patching mortar, where rapid work is required.

b) Repair of plaster

Suitable materials:

• UNICRET, cement-lime mortar, reinforced with ADIPLAST polymer latex, or
• UNICRET-FAST, fast setting cement-lime mortar, reinforced with ADIPLAST polymer latex, where rapid work is required and the surface is not extended.

III. APPLICATION

The complete repair procedure is as follows:

a) Repair of cracks

1. The plaster is removed over the entire surface of the masonry.
2. The cracks are widened along their entire length by breaking the surrounding bricks with a sharp tool.
3. The cracks are thoroughly cleaned with compressed air or with a brush.
4. Subsequently, the substrate is thoroughly dampened.
5. DUROCRET polymer modified cement mortar or RAPICRET fast-setting patching mortar is introduced as deeply as possible into the widened crack, using a gouging trowel. These mortars are to be mixed with water only. After the material has hardened, repair of the plaster can follow.

b) Repair of plaster

1. The underlying surface should be carefully cleaned of loose particles, dust, etc. and dampened thoroughly with water.
2. A first coat of plaster is applied, using UNICRET cement-lime mortar or UNICRET-FAST fast setting cement-lime mortar, reinforced with ADIPLAST polymer latex. ADIPLAST is added to the mixing water in the ratio of ADIPLAST : water = 1 : 3.
3. While the first coat is still fresh, the glass mesh is laid over the entire surface and is lightly pressed onto the first coat.
4. Once the first coat has set, the final plaster coat of UNICRET cement-lime mortar or UNICRET-FAST fast setting cement-lime mortar is applied. The product is now mixed with water only. In case that a plaster of higher strength is desired, ADIPLAST polymer latex is added to the mixing water in the ratio of ADIPLAST : water = 1 : 5.

IV. REMARKS

• Temperature during application must be between +5⁰C to +35⁰C.
• Material that has started to set must not be softened again with water.
• During summer months it is recommended that the plaster dampened after being applied, to protect it from dehydration due to high temperatures.
• Consult the directions for safe use and precautions written on the packaging.