The main issue with cracked brickwork is that the cracks provide the perfect route for wind-driven rainfall to penetrate masonry walls. When the weather is cold, water within the openings freezes and, as water expands by around 10% in volume when it turns into ice, the cracks are widened by the resulting pressure. The tiniest hairline cracks can thus become much larger very quickly, allowing more water to penetrate each time. More water means more expansion and the freeze-thaw cycle is set in motion, progressively worsening the issue and causing more damage to the bricks.
An effective filler, properly utilised, will get rid of any fissures and crevices that may have developed. When filling cracks in mortar joints, the process involves mechanically widening the cracks in order to allow for repointing of the wall at a sufficient depth using new mortars.
Cracks in brickwork require a purpose-made injection system to make sure that they are filled to an adequate depth.
PREPARE the cracks by using a vacuum or air-line. This is essential to remove loose or friable particles as the substrate must be free from dust, dirt and other contaminants if a long-lasting, successful repair is to be achieved.
MIX the injection mortar in strict accordance with the manufacturer’s instructions. Be aware that mixing adhesives causes an exothermic chemical reaction and the generated heat can limit workability of the product, meaning it has to be applied within a short time of being prepared. Users should therefore have everything they are going to need ready before this stage.
TRANSFER the injection mortar to a caulking cartridge that is fitted with a nozzle suited to the width of the crack to be filled. Nozzles are available that can inject resin into cracks a single millimetre wide.
INJECT the crack sealant as deep as possible, ensuring that the opening is completely filled from base to surface.
MATCH the colour of the repair to the substrate while the sealer is still tacky, using tinting agents or brick dust.