MORTAR: Use the weakest allowed. A good general purpose mortar (class II) is 1cement: 1 lime: 6 parts sand by volume. The lime may be omitted if the sand has a high fines content. Keep the mortar relatively dry to avoid smearing on the sides of the block.

JOINT THICKNESS should be 10mm

PLASTER: The recommended mix is 1 cement:2 lime: 8 sand by volume. High cement concentration may give rise to crazing. The surface should be dry or very nearly so before applying plaster.

SETTING OUT: Lay the first course out without mortar to fit the blocks to the configuration. Joints may be shrunk or stretched to obtain a good fit.

BONDING: The blocks of adjacent courses should lap at least 100mm (about one quarter of the unit length).

LAYING: Lay blocks dry. Place blind side up to provide a bed for the mortar. Avoid smearing the mortar on the sides of the block as this will show up through the paint.

POINTING: Joints should be pressed after the mortar has partially set (1-2 hours). The ˝ round style is the most practical. Avoid raked joints as they highlight chipped edges and attracts dirt.

CUTTING: Avoid chopping with a bolster that creates untidy edges and causes scrap. Preferably the complimentary units should be used.

CHASING: Use a carborundum saw to cut channels in preference to a chisel which creates untidy broken edges and scrap.

CLEANING: Mortar droppings should be scraped off after partially drying (+-24hrs). Persistent marks may be abraded off with another piece of block. Acid solutions should be used with care as the may change the colour of the surface.

PAINTING: Normal alkali resistant paints should be used in accordance with manufacturers’ instructions. Note that mortar smears will show up through the paintwork unless carefully abraded off.

CONTROL JOINTS: These should be placed at 5-8 meter intervals depending on the position on windows, doors and corners. Joints may also be cut with a carborundum saw after the wall is built. The open joint may be filled with mastic to prevent the ingress of dust etc.

USERS ARE REFERRED TO THE MASONRY MANUAL OF THE CONCRETE MANUFACTURERS ASSOCIATION FOR DETAILED INFORMATION ON THE ABOVE POINTS AND OTHER ISSUES.

INCA concrete products are made to high standards and the texture is suitable for painting or rendering. We do our best to be as consistent as possible, but the natural colour is grey and may vary slightly with changes in the ingredients. The general purpose unit is not intended to be used externally without at least a paint coating.