Cortite is a new concrete waterproof from Cormix Construction Chemicals. The company describes it as a permeability reducing admixture which is integrally added to concrete mixes to waterproof all types of concrete.Cormix says that the new additive provides a hydrophobic coating within the pores of the concrete, reducing its tendency to absorb water. Cortite is made from blended long chain acids and can be used in structural concrete, including ready-mix, precast and in situ materials. It can also be used in concrete blocks, tiles, cast and reconstituted stone and in screeds.Tested to BS1881 Part 122, water absorption of concrete with the new additive is claimed to be about 50 per cent of control values.Cortite is said to reduce efflorescence. This is a useful advantage when used in pigmented mixes.