The Bristol University architecture and planning studio does not appear unusual until closer inspection whereupon what appears to be red terracotta tiling reveals itself as precision made stack-bonded brickwork glued together with completely regular 3mm joints. The bricks which form 8m wide storey high panels are laid to a tolerance which would be unthinkable in traditional methods of construction.
Among other highly innovative features, the building is the first in the UK to use glued brickwork and the team had to be trained in Belgium. The advantages of glued brickwork are that it can be stack-bonded without horizontal reinforcement. The strength of the bonds avoids the need to use lintels for spans under 4.5m. The glue sets in 24 hours compared to the 28 days required for mortar. Finally, there is no subsequent need to clean or point the brickwork as the joints are waterproof and frost resistant and the brickwork is not liable to efflorescence.
The glue, called Anker Plast, is a cementitious resin mortar based on a mixture of fine-grained calibrated sand and Portland cement, modified with artificial resins and other ‘secret’ components. The precise composition is dependent on the nature of laying temperatures and materials used. It is important to get the mix right, as the glue will not flow properly if the mixture is too thick, and if it is too wet the bricks sink. In cold weather the glue sets very quickly indeed, while laying speeds are much slower.
The longer term benefits are clear, but the technique requires additional site practices to accommodate and care for the equipment, while the brick-laying standards have to be very high.