Bill Price, National Commercial Technical Manager for Tarmac Cement, explains how to work with bricks in the heat.
In hot weather, laying bricks is a little less straightforward than in cooler conditions. The high temperature speeds up the setting of the mortar and also allows more water to evaporate, which also accelerates setting and hardening.
Short of laying bricks in the cool of the night (not recommended), storing the sand and cement out of direct sunlight is a good idea.
If you are using water straight from the mains, no problem, but if you are storing water in containers ready for use, it is doubly important to keep them cool. Hot water in mortars has a much bigger effect on reducing setting times than hot cement.
Also, do not make up batches any larger than you can use in a short time and cover the barrow of fresh mortar with damp sacking or a tarpaulin, to minimise evaporation (and stiffening) in the mortar before you use it.
For smaller jobs, Tarmac’s plastic tubs of Blue Circle products allow for a small amount of product to be used and the rest sealed away and stored – preferably in the shade!
Secondly, the bricks themselves are drier and will suck more water than usual out of the freshly placed mortar. Although suction from the bricks is an integral part of the way in which brickwork (and blockwork) mortars set and harden, too much suction will result in a poorly hydrated, low strength, crumbly mortar.
Storing the bricks in the shade will help and dampening (but not saturating) the bricks before use will help to control the suction and keep the mortar from losing too much water.