Utilising Heaters to Optimise Concrete Mixes in Cold Weather

During winter when the weather is colder, you need to pour with a concrete with higher carbon content as this will allow it to cure correctly. By using heaters on slabs, this has allowed them to optimise concrete mixes. The goal is to be able to pour slabs using the summer mixes all year, therefore offering a carbon saving of >45% taking into consideration of heating the slabs.

From carrying out trials, it was discovered that the carbon for heating of the slabs is significantly less than the impact of pouring with a more carbon intensive mix. It is not common construction practice to carry out this and heating of the slab has started the ball rolling of how heating elements can be built into formwork or decking to allow for a less intensive labour.

It offers significant carbon savings to heat the slabs and increase the ambient temperature, comparing CEM1 mix (winter, high carbon mix) to same strength GGBS content it would offer up the following benefits:

• 0% GGBS to 20% GGBS – Average 16.99% carbon reduction
• 0% GGBS to 40% GGBS – Average 35.76% carbon reduction
• 0% GGBS to 70% GGBS – Average 46% carbon reduction

These values are taking into consideration the carbon usage of the heaters.