We’d all like to think we’re prepared for cold weather working – but with this winter seeing more snow than in recent years, there’s no harm in brushing up on the sort of best practice tips that can make working with bagged cement easier. And, often, it’s all about the temperature…
1. Special care for young concrete: When concrete is cast in winter, take care not to let the water in young concrete freeze. This will make it unusable. Until the strength has reached 5MPa, don’t let the temperature of the concrete drop below 5°C. Any surfaces that will come into contact with the newly-placed concrete – including sub-grade materials – must be a few degrees above freezing (e.g. 2°C). Avoid placing concrete against any formwork or reinforcement covered in ice or snow.
2. Cold weather screeding: It’s good news regarding flooring projects – screed can be laid in almost any weather (as long as the outside temperature stays above 3°C). You’ll still need to take extra care, though. Transport/store materials correctly, making sure the building is watertight and allowing the screed to dry completely. Transport cement in bags, while protecting it from water. Store all materials in dry environments and protect them from moisture and rain. Regarding curing and drying, don’t lay screeds when the air temperature falls below 5°C. And, of course, it’s vitally important to test screeds.
3. Masonry means strategy: Depending on how bad the weather is, consider various strategies for cold weather masonry construction. Aim to optimise the selection of masonry materials for cold weather performance, protect materials, heat materials, enclose – or at least protect – work areas, and heat work areas and also in-place work. Keeping the water content of the mortar below 6% will avoid disruptive expansion upon freezing. And, when mixed, the mortar should be between 4.4°C and 48.9°C – and kept above freezing until it’s used in masonry.
Breedon’s bagged cement products are packed in weatherproof packaging and can be stored outside.