Page 64 - Visual Guidance Handbook

Let’s all
PLACEMENT OF CONCRETE IN COLD WEATHER get home safely,
every day

Stage 1: Pre concrete preparation Stage 2: Required Temperature
• Concrete should never be poured directly onto snow,
ice, frosted or frozen ground. Concrete Less than 5ºC Between 6ºC to Between 12ºC to 15ºC
• Check weather forecast and carefully plan concrete Temperature at 11ºC
pour accordingly in sequence, such that it can be Delivery
covered with blankets. Recommended Reject the concrete Accept and Use frost blankets at
• Cover the area of pour to prevent overnight frost. Action and send back to the upgrade the early stages of the
• If ice / snow is present, ensure it is removed. supplier. If already concrete to pour if frost is
• Metal surface temperature is to not be less than 2ºC. accepted then heated concrete expected over-night
• Choose concrete mix proportions carefully for prompt heating from below for the following or if air temperature is
hydration process. should already be in deliveries expected to fall below
• For cold weather order heated concrete. This raises the place or introduced to thereafter and use
concrete temperature further by about 3ºC to 7ºC. accept concrete. frost blankets.
• Air temperature is to be 2ºC and rising

Stage 3: Concrete placing

SLABS THIN SLABS ON METAL DECKS WALLS & COLUMNS
• Start pouring concrete early morning and use • Blankets on their own are not sufficient, • Shutters on thin walls and columns should be
frost blankets during the first hours of pour. space heaters (one every 25m2 ) directed wrapped with blankets and keep the shutters in
• Reject concrete less than 5ºC upwards from below metal decking is place for extra day or two before striking to prevent
• Place Ethafoam blankets over wet concrete required for concrete delivery damage to concrete edges or sudden collapse by
immediately after initial levelling to contain heat temperatures of 7ºC or less. the force of shutters removal.
and to start hydration process of the concrete. • The concrete mix may be designed such • Top of columns and starter bars will also be covered
• Close monitoring of surface hardening is that higher blend of cement in the range of with blankets
important to carry out final surface levelling or to ∞ 50% for the thinner slabs is used. • When struck, columns will be covered with blanket
achieve a greater smooth surface i.e. power for further 24-48 hours
floating.

Page 64