1. Cold-Weather Concreting

2. Cold Weather When air temp. is at or below 5°C or when there is a probability of it falling below 5°C within 24 hours of placing — CSA A23.1

3. Cold-Weather Concreting

4. Effect of Freezing Fresh Concrete  Up to 50% reduction of ultimate strength can occur if frozen —  within a few hours  before reaching a str. of 3.5 MPa  Frozen only once at an early age —  With curing nearly all strength can be restored  Less resistance to weathering  More permeable

5. Cold-Weather Concreting Relationship Between Initial Set and Casting Temperature

6. Cold-Weather Concreting Relationship Between Final Set and Casting Temperature

7. Cold-Weather Concreting Relationship Between Slump and Casting Temperature

8. Cold-Weather Concreting Effect of Temperature on Strength Development

9. Cold-Weather Concreting Effect of Low Temperature on Strength

10. Cold-Weather Concreting Early-Age Strength

11. Cold-Weather Concreting Retaining Heat of Hydration

12. Cold-Weather Concreting n Type 30 High-early-strength cement n Additional portland cement (60 to 120 kg/m 3 ) n Chemical accelerators Methods to accelerate strength gain:

13. Cold-Weather Concreting

14. Effect of F/T on Strength of Non-Air-Entrained Concrete

15. Cold-Weather Concreting

16. Permissible Concrete Temperatures at Placing Thickness of Section, m Temperature, °C MinimumMaximum Less than 0.3 0.3-1 1-2 More than 2 10 5 35 30 25 20 CSA A23.1

17. Cold-Weather Concreting Effect of Temperatures of Materials on Concrete Temperature 0.22(T a M a + T c M c ) + T w M w + T wa M wa 0.22(M a + M c ) + M w + M wa T = T = temperature of the freshly mixed concrete, °C T a, T c, T w, and T wa = temperature in °C of aggregates, cementing materials, added mixing water, and free water on aggregates, respectively M a, M c, M w, and M wa = mass, kg, of aggregates, cementing materials, added mixing water, and free water on aggregates, respectively

18. Cold-Weather Concreting

19. Max. Permissible Temp. Differential Between Concrete Surface and Ambient Air — Wind up to 25 km/hr. Thickness of concrete, m Max. permissible temp. differential, °C L to H ratio of structure 035720 or more 0.3 0.6 0.9 1.2 1.5 29 22 18 17 16 22 18 16 15 14 19 16 15 14 13 17 15 14 13 12

20. Cold-Weather Concreting Checking Fresh Concrete Temperatures

21. Cold-Weather Concreting Checking Hardened Concrete Temperatures

22. Cold-Weather Concreting Temperature of Test Cylinders

23. Cold-Weather Concreting Recommended Duration of (A) Concrete Temp. in Cold Weather Air-entrained concrete Service category Protection from early-age freezing For safe stripping strength Convent. concrete, days High-early strength concrete, days Convent. concrete, days High-early- strength concrete, days No load, not exposed, favorable moist-curing 2121 No load, exposed, but later has favorable moist- curing 32 32 Partial load, exposed64 Fully stressed, exposedSee next slide (B)

24. Cold-Weather Concreting Recommended Duration of (B) Concrete Temp. in Cold Weather Fully stressed, exposed, air-entrained concrete Required % of standard- cured 28-day strength Days at 10°CDays at 21°C Type of portland cement 10 I or GU 20 II or MS 30 III or HE 10 I or GU 20 II or MS 30 III or HE 50 6 9 3 4 6 3 651114 5 810 4 85212816 1812 95293526232420

25. Cold-Weather Concreting Cold-Weather Insulation, Aboveground

26. Cold-Weather Concreting ness of Thermal Resistance (R) for 10-mm Thickness of Material Board and Slabs Density kg/m 3 (m 2. ° C)/W Expanded polyurethane 240.438 Expanded polystyrene 290.277 Mineral fiberboard 256 - 2720.204 Plywood 5450.087 Loose fill Wood fiber, soft woods 32 - 560.231 Vermiculite112 - 1310.148

27. Cold-Weather Concreting Insulating Blankets Thermal resistance of mineral fibre blanket (50 to 70-mm thick) 1.2 (m 2 ·°C)/W

28. Cold-Weather Concreting Insulating Concrete Forms (ICF)

29. Cold-Weather Concreting Insulated Column Forms High-density plywood Rigid polystyrene Rough plywood

30. Cold-Weather Concreting Enclosures  Wood  Canvas  Tarpaulins  Polyethylene Film

31. Cold-Weather Concreting Heated Enclosure

32. Cold-Weather Concreting Direct-Fired Heater

33. Cold-Weather Concreting Indirect-Fired Heater

34. Cold-Weather Concreting Hydronic Systems

35. Cold-Weather Concreting Maturity Concept M =  (C + 10)  t where u M = maturity factor u  = summation u C = concrete temperature, °C u  t = duration of curing at temperature °C, usually in hours

36. Cold-Weather Concreting

37. Video Concreting on Ground