1. “HOT WEATHER CONCRETING”
Presented by
Rajesh Sharma,
Trainee Scientist,
M.Tech.-Final year,
CSIR-CBRI,Roorkee

2. Introduction
Difficulties in Hot Weather
Precautions
Effect of High Concrete Temperature
Properties of Concrete Materials
Durability issue of concrete
Conclusion

3. Hot weather conditions include:
- High ambient temperature (T>35⁰C)
- High concrete temperature
- Low relative humidity
- Solar radiation

4. Difficulties in Hot Weather
Increased water demand
Accelerated slump loss
Loss of compressive strength
Increased tendency of plastic shrinkage
cracking

5. Precautions Depends on
Type of construction
Characteristics of the materials being used
The experience of placing and finishing crew in
dealing with the atmospheric conditions in the
site

6. Effect of High Concrete Temperature
loss in slump

7. Use materials and mix proportions that have a
good record in hot weather conditions
Cool concrete and its ingredients
Use a concrete consistency that allows rapid
placement and consolidation
Reduce the time of transporting, placing,
and finishing as possible

9. Contd…
Increase the rate of setting and shorten
the length of time
Setting time can be reduced by 2 or more
hours with a 10°C increase in concrete
temperature

11. Contd…
Increased tendency for cracks to form
both before and after hardening
Rapid evaporation of water from freshly
placed concrete can cause plastic-
shrinkage cracks
Cracks may also develop in the hardened
concrete

13. Lower the temperature of concrete
materials before mixing
The contribution of each material is
related to-
Temperature
Specific heat
Quantity of each material

14.  Where T = temperature of the freshly mixed
concrete, °C
 Ta, Tc, Tw, and Twa = temperature (°C); Ma, Mc,
Mw, and Mwa = mass(kg), of aggregates, cementing
materials, added mixing water and free water on
aggregates respectively
Contd…

16. Courtesy:-www.concrete.org/pubs
Author:-Dr.J.D.Holmes

17. Associated with hot-weather concreting
Can occur any time ambient conditions
produce rapid evaporation of moisture from
the concrete surface
Cracks occur when water evaporates from the
surface faster than it can rise to the surface
during the bleeding process

18. Courtesy:-www.concrete.net.au

19. Contd…

20. Precautions to Minimize
Plastic Shrinkage Cracking
1. Moisten concrete aggregates that are dry
and absorptive
2. Keep the concrete temperature low by
cooling aggregates and mixing water
3. Dampen the subgrade and fog forms prior to
placing concrete
4. Erect temporary windbreaks to reduce
wind velocity over the concrete surface

21. Courtesy:-www.concrete.org/pubs

23.  It can be used effectively in construction of large
concrete elements in hot weather condition
 More research needs to be carried out on thicker
concrete specimens

24. http://www.concrete.net.au/pdf/Hot_Weather.pdf
http://www.nrmca.org/aboutconcrete/cips/12p.pdf
http://www.cement.org/tech/basics_hot_weather.asp
http://www.cemexusa.com/ProductsServices/files/T
echnicalServices/Hot_Weather_Concreting.pdf
http://www.concrete.org/pubs/newpubs/305R-
10web.pdf