Concrete applications may be considered hot weather concrete at temperatures ranging from 77 to 95 degrees Fahrenheit depending on the specific application. Precautions should be planned in advance to counter the effects of high temperature well in advance of execution to counter these effects.
How concreting is done during hot weather?
Hot weather conditions can produce a rapid rate of evaporation of moisture from the surface of the concrete and accelerate setting time etc. … High temperature increases the hydration of cement resulting in faster setting which means the time available for workability (concrete in plastic state) of concrete is reduced.
What is extreme weather concreting?
In countries which experience extreme weather conditions special problems are encountered in preparation, placement and curing of concrete. India has regions of extreme hot weather (hot-humid and hot-arid) as well as cold weather. 2007)-Hot weather concreting and IS: 7861 (Part 2-1981 Reaff. …
Which type of cement should be used in hot weather concreting?
Modifying the mixture to reduce the heat generated by cement hydration, such as the use of an ASTM Type II moderate heat cement and the use of pozzolans and slag can reduce potential problems with high concrete temperature.
What is hot and cold weather concreting?
The hydration of cement is a chemical reaction that produces heat. In cold weather, the cement hydration is slower and concrete gains strength less quickly, increasing the time to attain its design strength.
When should you cover concrete in hot weather?
Consider placing concrete early or later in the day when ambient temperatures are cooler. Apply QUIKRETE Acrylic Concrete Cure & Seal immediately after finishing procedures are completed to prevent surface moisture loss.
Why concreting in extreme temperature is different from normal condition?
High temperatures accelerate the hardening of concrete. At higher temperatures, more mixing water is generally re- quired for the same consistency. … Higher water contents also mean greater drying shrinkage. In very hot weather, fresh concrete may be plastic only an hour or less before it hardens.
What precaution should be taken when placing concrete in hot weather and why?
Precautions may include use of materials with a good performance history in high temperature conditions, cool concrete materials or concrete mixture, provide concrete consistency and placement equipment and crew for rapid placement, reduce time of transport, schedule placement to limit exposure to atmospheric …
What particular precautions would you take when concreting I in winter and II in hot weather?
Precautions for Hot Weather Concreting
1- Use materials and mix proportions that have a good record in hot-weather conditions, 2- Cool the concrete or one or more of its ingredients, … 5- Schedule concrete placements to limit exposure to atmospheric conditions (i.e. at night or during favorable weather conditions).
What is cold weather concreting?
Cold weather concreting is the process of placement, finishing, curing, and protection of concrete during cold weather, as per ACI 306.1. The cold weather occurs when the average outdoor temperature is below 4.4C (40F) for more than three successive days.
Why is it necessary to take precautions while concreting in cold weather?
The hydration of cement is a chemical reaction. Extremely low temperatures as well as freezing can significantly slow down the reactions, thus, affecting the strength growth. … The minimum strength before exposing concrete to extreme cold is 500 psi (3.5 MPa).