Hot weather concreting

Hot weather concreting

Do you live where it is hot most of the time of the year and you might need to pour a slab when it’s at the hottest? Or maybe it’s just regular hot summer and your project can’t wait and you’re looking for helpful tips?

There are times when it’s too hot and times when it’s too cold. Sometimes we just have to work in unfavorable situations and make the best of it.

For that reason, here is a guide and tips on hot weather concreting.

Concreting at hot temperatures

When you are working with concrete in hot weather, you need to alter your methods to hot-weather concrete techniques. This is important when concrete that is freshly mixed may be compromised because of high and rapid moisture loss as well as accelerated hydration of cement.

Not many who mostly deal with cold weather concreting know about these things. There are factors that come into the picture when hot weather concreting. Such factors as high concrete temperature, high ambient temperatures, wind speed, solar radiation, and low humidity.

Generally, a good thing to keep in mind is to begin thinking about hot weather concreting when the concrete temperature and the air becomes higher than eighty degrees Fahrenheit.

Aggregate use

Ready-mix suppliers aim to get the concrete you are working with as cool as it can before going to the job site. Aggregate does have a big effect on the temperature of the concrete and the supplier normally shades the piles of aggregate.

Water that is cool will also be utilized to reduce the temperature of the concrete even further. Some suppliers of concrete in climates that are hot use chilled ice or water to create a lower concrete temperature.

Retarding admixtures

Utilizing retarding types of admixtures is one way to control the concrete temperature in the months of summer when it is warm and sunny. Retarders are added to the job site since these increase the setting time of the concrete greatly. Make sure you remember that curing is very critical when you are utilizing retarders.

In addition, a retarder admixture you can use is of the reducing water variety. Water reducers that are mid-range increase the concrete’s air content. Keep in mind that if too much retarder is used, your slabs may start to crust.

Hydration control admixtures

Hydration controlling admixtures are used for controlling the hydration process. It’s different from concrete retarders in a way that once it wears off, the concrete starts curing slowly.

Retarders set quickly when they wear off so HCA is better in that sense when we think about hot temperatures and if we want the concrete to start setting at night for example.

You can use hydration control admixtures in hot weather that is extreme, or when the concrete needs to travel a very long distance to the job site from the supplier. Suppliers of the ready mix can also add this type of material in order to delay setting up by as much as 5 hours.

Fly ash

Fly ash is used as supplementary cementitious material. When it’s used in concrete, less portland cement is needed. It can be used to control temperature rise so it has a good application in this case.

You can utilize fly ash to slow down concrete setting times. This could change the concrete color. If you do not alter the fly ash percentage in your shipment, you can end up with discolored concreting supplies. Fly ash is also not effective in temperatures that are higher.


The ideal condition is that you need to put your concrete in place during the early evening in the warm summer months. Make sure that the crew you have and their equipment are ready to begin working as soon as the concrete arrives on the site.

This is because the temperature of the concrete can considerably increase by waiting in the truck before you start working with it. Just imagine having your soda in a metal tube on hot summer day.

Be sure to protect concrete from the sun. Using sunshades can be useful as you avoid direct sunshine on the wet surface. You need to keep your equipment and tools shaded especially if it will hit the concrete directly.

Concrete surface curing too fast might lead to concrete dusting and crumbling. It’s usually something that customers will not be happy about so if it can be avoided, it should.

If you are laying concrete for exteriors on a sub-grade, ensure that you spray all the elements using cold water. This includes the different kinds of sub-grades, even before concrete installations. This will protect the forms and the sub-grade from water absorption from the concrete itself.

Once the concrete is set and is bull-floated, utilize a retarder for evaporation or a film that is monomolecular in order to slow down the process of evaporation and retaining the water on the surface.

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