Concrete Pour at High Temperature
Concrete Pour at High Temperature
(OP)
Hi
Is it harmful, if freshly poured concrete is subjected to 40 to 50 degrees celcius during its curing period?
Does anybody think I should be using retarder in the mix?
Thanks guys
Is it harmful, if freshly poured concrete is subjected to 40 to 50 degrees celcius during its curing period?
Does anybody think I should be using retarder in the mix?
Thanks guys





RE: Concrete Pour at High Temperature
RE: Concrete Pour at High Temperature
RE: Concrete Pour at High Temperature
ACI 305R Hot Weather Concreting
RE: Concrete Pour at High Temperature
RE: Concrete Pour at High Temperature
RE: Concrete Pour at High Temperature
Assuming it is ready-mix concrete, then that temperature range greatly exceeds the typical limits of ASTM C94.
We have had to go to nitrogen cooling and other means (ice replacing mix water) in temperatures that were not nearly as high as 50C, just to keep the concrete properties within reason.
RE: Concrete Pour at High Temperature
We are replacing a 12-inch top slab with a 10-inch slab (19' x 13')for a steam manhole on existing walls. Live Steam piping within manhole at time of pour. Currently, temperature inside manhole with the existing top slab is about 50 degrees that is why I am assuming the same temperature for the pour and curing period.
By the way, is it correct to assume that concrete gains 2 MPa compressive strength per day after it's poured? i.e. 20 MPa after 10 days........
Thanks
RE: Concrete Pour at High Temperature
I assume no steam is released, so humidity is relatively low? can you place insulation over the steam lines prior to pouring the concrete? Can you ventilate the space through the manhole opening? You might also be concerned with the temperature differential between the inside and the outside during the curing period. What is the ambient temperature outside of the vault? Is it much cooler than 50?
RE: Concrete Pour at High Temperature
RE: Concrete Pour at High Temperature
RE: Concrete Pour at High Temperature
Mass concrete requires cooling for placement in the normal temperature range, because of the heat generated through hydration is much higher than the ambient temperature. Without cooling, the crust sets much faster than the core, resulting in random shrinkage cracks, and affecting durability of the concrete.
In cold region, the mixing water and aggregates need to be heated, and the finished surface needs to be covered to avoid freezing.
In hot region, fast vaporization is the culprit, especially on a dry, breezy day (On the other hand, humid, airless day helps fresh concrete mix to hold on to the surface water). Here again, with proper surface protection to avoid escaping of surface water, the high temperature itself hardly has any effect on concrete curing. However, the temperature differential between day and night colud be crucial, which shall be take into account when selecting curing method.
I don't think any chemical additive would do better than a good planning on curing/surface protection technique.
RE: Concrete Pour at High Temperature
The autoclave is the ultimate curing method,but is limited to certain size and shape elements and is not possible on a job site. - Absolute control of the moisture and temperature.
For a construction site, do not be mislead by the air temperature since the controlling factor is the temperature of the concrete, assuming the mix is an ordinary mix using ASTM spec cement and admixtures and not the highly research materials, cements and admixtures designed for site work.
Uber accelerated conditions. the strength gain can be measured in psi per hour and not per day. Your conditions are not normal and it appears you are trying to use a conventional fot that application, so you should use the traditional limitations and guidelines. Concrete cylinders will give no meaningful information.