Reported by ACI Committee Nicholas J. Carino Pl. Standard Specification ACI is intended to be used by . in ACI R, “Cold Weather Concreting. The following are highlights of requirements of APWA 30 04 – 10 and ACI R Standards concerning placement of concrete in cold weather conditions . 14 Jan ACI Section states, “Take advantage of the opportunity provided by cold weather to place low temperature concrete,” then goes on.

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These temperatures should be maintained for the required protection period, as shown in Table 7. On the back end, ACI R recommends that the heat from external heating sources be reduced gradually to ambient temperatures before removing the protection.

As cold joints are more prevalent when the concrete sets faster, consider the addition of preformed construction joints within the slab, even when aci 306r slab is scheduled to be placed in a aci 306r day. Similarly, a plant may reduce the amount of accelerator in the concrete later in the day which aci 306r also reduce the concrete temperatures. Problems compound when they are not continually monitored. Depending on wci ambient temperatures, only some or all of these methods are utilized.

More exotic methods include the introduction of a network of pipes that control the internal temperature of concrete by the flow of aci 306r water through this network.

The aci 306r common methods include:. However, temperatures below 50 degrees and above 85 degrees require different concrete mixes and different weather related procedures.

The temperatures and time periods for protection are to prevent damage to the concrete by early-age freezing of the water required for cementitious hydration. The use of foggers and wet burlap are effective ways to cure slabs.

The full and complete returned product 30r aci 306r accepted if returned within 60 days of receipt and in salable condition. The most common methods used include:. It is important for field personnel to ensure that cold joints do not form during concrete placement, aci 306r they can cause significant structural problems with the introduction aci 306r shear failure planes between the layers of concrete.


This avoids the potential of the metal locally causing the concrete to freeze and thereby locally reducing the bond strength.

The addition of water to the mix would typically mitigate these issues. Fresh concrete under no load and not exposed to freeze-thaw cycles will have a minimum protection period of 2 days. This ensures adequate time for the structural engineer, contractors, and concrete producer to properly coordinate and prepare for inclement weather conditions.

The definition of when to aci 306r cold weather concrete provisions, per ACIdiffers based on the ACI edition referenced by aci 306r applicable building code. Proper curing is extremely important to reduce cracking. The newer definition requires cold weather concrete aci 306r to be enforced more often. Several factors affect this time period, aci 306r ambient temperature, the type of concrete, size of the pour and how soon the concrete will be exposed to load conditions.

Mass concreting during hot weather can be extremely challenging and is the aci 306r of a future article. For a listing of and access to all aci 306r errata, visit the Errata page. Direct heat should be avoided. Insulating blankets are used to direct heat directly into the concrete. These flexible heaters also thaw frozen ground and warm forms prior to concrete placement.

Time is required to test and practice with different temperatures and dosages and to adjust the cocktail of admixtures that form the basis of high-performance concrete today. Accelerating admixtures should be properly dosed based on aci 306r temperatures and should be adjusted throughout the concrete placement if needed.

ACI aci 306r that any surface that comes in contact with the concrete during placement should have a surface temperature above freezing. Your message Submit Comment. For a typical slab placement on a aci 306r day, the concrete needs to be at least 65 degrees while mixing and then needs to be maintained at 55 degrees once placed. Choose Product Language English. For more in-depth discussions of any of aci 306r items addressed in this article, these reports contain detailed information on the topics.

This is often achieved by tenting and covering the concrete with thermal blankets and utilizing heaters. If there are low breaks during hot or cold weather, one aci 306r the first suspects is the curing method of the cylinders.


The use of air heat requires construction of costly 306e, which must be heated in addition to protecting the concrete. Whereas aci 306r idea is theoretically sound, there are as yet no aci 306r and no big data available to provide ground rules and basic parameters for this calibration.

R Guide to Cold Weather Concreting

For a listing of and access aci 306r all product addenda and errata, visit aci 306r Addenda and Errata page. As with everything in construction, a smooth and continuous flow of operations is the difference between a project being successful and profitable or otherwise.

Because of the combustion by-products generated by direct fired heaters, they are not aci 306r for aci 306r concreting applications without first protecting the concrete. By monitoring these temperatures, this concern is proactively eliminated.

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While these chemicals provide a slight increase aci 306r the cost of the concrete, they can significantly reduce some of the costs associated with external heat aci 306r other methods. The newly added hydronic heating method offers contractors a much more efficient and cost-effective solution for cold-weather concreting.

For example, when trucks start backing up 3066r to a broken pump or for any other valid reason, sending one or two trucks away from the site may mean that the next dozen trucks stay within specifications. Unfortunately, additional water also reduces the concrete strength, aci 306r shrinkage, and causes additional cracking.

ACI R does not provide aci 306r temperatures for concrete during hot weather placement.

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Placing concrete at reduced ambient temperatures, such as night placements, can significantly ease the problems related to hot weather concreting.

Any applicable errata are included with individual documents at the time of purchase. Sep, By Cawsie Jijina, P. During cold or hot weather days, the maximum-minimum thermometer can be aci 306r to monitor the temperature 3066r the curing box.

The monitoring of concrete during hot weather is similar to that of cold weather concrete.