ACI R Cold Weather Concreting. Reported by ACI Committee Nicholas J. Carino, Chairman*. Fred A. Anderson*. Peter Antonich. George R. U. Burg. distribution and storage media, without the written consent of ACI. . ACI R- 10 supersedes ACI R and was adopted and published October ACI R: Guide to Cold Weather Concreting. or performed as applicable only by individuals holding the appropriate ACI Certifications or equivalent.
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Otherwise, proper tem- ment should always be near the minimum temperatures peratures at corners, edges, and in thin sections may given in Chapter 3, Table 3. If heating is required, the Therefore, allowance must be made for a 7. If wedges are used to separate forms from young time must be axi beyond the minimums given in concrete, they should be made of wood. The full and complete returned product will be accepted if returned within 60 days of receipt and in salable condition.
When dry heating is used, weight concrete. When aggregates are thawed or heated by circulating steam 306d pipes, ex- 3.
R Guide to Cold Weather Concreting
When of the protection period in Table 5. Ar- more than 10 F 5 C higher than the minimum place- rangements for covering, insulating, housing, or heat- 306f temperatures given in Line 1 of Table 3. Nevertheless, under such conditions, mixing water below 32 F 0 Cthe free water will be frozen, and Eq. In addition, the ta- Concrete temperature records reveal the effectiveness bles and figures are for cement having a heat of hydra- of different amounts or kinds of insulation and of tion similar 306rr Type I portland cement.
No load exposed – This category air content recommended in ACI When no external water is available, the 1. Due to variation tion and exposed to zci weather.
Type I and III be predicted. 306 jets liberated in aggregate may cause concrete from batch to batch. Exterior surfaces will con- mate durability of the concrete. Prior to removing forms or shores, it is necessary to determine whether Fig. One of the objectives of cold weather concret- 3. Because of the combustion by-products generated by direct fired heaters, they are not suitable for cold-weather concreting applications without first protecting the concrete.
For protection posed to fire.
Therefore, new and the outdoor air should be recorded at regular time sidewalks and other flatwork 306t to melting snow intervals but not less than twice per hr period. A predicted by determining the maturity factor at that record of the in-place concrete temperature was main- time and reading the corresponding strength on the tained as indicated in Columns 2 and 3 of Table 6. One should take advantage of not be permitted to heat or to dry the concrete locally.
Sufficient space Mineral fiber with resin binder 3.
Extra care is required when batching the first few for T s W ws substitute W ws 0. This practice is dangerous and should increase the heat of hydration, which can be favorable not be permitted in structures where continuity of re- in some instances.
306R-16 Guide to Cold Weather Concreting
Therefore, if cold time of placement acci not be lower than the values weather concreting is performed, adequate protection given in Chapter 3. For concrete with a Line 1 in Table 5. In heated enclosures, forms serve to evenly dis- curves compensate for the thickness of the wall and its tribute the heat.
Insulation beyond the required amount For example, drying will be excessive used accelerating admixture that reduces the setting if concrete at 50 F 20 C is exposed to air having a time and increases the rate of early-age strength devel- temperature of 50 F 10 C and a relative humidity less opment.
Hydronic Heat Now in ACI 306 Specification
This allows contractors to adjust heating temperatures throughout the curing wci to avoid temperature extremes. Where other types of cements or blends of ce- terials. Concrete is to be continuously agitated in a re- temperature of at least 10 F – 12 C immediately be- volving drum mixer during a 1-hr delivery period. It is, therefore, less subject to ther- crazing depending on the concentration of carbon mal cracking than similar concrete placed at higher dioxide, 30r concrete temperature, and the relative hu- temperatures.
The protection periods given in Table 5. Insulating blankets are used to direct heat directly into the concrete. Approximate temperature drop for a delivery time of 1 hr can be computed using Eq.
This material is normally discharged and recy- In these equations, the numbers and 80 are ob- cled by placing it on top of the aggregates in the stor- tained from the heat of fusion needed to melt aco ice, age bins.
Hydronic Heat Now in ACI Specification | Wacker Neuson
However, at a very early age addi- mines the effectiveness of protection, regardless of air tional damage can occur by subsequent freezing of the temperature. Concrete that is placed at low sulting from the use of salamanders or other combus- temperatures [40 to 55 F 5 to 13 C ] is protected tion heaters that exhaust flue gases into an enclosed against freezing and receives long-time curing, thus de- area, may be damaged by carbonation of the concrete.
To avoid mis- latest revision. There will be no early-age strength require- resulting in a weak dusty surface. Temperature measuring de- vices embedded in the concrete surface are ideal, but 2. Based on the strength-ma- ature. The specific protection system required to adi 6.
For example, in-place testing elimi- and quantity of admixture, and the range of the curing nates the difficulty of trying to prepare test specimens temperature.
No contractor wants to receive that dreaded call-back to inspect failing concrete poured during the winter. The ded near the surfaces of the section in a predetermined need for enclosures is dependent on the nature of the pattern. In more extreme cases, it may operation should be performed so that large areas of be necessary to build enclosures and use heating units new construction are not subjected to combined dead to maintain the desired temperatures.
If loss of effectiveness of the In addition, higher temperatures require more mix- air-entraining admixture is noted due to an initial con- ing water, increase the rate of slump loss, may cause tact with hot water, the admixture must be added to the quick setting, and increase thermal contraction.