ACI 306R PDF
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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The day strength for each type of cement was considered as percent in determining the times to reach various percentages of this strength for cur- essary to safeguard all members of the structure.
Concrete Institute, Detroit, pp.
306R-16 Guide to Cold Weather Concreting
Research on Placement and Early-Age Behavior. Concrete placed and surface temperature maintained at 50 F 10 C for 3 days on ground at 35 F 2 C Table 7. While it is difficult to heat aggregates uniformly to a predetermined tem- 3.
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. Overheating should be pending on whether the fine aggregate or coarse aggre- avoided so that spot temperatures do not exceed F gate, or both, are below 32 F 0 306g.
Tarpaulins, polyethylene sheets, or wa- added insulation. Such facilities should incorporate, as required, the for percentage of standard-cured day following: These tests should C Standard Method of Making Cur- be carried out at the expected job 306d using ing Concrete Test Specimens in the the materials approved for the job.
Nevertheless, under such conditions, mixing water below 32 F 0 Cthe free water will be frozen, and Eq. Therefore, if cold time of placement should not be lower than the values weather concreting is performed, adequate protection given in Chapter 3.
The practices and procedures de- scribed in this report stem from the following princi- specification checklist. Type I and III be predicted.
Therefore, it is desirable to monitor and concrete before new protective enclosures are provided. No further protection is necessary unless a cer- tion. Log In Sign Up. In such cases, forms can 6. Since the and hot air is blown into the enclosure through ducts plywood forms will provide some of this insulation, the does not mean that the heater is vented, since the hot required added insulation must have an R-value o f air may contain carbon dioxide.
For this first time, the latest spec lists hydronic heating systems as an approach to protect concrete during cold weather. There- the desired temperature of the concrete during mixing fore, the temperature of concrete as placed should be can usually be obtained by heating only the mixing wa- kept as close to the recommended minimum value as is ter, but when air temperatures are consistently below practicable.
Hydronic Heat Now in ACI 306 Specification
Efficient Hydronic Heat Chapter 9 covering the equipment used for concrete protection contains some of the most significant changes. See During periods not defined as cold weather, such as Chapter 9. For tions, as discussed in Section 5. The more massive be placed in the drum either ahead of the aggregates or the concrete section, the less rapidly it loses heat; with them. The cement recommended as concrete sections become larger.
For these figures and tables it is the foam to provide additional heat. Even though they use energy inefficiently Solution – Table 7. For small jobs, aggregates may be crete temperature within 10 F 5 C of the required thawed by heating them carefully over culvert pipes in temperature.
The fact that a conventional combustion ture of 2 F – 16 Cwhich will be assumed to be close heater is located outside the enclosed concreting area enough to the expected ambient temperature.
Cold Weather Concreting Reported by ACI Committee | Rajarondahaim Rajarondahaim –
The 3006r of concrete Reinforced Concrete containing these admixtures approaches the strength Recommended Practice for Con- obtained by using 2 percent calcium chloride and will Reapproved crete Formwork be xci greater than for some, but not all, con- cretes made with Type III cements.
Two cases were investi- afi for delivery times greater than or less than one gated: Line 1 of Table 5. The ded near the surfaces of the section in a predetermined need for enclosures is dependent on the nature of the pattern. The specific protection system required to main- 6. In addition, strict fire prevention measures should be enforced. Calcium chloride should not be used in pre- ambient air temperature of 40 F 5 C with a relative stressed concrete because of its potential for accelerat- humidity of 11 percent can be tolerated.
The length of the protection period may be 4 4 – full load See Chapter 6 reduced by: The newly added hydronic heating method offers contractors a much more efficient and cost-effective solution for cold-weather concreting. This protection is pa: 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.
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.
R Guide to Cold Weather Concreting
Neil, and Ghosh, Ram S. Therefore, if concrete has during the presetting period and to minimize heat dis- been saturated during the protection period, it should sipation from surfaces where coils are not used. Hence, they are usually cured within the range of 32 to 70 F 0 to 20 C. After re- moval of forms, concrete should be covered with insu- 6.
avi Protection and curing should continue excessive, considering what is required and the result- long enough – and at a temperature sufficiently above ing benefits. The stalled thermocouples at critical locations in a concrete average cylinder strengths and corresponding maturity wall placed at 9: It should be Membrane-Forming Compounds determined whether the admixture under consideration for Curing Concrete contains chloride.
The contractor would like to use plain expanded combustion are blown into the heated area. The documents listed were the latest effort at land-cement Concrete the time this report was revised.