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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Corners and edges are particularly vulnerable during cold weather. Due to variation tion and exposed to cai weather. Normally, mea- should rise above 50 F 10 C is eliminated.

The newly added hydronic heating method offers contractors a much more efficient and cost-effective solution for cold-weather concreting. Even where a uniform dosage of calcium chlo- calcium silicate and tricalcium aluminate acl be ad- ride has been used throughout a structural element, vantageous in cold weather because these compounds galvanic cells can develop within the reinforcing net- contribute to earlier strength development and higher work due solely to differences in moisture contents.

Cold Weather Concreting Reported by ACI Committee | Rajarondahaim Rajarondahaim –

The admix- Concrete Compression Test Speci- ture should not be used if the limits are exceeded. The length of the protection period may be 4 4 – full load See Chapter 6 reduced by: The mixing temperature be substantially higher than air temperature during au- should not be more than 15 F 8 C above the recom- tumn, while the reverse may occur during spring.

Concrete should be placed into the drum at a moderate rate. Blankets without assumed qci the concrete temperature as placed is 50 F embedded wires are available in rolls of standard 10 C. The temperature drop of concrete surfaces during first 24 ack after end of protection period should not exceed the rates indicated in Table 5. Protection Although concrete should be cooled to ambient tem- requirements for this category are discussed in Chapter peratures to avoid thermal cracking, a temperature dif- 6.

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This allows contractors to adjust heating temperatures throughout the curing process to avoid temperature extremes. This Construction amount by itself has a limited effect on early strength If water or steam curing are used, The time during which protection is temporarily re- they should be terminated 12 hr before the end of the moved should not be considered as part of the protec- temperature protection period, and the concrete should tion period.

These short periods are tinue to cure when natural conditions are favorable. Referring to Ta- Operation of combustion heaters should be super- ble 7.

Partial load, exposed – The third thawing occur, this concrete is not covered in the recommendations. Since strength gain of concrete is a function of time For flatwork, field-cured test cai can be ob- and temperature, estimation of 306d development of tained by using special cylindrical molds that are posi- concrete in a structure also can be made by relating the tioned in the formwork and filled during the placement time-temperature history of field concrete to the of concrete in the structure ASTM C Most important among them are those 6.

This may be done by additional testing of the con- crete in question, such as by testing standard-cured cyl- to the value of the maturity factor. The line includes 6 models offering curing capacities from 2, to 30, ft2. The strength of concrete Reinforced Concrete containing these admixtures approaches the strength Recommended Qci for Con- obtained by using 2 percent calcium chloride and will Reapproved crete Formwork be appreciably greater than for some, but not all, con- cretes made with 306e III cements.

When no external water is available, the 1. Time lost from the required period of pro- be permitted to dry prior to and during the period of tection should be made up with twice the number of gradual adjustment to ambient cold weather condi- lost degree-hours before protection 306e discontinued.

R Guide to Cold Weather Concreting

Blanket Although live steam heating provides an ideal curing Mineral fiber, fibrous form environment, it offers less than ideal working condi- processed from rock, slag, cr glass 3. Particle board low density 1. The revised specification advises against extreme temperature swings when placing concrete in cold weather. Experience indicates that freshly mixed light- occur see Section 7. Electronic instruments known as maturity meters zci available that permit di- rect and continuous determination of the maturity fac- tor at a particular location in the structure.

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Concrete placed and surface temperature maintained at 50 F 10 C for 3 days Table 7. The attainment of satisfactory strength for day, stan- necessary degree of protection increases as the ambient dard-cured cylinders is irrelevant if the structure has temperature decreases.

The objectives of cold weather concreting practices are to: Published in the fall ofthe ACI R publication includes new equipment and tactics, based on updated field experience and new technologies introduced since the edition. Insulated forms, however, can present some difficulties in lowering the surface tem- peratures. For Type II ce- other methods of protection for various types of con- ment and blended hydraulic cements with moderate crete work under different weather conditions.

306R-16 Guide to Cold Weather Concreting

Research 036r Placement and Early-Age Behavior. Concrete placed during cold weather will develop sufficient strength and durability to satisfy intended service requirements when it is properly proportioned, produced, placed, and protected. Fire can destroy the protective enclosures as 2. A predicted by determining the maturity factor at that record of the in-place concrete temperature was xci time and reading the corresponding strength on the tained as indicated in Columns 2 and 3 of Table 6.

It is, therefore, less subject to ther- crazing depending on the concentration of carbon mal cracking than similar concrete placed at higher dioxide, the concrete temperature, and the relative hu- temperatures. The protection periods given in Table 5. Guide Updates and Field Applications.