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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Rapid batch after the water 3066r has been reduced by moisture loss from exposed surfaces of flatwork may contact with the cooler solid materials. Initial loosening of forms away from the with their design strengths and will have an opportu- concrete and covering with polyethylene sheets to allow nity for additional strength development prior to the some air circulation can alleviate the problem.
With regards ai external heating sources, it more clearly defines combustion heaters by breaking them into direct fired and indirect fired types. Some should be exceeded as little as is practicable. Wenzel The general requirements for producing satisfactory concrete during Chapter 3 – Temperature 306g concrete as mixed cold weather are discussed, and methods for satisfying these require- and placed and heating of materials, p.
306R-16 Guide to Cold Weather Concreting
In to determine the level of strength development. However, water curing is not recommended and the entire recommended protection period. Seasonal variations must be increased to offset the heat lost in the interval be- be considered, as average aggregate temperatures can tween mixing and placing.
Example 1, the concrete will be delivered within 1 hr and the drum will not be revolved except for initial 4. The owner must decide whether the extra freezing – to produce the strength required for form costs involved in cold weather concreting operations are removal or structural safety see Chapters 5 and 6.
Insulated forms, 306, can present some difficulties in lowering the surface tem- peratures. If wedges are used to separate forms from young time must be provided beyond the minimums given 30r6 concrete, they should be made of wood. For this reason, early strengths high enough to ter-reducing and accelerating. To permissible only when: 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 C.
This preferable to testing field-cured specimens prepared ac- value may not be applicable to other types of cements cording to ASTM C Concrete temperatures must be monitored so that the recommended values are not exceeded. If chloride is present, the percentage C Standard Specification for Chemi- of chloride, by weight of cement, that would be intro- cal Admixtures for Concrete duced into the concrete if the admixture were to be used C Standard Method of Making, Ac- should be determined and compared with the permis- celerated Curing, and Testing of sible limits given in ACIor ACI Urethane foam should be used with caution thermal resistance R, for different cement contents, and because it 306e highly noxious fumes when ex- for protection periods of 3 or 7 days.
The stalled thermocouples at critical locations in a concrete average cylinder strengths and corresponding maturity wall placed at 9: What should be the haust gases are vented from the firebox to the outside thickness of the polystyrene boards?
After thawing is completed, the balance of the materials before and after mixing and b y steam supply can be reduced to the minimum that will assuming that the specific heats of 306rr cement and ag- prevent further freezing, thereby reducing to some ex- gregates are equal to 0.
R Guide to Cold Weather Concreting
The next time you pour concrete in cold weather, protect it with efficient and easy-to-use hydronic heaters from Wacker Neuson Climate Technology. Interior portions of these thereby assure 036r there is no impairment to the ulti- structures are self-curing. Materials should be heated uniformly since considerable variation in their for T a W wa substitute W wa 0. This ence the same temperature history as the structure. Therefore, if concrete ac 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.
Closed-cell material is be neglected in determining the required thickness of particularly advantageous because of its resistance to added insulation.
The newly added hydronic heating method offers contractors a much more efficient and cost-effective solution for cold-weather concreting. To use this tech- inders at early ages, by using accelerated strength tests nique, a strength versus maturity factor curve is estab- as described in ASTM Cby testing field-cured cyl- lished by performing compressive strength tests at var- inders for which the maturity factor has been moni- ious ages on a series of cylinders made with concrete tored, or by using one of the in-place tests listed in 6.
A copy of the tempera- surface will have a lower strength and may be prone to ture readings should be included in the permanent job dusting and subsequent freeze-thaw damage if exposed. Based on the strength-ma- ature.
Aci 306 Cold Weather Concreting Books
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. 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.
Unless the work area is housed, this work should be done immediately prior to concrete place- Thus provisions must be made for a concrete tempera- ment to prevent refreezing. As anticipated load increases and concrete is exposed to freeze-thaw cycles, the protection period can be as many as 6 days.
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.