Set retarding admixture ASTM C494 Type B and D
Daratard® 17 admixture is a ready-to-use aqueous solution of hydroxylated organic compounds. Ingredients are factory pre-mixed in exact proportions to minimize handling, eliminate mistakes and guesswork. Daratard 17 admixture weighs approximately 10.2 lbs/gal (1.17 kg/L).
Daratard 17 retards the initial and final set of concrete. At the usual addition rate of 3 fl oz/100 lbs (195 mL/100 kg) cement, it will extend the initial setting time of Portland cement concrete by 2 to 3 hours at 70 °F (21 °C). Daratard 17 is used wherever a delay in setting time will insure sufficient delivery, placement, vibration or compaction time, such as in:
- Hot weather concreting
- Transit mix concrete
- Prestressed concrete
- Daratard 17 is also used in special applications, as in bridge decks where it extends plastic characteristics of the concrete until progressive deflection resulting from increasing loads is completed.
Addition rates for Daratard 17 will range from 2 to 8 fl oz/100 lbs (130 to 520 mL/100 kg) of cement. The amount to be used will depend upon the degree of retardation required under job conditions. Longer setting times or higher temperatures will require higher addition rates. Conversely, the addition rate will be lower for shorter extensions of time.
Compatibility with Other Admixtures and Batch Sequencing
Daratard 17 is compatible with most GCP admixtures as long as they are added separately to the concrete mix, usually through the water holding tank discharge line. In general, it is recommended that Daratard 17 be added to the concrete mix near the beginning of the batch sequence but after the cement and water is combined for optimum performance. Different sequencing may be used if local testing shows better performance. Please see GCP Technical Bulletin TB-0110, Admixture Dispenser Discharge Line Location and Sequencing for Concrete Batching Operations for further recommendations.
Pretesting of the concrete mix should be performed before use, as conditions and materials change in order to assure compatibility, and to optimize dosage rates, addition times in the batch sequencing and concrete performance. For concrete that requires air entrainment, the use of an ASTM C260 air-entraining agent (such as Daravair® or Darex® product lines) is recommended to provide suitable air void parameters for freeze-thaw resistance. Please consult your GCP Applied Technologies representative for guidance.
Packaging & Handling
Daratard 17 is available in bulk, delivered by metered tank trucks, totes and drums.
Daratard 17 will freeze at about 28 °F (-2 °C), but will return to full strength after thawing and thorough agitation.
A complete line of accurate, automatic dispensing equipment is available. Daratard 17 may be introduced to the mix with the sand or with the water.
Concrete shall be designed in accordance with Standard Recommended Practice for Selecting Proportions for Concrete, ACI 211.1.
The set-retarding/water-reducing admixture shall comply with ASTM Designation C494, Type D admixture, and shall be Daratard 17, as manufactured by GCP Applied Technologies, or equal. Certification of compliance shall be made available on request. It shall be used in strict accordance with the manufacturers’ recommendations.
The addition rate shall be adjusted to produce the specified retardation of the concrete mix at all temperatures.
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Last Updated: 2021-02-05