Water-reducing admixture -- ASTM C494 Type A and D
ZYLA® 625 water-reducing admixture is a proprietary formulation incorporating polycarboxylate and highly purified specialty organic chemicals. It promotes more complete hydration of Portland cement and has minimal effect on concrete air entrainment. The ZYLA® product line of water reducers is specially formulated to have a synergistic effect with polycarboxylate-based mid-range and high-range water reducers that improve flat-work finishability. This product is manufactured under rigid controls that provide uniform, predictable performance.
ZYLA® 625 water reducer is supplied as a light brown, low viscosity liquid, and is ready-to-use as received. One gallon weighs approximately 9.1 lbs (1.09 kg/L). This product meets the requirements of Specification for Chemical Admixtures for Concrete, ASTM Designation C494 as a Type A and D admixture. Please consult your GCP representative for guidance on the ZYLA® product line.
- Minimal impact on concrete air content
- Better control of water reduction and setting times as compared to traditional lignin-based water reducers
- Synergistic performance of polycarboxylate-based mid-range and high-range water reducers, which include water reduction, concrete strength and air control
- In the hardened state, improves the compressive and flexural strengths at all ages of concrete versus traditional lignin-based water reducers
ZYLA® 625 water reducer is used to produce concrete mixes with lower water content (typically 3% to 10% reduction), greater plasticity and higher compressive strengths. It is suitable for normal weight and light weight concrete in ready-mix, precast and prestressed applications.
The unique chemistry of ZYLA® 625 product positively impacts the finishability of concrete by providing a creamier and more homogenous texture, with more uniform bleed rate relative to traditional lignin-based water reducers. The influence of ZYLA® 625 product on the finishability of lean mixes has been particularly noticeable. Floating and troweling, by machine or hand, imparts a smooth, close tolerance surface.
The addition rate range of 3 to 5 fl oz/100 lbs (195 to 325 mL/100 kg) of cement or cementitious is typical for most applications. However addition rates of 2 to 10 fl oz/100 lbs (130 to 652 mL/100 kg) of cement or cementitious may be used if local testing shows acceptable performance. Pretesting is required to determine the appropriate addition rate for desired performance. The optimum addition rate depends on the other concrete mixture components, job conditions, and desired performance characteristics.
Compatibility with Other Admixtures and Batch Sequencing
ZYLA® 625 water reducer is compatible with most 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 ZYLA® 625 admixture be added to the concrete mix near the end of the batch sequence 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. ZYLA® 625 water reducer should not come in contact with any other admixture before or during the batching process, even if diluted in mix water.
Pretesting of the concrete mix should be performed before use, and 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 representative for guidance.
Packaging & Handling
ZYLA® 625 water reducing admixture is available in bulk, delivered by metered tank trucks, in 275 gal (1,040 L) totes, and in 55 gal (210 L) drums. It will freeze at about 28°F (-2°C), but will be completely uniform after thawing and thorough agitation.
A complete line of accurate, automatic dispensing equipment is available. ZYLA® 625 product may be introduced to the mix through the water holding tank discharge line. The ZYLA® product line is formulated to be free of sediment.
Concrete shall be designed in accordance with Standard Recommended Practice for Selecting Proportions for Concrete, ACI 211.
The water-reducing admixture shall be ZYLA® 625, as manufactured by GCP Applied Technologies, or equal. The admixture shall not contain calcium chloride as a functional ingredient. ZYLA® 625 admixture will not promote corrosion of reinforcing steel embedded in concrete. It shall be used in strict accordance with the manufacturers’ recommendations. The admixture shall comply with ASTM Designation C494, Type A and D water-reducing admixtures. Certification of compliance shall be made available on request.
The admixture shall be delivered as a ready-to-use liquid product and shall require no mixing at the batching plant or job site.
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Last Updated: 2022-05-06