MIRA® 85

Mid-range water-reducing admixture ASTM C494 Type A and F

Product Description

MIRA® 85 is a mid-range water reducer specifically formulated to produce concrete with enhanced finishing characteristics and neutral set times. It provides superior water reduction and versatile mid-range water reducer performance across a wide range of concrete slump requirements.

MIRA® 85 is an aqueous solution of complex organic compounds, each of which contributes uniquely to the concrete’s final properties. It is manufactured under rigid control which provides uniform predictable performance. MIRA® 85 contains no calcium chloride. It is supplied as a dark brown, low viscosity liquid. One gallon weighs 10.41 lbs (one liter weighs approximately 1.25 kg).

Product Advantages

MIRA® 85 offers significant advantages over conventional water reducers. Laboratory and field work has consistently demonstrated:

  • Superior workability and finishability. The exceptional water-reducing capabilities allow for production of high quality, workable concrete with better water retention, internal cohesiveness and placement properties. Formulated with proven finishing enhancing components, MIRA® 85 controls bleeding while bringing the mortar to the surface. MIRA 85 is recommended for lean harsh concrete mixes to improve paste quality pumpability and finishability. Floating and troweling, by machine or by hand, easily imparts a smooth, close tolerance surface with less machine time and labor
  • Neutral setting times. MIRA® 85 provides neutral setting times throughout its recommended dosage range. Therefore, concrete can be produced with excellent workability [5 to 8 in. (125 to 200 mm) slumps] without extending set times.
  • Superior strength performance. Concrete manufactured with MIRA® 85 shows superior compressive and flexural strength development at all stages.


MIRA® 85 is recommended for residential and commercial flatwork and formed concrete surfaces including ready-mix, job site, precast and concrete paving plants for normal and lightweight concrete. MIRA® 85 imparts a “slickness” to the surface of the concrete which is highly desirable for slipformed placements.

MIRA® 85 is also highly effective to improve paste quality in lean, harsh mixes and concrete containing fly ash and GGBF slag. MIRA® 85 produces concrete with improved placement properties including improved pumpability. It yields a less permeable concrete that is more resistant to damage from freeze-thaw exposure.

Addition Rates

The typical addition rate range of MIRA® 85 is 3 to 12 fl oz/100 lbs (195 to 780 mL/100 kg) of cementitious material. Addition rates may vary depending on materials, job conditions and desired performance characteristics. Please consult your GCP Applied Technologies representative for information and assistance.

Compatibility with Other Admixtures and Batch Sequencing

MIRA® 85 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 MIRA® 85 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.

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. Due to a synergistic effect between MIRA® 85 and air-entraining agents, the amount of air-entraining agent may be reduced by 25 to 50% when added to concrete that contains MIRA 85. Please consult your GCP Applied Technologies representative for guidance.

Packaging & Handling

MIRA® 85 is available in bulk, delivered in metered tank trucks, or in totes and drums.

MIRA® 85 will freeze at approximately 18°F (-8°C), but will return to full strength after thawing and thorough mechanical agitation.

Dispensing Equipment

A complete line of accurate, automatic dispensing equipment is available. MIRA® 85 may be added to the concrete mix on the sand or in the batch water.


Concrete shall be designed in accordance with Standard Recommended Practice for Selecting, Proportions for Concrete, ACI 211.

This water-reducing admixture shall be a mid-range waterreducing admixture such as MIRA® 85 as manufactured by GCP Applied Technologies. The admixtures shall not contain calcium chloride. It shall meet the requirements of Specification for Chemical Admixtures for Concrete, ASTM C494 as a Type A (Water Reducing) and Type F (Water Reducing, High Range) admixture. Certification of compliance shall be made available upon request.

The admixture shall be delivered as a ready-to-use liquid product and shall require no mixing at the batching plant or at the job site.

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We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right. 

MIRA, DARAVAIR and DAREX are trademarks, which may be registered in the United States and/or other countries, of GCP Applied Technologies, Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status. 

© Copyright 2018 GCP Applied Technologies Inc. All rights reserved.

GCP Applied Technologies Inc., 2325 Lakeview Parkway, Suite 450, Alpharetta, GA 30009, USA
GCP Canada, Inc., 294 Clements Road, West, Ajax, Ontario, Canada L1S 3C6.
This document is only current as of the last updated date stated below and is valid only for use in the Canada. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on www.gcpat.com. Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2023-06-29