Efflorescence control admixture

Product Description

OPTEC® EC-935 is a liquid admixture added to the concrete during the batching process. It controls efflorescence in pavers, segmental retaining wall units and other low slump concrete products. It also provides workability, increased strengths and a tight surface texture.

Product Advantages

Reduced efflorescence
Smoother, denser surface
Set-time control
Sharper corners and edges

Product Function

OPTEC® EC-935 is recommended for use in the production of pavers, segmental retaining wall units and other products where quality, increased strengths, enhanced production and the resulting surface texture are important.

OPTEC® EC-935 is designed to reduce the efflorescence potential in concrete masonry units. OPTEC® EC-935 works in zero or low slump concrete mixes which are characteristically dry, containing only sufficient water for the hydration of the cement. OPTEC® EC-935 compensates for the water deficiency in such mixes and improves the workability of the mix.

OPTEC® EC-935 is especially beneficial when the manufacturer is producing multi-color (variegated color) concrete masonry units. OPTEC® EC-935 provides set-time control allowing the producer to better manage the production process and avoid waste.

OPTEC® EC-935 allows for better compaction of the unit with less cracking, sharper corners and edges, resulting in fewer culls. Production can be increased, absorption reduced, and appearance and texture greatly improved.

Addition Rates

OPTEC® EC-935 is used at a rate of 4-10 oz/cwt (260-650 mL/100 kg ) of cementitious material. OPTEC® EC-935 should be added separately to the mix after the initial wetting of the cementitious material or with the addition of the final mix water. Once OPTEC® EC-935 is batched, it should be mixed for a minimum of one minute, but preferably two minutes. Never add OPTEC® EC-935 to dry cement.

Dispensing Equipment

A complete line of admixture dispensing equipment is available.


OPTEC® EC-935 is available in 55 U.S. gal (208 L) drums and 275 U.S. gal (1,040 L) returnable totes.

Heath & Safety

All precautions defined on the SDS (Safety Data Sheet) for OPTEC® EC-935 must be followed.


OPTEC® EC-935 must be protected from freezing at temperatures of 32°F (0°C) and below, as the admixture is not usable once frozen.


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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 donot 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.

OPTEC is a trademark, 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.

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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