TB-01D - DRY-BLOCK® System Technical Bulletin

DRY-BLOCK® is a system specially designed to provide concrete masonry structures with outstanding water-repellent characteristics. The DRY-BLOCK® System consists of two separate admixtures. DRY-BLOCK® Block Admixture is mixed throughout the concrete during manufacture of the concrete masonry units and DRY-BLOCK Mortar Admixture is added to the mortar. To complement DRY-BLOCK admixtures, a VOC compliant water-based, clear penetrating sealer, can be field applied to provide maximum protection to the masonry wall.

DRY-BLOCK® Block and Mortar Admixtures are chemically different and are NOT interchangeable. The differences between concrete block and mortar are extensive and a well-engineered admixture system will address the requirements of each wall component separately by providing a unique formulation for each.

On one hand, concrete block is manufactured with low-slump concrete using relatively low cement to aggregate ratios, a wide variety of aggregates, a relatively small amount of water and special curing conditions. DRY-BLOCK® Block Admixture is formulated for use in concrete masonry units and provides the block producer with a single, easy to use product that imparts water-repellency. DRY-BLOCK® Block Admixture also provides other useful benefits to manufactured low-slump concrete, like improved compressive strength and absorption properties, as well as improved “machinability” or ease of manufacturing units.

Mortar, on the other hand, is produced to a more fluid consistency with higher cement to aggregate ratios, a finer aggregate, greater amounts of water and curing under open air conditions. Taking these characteristics into account, DRY-BLOCK® Mortar Admixture is formulated to provide water-repellency and workability to the mortar. It is specifically formulated to work with concrete masonry units containing DRY-BLOCK® Block Admixture. This combination provides a wall system with water-repellent properties able to meet and exceed the most stringent industry standards.

When a DRY-BLOCK® water-repellent wall system is desired, both the block and mortar admixtures must be used. Elimination of either component will compromise the integrity of the water-repellent properties of the masonry structure and is not allowed by the DRY-BLOCK® specification.

DRY-BLOCK® Block and Mortar admixtures have successfully performed as a standalone system for years. But, if a “belt and suspenders” system is desired, then field apply a VOC compliant water-based, clear, penetrating water-repellent sealer to the exterior of the wall.

DRY-BLOCK® is a system engineered to impart superior water-repellent properties to concrete masonry assemblies. Each admixture is designed to provide the necessary properties to both the block and mortar so that the resultant wall offers a high level of performance. DRY-BLOCK® Admixtures have achieved more than 30 years of success in creating superior masonry structures.


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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.

DRY-BLOCK® 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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In Canada, 294 Clements Road, West, Ajax, Ontario, Canada L1S 3C6.


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 United States. 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: 2022-05-10