Mvra 900 Admixture

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Nell Barreto

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Aug 3, 2024, 4:31:38 PM8/3/24

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NRCA's Technical Services Section has been receiving inquiries regarding the use and effectiveness of specific concrete mix additives and topical surface treatments to address moisture release-related concerns with concrete roof decks. Such admixtures broadly are referred to as moisture vapor reduction admixtures (MVRAs) or porosity-inhibiting admixtures. NRCA provides recommendations regarding their use.

Concrete admixtures intended as MVRAs are specific chemicals added during concrete's batching and mixing to provide an additional chemical reaction during the concrete's hydration and curing process. MVRAs use the concrete mix's excess water and chlorides to create a calcium silicate hydrate gel within the concrete. The gel is said to fill the small pores and capillary openings in curing concrete, minimizing the concrete's ability to pass and release moisture vapor. The gel is intended to be permanent and integral throughout the concrete's entire thickness.

MVRAs are available from several manufacturers and typically are added to a concrete mix at the concrete batch plant separately from the addition of any other admixtures. Some MVRA manufacturers permit their MVRAs to be added to concrete mixers at job sites provided a concrete mixer's drum is rotated for a manufacturer's recommended minimum amount of time after dosage and before concrete discharge and placement. Recommended MVRA dosages typically range from about 10 to 14 ounces per 100 pounds of cementitious materials.

MVRAs reportedly have been used successfully to address moisture release affecting flooring covering applications over concrete slabs on grade and intermediate floor levels. To attempt to address the roofing industry's concerns with moisture release from concrete roof decks, several MVRA manufacturers are promoting the use of MVRAs in concrete roof decks.

Several manufacturers also are promoting the use of spray-applied, porosity-inhibiting, topical surface treatments intended to function and perform similarly to MVRAs. Such surface treatments are applied after concrete placement and reportedly penetrate concrete to seal the concrete's surface to minimize the passage of moisture vapor. The depth of surface treatment penetration into concrete depends on several factors, including the specific type and amount of surface treatment being used and the concrete's surface porosity at the time of surface treatment application.

Designers' and general contractors' interest in specifying the use of MVRAs and porosity-inhibiting surface treatments are their acknowledgement and attempt to address moisture release-related concerns with concrete roof decks.

However, though MVRAs and porosity-inhibiting surface treatments may perform successfully in concrete slab on grade and intermediate floor level applications, concrete roof decks experience fundamentally different conditions.

Environmental conditions (temperature and humidity) above and below a building's intermediate floor slabs typically are about the same because these conditions are controlled by the building's HVAC system. As a result, there usually is little to no vapor pressure drive through floor slabs.

Conversely, with concrete roof decks the environmental conditions on the bottom side (interior) of a roof deck differ from those on the top side (exterior), resulting in measurable vapor pressure drive through roof decks. The magnitude and direction of this vapor pressure drive will change with weather conditions.

For MVRAs and porosity-inhibiting surface treatments to perform successfully in concrete roof deck applications, they need to be able to withstand the magnitude and direction of vapor pressure drive a roof assembly will experience during its service life. NRCA is not aware of any data documenting MVRAs' or porosity-inhibiting surface treatments' abilities to withstand these roof assembly conditions. There is anecdotal evidence and field experience to the contrary.

NRCA maintains its recommendation that designers specify a vapor retarder with high bond strength be adhered directly to newly placed concrete roof decks. This also applies to concrete roof decks on which MVRAs or porosity-inhibiting surface treatments are used. Roof system designs using mechanical fasteners penetrating vapor retarders should be avoided.

Additional information about concrete roof decks and moisture-related concerns is contained in Chapter 2-Roof Decks of The NRCA Roofing Manual: Membrane Roof Systems, which is available as a free download for NRCA members at shop.nrca.net.

Also, during the 2019 International Roofing Expo, which will be held Feb. 11-13 in Nashville, Tenn., NRCA will present the latest findings from its concrete moisture research at the NRCA Technical Operations Committee: Technical Programs and Issues program.

Barrier One Concrete Admixtures sets the standard for concrete enhancement, with a full range of admixtures designed to reduce moisture vapor and inhibit porosity. All of our concrete admixtures are extensively tested in independent laboratories to ensure quality and repeatable performance in every application.

ISE Logik Industries
Concrete moisture vapor reduction admixture (MVRA) added directly to the ready mix concrete. MVRA 900 permits architects and engineers to address proactively concrete moisture in the design phase at a fraction of the cost in time and money it would take after the placement and curing of concrete.

4specs Discussion Forum - Great place to ask questions about specifications, products and technical data. Free - no registration required to read or post (subject to moderation).

Our MVRA admixture in Adelaide is ideal for the flooring industry, as it enables the laying of commercial flooring within 14 days of the concrete pour. This means you can complete your project faster and more efficiently, without compromising quality or performance. Whether you are working on a residential, commercial, or industrial project, MVRA admixture in Adelaide can help you achieve optimal results that meet the highest standards.

CLEVA CRETE are a South Australian, independent, and privately owned company specialising in waterproofing admixtures for the construction industry in the commercial, infrastructure, military and government sector. We have over 10 employees, several private contractors, and a robust growth strategy.

Our technology disrupts normal capillary formation, delivering a proven solution where ultra-low permeability and superior long-term shrinkage reduction is required. The admixtures that we offer, lower the heat of hydration, reduce slab curl, add durability and longevity to your concrete structure and greatly reduce the risk of early onset concrete cancer.

Gianni Vial, who has been pouring concrete for 25 years, shares his experience with using CLEVA CRETE 842 MVRA for the Adelaide High School Project. His comments include his initial hesitation, the outcome, and advantages of using our admixture as well as his thoughts on using this admixture for future projects.

Project Manager Andrew Cundle shares his experience utilising 842 MVRA in the four storey building in Adelaide CBD. The most value that BADGE received from using our admixture is the cost and time benefit. As they did not need a moisture barrier which cost them 5x the price, they had an average saving of $20per sqm which equated to thousands of dollars across a 4- storey build. In terms of time, they were able to deprop and move onto the next level faster and lay flooring 14 days following the pour.

Site manager Steve Wesbroom, along with Joe Parisi, shared their experience using both the 842 MVRA admixture and the 842 WP admixture. They used 842 MVRA for the ground slab and the WP for the plant room, to ensure no moisture ingress or egress was possible. His comments reflect his experience with us and how the concreters found it working with the CLEVA CRETE admixtures.

The state of Mississippi's new Department of Public Safety building benefited from the use of the Assurance LWC system. Lightweight aggregate brought cost savings and a higher fire rating to the structure, while the MVRA 900 admixture ensured flooring contractors were able to move quickly without concerns about lingering moisture affecting the adhesives.

Admixtures are ingredients in concrete mix designs that are used to alter the properties of the concrete. Different types of admixtures can be used to change the concrete's viscosity, permeability, set time, water requirements, and more.

On this page, you can learn about different types of concrete admixtures and how they are used. Click on any of the admixture types listed below to see all of the GCP products and technical documents related to it.

The primary use of CONCURE SYSTEMS Admixture is for waterproofing new on-grade, below-grade concrete slabs and elevated decks. This type of admixture takes the guesswork out of where to use a vapor retardant

CONCURE SYSTEMS is added at the concrete batch plant or jobsite at a rate of 14oz (397 g) per 100 lbs. of cementitious. Additional dosage may be required for an increase in high early strength benefits.

The accuracy of measurement of any admixture should be within plus or minus 3%. Two or more admixtures may be used in the same concrete batch, provided such admixtures are added separately and that the combination has no deleterious effect on the concrete.