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    MasterMatrix UW 440

    Anti-washout admixture for concrete

    How does MasterMatrix UW 440 work?

    MasterMatrix UW 440 anti-washout admixture is a ready-to-use, powdered admixture specially developed for concrete placed underwater. Concrete treated with MasterMatrix UW 440 has superior resistance to washout of cement and fines.

    MasterMatrix UW 440 complies with BS 8443:2005 - Specification for establishing the suitability of special purpose concrete admixtures - Table 2 - Underwater Concrete Admixtures.

    Where to use MasterMatrix UW 440?

    MasterMatrix UW 440 admixture is recommended for all types of concrete pumped or placed underwater where thixotropic action is beneficial. It is especially helpful in extreme conditions where conventional concrete or placing techniques would result in high material loss due to washout.

    What are the benefits of MasterMatrix UW 440?

    MasterMatrix UW 440 admixture produces a concrete mixture highly resistant to washout while maintaining workability, pumpability and placeability. It also provides the following special qualities:
    • Minimal to no effect on water demand
    • Reduces or eliminates concrete bleeding
    • Workability characteristics equal to untreated concrete.
    • Virtually eliminates segregation, even with highly fluid, high water-cementitious ratio mixes
    • Reduces/eliminates costly methods of de-watering
    • Thixotropic action provides stiffening after concrete placement
    • Minimises environmental impact of cement washout in water
    • Minimal to no effect on set time

    Washout resistance 

    As determined by Annex A of BS 8443:2005 “Determination of Washout”, washout demonstrates the performance of MasterMatrix UW 440 admixture-treated concrete compared to untreated concrete. This requirement states that an anti-washout admixture must result in a washout value of less than 15% when compared to the EN 480 control mix.

    Workability retention

    Results from slump loss studies taken over 60 minutes indicate MasterMatrix UW 440 admixture does not adversely affect concrete workability retention.

    Set time

    MasterMatrix UW 440 admixture has little to no effect on concrete set time.

    Air content

    A slightly higher dosage of air-entraining admixture may be needed to achieve the desired air content when using MasterMatrix UW 440 admixture.


    MasterMatrix UW 440: Technical Data Sheet

    pdf (297.19 Kb)

    Direct contact

    For Technical Advice

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    +44 1634 848 742


    MasterMatrix UW 440: Technical Data Sheet

    pdf (297.19 Kb)