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 exhibits 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.

What is MasterMatrix UW 440 used for?

MasterMatrix UW 440 admixture is recommended for use in all types of concrete pumped or placed underwater, where thixotropic action is desired. MasterMatrix UW 440 admixture is especially helpful in extreme conditions where conventional concrete or placing techniques would result in a high percentage of 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. The following special qualities are also provided:

  • 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 is placed.
  • Minimises environmental impact of cement washout in water.
  • Minimal to no effect on set time.

Washout resistance - Washout as determined by Annex A of BS 8443:2005 “Determination of Washout”, reports the performance of MasterMatrix UW 440 admixture treated concrete compared to untreated concrete. This requires 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 a 60 minute period 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 required to achieve the desired air content when using MasterMatrix UW 440 admixture.

Direct contact

Ian Ellis

Technical Services Manager

+44 7966 123447


MasterMatrix UW 440: Technical Data Sheet

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