MasterSeal 501 - A surface applied capillary waterproofing system for concrete and block work


The MasterSeal 501 waterproofing system ensures a total and permanent solution to water leakage, ingress, or seepage in concrete structures or any cementitious substrate. The formation and development of insoluble crystals into water bearing capillaries and interstices effectively blocks the further passage of water. MasterSeal 501 is supplied as a powder and consists of a blend of moisture activated chemicals, high grade silica aggregates and selected cements which mixed on site to a slurry consistency with potable water.

MasterSeal 501 is applied directly to concrete, blockwork or cement renders in areas where general waterproofing is required. In powder form, the product may be used as a dry shake on horizontal construction joints. Moisture and free lime present in the substrate react with the active chemicals in MasterSeal 501 to create a continuous barrier of insoluble crystals. The crystal formation will penetrate deep into the capillary structure of the concrete, blocking capillaries and interstices from the passage of water, whilst permitting the transmission of air and water vapour, enabling the structure to breathe. Rate and penetration of crystalline development varies with the density and surface absorption of the concrete, but the crystals will penetrate to the depth to which water is present.

Where is MasterSeal 501 applied?

MasterSeal 501 is equally effective against both negative and positive water or osmotic pressure and can be applied to the internal or external surface. Wherever possible however, MasterSeal 501 should be applied to the surface with which the water is in direct contact. This will result in an accelerated rate of penetration and crystallisation into the concrete structure. After the crystallisation process has successfully waterproofed the structure, the MasterSeal 501 active chemicals remain dormant in the concrete. Any later contact with water will reactivate the sealing process.

MasterSeal 501 is designed for use on both water retaining and water excluding structures:

  • Water Retaining 
    • Water tanks / towers
    • Reservoirs
    • Water treatment work
    • Dams
    • Canals
    • Harbours
    • Concrete pipes
    • Sea defence walls
    • Bridge decks
    • Jetties
    • Pontoons
  • Water Excluding
    • Basements
    • Tunnels
    • Inspection pits
    • Foundations
    • Retaining walls
    • Lift shafts
    • Construction joints

What are the advantages of MasterSeal 501?

MasterSeal 501 offers the following advantages:

  • Provides total and permanent waterproofing properties by becoming an integral part of the structure to which it is applied. Active ingredients will not delaminate, peel off or wear away.
  • Protects concrete and reinforcement against corrosive waterborne substances.
  • Crystalline action is reactivated by contact with water providing permanent and continuous protection.
  • Effective against both positive and negative water pressure.

Product Information

Info & price request

Midrand: +27112032405 Westonaria: +27117541343
Coastal Regions: +27112032405


MasterSeal 501 TDS

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