MasterSeal® 501 – Surface Applied Capillary Waterproofing Coating for Concrete and Mortar | MCT CHEMICALS

Product Description
MasterSeal 501 is a waterproof coating designed to provide a permanent solution to water leakage, infiltration, or seepage in concrete structures or any cement-based substrate. It works by forming insoluble crystals within water-bearing capillaries, which effectively block the passage of water, ensuring lasting water tightness throughout the structure’s life.

MasterSeal 501 is supplied as a powder, which is mixed with water to create a slurry consistency for application. It can be directly applied to concrete, blockwork, or cement renders in areas requiring general waterproofing. In its powder form, it may also be used as a dry shake on horizontal construction joints.

Typical Applications

• Water Retaining Structures:
  • Water tanks/towers
  • Reservoirs
  • Swimming pools
  • Water treatment plants
  • Dams
  • Canals
  • Harbours
  • Concrete pipes
  • Sea defense walls
  • Bridge decks
  • Jetties
  • Pontoons
• Water Excluding Structures:
  • Basements
  • Tunnels
  • Foundations
  • Retaining walls
  • Inspection pits
  • Lift shafts
  • Construction joints

Standard

• BS 1881 Part 124: 1988

Advantages

• Provides complete and permanent waterproofing by becoming an integral part of the substrate. The active ingredients will not delaminate, peel, or wear away.
• Protects concrete and reinforcing steel from corrosive waterborne elements.
• The crystalline reaction is reactivated upon contact with water, offering ongoing protection.
• Effective against both positive and negative water pressure.
• Non-toxic and non-tainting.

Packaging
MasterSeal 501 is supplied in 25kg paper bags.

Coverage

• Two-coat slurry application: 0.8–1 kg/m² per coat
• Dry shake application (unmixed): 1 kg/m

Composition
MasterSeal 501 is made from a combination of moisture-activated chemicals, high-grade silica aggregates, and selected cements.

Action
When MasterSeal 501 is applied, the moisture and free lime present in the substrate react with the active chemicals in the product, forming a continuous barrier of insoluble crystals. These crystals penetrate deeply into the capillary structure of the concrete, blocking water from passing through while allowing the transmission of air and water vapour, enabling the structure to breathe.

The rate of crystalline development depends on the density and surface absorption of the concrete, but the crystals will penetrate to the depth where water is present. Full waterproofing properties can typically be achieved within 5-7 days of application.

MasterSeal 501 is effective against both positive and negative water pressure or osmotic pressure and can be applied to both the internal and external surfaces of a structure. However, whenever possible, it is recommended to apply it on the internal surface.