PROTECTING CONCRETE WITH CEMENTITIOUS WATERPROOFING SLURRIES

While durable, concrete is not unfailing, and if exposed to water, it can weaken over time


This is because concrete is porous, so water and other fluids can easily infiltrate the surface. To prevent this and increase the longevity and durability of a concrete structure, Hychem says it is imperative to apply a protective waterproof coating.
The main problem with water coming into contact with concrete is that it causes it to erode, exposing matrix materials and base concrete. This weakens the structure and causes surface damage. This process generally takes years to occur, but in some extreme circumstances, the concrete can erode quickly.
Hychem Product Manager, Colin Murphy, said installing a waterproof coating will help protect the concrete from erosion, as well as protect the rebar inside from corrosion and rust.
“Waterproofing has other advantages such as preventing mould and mildew from getting into the concrete which can affect structural integrity and health, and reduce maintenance costs and clean-up,” Colin said.
Cementitious waterproofing slurries have been successfully used to waterproof and seal a wide range of concrete structures including wet rooms, water tanks and swimming pools.
Hychem says they are a great option for such structures as they have excellent weathering resistance, excellent resistance to water – even when exposed permanently – good scratch resistance, good load bearing capacity, are resistant to aggressive chemicals, and a higher water vapor permeability compared to many other products.
“Cementitious waterproofing slurries are versatile and durable, so that is why Hychem are expanding our waterproofing offering with the introduction of VELOSIT WP 120,” Colin said.
“VELOSIT WP 120 is a highly flexible polymer modified cementitious waterproofing slurry for concrete and masonry and is a good substrate for coatings and overlays.
“It has a quick curing time with foot traffic allowed three to four hours after application; creates a crack bridging and abrasion resistant coating on the substrate; surpasses the requirements of EN 1504-2 for coatings (C) and can be used according to the principles 3.1 and 3.3 according to EN 1504-9; and can be applied by brush, trowel or suitable spray equipment.
“As part of the wider VELOSIT product portfolio, WP 120 can be used in conjunction with other products such as VELOSIT CP 201 and 204/205 to re-profile a structure to prepare the base for WP 120 to be applied.
“It has also been tested and approved when used with VELOSIT WP 101 and RM 205 to AS/NZS 4020:2005 Testing of Products For Use in Contact With Drinking Water by the Australian Water Quality Centre.”
Hychem states the benefits of VELOSIT WP 120 include:
• Crack bridging
• Highly flexible, tensile elongation >100 per cent
• Easy to apply
• Resists 50m water pressure according to EN 12390-8
• 60 minutes working time
• Final strength is achieved within five to seven days
• Open to foot traffic after three to four hours (23°C/60 per cent r.h.)
• Ready for water pressure after five days
• Very good adhesion to concrete and masonry
• Good resistance against aggressive media with a pH range of three to 12 and against soft water with low ion content
• Good weathering resistance
• Potable water tested and approved to AS/NZS 4020:2005 Testing of Products For Use in Contact With Drinking Water
• Good sulfate resistance

For more information on VELOSIT WP 120, call Hychem on 02 4646 1660.