When specifying a tanking system, it is not only important to be sure the chosen system is suitable for the ground conditions it’s going to be used in, but also that the chosen system will be able to continue to provide the protection required, irrespective of any changes in the ground conditions during the life of the building.
While building on brownfield sites can uncover a multitude of contaminants in the soils, both greenfield and brownfield builds need to take into account the possibility of changes in the ground conditions in the future. If you need to test the soils for the membrane you are specifying now, what guarantees do you have that the membrane will still perform as required in 10 or 50 years time?
One of the biggest concerns we face today is climate change and the effects that rising sea levels will have on low lying ground conditions. Low lying areas of freshwater have the risk of being displaced by saline water from the ocean. Historically, the gradual rise in sea level has accumulated to be around 20cm over the 20th century through to present. This can be enough, in combination with a severe storm-tide event, to cause seawater inundation of low-lying coastal margins, as occurred in parts of Auckland in 2011 and 2014. Further rises in sea level will further exacerbate such situations with more frequent coastal inundation and erosion of vulnerable coastal areas. Research has shown that sea level in the wider sea around New Zealand will rise by 5-10% more than the global average rise.
Another key concern in New Zealand is ground movement, this can be brought on by a multitude of sources from neighbouring construction to tremors as a result of earthquakes of which we experience over 15,000 annually. Membranes that rely on mechanical bonding and compaction for performance may be vulnerable to failure in the event of ground movement. Having a fully bonded membrane that forms a homogenous seal to the substrate will provide reliable protection in the event of ground movement.
Several series of tests have been conducted to define the chemical resistance of Nuralite’s waterproofing membranes — Preprufe and Bituthene. Both membranes are highly resistant to normal ground water conditions, which range from alkaline to acidic. In addition, they are unaffected by exposure to salt water.
Preprufe 300R Plus and Preprufe160R Plus pre-applied waterproofing membranes are composite sheets comprised of a thick HDPE film, pressure sensitive adhesive and weather resistant protective coating. The membranes form an integral bond to poured concrete.
This integral bond of membranes like these is specifically designed to provide a robust barrier to water, moisture and gas to prevent both the ingress and lateral migration of water. This integral bond to concrete will ensure the building maintains its waterproofing integrity irrespective of any ground movement that takes place.
|Exposure Conditions||Rating Prepufe and Bituthene Membrane Resistance|
|Sea water, de-icing salt||Excellent|
|Acids in solution e.g. sulfuric, acetic, hydrochloric and nitric acid||Excellent|
|Alkalis e.g. Sodium hydroxide, ammonium hydroxide||Excellent|
|Organic or fuel oils, solvents||Variable|
Photo: Applicator — Sansom Construction Systems