Do you use surface applied membranes to waterproof your structure? If you do, you should be aware that regardless of product, cost or technology – that surface applied waterproofing membranes are not very reliable.
Surface applied waterproofing membranes frequently have installation challenges that can lead to missed seams and de-bonding. Even when installed correctly they are then easy to damage and puncture, and tend not to age well – deteriorating over time. When they do fail, water will eventually find its way into your structure through the easiest path possible – your concrete construction joints.
Construction joints, also known as cold joints, are where hardened concrete and fresh concrete meet. This interface provides one of the most well-known and easiest pathways for water to enter (or exit) your structure. By placing a physical barrier to stop water from passing, you can effectively stop water when that membrane fails.
The most popular types of waterstops are PVC, Bentonite, Synthetic Rubber and Crystalline.
PVC waterstops are embedded in the concrete, but frequently lead to difficulties in getting proper concrete consolidation around the waterstop. This results in larger voids where water collects and finds a path. Since concrete shrinks and bond between concrete and PVC is poor, it is common to find gaps between the two materials which will allow water to pass.
Bentonite is a soft clay based material that is adhered to the concrete and expands when exposed to water. The expansion fills the space to stop water. Bentonite is a popular choice, but when your membrane fails and water is entering through the space in the construction joint, bentonite can lose its physical integrity and disintegrate over time. This limits its ability to withstand long term hydrostatic pressure.
Synthetic Rubber swelling waterstops work along similar lines as bentonite, but swell when they come in contact with water. The swelling creates a pressure seal that does not allow water to pass. The king of this category is Krytonite by Kryton. Krytonite has the ability to swell to 1100% of its original shape and size and has been proven to withstand 267 ft of head pressure (8 Bar). Since it is a synthetic rubber, Krytonite will not deteriorate and its low profile with angled edges improves consolidation of the concrete in the areas where you need it the most, when you need it the most. Krytonite also works where many swelling waterstops don’t, in salt and contaminated water.
Being the inventor of the crystalline admixture, which has eliminated the need for surface applied membranes altogether, Kryton has been waterproofing constructions joints since the 70’s. “We are tanking structures by adding our crystalline technology to the concrete itself” says Kris Till, Product Manager at Kryton, “…so we are very advanced with keeping water from passing through construction joints and details. We actually have single, double and triple protection options based on project risk”. Kryton uses different combinations of their Krytonite Swelling Waterstop, crystalline grout and crystalline slurry treatment to provide options for a waterproof construction joint. Since they are designing structures that don’t have membranes to start with, they can offer solutions for your construction joints for when that surface applied membrane leaks.
Kryton’s Krystol crystalline technology is a unique chemistry that reacts with water and unhydrated cement particles to form insoluble needle shaped crystals. These crystals fill space in the concrete to prevent water from passing through it. “We typically apply our Krystol Waterstop Treatment, which is a crystalline slurry treatment, to the joint and then use either our Krystol Waterstop Grout to form a physical crystalline waterstop or our Krytonite Swelling Waterstop. In very high risk projects we would use a combination of all three products” says Mr. Till.
The benefit of Krystol crystalline technology is that it is a permanent waterproofing system. Whenever water is introduced, it initiates a reaction that essentially self-seals the concrete and fills the space in the joint. This, combined with the physical waterstop element has proven to be very effective at keeping water in or out of structures all over the world. It has proven itself in some of the highest risk and highest profile projects, including Asia’s largest integrated resort and casino – the Marina Bay Sands in Singapore.
So, we ask the question – When your waterproofing fails….will your waterstop protect you? Waterproofing is risky and can be very costly when repairs and remediation are required. Building reliable waterproofing solutions into your construction joints can help mitigate those long term costs for when you hand the project over to the owner.
Excerpted From CAD details Blog