Overall, cold-applied waterproofing can handle greater loads and a higher number of cycles of abrasion than hot-applied. Low temperature crack-bridging Crack-bridging is a critical feature of liquid waterproofing materials due to the natural dynamic movement of buildings and structures that understandably creates cracks. In climates with temperature changes from seasons to season, these cracks can shift, open, and close. This back and forth movement of cracks as temperatures change creates many fatigue cycles for the waterproofing membrane. Waterproofing materials need to withstand these various temperatures, and low temperatures in particular, so that when there is a crack in the substrate (typically concrete), the waterproofing membrane stays in its original condition. There will be no fine-line cracks or breaks in the membrane and it will remain monolithic, protecting the structure underneath by preventing water from getting through and damaging the structure. Materials can become rigid, and some even brittle, when the tempera- ture drops, rendering them unable to maintain their original condition under stress or repetitive movement. That is why, when choosing a waterproofing system, the material’s temperature related properties and overall chemistry should be given serious consideration. Hot-applied liquid waterproofing requires continuous maintenance to ensure the membrane’s protection of the surface below. With respect to durability, enduring fatigue cycles of building movement or maintain- ing integrity over time, especially in cold temperatures, is a challenge for hot-applied liquid waterproofing. The elastomeric qualities inherent in cold-applied liquid waterproofing membranes mean that they easily withstand building movements and fatigue cycles, maintaining their integrity over a long period of time and requiring no ongoing maintenance. Cold-applied liquid water - proofing can also handle more extreme temperatures, down to -15° F. Application durability When applying hot rubberized asphalt at high temperatures, air will try to escape and moisture will try to evaporate through any defects in the primer, which can cause a good deal of blistering or pinholes.
Damage resistance Asphalt-type hot-applied liquid waterproofing is composed of large proportions of low and medium molecular weight components and con- sequently does not stand up well to equipment grease and solvents that may be dropped on the surface. Also, it can handle only limited loads or cycles of abrasion on its surface before showing wear or penetration. Most cold-applied liquid waterproofing systems are reactive and made to form a high molecular weight or cross-linking polymer. This re - sults in good resistance to wear and tear, the hydrocarbons, grease, or solvents that are often spilled on the jobsite. A properly selected cold-applied liquid system can handle construction or ongoing activ - ity, including mishaps, such as equipment and tools dropping on the surface. In a worst case scenario, an impact may break the concrete deck underneath the membrane and the waterproofing must have crack bridging capability to maintain its integrity. Reactive cold-applied liquid waterproofing is often designed with ability to handle “point loads,” which can be caused by a heavy piece of equipment with a narrow leg at the bottom or similar point load situations. Even in those instances, the membrane will not show a dent or penetration. One cold-applied waterproofing membrane, SILCOR® liquid waterproofing , has demonstrated the ability to withstand point load of 3000psi without causing a dent on the membrane.
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June 2021
csengineermag.com
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