The function or service conditions of concrete structures can change over time, leaving an unprotected or under-protected system exposed to aggressive species. This paper explores the use of anchored thermoplastic liners to rehabilitate deteriorated concrete structures and to protect them from degradation long-term.
The function or service conditions of concrete structures can change over time, leaving an unprotected or under- protected system exposed to aggressive species. For example, the composition ofwastewater to which a process drainage system is exposed over its service life can change many times. As new manufacturing processes are added and others are nmdified, new constituents may be introduced to the drainage systems. Similarly, a tank previously used to store water for fire management may have a second life in wastewater storage.
Regardless of the reason for the change in service conditions, the result is the same: the adequacy of the original design for the new service or function is in question. Yet, often the suitability of the structure for the new service is presumed acceptable. While this could be the case, many times the changes in service stretch or exceed the limits of the original materials of construction. Over time-sometimes a short time-the existing lining and/or the concrete itself begins to deteriorate.
At this point, the system owner must review the chemical and thermal exposure to identify a more resistant barrier system. With the wide variety of corrosion protection systems available, the selection process can be daunting Factors beyond service chemistry and temperatures must be considered in order to identify an optimal system.
Consider carefully the limitations of each system under evaluation. Many rehabilitation systems require several time- consuming steps. Some require special handling and the use of personal protective gear.
Others may not be suitable for continuous immersion. The expected service life could be too short or the maintenance requirements too high. Anchored thermoplastic liners, such as ACROLINE® Systems 1, can be a cost-effective solution for rehabilitating deteriorated concrete structures. These systems are available in various types of thermoplastics to resist different chemical and thermal exposures.
Anchored plastic concrete protection liners are maintenance-free, although they can be repaired in the event of mechanical abuse. Prefabrication of liners can minimize installation time, thus minimizing system downtime. Finally, anchored plastic liners have a long expected service life.
REASONS TO CHOOSE A CAST-IN-PLACE ANCHORED LINER SYSTEM
Cast-in-place anchored liner systems offer a variety of features and benefits, which position them as good materials for rehabilitating concrete structures.
1. Cracks in the substrate do not reflect through the liner. Although cracks in the substrate can reflect through the grout layer into which the liner is cast, they will not reflect through the liner. The discrete anchoring system and elongation of thermoplastic materials allow the concrete protection liner to bridge cracks in the substrate, while maintaining the integrity of the barrier.
2. Anchored concrete liners can resist more than 10 meters of hydrostatic head pressure acting on the anchored side of the liner without pulling out of the substrate. This is particularly important in areas with a high groundwater table. Cracked structures or structures lacking a waterproofing coating on their exterior surfaces can be subject to groundwater infiltration.
3. Anchored concrete liners can be used to seal these structures to prevent both infiltration and exfilt
