Abstract
Waterproofing concrete substrates such as fountains, water-retaining tanks, plaza decks, parking decks, planters and other underground structures is substantially different from roofing. For this reason, it is imperative that the designers and contractors be aware of the differences and potential problems associated with waterproofing concrete substrates. Improper waterproofing design and installation can lead to water leakage, deterioration of concrete substrate materials and waterproofing membrane delamination. This article will provide a general overiew of common failure mechanisms in LAMs including crack reflection, high moisture vapor emission rates and curing problems, a summary of the current state of the industry and a detailed discussion of the following case history: evaluation of waterproofing system on Cincinnatie Museum Center plaza fountain. The fountain was construction of cast-in-place concrete in the early 1900s. The original waterproofing system consisted of a lead sheet membrane placed directly over the structural concrete deck. The fountain was then constructed on this lead sheet and was surfaced with terrazzo. In a recent rehabilitation projecct, the exposed surfaces of the fountain were repaired and coated with a liquid-applied waterproofing membrane (LAM). Shortly after the rehabilitation project, leaks were detected below the plaza. The evaluation of the waterproofing system revealed inter-ply delamination of the LAM, delamination from the concrete substrate and cracking of the concrete components of the fountain. The field investigation included visual inspection, exploratory openings, water testing of the fountain features and sampling of concrete and membrane. Laboratory testing included microscopic examination of the membrane-concrete interface to evaluate the cause of the membrane delamination.
Waterproofing concrete substrates such as fountains, water-retaining tanks, plaza decks, parking decks, planters and other underground structures is substantially different from roofing. For this reason, it is imperative that the designers and contractors be aware of the differences and potential problems associated with waterproofing concrete substrates. Improper waterproofing design and installation can lead to water leakage, deterioration of concrete substrate materials and waterproofing membrane delamination. This article will provide a general overiew of common failure mechanisms in LAMs including crack reflection, high moisture vapor emission rates and curing problems, a summary of the current state of the industry and a detailed discussion of the following case history: evaluation of waterproofing system on Cincinnatie Museum Center plaza fountain. The fountain was construction of cast-in-place concrete in the early 1900s. The original waterproofing system consisted of a lead sheet membrane placed directly over the structural concrete deck. The fountain was then constructed on this lead sheet and was surfaced with terrazzo. In a recent rehabilitation projecct, the exposed surfaces of the fountain were repaired and coated with a liquid-applied waterproofing membrane (LAM). Shortly after the rehabilitation project, leaks were detected below the plaza. The evaluation of the waterproofing system revealed inter-ply delamination of the LAM, delamination from the concrete substrate and cracking of the concrete components of the fountain. The field investigation included visual inspection, exploratory openings, water testing of the fountain features and sampling of concrete and membrane. Laboratory testing included microscopic examination of the membrane-concrete interface to evaluate the cause of the membrane delamination.
Date
9/2002
9/2002
Author(s)
Karmi Farahmandpour
Karmi Farahmandpour
Page(s)
Keyword(s)
blistering; concrete; crack reflection; debonding; failure; LAM; liquid applied membrane; moisture vapor emission rate; pinhole; waterproofing
blistering; concrete; crack reflection; debonding; failure; LAM; liquid applied membrane; moisture vapor emission rate; pinhole; waterproofing