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ASTM Selected Technical Papers
Roofing Research and Standards Development: 10th Volume
Editor
Sudhakar Molleti
Sudhakar Molleti
Symposium Chair and STP Editor
1
National Research Council Canada
,
Ottawa, ON,
CA
Search for other works by this author on:
Walter J. Rossiter, Jr. Jr.
Walter J. Rossiter, Jr. Jr.
Symposium Chair and STP Editor
2
W.J. Rossiter & Associates
,
Clarksburg, MD,
US
Search for other works by this author on:
ISBN:
978-0-8031-7747-5
No. of Pages:
254
Publisher:
ASTM International
Publication date:
2023

Hot-applied rubberized asphalt (HRA) waterproofing is widely used for plaza decks, terraces, and vegetative roofs. Its thick, seamless application and soft, sticky consistency, which promotes crack bridging, adhesion, and possible self-sealing or gasketing at incidental penetrations, make it an attractive choice for many projects. However, its softness limits its ability to support concentrated loads on some projects, such as masonry veneer or precast concrete bearing points, parking lot wheel loads, or even pavers on undersized pedestals. On some projects, we observed that the HRA assembly deformed to negligible thickness, which created alignment problems for the overburden and raised concerns about whether the membrane would remain watertight. An initial review suggests that HRA exhibits a variety of deformation mechanisms, including elastic, plastic, creep, and viscous fluid flow. We hypothesize that deformation depends on pressure, temperature, time, and confinement. These complexities make it challenging to quantify compressive resistance in terms that are adequate to address real-world applications. Limited compressive deformation data are available from manufacturers. To address these challenges, the authors conducted two phases of research. First, we compiled anecdotal data from projects where HRA had experienced significant thickness loss under concentrated loads. Then we prepared laboratory test specimens of an HRA assembly, applied compressive loads, and measured deformation periodically over approximately three years. The laboratory testing phase investigated deformation as a function of bearing area, pressure, and temperature. We concluded the following: bearing area, pressure, temperature, and time have quantifiable effects on the HRA compressive deformation; our 38-year case study (compared to our laboratory experiment) shows that long-term deformation continues to increase well beyond the first three years; and new industry standards could be developed to help manufacturers establish time-deformation curves for a range of commonly encountered loading conditions and to help project teams avoid problems caused by excessive deformation.

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Walls Built onto Waterproofing Systems
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:
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,
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Spink
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,
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Standard Test Method for Accelerated Tensile Creep and Creep-Rupture of Geosynthetic Materials Based on Time-Temperature Superposition Using the Stepped Isothermal Method
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West Conshohocken, PA
:
ASTM International
, approved February 15,
2016
),
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