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Abstract
Predictive lab tests for the durability of roofing membranes require the development and validation of accelerated weathering regimes, based on factors that are known to cause degradation in service. Both heat aging and artificial weathering machines have been used in these durability studies. In assessing the changes caused by exposure of roofing membranes to natural and lab weathering, a major problem is to identify physical properties that may be readily measured and which can be used as effective "performance indices" for durability assessments. Tensile properties such as elongation and stress at failure of membrane specimens have not generally been found to show consistent and significant changes after exposure to weather. Assessments of fatigue resistance after subjecting membrane samples to repeated cycles of movement have yielded results that generally accord with experience of durability in service. Fatigue measurements at subzero temperatures have proved sensitive to adverse changes due to weather exposure. The results of long-term natural weathering at various sites with different climatic conditions are reported and compared with the changes in materials exposed to artificial weathering and aging in the lab. The significance of these data for the prediction of service life is discussed, together with the influence of other factors, such as the durability of jointed seams in single-ply membrane systems.
Predictive lab tests for the durability of roofing membranes require the development and validation of accelerated weathering regimes, based on factors that are known to cause degradation in service. Both heat aging and artificial weathering machines have been used in these durability studies. In assessing the changes caused by exposure of roofing membranes to natural and lab weathering, a major problem is to identify physical properties that may be readily measured and which can be used as effective "performance indices" for durability assessments. Tensile properties such as elongation and stress at failure of membrane specimens have not generally been found to show consistent and significant changes after exposure to weather. Assessments of fatigue resistance after subjecting membrane samples to repeated cycles of movement have yielded results that generally accord with experience of durability in service. Fatigue measurements at subzero temperatures have proved sensitive to adverse changes due to weather exposure. The results of long-term natural weathering at various sites with different climatic conditions are reported and compared with the changes in materials exposed to artificial weathering and aging in the lab. The significance of these data for the prediction of service life is discussed, together with the influence of other factors, such as the durability of jointed seams in single-ply membrane systems.
Date
0/1992
0/1992
Author(s)
J C Beech; G K Saunders; K Tanaka
J C Beech; G K Saunders; K Tanaka
Page(s)
152-165
152-165
Keyword(s)
durability; natural weathering; predictive testing; tensile test; fatigue resistance
durability; natural weathering; predictive testing; tensile test; fatigue resistance