Abstract
Within the last decade flexible polyolefin roofing membranes have gained wide acceptance in the European as well as in the North American market place. With over ten years of field experience in the background a European manufacturer of such membranes has carried out three different field investigations on existing roofs. For the first project this report presents data gained from the constant monitoring of 42 roofs and a specific sampling and testing project carried out on 6 roofs by a testing institute. The roofs' age ranged between three and eleven years. Mechanically attached and gravel ballasted rofs have been considered. Properities such as tensile strength, elongation at break, low temperature flexibiilty, peel and shear strengths of the welded seams were determined, accompanied by surface examinations using optical and electronic microscopy. The conclusions are that the investiged types of flexible polyolefin roofing membranes will fulfil their waterproofing and protection function for several more decades. In a second investigation mechanical stresses induced by temperature cycles in the flexible polyolefin membranes were studied using finite element method analysis. The simulation calculations were run using material parameters determined from virgin material and form sampls aged in the field. The results give evidence that material failure of flexible polyolefin membranes due to thermally induced stresses can be excluded. In a thrid project the long term performance of field seams was studied. Provided proper seam preparation and welding techniques the long term funcationality of the seams was proven
Within the last decade flexible polyolefin roofing membranes have gained wide acceptance in the European as well as in the North American market place. With over ten years of field experience in the background a European manufacturer of such membranes has carried out three different field investigations on existing roofs. For the first project this report presents data gained from the constant monitoring of 42 roofs and a specific sampling and testing project carried out on 6 roofs by a testing institute. The roofs' age ranged between three and eleven years. Mechanically attached and gravel ballasted rofs have been considered. Properities such as tensile strength, elongation at break, low temperature flexibiilty, peel and shear strengths of the welded seams were determined, accompanied by surface examinations using optical and electronic microscopy. The conclusions are that the investiged types of flexible polyolefin roofing membranes will fulfil their waterproofing and protection function for several more decades. In a second investigation mechanical stresses induced by temperature cycles in the flexible polyolefin membranes were studied using finite element method analysis. The simulation calculations were run using material parameters determined from virgin material and form sampls aged in the field. The results give evidence that material failure of flexible polyolefin membranes due to thermally induced stresses can be excluded. In a thrid project the long term performance of field seams was studied. Provided proper seam preparation and welding techniques the long term funcationality of the seams was proven
Date
10/2000
10/2000
Author(s)
Hans-Rudolf Beer; Stefan Keiser
Hans-Rudolf Beer; Stefan Keiser
Page(s)
154-172
154-172
Keyword(s)
polyolefin; field experience; tensile strength; elognation; mechanical stress; long term performance
polyolefin; field experience; tensile strength; elognation; mechanical stress; long term performance