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The prevalence of splitting in built-up roofing during recent years has prompted special studies to be undertaken by the Division of Building Research to determine the causes for these serious failures. The determination of certain engineering properties of the components used in built-up roofing and the complete membrane have received special attention. To determine these properties, a roller-coating technique was developed to prepare membranes and a special grip arrangement was constructed for the tensile studies. These studies were made at 75 F and at -20 F, using two rates of straining. The results emphasize the secondary role of the bitumen in the strength of the membrane. At both temperatures the felts contribute 80 to 90 per cent of the strength of the membrane, although the actual strengths increased by 70 to 250 per cent as the temperature changed from 75 F to -20 F. The small amount of creep and of notch sensitivity also serve to confirm the secondary role of the bitumen., Recent Research on Bituminous Materials

Le présent Digest traite des propriétés, des avantages et des inconvénients de nouveaux matériaux de couverture synthétiques, y compris les membranes préfabriquées appliquées en feuilles et les membranes appliquées sous forme liquide.

Quality control of roofing and waterproofing membranes occurs at four distinct stages: 1) characterization of raw materials with respect to degree of purity required for an established formulation prior to production; 2) control of processing and manufacturing variables during production to permit necessary corrections before defective materials are produced; 3) testing and evaluation of finished products for conformity with the established standards or as agreed upon by the supplier and purchaser; where the latter is a large company or a government agency, compliance with a specification is usually required; 4) control and inspection of workmanship quality on the job site during the application in accordance with the architect's, engineer's or project manager's detailed job specification. Stage 3 has already been discussed in the author's previous publications. This paper highlights some of the quality control aspects and methods that could be implemented in stages 1, 2, and 4., 5th International Congress on Roofing and Waterproofing: 01 June 1983, Strasbourg, France

This paper introduces built-up-roofing, single-ply and liquid elastomeric membranes and polyurethane foam roofs. It discusses the factors concerning the performance of membranes, and how they are related to standards., Building Science Insight 1989: Roofs that Work: 1989, Canada

This paper discusses the design of correct roof details, strategies a designer can pursue to improve the potential for proper roof construction and a general approach to an integrated roof management program., Aussi disponible en francais: Conception, exécution et entretien, Building Science Insight 1989: Roofs that Work: 1989-10, Canada

New synthetic roofing materials, including prefabricated sheet-applied membranes and liquid-applied membranes, are described. Their properties, advantages and disadvantages are discussed.

Several hundred new roofing materials have become available in the past two decades. This paper describes the materials under three main generic classes: synthetic thermoplastics, thermosetting vulcanized elastomers, and polymer modified bitumens. Comparisons are made with conventional roofing materials and techniques, and some considerations necessary for selecting an appropriate roofing system are discussed.

A development study of test methods and criteria for evaluating new roofing materials is described: prefabricated polymeric and elastomeric sheets, prefabricated modified bituminous membranes, and liquid applied membranes. Results are summarized for a number of materials selected as typical of the three groups in order to illustrate the problems and the limitations associated with the different tests., Proceedings of the 1st International Conference on Durability of Building Materials and Components: 21 August 1978, Ottawa, Ont. Canada

Mineral aggregate surfacing is applied to built-up roofing to protect the top coating of bitumen from direct sunlight and to reflect solar radiation. It reduces the maximum surface temperature, the seasonal range of temperatures and the short-time fluctuations at the black surface. It thus inhibits weathering of the bitumen and the bituminous felts of the roofing membrane. There are some disadvantages to the use of mineral aggregate surfacing. Apart from the added dead weight, which must be carried by the deck and structure, the principal difficulty relates to inspection and maintenance. The aggregate surfacing hides defects and breaks in the membrane and must be removed to make repairs.

En vue de protéger le revêtement contre le rayonnement solaire directe et de réflichir la radiation solaire, on applique sur les toitures multicouches des revêtements en aggrégats minéraux. Ils provoquent une décroissance de la température superficielle maximale; ils réduissent aussi l'éventail des températures saisonnières et les fluctuations rapides de température sur la surface noire. Ils empêchent ainsi que les intempéries ne déteriorent le bitume et les feutres bitumineux du revêtement d'étanchéité de toiture. Le surfacage par agrégats minéraux présente certains désavantages. Si on met à part le poids mort supplémentaire que doivent supporter le tablier et la charpente du toit, la principale difficulté concerne l'inspection et l'entretien. Le surfacage par agrégats dissimule les défauts et solutions de continuité du revêtement d'étanchéite et l'agrégat doit naturellement être enlevé lorsqu'on exécute des réparations.

In order to study the low temperature performance of asphalts, improvements have been made to the Institute of Petroleum Specification IP 80/53, for determining the brittle point of bituminous materials. A new procedure for preparing the coated plaques is proposed which enables a film of asphalt of known thickness to be prepared. The apparatus has been mechanized and the spring steel plaque replaced with a clear polyvester film. The brittle point unit is cooled at any desired rate using alcohol as the coolant. Studies have been made of effect of film thickness and rate of cooling upon the brittle point temperature. Study of the effect of overheating a dead-level roofing asphalt is shown to be one of the uses of the instrument., Proceedings of the Seventh Annual Conference of Canadian Asphalt Association: 1962-11

A modified Fraass brittle point test is used to study the hardening of asphalts that accompanies accelerated weathering. Four roofing asphalts exhibit variations in the initial brittle point temperature that may be related to the performance of the materials in an accelerated weathering test. The progressive hardening accompanying weathering is followed by an increase in the brittle point temperature.

The investigation involved the application of ASTM Method D 1866-64 by subjecting individual pieces of aggregate to an ultraviolet light source. Using the same light source and the same method of photograhic interpretation but using graded aggregate layers, it was noted that unreasonable layer thicknesses would be required to prevent penetration of light through void spaces. The method was further modified by replacing the photographic interpretation with a phototube to obtain a quantitative measure of transmitted light. Aggregate types and thicknesses influenced phototube current and consequent voltage drops were measured by a sensitive voltmeter. Results show that only a small amount of ultraviolet light is transmitted through thicknesses normally used in roofing application with an aproximate 0.03 per cent difference between white marble and gravel. Results suggest that the advantage of white aggregate in reducing surface temperature may outweigh any disadvantages from its translucency.

The load-strain properties of several bituminous membranes when tested in tension are examined and the effect of temperature on the breaking load, load-strain modulus, and breaking strain is considered. The shear properties of the bitumens used as adhesives in the production of the membranes are examined at temperatures from -15 F (-26 C) to 32 F (0 C) at a rate of shear of 0.21 per min. The observed transition in the shear modulus of the asphaltic material at 0 F (-18 C) is found to coincide with the glass transition temperature of this material. The development of a critical- thickness concept is described, and it is suggested that the performance of roofing membranes under deformation may be controlled by the load-strain properties of the membrane and the shear properties of the adhesive.