皮膜防水層のひびわれ抵抗性

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タイトル別名
  • Resistance of Roofing Membranes to Cracks in Concrete of Roof-Deck
  • ヒマク ボウスイソウ ノ ヒビワレ テイコウセイ

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抄録

Concrete is subject to cracks because of its high hardening-and-drying-shrinkage, and also of its low tensile strength and extensibility. It is owing to that defect in concrete that the roof-deck cannot be perfectly free from cracks. Various plans have so far been devised and carried into effect to cope with these drawbacks in concrete of generating cracks and propagating them, so as to secure for the roof-deck complete waterproof virtue. Most of these waterproof contrivances consist of covering the roof-deck with layers of films which we may call roofing membranes.<br>Of the roofing membranes then it is required as of paramount importance in the roofing system that they will on no account rupture, whatever may be the width of the cracks that occur in the concrete of the roof-deck. Special attention must, therefore, be paid to adjustment of such physical properties of the roofing membranes as its tensile strength, its maximum elongation, its modulus of elasticity and its resilience, of its thickness and of its adhesive strength to the roof-deck.<br>In this paper the resistance of the roofing membranes to the cracks in the concrete of the roof-deck is theoretically and experimentally discussed. As the result the condition that effectively protects the roofing membranes from rupture in spite of the cracks in the concrete of the roof-deck is proposed as follows:<br>τs≤4d/lRs<br>where<br>τs: Shear-adhesive strength of the roofing membrane material to the concrete of the roof-deck in kg/cm2<br>d: The thickness of the roofing membrane in cm<br>Rs: The limit of resilience of the roofing membrane in kg/cm2<br>l: The crack width in the concrete of the roof-deck in cm.<br>This equation has also been applied to polymer roofing membranes which were made up of synthetic polymeric roofing sheets and polyurethane fluid-applied roofings, and their resistance to cracks in the concrete of the roof-deck has been tested.

収録刊行物

  • 材料

    材料 20 (208), 52-58, 1971

    公益社団法人 日本材料学会

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