Hiroshi Hashida

DEVELOPMENT OF EVALUATION METHOD OF WATERPROOFING MEMBRANE WITH AIR PERMEABLE SHEET FOR BLISTER PREVENTION

This paper describes the effect of an air permeable sheet on reduction in pressure between a polyurethane membrane and wetted concrete substrate. The outdoor measurement of pressure in the artificial voids of full scale concrete slabs on which a polyurethane membrane was applied, showed 9kPa for the specimen in which air was prevented from leaking from the bottom of the slab by a basal plate, and almost zero for the specimen the air permeable sheet inserted between the concrete slab and the membrane. The new method for measuring the air permeability of air permeable sheets was further developed and numerical calculation was carried out using the measured value of air permeability of the sheet. The effect of the air permeable sheet on reduction of pressure beneath the membrane was also confirmed from the calculation.