Masayuki Tsukagoshi

MICROSTRUCTURAL OBSERVATION AND SIMULATION OF POLYMER CEMENT WATERPROOFING MEMBRANE

A polymer-modified cement waterproofing membrane is formed by simultaneous cement hydration and polymer film formation, these rates are affected by the moisture content of the polymer emulsion used. The moisture content gradually decreases due to cement hydration and evaporation from the surface. This study focused on the changes caused in the waterproof layer by differences in the moisture environment. Four test pieces with different cement, polymer, and moisture contents were prepared and cured at 20 °C and relative humidities of 25, 60, and 98 %. The basic physical properties of the test pieces were studied in tensile tests; the structures were observed using an EPMA. Furthermore a simulation was carried out using a model that considers cement hydration, polymer film formation, and moisture evaporation rate. The simulation results well reproduced the experimental results.

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.

EFFECT OF DETERIORATION OF SURFACE COATING TO CARBONDIOXIDE PERMEABILITY OF POLYUREHTANE WATERPROOFING MEMBRANE AT CRACK IN CONCRETE SUBSTRATE

This paper describes the effect of deterioration of surface coatings applied on polyurethane membranes due to weathering, to carbonation of cracked concrete substrate. The specimens with various thicknesses of membranes, which were stretched at the crack of 1mm wide of concrete beams, were exposed outdoors in Yokohama for 5 years. Carbonation area in cracked zones of the specimens was observed. On the basis of the observation, a numerical simulation method that is considered the influence of degradation of surface coatings and membranes was developed. It was made clear from experimental and analytical studies that carbonated area of cracked concrete increased according to deterioration of surface coatings.

EFFECT OF REINFORCING FABRICS TO FATIGUE RESISTANCE OF FLUID-APPLIED POLYURETHANE MEMBRANES AT JOINT OF SUBSTRATE

The effect of reinforcing fabrics to fatigue resistance of fluid-applied polyurethane membranes is described in the study. The membranes reinforced by the two kinds of reinforcing fabrics such as grass fiber and polyester fiber at various height in cross section were prepared. They were moved at three levels of movements of 0.5-1.0mm, 1.0-2.0mm, 2.5-5.0mm by the fatigue machine. It was made clear that the reinforcing fabrics improve the fatigue resistance of the membranes and the effect of them is noticeable for the membranes inserted at the lower position in cross section. It was also found out that fatigue resistance of the membranes is related to the property of reinforcing fabrics.