EFFECT OF APPLICATION TOOLS AND VISCOSITY ON THICKNESS OF POLYURETHANE WATERPROOFING MEMBRANE IN VERTICAL PART

Abstract

 The polyurethane waterproofing membrane is used to form a waterproofing layer by applying a liquid material to the waterproofing base of a construction site. Particularly, because the construction surface is vertical, the thickness of the polyurethane membrane tends to be uneven, and good construction skills are required. However, relevant studies are scarce, and sufficient knowledge has not been acquired to date. Therefore, this study investigated the actual conditions affecting the membrane thickness of in the vertical part of an actual building and the appropriate tools and viscosity to ensure an appropriate membrane thickness.

 In the examination, two experiments were conducted, which confirmed the effect of the construction work and reinforcing fabrics in practical applications, and the effect of application tools and viscosity on the membrane thickness.

 In the first experiment, the thickness distribution of the vertical part was compared by observing the work carried out by a skilled worker and an unskilled worker using a concrete wall. It was found that the construction of the vertical part consisted of the work for distributing the waterproof material and finishing work, and that the application tools were properly used. Additionally, it was clarified that, by uniformly applying the waterproof material to the reinforcing fabrics, the dispersion of the membrane thickness was effectively reduced, regardless of the construction skill level.

 In the second experiment, the effect of the application tools and viscosity on the membrane thickness during the distribution work was investigated. It was found that the amount of coating per application tended to decrease with the viscosity, regardless of the application tools. Next a T-shaped frame using plywood backing was manufactured, and the effects of the application tools, viscosity (dilution ratio 0%–5%), and reinforcing fabrics on the membrane thickness was investigated. The dispersion of the membrane thickness increased as the viscosity decreased, but a difference was hardly observed in the average value of membrane thickness. Additionally, when the rubber spatula was used, the working time tended to be longer compared with the roller.

 The following results were drawn from this study.

 (1) The reinforcing fabrics of the vertical part held the uncured waterproof material, and effectively ensured the membrane thickness, regardless of the construction skill level.

 (2) In the distribution work, when the viscosity decreased, it became difficult to distribute the waterproof material throughout the construction surface, and the dispersion of the membrane thickness tended to increase. This tendency was particularly remarkable in the rubber spatula case.

 (3) When the viscosity of the waterproof material decreased, the work time tended to be longer, because the amount of coating in the distribution work decreased. Therefore, to ensure an appropriate membrane thickness, the waterproof material should not be diluted.

 (4) In practical situations, it is important to consider a balance amongst the application tools, viscosity, and working time.