Membrane waterproofing materials

Increasing Demand for Hydrated-Type Liquid- plied Membrane Waterproofing Materials (in Japanese), The Bosui Journal, 21(10) 43-46 (Nov. 1990)... 

Bentonite clay expands when moist to create a waterproof barrier. Bentonite is sold in various forms, including panels and mats. Bentonite is not as resistant to chemicals as the thermoplastic membranes, nor is it puncture resistant. The major flaw of bentonite as a radon barrier, however, is that it is only tightly expanded when wet. This is acceptable for a waterproofing material, but not for a gas barrier. 

A relatively new development which promises to gain in importance in the future is the modification of asphalt by butadiene-styrene block polymers.44 The block polymers help reduce the low temperature brittleness and impart resistance to flow at elevated temperatures. Applications in mastics, automobile body undercoatings and waterproofing materials such as high quality roofing membranes are envisaged. 

Siloxane polymers (better known in the commercial market as silicones) have widespread applications, a few of which are personal care products, greases, sealants, varnishes, waterproofing materials, synthetic rubbers and gas-permeable membranes such as those used in soft contact lenses. Medical applications are increasing in importance, although the use of silicone breast implants is a controversial issue because of claims of the migration of low molecular weight siloxanes from the implant into the surrounding body tissue. 

This test method is under the jurisdiction of ASTM Committee D-g on Roofing, Waterproofing, and Bituminous Materials and is the direct responsibility of Subcommittee D08.03 on Surfacing and Bituminous Materials for Membrane Waterproofing and Builtup Roofing. 

In modem PMR constmction, thermal iasulation that is unaffected by water or that can be kept dry ia some manner is required. Extmded polystyrene (XEPS) foam iasulation boards ate commonly employed (see Insulation, thermal). They ate placed on top of the waterproofing roof membrane, which is next to the deck. The iasulation should not be adhered to the membrane. Ballast at the rate of >48.8 kg/m (1000 lb/100 ft ) holds the iasulation ia place and offers protection from the sun. The iasulation joiats ate open and drainage must be provided. Various other materials, eg, patio blocks and concrete slabs, ate also used as sutfaciags and ballast. The extra weight imposes mote exacting requirements on constmction. 

Membrane Roofing. Many of the same types of materials used in membrane roofing are also used in waterproofing appHcations, because usually a membrane is needed to maintain the waterproofness of the foundation. They are used mainly on large commercial buildings. 

Asphalt—mbber is mixed and applied to roadways by several techniques. In one method, mbber and asphalt are mixed at ca 175—220°C for one to two hours. The hot mixture is applied to the roadway and covered with a layer of stone chips to form a chip seal. The mbber cmmb consists of scrap tires ground into particles less than 2 mm in diameter. Rubber-modified asphalt is also used for waterproofing membranes, crack-and-joint sealers, hot-mix binders, and roofing materials. The mbber improves asphalt ductility and increases its softening point. The aggregate adhesive bond is stronger, and the asphalt lasts longer. Production of rubber-modified asphalt has increased from 405 t in 1970 to 27,000 t in 1980 (41). Typically, about 2 t of mbber is used for 1 km of roadway. If it is assumed that asphalt—mbber contains ca 25% mbber and 75% asphalt, the potential demand for scrap mbber would be ca 40,500 t/yr, or ca 2% of the amount available. 

Exemplary materials for the waterproofing of masonry surfaces are waterproof membranes such as poly(vinyl chloride), PE, butyl rubber, and sealants such as tar, asphalt, paints, poly(urethane), epoxy or mastics. While these waterproofing agents can offer excellent resistance to water penetration and other contaminants, they can alter the appearance of the masonry surface, e.g., they may change the color of the surface or leave it with a shine. Waterproofing treatments can also trap moisture within the masonry surface and promote spalling. 

Silicone liquids are used by dentists in the preparation of dentures. Dentures become waterproof, their material is not leached by saliva. Food particles do not stick to such dentures mucous membranes in the mouth are not irritated, which often happens when dentures are produced from organic plastic masses. If silicone toothpaste is used, teeth are covered with a colourless film that prevents them from tartar. 

This means that the designer must make certain that his specifications are not misunderstood. He must carefully specify what the exact surface of the slab must be in order to be accepted, exactly what membrane shall be used instead of the waterproofing and how it shall be installed, exactly what bedding material shall be used to set the tile, and exactly what "grout" shall be used in the open joints. If a thin bed is to be used to bond the tile directly to the concrete substrate, he must indicate acceptable thicknesses for it and specify that the application Is to be made with a flat trowel-/iof a ribbed or serrated one that will lay ribbons of bed rather than a smooth, continuous, void-free bed on the concrete. All materials should be identified generically so that there is no mistake and so that if later another product said to be "equal" is substituted, the installer will be able to determine whether it is indeed equal. 

Because intact skin is usually more resistant to hazardous substances than wounds, mucus membranes or eyes, decontamination should begin at the head, and work downward, paying close attention to contaminated eyes and open wounds (9). Wounds should receive irrigation with copious amounts of normal saline. Deep debridement and excision are necessary only if particles or pieces of contaminated material are embedded in the tissues (9). After cleaning, covering wounds with waterproof dressings can help prevent recontamination (9). 

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