Asphalt substrate

Rubber crumb can be used very successfully in the manufacture of sports surfaces such as running tracks in sports stadiums and artificial turf for a variety of uses. Commercial examples of such products include a track marketed by Conica, a division of BASF, as Conipur SW, which is a sandwich system comprising an elasticated layer of recycled rubber granules and a PU binder that is applied in situ to an asphalt substrate with built-in finishers [76]. 

The modulus of elasticity can also influence the adhesion lifetime. Some sealants may harden with age as a result of plasticizer loss or continued cross-linking. As a sealant hardens, the modulus increases and more stress is placed on the substrate—sealant adhesive bond. If modulus forces become too high, the bond may faH adhesively or the substrate may faH cohesively, such as in concrete or asphalt. In either case the result is a faHed joint that wHl leak. 

Typical apphcation of a BUR would be to mop or apply asphalt to a substrate to approximately 1.1 kg/m (23 lbs/100 ft ), or the thickness of a dime. A ply sheet would then be unroUed into the hot asphalt. Additional ply are then mopped in, with each layer offset so that the roof has three or four phes of felt over the entire roof. The amount of offset is calculated by the formula, offset = 34 in. (86.4 cm) /number of pHes. Manufacturers of pHes print laying lines on the felts at the correct locations to assist in laying up the roof with the correct offset. 

Differential thermal expansion of the brick, its joints, and the vessel substrate necessitates an intermediate lining of lead, asphalt, rubber. 

Cured concrete can be bonded to cured concrete, as in the installation of precast buttons to a highway surface. Steel bridge railings can also be bonded to the concrete surface of a bridge sidewalk. In the case of deteriorated concrete, the adhesive can be used to rebuild the structure to its former line and grade. Epoxy adhesives are also commonly used on other roadway materials, such as asphalt and brick however, the predominant application is concrete substrates. The most frequent combinations of substrates that are bonded with adhesives in this market segment are... 

Most asphalts when dissolved in such concentrations in organic solvents can hardly be filtered. Even centrifuging some fails to separate minerals from the bitumen solution cleanly. Application of the Duffy standardized procedure for analyzing asphalts (5) by adsorbing on suitable substrates and eluting successively with appropriate solvents proved to be a more satisfactory way of attacking the problem. Bitumens are thereby resolved into three fractions hydrocarbons, resins, and asphaltenes any insoluble components remain behind on the adsorbent and are determined by difference. The procedure can be used for entire asphalts as well as bitumens, and the difficulty is thus circumvented. 

Note. Asphaltic membranes will bridge minor joints or cracks in substrates. Thin membranes are very rigid and will not absorb movement in the substrate. Movement will telegraph through to the finished work. Expansion joints in the finished surface must be located directly over the joints in substrate. 

Quarry Tile Tile is used in much of the food process and food preparation areas, also toilet and change areas. In general, it is installed without an asphaltic membrane but with a thin adhesive membrane usually an epoxy type. As noted above, the concrete substrate must be true to line without irregularities such as humps and bumps. All such flaws will telegraph through to the finished surface. Cleanliness is a major attribute of the quarry tile installation. For example, in a synthetic elastomer plant the raw latex when spilled stuck tightly to the concrete floors. Quarry tile was used with an epoxy bed and a furan joint (very narrow, Vie"). Due to the greater density of the quarry tile the unvulcanized material cleaned up easily. 

Resin Mortars This group includes the furans, phenolics, polyesters and the epoxies. Some of these mortars are used as thin membrane beds in lieu of asphaltic. Except for the epoxies and polyesters, most of these are acid catalyzed materials. The alkalinity of the concrete will retard the catalyzing reaction. Therefore, the concrete substrate must be neutralized before such a mortar is installed in direct contact with concrete. 

While this book was in its final preparation stage, two additional types of adhered sheet linings for chemical exposures have come to our attention. One is a sheet with, as the exposed face, a Tedlar(sf film adhered to a layer of rubber-asphalt blend. The sheet is applied with rollers to a substrate surface that has been coated with an adhesive primer. Sheet edges are butted with an adhesive lap strip of Tedlar applied over the joint to protect it. This is a proprietary product presently available from only one source, which will supply particulars of the application procedure and chemical resistance tables upon request. 

Concrete (or other suitable substrate) to receive a hot asphalt membrane must be clean, dry, and free of curing oils and from release compounds. 

You may wonder what the source of these bubbles or blisters may be. Blisters are caused by one of two things-water or air. If the substrate is at all porous, it contains air. Or there may be some water inside the concrete, too deep to see. When the hot asphalt is applied, the heat, transmitted into the concrete, causes the air to expand or the water to vaporize. In either case, it tries to escape, and in doing so, causes bubbles. An alternative possible source is the kettle. If a few drops of rain get into the kettle, and the pot tender has not stirred it all out, some foam may have gotten into the pail the mechanic has just used-and as this hot material is spread, a bubble formed. If the pot is stirred with a power mixer, or even vigorously by hand, the surface can trap air which can get into the applied hot asphalt membrane in the same manner. A few random blisters can be repaired without too much trouble-but if there are more than one per square foot this problem should be corrected before proceeding. 

Where the bubbles are caused by air or water in the substrate, another application of hot asphalt will again expand the water or air in the substrate and again cause blisters. Repeated applications will continue to cause blisters as long as water or air is present. It is, therefore, a waste of time to apply more hot material before removing the source of the trouble. The best procedure is to dry the area thoroughly with heat or with a dessicant or both. If time does not permit, and there is not a great deal of moisture or air present, it may be possible to seal the surface with a concrete sealer, such as an amide-hardened epoxy, and then apply the primer and hot asphalt over this. 

In any case, the bond of hot asphalt applied in this manner is negligible and even without expansion or contraction of the substrate, this kind of seal is of little value. 

Where moisture (or air) in the substrate is so extensive that it appears impossible to eliminate it, or where it is fed from a subsurface source, a satisfactory membrane can sometimes be attained by ignoring the blisters in the first thin layer of hot asphalt, and then laying over this layer a 6 to 12 mil thick pinhole-free, plasticized PVC sheet, lapping all edges 2" or more, and rolling out all wrinkles and air bubbles, then laying another Vs" thick layer of hot asphalt on top of it. The use of visqueen and other stiffer plastic sheets yields mixed results due to poor bond to both asphalt and mortar, and the difficulty of working out air pockets and wrinkles. 

Urethane Asphalt Adhesive/Membrane A urethane asphalt elastomer serves as both an adhesive and a membrane to protect the substrate. It is a two-component material which bonds the blocks to each other and to carbon steel, alloy steel, concrete or other organic linings and also functions as a moisture and chemical-resistant barrier (or membrane) between the block and the substrate. 

The mortar may be applied to properly prepared concrete or steel substrates by usual acid-resistant bricklaying methods. An epoxy, urethane asphalt, bi-tumastic, polyester or vinyl ester membrane is required behind the block to ensure corrosion protection of the substrate. Because the mortar joints are rigid, a system of expansion/contraction joints, usually filled with ceramic paper, must be designed to prevent cracks. 

If the substrate is concrete, the most frequently employed membrane is hot asphalt. 

If sulfur mortar is to be used, read the section in this book on sulfur mortar, noting carefully all warnings and instructions. Verify cleanliness and dryness of the melting pot and all handling equipment. See that all safety precautions are observed, that no work whatsoever is done if substrates, brick or other materials that may be in contact with the hot sulfur are wet. See that the pot is stirred thoroughly at least once every few minutes, and kept stirred and covered, with heat removed when not in use. Handle fires in the same manner as asphalt fires (above). 

Figure 52-6 Note rough surface. Blisters indicate either wet surface or water in the substrate, drawn up by the heat of the hot asphalt. The interior of the kettle may have been wet, or rain water may have fallen into the kettle before or while the kettle was being heated.

Fig. 3 represents an example of the mat-like paving materials. According to the execution method as shown in Fig. 4, the mat-like paving materials are generally bonded to cement concrete or asphalt concrete substrates by using adhesives, and finished with acrylic resin topcoatings. Sometimes, fresh compositions with the same formulations are placed on the primer-treated cement concrete or asphalt concrete substrates, pressed with hot rollers, and finished with the same topcoating in the field. 

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