The quantities of cement, sand, and Trus-Con waterproof filler required for 100 square feet of surface with various mixtures and thicknesses of mortar, are shown in the accompanying table: Whitehall Waterproofing Compound. This compound is essentially a form of precipitated paraffine which is incorporated with the cement used in making concrete. Its particles are ex cessively fine, and its action is based on the well known water-repelling properties of paraffine. It is claimed to have been shown by competent tests, that the addition of this waterproofing material does not decrease in any way whatso ever either the tensile or the compressive strength of the cement.
Surface-Treatment Methods of Waterproofing Under this head we find the widely used processes of asphalt and tar-product water proofing, together with a long list of special proprietary compounds (many of which are asphaltic or bituminous in their nature) sold in paste or liquid form for direct application to the surface; also various special brands of weather-proofing and damp-proofing paints.
Asphalt Waterproofing. Asphaltic coatings, either alone or in combination with felt or other fabric, may be applied to the surface or between two sections or layers of the concrete structure. The latter method, in which the coating is ef fectively protected from abrasion, gives the most satisfactory results. A method very fre quently adopted is the use of an inch layer of asphalt poured hot between the face of the main wall and a thin protecting wall of brick or con crete built in front of it and carried up as the work progresses.
Asphalt, or asphaltum—sometimes called mineral pitch or Jews' pitch—is a natural bi tuminous product found in many widely scat tered localities. It occurs on the surface and shores of the Dead Sea, which is therefore some times called the "Asphaltic Lake," and in many parts of Europe and Asia; but the principal sources of supply are extensive deposits found in the West Indies (notably Trinidad and Cuba), in Venezuela, Utah, California, and other parts of both North and South America. It is brittle, of a black or brown color, and high luster on a surface or fracture; and it melts and burns, when heated, leaving little or no residue. In combination with coal-tar, lime, sand, etc., it is used in the manufacture of a large number of compounds employed for paving, waterproofing, etc.
As might naturally be expected, asphalts differ greatly in their quality and their degree of usefulness for certain purposes. The Utah, Trinidad, and Venezuela products are generally recognized as of the highest grade.
It is essential to a satisfactory waterproofing material that it should not only be impervious to moisture, but also unaffected by water and weather conditions; it should, moreover, be elas tic, so as to allow for settlement and shrinkage in structures without breaking or cracking the waterproof stratum; and it should not dry out or disintegrate on exposure to air, water, alkalis, or acids.
"Pioneer" asphalt is claimed by its proprietors to meet all the requirements of a satisfactory waterproofing material as spe cified above. It is applied at a temperature of about 425° F., with ordinary roofers' mops. In order to overcome the difficulty of making hot asphalt stick to a concrete surface, the same proprietors have developed a special priming paint known as "Pioneer" primer paint, in tended for the first coat to secure the necessary bond.
An effective bonding coat for use with any brand of asphalt waterproofing may be made by cutting asphalt with naphtha, the product being then applied like ordinary paint to the surface, which should first be thoroughly dry.
The following specifications, issued by the proprietors of the "Pioneer" products, may be taken as typical instructions in methods in gen eral use for the application of asphaltic com pounds to various waterproofing purposes: