Asphalt

Asphalt, oxidized bitumen, a resinous mineral of black or dark brown color, represents naturally occurring substances, in some cases derived from catabitumens (e.g., from petroleum through evaporation, oxidation, and condensation), and in others directly from anabitumens (original waxy organic substance, probably of planktonic origin, through the action of heat), brown or black, viscous, and sometimes solid masses that are a complex of hydrocarbons (mainly cyclic), insoluble in water, partially soluble in ether, and almost completely soluble in carbon disulfide, benzene, chloroform, and turpentine. Terminologically, they are not clearly distinguished from natural and artificial asphaltic gudrons, also called resins and tars, and, in relation to natural products, also malts and bitumens. These are semi-liquid or viscous-solid substances, intermediate products in the formation of the corresponding type of asphalt. Deposits of asphaltic pyrobitumens and asphaltites are known in Palestine in the U.S.S.R., in Mexico, in Abkhazia, etc.; proper asphalt is found on the island of Cuba, in California, in Mexico; finally, asphaltic limestones occur in Switzerland, France, Germany, Abkhazia, and asphaltic sandstones in Hungary, in the middle Volga region, etc. Possessing invariability, water and gas impermeability, chemical resistance, elasticity, the ability to easily soften and melt, good adhesion, odorlessness, harmlessness, and in many cases a beautiful glossy black color, asphalt has been used as a building material for cementing, surfacing, and impregnation since ancient times and to this day has no worthy rivals. All artificial products similar to natural asphalt can only partially replace it. Natural asphalt is used as a material for paving sidewalks, for pouring floors, and for moisture and acid insulation. Such work is done by tamping or rolling asphalt powder, which consists of crushed asphalt rocks, mainly limestone, or by casting asphalt mastic, obtained by adding gudrons to asphalt powder. When rolling, a mixture of asphalt, crushed stone, and sand is also used. Asphalt as a paving material is one of the best from a sanitary point of view as a relatively durable material that produces little dust and dirt, is easily cleaned and washed, and finally reduces street noise. The water impermeability and chemical resistance of asphalt are also used in the layers of stone masonry as a means to prevent capillary absorption of soil water and thus protect walls from moisture, when lining sewer pipes, water basins in factories and in horticulture, as well as in the manufacture of various waterproof glues and putties ('marine glue' etc.). Therefore, here too asphalt plays a hygienic role, protecting house walls from moisture. Artificial asphalts are used as cheapening or falsifying admixtures to natural ones: in the construction of 'macadam' roads from blast furnace slag and various rocks with a mixture of coal tar pitch; in the manufacture of roofing felt and 'wood cement' for gluing felt; in the impregnation of long-fiber material to obtain moisture-insulating asphalt slabs; in the production of heat and sound insulating 'cork asphalt', which is not affected by moisture, acidic and alkaline vapors and is therefore used in kitchens, spinning rooms and weaving workshops, laundries, baths, and for the installation of ice cellars and refrigerating machines operating on ammonia or sulfur dioxide. The use of asphalt as a flooring material in residential premises is not recommended due to its rapid cooling. Among other applications of natural and partly artificial asphalt, it is necessary to mention waterproof and acid-resistant surfacing, in the form of paints and varnishes, as well as numerous electrical insulating compositions.

P. Florensky. B. M. E.t.I. Professional diseases in workers dealing with asphalt are often encountered in the form of skin diseases, which most authors consider as a result of mechanical blockage and contamination of the sebaceous glands and constant irritation of the skin by resinous substances. The most common diseases are acne, furuncles, dermatitis, benign hyperkeratoses (papillomas), localized mainly on the hands, forearms, shins, scrotum. Special attention should be paid to the skin cancer observed in asphalt workers (with prolonged work), which mainly affects the thin skin of the scrotum, but also occurs on other parts of the body and develops in most cases from hyperkeratoses, warts, etc.