ABSTRACT
Bituminous products, particularly pitch, are damaged by heat and sunlight. Although bituminous materials are combustible, composite products such as mastic asphalt and pitch mastic are not readily ignited and do not support combustion. The bituminous products comprise bitumen, natural or derivative, coal tar and pitch. Coal tar runs at a lower temperature than bitumen and oxidizes much more easily. Bitumen is a non-crystalline solid or viscous material comprising complex hydrocarbons which is soluble in carbon disulphide, softens when it is heated, is waterproof and has good powers of adhesion. Coal tar and pitch soften at lower temperature, are less plastic, are less able to resist temperature variations and are less costly than bitumen. Pitch is not suitable for damp-proof courses and as roofing it should be used only for temporary work. Pitch mastic evolves fumes when it is hot and in confined spaces care must be taken to avoid inhaling them.
