Bitumen mastic has been known and used for many years as a weather and wearing surface for roofs, floors, foot walks and light driveways. It is composed essentially of a graded mineral aggregate and a bituminous binder, and is distinguished from the bituminous wearing surface of streets and roadways by containing so much of the bituminous binder that when hot it is of dough like consistency so that it can be compressed and smoothed to a true surface with light hand tools such as a wood float or spatula. On the other hand, the bituminous wearing surface of the streets and roadways is com paratively lean in bituminous binder and even when hot is still of a granular and relatively dry appearance and condition.
Bitumen mastic paving
It is spread with rakes as a loose mixture and afterwards compressed with heavy mechanically operated rollers, weighing from 5 to 1.0 tons. As bituminous mastic is used in buildings as a floor surface or over light foundation course as in a park or sidewalk or light driveway, it must necessarily be of such a nature that it can be put in place without a heavy roller, as is the practice in compressing bituminous street paving surfaces.
Bitumen mastic flooring
The presence in bituminous mastic of a surplus of bituminous binder has constituted a defect in such mastic making it more or less plastic, and when heavy loads, or even moderate loads supported upon but a small area. Are placed upon it, they sink into and mark by indentations the floor or walk to an objectionable degree, making it unsightly and rough.
Bituminous, mastic has heretofore been made in two ways. The first and earliest way is to select and pulverize a native rock asphalt, usually and preferably a calcareous rock which is of a porous nature and has become impregnated through natural causes with a maltha or other form of native bitumen. Such rock carries from 5 to 10% bitupulverized and even when heated does not, bituminous mastic