HP Bitumen Handbook - Hindustan Petroleum Corporation Limited

Appendix-I : road metals and
materials
ABRASION : The abrasion test measures the abrasion or wear and tear
resistance of the aggregate. The test is performed in the Los Angeles drum
which is charged with a given weight of aggregate meeting one of the sieve
grading. The drum containing the charge and the abrasion steel balls is rotated
for 500 revolutions after which the material is screened through a No.12 sieve.
The percentage passing is the wear percentage.
AROMATICS: About 40 to 65 % of bitumen weight is due to aromatics. This is a
dark brown viscous liquid consisting of non polar carbon chains. They have high
dissolving ability and act as dispersion medium for asphaltenes. Increase in
aromatic content results in reduced shear strength.
ASPHALTENES:
Asphaltenes are highly polar and complex aromatic
hydrocarbons of high molecular weight. Asphaltene content largely affects the
rheological (flow
BLEEDING - The exudation of bituminous material on a roadway surface after
construction.
BLINDING - A covering of stone chips, sand or other suitable material applied to
a road surface after an application of asphalt.
BORROW - All material used in making embankments which does not come
from necessary excavation.
BRACCIA - Braccia is a deposit containing a large proportion of coarse angular
rock fragments.
BRICK - A building and paving material made from moist fire clay, semi-fire clay,
or shale or clayey-silt-sand, or combinations thereof, cut or moulded into blocks
and hardened by burning.
CALCINED GYPSUM - Gypsum partially dehydrated by means of heat.
CALIFORNIA BEARING RATIO : The strength of the sub grade and unbound
granular material is measured in the California Bearing Ratio test. In this test a
circular piston 1932 sqmm in area is driven into the material at a specific rate.
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