Page 36 - Lecture Notes DCC3113

PAVEMENT MATERIALS

3.1 THE MATERIALS AND TEST ON MATERIAL

3.1.1 The materials used in highway construction:

The materials used in pavement consist of aggregate mixed with binder which is:
a. Aggregate
b. Bitumen and asphalt
c. Tar
d. Cement
e. Fillers
f. Steel reinforcement

The function of each material is as follows:
a. Aggregate – main material that makes up about 93 % of the mix. The strength is resulted from
the interlocks between the aggregate and assist to distribute loads from the traffic in the
pavement
b. Bitumen or Asphalt – is a binder to glue the aggregate together to form an improved mix
c. Tar - a product of coal (black or dark brown rock consisting mainly of carbonized plant matter,
found mainly in underground deposits)
d. Cement - is a binder, a substance that sets and hardens independently and can bind other
materials together.
e. Filler – its fills the voids between aggregate and help stiffening the binder to produce a
stronger and stiffer mix that could last long.
f. Steel reinforcement - also known as reinforcing steel, reinforcement steel, or a deformed bar, is
a common steel bar and is commonly used as a tensioning device in reinforced concrete and
reinforced masonry structures holding the concrete in compression.

3.1.2 The objectives and characteristics of asphaltic concrete mix

Asphalt Concrete is the asphalt mix in place on the road including levelling and surface courses
during and after spreading and compacting. The design of an asphalt concrete mixture includes the
selection of the best blend of aggregates and the optimum asphalt content to provide a material that
meets the required specifications as economically as possible.

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