Page 38 - Unit 2: Pavement Material

Civil Engineering Department | DCC3113 : Highway & Traffic Engineering

Type of test The objectives of tests on road construction materials

Softening point test (AASHTO T53)
o
• To determine the softening point of bitumen with range 30 C to 157 C by means of the
o
Ring and Ball apparatus.
• In this test, bitumen is heated and poured in pair of rings. When the bitumen is hard,
placed the rings in a container filled with water at 5C. Two steel balls are placed on the
rings and gradually heat the water container. When temperature increases, the bitumen
softens thus the balls which act as weight, start to fall and land on the plate, 25.4 mm
below. The temperature at which ball touches the plate is called softening point

• Softening Point (SP) together with Penetration Value (P) are used to determine the
Penetration Index (IP). IP can indicate the properties of bitumen tested and its suitablity.

• IP can be determined using nomograph or the following eqution (BS 4987):

IP = 1951.4 – 500 log P – 20 SP x 100

50 log P – SP – 120.14

• Normally IP of bitumen for road construction is 25 mm
between -1 and +1

3.5g steel ball
Bitumen in brass ring Heater and magnetic stirrer unit
Starting point End Point

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Prepared by : SITI ZURAIFA BINTI MD SAH, zuraifa@pmu.edu.my