Bitumen binders are used in flexible pavement construction. It is important for bituminous material to form ductile thin film around the aggregates, which serves as a binder. If the binder material does not have sufficient ductility, it leads to spurious pavement surface and leads to development of cracks. Therefore it is extremely important to carry out the ductility test on bituminous material.
Ductility is defined as distance in centimeters to which a standard briquette of bitumen can be stretched before the thread breaks.The briquette is stretched at a rate of 50 mm /min. +/2.5 mm per minute at a temperature of 27ºC +/0.5ºC.
The apparatus consists of water bath with a thermostatic heater and a circulating pump to maintain uniform water temperature One half of the briquette moulds is fixed on a fixed plate in the water bath, the other half of the briquette mould is fixed to a carrier which slides over a rotating the threaded shaft with a clutch. The motor and gears to rotate the shaft are housed in a cabinet fixed above the other end of the bath. A pointer fixed to the carrier moves over a scale graduated from 0-110 cm x 1 mm fixed on the bath with “0” (Zero) of the scale towards the fixed plates side. The rotating shaft has 2 speeds of travel for the bracket, 5 cm/min and 1 cm/min. selected by a clutch.
Water bath inside is of S. steel, its is an insulated water bath Water bath is provided with a drain. A heater with thermostatic control is fixed inside the water bath. Control switches for motor pump heater and indicator lamps are fixed at a convenient place on the water bath. Complete with three briquette moulds and one base plate, steel all made of brass operates on 230V A.C. supply single phase.
Ductility mould with base plate made of Gunmetal.