SOFTENING POIN TEST ( RING AND BALL TEST )

SOFTENING POIN TEST ( RING AND BALL TEST ).
( IS : 1205 – 1978 )

INTRODUCTION:

Bitumen does not suddenly change from solid to liquid state, but as the temperature increases, it gradually becomes softer until it flows readily. All semi-solid state bitumen grades need sufficient fluidity before they are used for application with the aggregate mix. For this purpose bitumen is sometimes cutback with a solvent like kerosene. The common procedure however is to liquefy the bitumen by heating. The softening point is the temperature at which the substance attains particular degree of softening under specified condition of test. For bitumen, it is usually determined by ‘Ring and Ball’ test. 

Object:

To determine the softening point of the bitumen by ‘Ring and Ball’ apparatus.

Apparatus:

a) Ring and Ball apparatus – It consists
(i)  Steel Balls – 2 nos.each has a diameter of 9.5mm and weight is 2.5+/-0.05gm.
(ii) Brass Rings – 2 nos. each 6.4mm depth, inside diameter at top 17.5mm, inside diameter at bottom 15.9mm and outside diameter 20.6mm and three equally spaced ball guides.
(iii) Support - The metallic support is used for placing pair of rings. The upper surface of the rings is adjusted to be 50mm below the surface of water or liquid contained in the bath. A distance of 25mm between the bottom of the rings and top surface of the bottom plate of support is provided. It has a housing for a suitable thermometer.

b) Thermometer – 00C to 3500C – sensitivity 0.10C.

c) Bath and stirrer – A heat resistant glass container of 85mm diameter and 120mm depth is used.

Procedure:

Sample material is heated to a temperature between 75 and 1000C above the approximate softening point until it is completely fluid and is poured in heated rings placed on metal plate. To avoid sticking of the bitumen to metal plate, coating is done to this with a solution of glycerin and dextrin. After cooling the rings in air for 30 minutes, the excess bitumen is trimmed and rings are placed in the support as mentioned in item(iii) above. At this time the temperature of distilled water is kept at 50C. This temperature is maintained for 15 minutes after which the balls are placed in position. The temperature of water is raised at uniform rate of 50C per minute with a controlled heating unit, until the bitumen softens and touches the bottom plate by sinking of balls. At least two observations are made.
Results:

The temperature at the instant when each of the ball and sample touches the bottom plate of support is recorded as softening value.


Limits:


Bitumen Grade A 35 & S 35  A 45 & S 45  A 55 & S 55  A 65 & S 65     A 90 & S 90  A 200 & S 200
Softening point 50 to 650 C  45 to 600 C  45 to 600 C  40 to 550 C  35 to 500 C  30 to 350C




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