Hardness tester for Mastic Asphalt has been fabricated to meet the essential requirements od IS 1195 - 1968 in finding out the Hardness Number of mastic asphalt.
Hardness Number is defined as the figure denoting the depth in hundreds of a centimeter, to which a flat ended identation pin in the form of a steel rod 6.35 mm in diameter will penetrate the mastic under a load of 31.7 kg applied for 60 seconds, the temperature being maintained at
The apparatus consists of a frame supported by means of four leveling screws.On the top plate ,a lever with a counter balances weight and a load hanger is fixed .The ration of the lever to weight is such that when the weight is kept on the hanger ,the ultimate load acting on the penetration pin is 31 kg. A thermometer is fixed by a clip ,which records the temperature of the water in the container .
The load transfer bar passes through the support bracket and rest on the specimen . The penetration load can be adjusted and locked before the test is conducted .An adjustable ring is provided on the load transfer bar and a rest point.The dial gauge of 0.01 mm accuracy to record the depth of penetration is also provided .The ring can be adjusted and locked in position for initial setting of dial gauge. A cam which is operated by the handle is provided to lock or free the load transfer bar .