Marshall Stability Test Apparatus

Marshall Stability Test Apparatus

Originally developed by Bruce Marshall, a highway engineer in U.S.A later on standardized by ASTM. Generally the test is applicable to hot mix designs using bitumen and aggregates upto a maximum size of 25mm. In this method, the resistance to plastic deformation of cylindrical specimen of bituminous mixture is measured when the same is loaded at periphery at 5 cm per min. This test procedure is used in designing and evaluating bituminous paving mixes. The test procedure is extensively used in routine test programmers for paving jobs.

There are two major features of the Marshall method of designing mixes namely.

a) densityvoids analysis, b) Stability-flow tests.

The Marshall stability of mix is defined as a maximum load carried by a 0 compacted specimen at a standard test temperature of 60 C. The flow value is deformation the Marshall test specimen at under goes during the loading upto the maximum load, in 0.25 mm units. In this test and attempt is made to determine optimum binder content for the type of aggregate mix and traffic intensity.