This test method is intended to measure the reduction in Marshall stability resulting from the action of water on compacted bituminous mixtures. A numerical index of retained stability is obtained by comparing the stability of specimens determined in accordance with Marshall procedures (CRD-C 649) with the stability of specimens that have been immersed in water for a period of 24 hours. This method is based in part on ASTM D 1075, “Standard Method of Test for Effect of Water on Cohesion of Compacted Bituminous Mixtures.”

This test operation of the (a) GTM fixed method employs two separate modes of Gyratory Testing Machine (GTM), namely: roller mode: and (b) GTM oil-tilled roller mode. The fixed roller mode of operation is employed in testing for compaction and strain indices only, while the oil-tilled roller mode of operation is employed in testing for strength properties as well as compaction and strain indices. This test method is for use with mixtures containing asphalt cement, asphalt cut-back, asphalt emulsion, or tar and aggregate up to 1 in. (25.4 mm) maximum size in the 4-in.