Compatibility Of Chemical Admixture With Cement: Marsh Cone Test
In order to meet the performance requirements of concrete for various infrastructure projects, concrete mixtures
have to be designed and produced using combination of different cementitious materials with water and aggregate and
chemical admixtures. The active constituent of concrete is cement paste and largely it determines the performance of
concrete. Admixtures in concrete confer some beneficial effects such as air entrainment, water reduction, plasticity, etc. on
the cement paste. Also setting time acceleration / retardation can be achieved by the use of admixtures. Addition of some
particular admixture may develop undesirable interaction between varying ingredients of concrete. Many times addition of
admixture beyond certain limit may show incompatibility. The term “incompatibility” has been applied to various types of
abnormal performance characteristics of concrete in both plastic and hardened stages, including setting and strength gain
issues, excessive slump losses and increased water demand. Marsh cone test is used to formulate the optimum dose of
particular admixture to the cement thereby avoiding cement-admixture incompatibility. For high Strength concrete and high
performance concrete, depending on location i.e. distance of site from the plant, the retention time of the concrete plays
important role. Because of retention time, the workability of concrete mix is increased as well as other properties like
flowability, setting time of concrete is enhanced.
Keywords— Compatibility, Marsh cone Time, Retention time, saturation point.