Influence of aggregate type, size and grading on interfacial transistion zone in concrete

摘要

Concrete has a highly heterogeneous and complex structure. At the macroscopic level (i.e. that which can be identified with human eyes) concrete may be considered to be a two phase material, consisting of aggregate particles dispersed in a matrix of the cement paste. At the microscopic level (i.e. that which can be identified with a microscope), a third phase - the interfacial transition zone (ITZ) - may be identified. This represents the interfacial region between the particles of aggregate and the hydrated cement paste (hcp), existing as a thin shell, typcially 10 to 50 umm thick around aggregates. The size of the ITZ depends on the size and grading of aggregate in addition to its dependence on other mix parameters. The former aspect was investigated by the authors and the findings are reported in this paper. It has been observed that the size of the ITZ increases with the size of the aggregate and the volume concentration of larger size aggregates.