Abstract
For traditional concrete it has been found that the tensile strength (split) could be satisfactorily predicted from the compressive strength value which is obtained very easily according to American Concrete Institute codes. However, for two-stage concrete (TSC) there is no research work available for evaluating its tensile strength. TSC differs from the normal concrete not only in the method of placement but also in that it contains a higher proportion of stone aggregate. It may be regarded as a ‘skeleton concrete’, as the stone aggregates effectively rest against one another and the remaining voids are filled with grout. Because of the initial point-to-point contact of the aggregate, as placed, the tensile strength of TSC is expected to be different from conventional concrete. Apparently, this aspect has not been investigated thoroughly. The objective of this research was to present the effect of the grout proportions on the tensile strength of the TSC observed during split and double-punch tests. The relation between the tensile strength and compressive strength of TSC was obtained. It was found that the strength of TSC (compressive as well as tensile) is mainly governed by the water-to-cement ratio of mortar; however the use of different cement-to-sand ratios was shown to have some effect on the strength of TSC.