Quantitative Evaluation in the Box Test and Evaluation of Field Mixtures by the Tarantula Curve

Abstract

In this research project, a proposed evaluation technique of the surface voids concentrations in the Box Test was introduced. This was done by the development of a point count template that can allow critical surface voids to be identified and the evaluation to be more systematic. This method showed reliable results with low variability and can be considered as a useful tool in the Box Test surface voids assessment. Vibrators consolidate the concrete by removing unwanted air voids from its matrix. Frequency of a vibrator is one of the key parameters that impacts the vibration effort. An investigation was made to determine the effect of changing the vibrator’s frequency on the consolidation degree of concrete in terms of the amount of surface voids concentrations by the use of the Box Test. Results showed that a reduction in the frequency level could dramatically increase the surface voids concentrations at the sides of a Box Test sample. Finally, the Tarantula Curve, which is a new aggregate gradation technique that gives recommendations of aggregate gradations used in designing concrete mixtures. Hundreds of field mixtures that were made and placed and utilized in different states were compared to the suggested recommendations. Results showed that there were high agreement between the evaluated aggregate gradations and the Tarantula limits.