Role of particle characteristics in the compression behaviour of gap-graded sands

The compression in gap-graded mixtures of sands with combined mineralogy has been investigated in recent research, focusing on the key factors that might imply the occurrence of convergent or non-convergent paths in compression (i.e., transitional or non-transitional behaviour). From previous work, the mineralogy of a matrix composed of larger grains seems to determine the possibility of the occurrence of transitional behaviour. Hence, if there is a strong and stiff matrix made of quartz sand particles, which are either larger than or at least of similar size to the other component, then non-convergent compression paths (i.e., transitional behaviour) are likely to occur. As a further confirmation of this hypothesis, this technical note presents the results of oedometer tests on the same range of mixtures of a quartz sand and a carbonate sand as was used in previously published work, but with the larger component being of the stiffer and stronger quartz sand. In agreement with the hypothesis, transitional behaviour occurred.