Atterberg limits of baseball infield soils containing over-size particles, Part II: effects of sand angularity and uniformity

Abstract

Context Atterberg limit tests may be useful for evaluating baseball infield soils because these tests directly link soil behaviour to water content. Prior research has demonstrated that the liquid and plastic limits (LL and PL) of sand-clay mixtures are affected by sand properties. However, these studies have used sand exclusively <425 μm and little attention has been devoted to sand angularity or sand-size uniformity. Aims This research tested the effects of sand angularity and sand-size uniformity on the Atterberg limits of infield mixes containing 0–80% sand with much of the sand 425–2000 μm. Methods Experiment 1 compared the effect of mixing angular or round sand of equivalent size with a kaolinitic clay. Experiment 2 compared the effect of mixing one of two sands having a similar average particle size but varying uniformity with an illitic clay. Key results For mixes having equivalent sand content and sand size, the shape of the sand particles did not affect LL (P = 0.47) or PL (P = 0.80). Mixtures with non-uniform sand yielded higher LL than those with uniform sand (mean difference ~0.6% water content g g−1). The mixtures with non-uniform sand also remained plastic at higher sand content (~72.5%) than mixtures with uniform sand (~67.5%). Calculated threshold sand contents for the two sets of mixtures agreed closely with the experiments. Conclusions Sand angularity was shown to be unimportant in this context. When average particle size was held constant, sand uniformity affected the LL water content and the sand content corresponding to a transition between plastic and non-plastic behaviour. Implications This research suggests that baseball field managers need not consider the angularity of sand in an infield mix but should be aware of the uniformity of the sand used to produce the mix as this may influence the mixture’s plasticity.