The main requirement of an equestrian sand is to provide the horse with a riding surface that is sufficiently firm, supportive and which gives adequate traction. If the surface is too soft, it will ride deep and potentially cause strain injuries to the horse, whilst a surface that is too hard fails to provide enough cushioning; this can result in higher impact shock to both the horse’s legs and potentially the rider, should they fall from the horse.Other aspects to consider, that can all be affected by the choice of sand are:
- Good drainage – This is not only a function of the sand but also the aggregate layer beneath it, both need to be suitable and of a high quality.
- Consistency – The surface should be level and provide consistent performance across the whole arena.
- Durability – The chosen sand should have grains that do not break down when ridden on.
At present there are no official specifications or standards that apply to sand used in Equestrian surfaces, it is however possible to identify key parameters that result in a high performing sand surface:
- Chemical composition – High purity silica sand is durable, meaning the individual grains are less susceptible to breaking down through usage, which will help the surface remain consistent.
- Particle shape – Sands that are classified as either “subangular to rounded” or “subangular” have grains that compact well to provide a firm riding surface. If the grains are too rounded they will not compact fully and angular grains can compact too much resulting in a hard surface. Additionally, highly angular grains are more susceptible to fracturing under impact.
- Particle size – A fine to very fine sand is preferred, small grain size also aids with moisture retention while conversely providing good drainage.
- Particle size distribution – A range of grain sizes helps the sand compact due to the smaller particles filling the voids between the larger ones.
- Clay/silt content – Low clay/silt content helps with drainage especially over time as the extremely fine particles can migrate down through the surface and block the membrane. Additionally, when used in a waxed surface, clay/silt creates a larger surface area for the wax to cover, meaning that the sand itself may not be coated sufficiently.
The particle size distribution can be plotted onto a graph, the sands that perform well typically have a similar grading curve. This allows us to set parameters for grading that should indicate that the sand complies with the last three points above. Please see the table and graph below for examples: