Since the early 1980s, specifications for bedding and jointing sand have become more stringent. This has taken place as designers realised that the permeability and shear strength characteristics of those sands play an important role in the serviceability and performance of pavements surfaced with segmental pavers. This paper presents the outcome of an investigation into the role of fine fractions (minus 75 micrometre material) on the permeability and shear strength characteristics of bedding sand. It was found that the inclusion of fine material greatly reduced the capacity of the bedding sand to drain water flowing into the pavement structure through paver joints while the shear strength of the bedding material was also reduced. It was concluded that specifications for bedding sands should limit the minus 75 micrometre material to below 2 per cent to optimise drainage and enhance stability. (a).
Abstract