The bulk density of an aggregate is defined as the mass of the material in a given volume and is expressed in kg/litre.
• This volume includes the voids between, as well as the pores within, the particles.
• Bulk density is a function of particle shape, density, size, grading, and moisture content, as well as the method of packing the material (loose, vibrated, rodded) and varies not only for different materials, but for different sizes and gradings of a particular material.
• The bulk density of an aggregate can be used for judging the quality of aggregate by comparison with normal density for that type of aggregate.
• The bulk density is also required for converting proportion by weight into the proportions by volume.
Bulking of Fine Aggregate (Sand)
• The increasing in volume of a given weight of fine aggregate (sand) caused by the films of water pushing the sand particles apart.
• The extent of bulking depends on the percentage of moisture present in the sand and on its fineness.
• Figure 1 show shat the variation of percent bulking with moisture content.
Figure1. Effect of moisture content on the bulking of sand
• It seen that the bulking increases gradually with moisture content up to certain point and then begin to decrease with further addition of water due to the merging of films, until when the sand is inundated.
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