The Relationship between dry rheology and particle shape of natural and manufactured sand
Paper i proceeding, 2014
Understanding the effect of particle shape on dry rheology is considered to be an important aspect in
order to replace natural sand used in concrete with manufactured sand. Crushed particles from solid
rock are normally less rounded and have less equally shaped dimensions compared to natural sand.
Thus, the flowability and workability of the concrete will be different. In previous research, it has been
demonstrated how different crushing techniques affects the shape of the particles. In many cases it is
believed that Vertical Shaft Impact (VSI) technology is a way forward to replace natural sand. To be
able to study the effect of VSI at the smaller fractions (63-2000 µm) sufficient measurements methods
to determine particle shape are required.
Optical tools to analyze the aggregates would make it possible to study a large amount of particles at
small fractions. The determination of particle shape of aggregates is challenging since the shape is
highly irregular and the size span of particles are very large. This study aim to evaluate one of the
available optical tools, the Camsizer, for digital imaging determination of shape and size distribution.
The available default shape parameters of the Camsizer are studied to understand the meaning of the
parameters and their suitability for determining the quality of manufactured sand.
To evaluate the capacity to determine particle shape, tests are made with 35 different materials. The
results are compared with the dry rheology measured with the standardized “flow cone” test.
Dependence has been previously proven between particle shape and the mass flow rate in the cone.
Three different shape parameters, aspect ratio, sphericity and symmetry, are studied with the Camsizer
and the results are compared with the mass flow rates in the cone. The results indicate a strong linear
relationship between the optical parameters and the flow cone test.