Silo storage of building industry powders: consideration of the stress dependence of the bulk density

In this study, the stress dependence of the bulk density of various building industry powders like cements, tile cements, plaster, hydrated lime, etc. has been studied using a ring shear tester. The results of the measurements showed that the stress dependence of the bulk density for these powders can be approximated very well by a simple equation. The correlation coefficients were >0.993 for all 15 powders investigated. The constant in the approximation function, the bulk density at 1.0 kPa, correlates very well with the bulk density measured according to EN ISO 60. For the exponent c in the approximation function, a tendency is evident that for coarser dusts the value of c is lower and for fine dusts it is higher. However, this correlation is not very distinct.