Determination of the water content of fillerised fine aggregates in the saturated surface dry state

Abstract

An experimental setup designed to capture the saturated surface dry (SSD) state of porous fine aggregates incorporating significant amounts of fines is presented. This setup is validated upon testing fine aggregate sources with different water absorption values up to 5.6%, and at least 8% of fines. Test duration is found to lie in the 120-to-240-min-range, depending on test sample initial mass and water content. Several procedures for calculating the water content in SSD state are presented and discussed. One of these procedures uses the drying theory to fit curves depicting water content shift as a function of drying time and identify breakpoints. A more straightforward strategy is focused on the transition point between retained and free water on charts representing the variations of water content as a function of relative humidity. In both cases, fairly repeatable and discriminant water content values in SSD state are obtained. As expected, these values are found significantly higher than those determined in the absence of fines according to the usual cone test (CEN, 2014). Moreover the lack of reliability of water absorption values determined in the presence of fines according to the cone test procedure is verified. Eventually, several perspectives are pointed out to improve the setup which could easily be automated.