Flowable Slurry Containing Foundry Sands

This research was carried out to evaluate the use of foundry sands on properties of flowable slurry. Two different flowable slurry mixtures were proportioned for strength levels in the 0.34–0.69 MPa (50–100 psi) range, at 28 days, using two different sources of foundry sand and two different sources of ASTM Class F fly ash. Flowable slurry mixtures containing fly ash, without any foundry sand, were used as reference mixtures for this investigation. For each reference mixture, additional mixtures incorporating clean and used foundry sands as a replacement for fly ash were also proportioned. These flowable mixtures made with and without foundry sand were evaluated for bleeding, depth of nail penetration, settlement, shrinkage, condition of set, etc. In general, bleed water increased with an increase in the added mix water or foundry sand content of the mixtures tested. The settlement decreased with a decrease in the slurry water content. All the test specimens showed no sign of shrinkage cracks. The depth of nail penetration decreased with increasing age or decreasing water content. Compressive strengths of the test mixtures were found to vary between 0.28 and 0.62 MPa (40–90 psi) at 28 days. The overall results showed that excavatable flowable slurry with desirable physical properties can be manufactured using foundry sand as a replacement for fly ash up to 85%.