Engineering properties of mixtures of fly ash and waste foundry sand

The purpose of this paper is to present values of engineering properties of co-mixtures of fly ash and Waste Foundry Sand (WFS), which are presently used as fill or flowable backfill, The class-F fly ash generated at the Tae-An thermoelectric power plant was used in the testing program. Green sand, Furane sand, and Coated sand, which had been used at a foundry located in Pusan, Korea, were the sands used in the testing program. Laboratory experiments were performed to obtain the physical properties of the co-mixtures of fly ash and WFS. The hydraulic conductivity of the co-mixtures ranged from 3.0*10-5 m/s to 6.0*10-5 m/s. The 7-day unconfined strength of specimen prepared with Green WFS as high as 94% of the 28-day strength, but for specimen prepared with Furane WFS and Coated WFS, this ratio was only 64% and 66% of the 28-day strength, respectively. Results of the consolidated-undrained triaxial tests showed that the co-mixture of Furane WFS showed a distinct increase of the internal friction angle, while the other co-mixtures showed negligible increase. In the case of 28-day cured specimens, specimens of Furane WFS showed an internal friction angle of 41.8°, while specimens of Green and Coated WFS showed those of 33.5° and 35.0°, respectively. From the shrinkage test, the shrinkage ratios of all specimens did not exceed 0.25%.