Engineering Properties of Waste Foundry Sand Mixtures as Controlled, Low-Strength Materials

Lee et al.
Assistant Professor, Dept. of Civil Engrg., Kyungsung Univ., Pusan, Korea

ABSTRACT

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 41.8o, while specimens of Green and Coated WFS showed those of 33.5o and 35.0o, respectively. From the shrinkage test, the shrinkage ratios of all specimens did not exceed 0.25%.

KEYWORDS: controlled low-strength material (CLSM), fly-ash, flowable backfill, waste foundry sand

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