Wind-blown sand is widely distributed on the ground surface and can be used as backfill material. Mining with backfill is a proven mining practice in the coal industry and using cementitious backfill material of high concentration is an important development. The usual backfill material is composed mainly of wind-blown sand, fly ash, and cement. My team experimented with adding loess to the backfill mix to improve its characteristics. We determined the optimum proportion of loess to be added to backfill material to produce a high-quality, sand-rich cementitious material. In assessing the material, important parameters are compressive strength, bleeding rate, degree of stratification, setting time, and slump. When these were tested, results showed that the proper proportion of loess could improve performance. As the proportion of loess increased, the strength initially decreased but then increased; the bleeding rate, degree of stratification, and setting time decreased; and the slump rose. Loess is an inexpensive and widely available material that can improve the quality of cementitious material rich in wind-blown sand. The optimal mix proportion must be determined by test.
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