The formation of porous light ceramsite using Yellow River sediment and its application in concrete masonry production

The accumulation of large amounts of sediment in Yellow River has posed a threat to the local ecological environment. In this study, Yellow River sediment was used as the main raw material to prepare lightweight ceramsite and masonry mortar. The effects of pulverized coal addition, calcination time, and calcination temperature on the microstructure of ceramsite were investigated. The effects of the amount of raw materials, concentration of glutinous rice slurry, and substitution amount of ceramsite (as opposed to standard sand) on the properties of masonry mortar were then studied. For a pulverized coal addition of 10%, the calcination temperature was 1125 ℃, calcination time was 30 min, bulk density of the ceramsite was 879 kg m−3, water absorption was 5.9%, and cylinder pressure strength was 9.1 MPa. When the mass ratio (hydrated lime: Yellow River sediment: standard sand) was 3:4:2, glutinous rice slurry with a concentration of 3% was added and then cured in a curing box at a temperature of 25 ± 2 ℃ and humidity of 95 ± 2% for 28 days. The surface hardness of the obtained masonry mortar was 97 HA, and the unconfined compressive strength was 1.1 MPa. After 28 days of curing with ceramsite instead of standard sand, the surface hardness of the masonry mortar was 94.5 HA and the unconfined compressive strength was 0.91 MPa; this indicated that the standard sand can be completely replaced by ceramsite, thereby effectively increasing the utilization rate of Yellow River sediment. This work provided a feasible method for efficient utilization of Yellow River sediment resources.