An effective recycling direction of water-based drilling cuttings and phosphogypsum co-processing in road cushion layer.

The technology used in the production and exploration of shale gas creates a new source of clean energy. However, during the processes, large amounts of water-based drilling cuttings (WDC) are generated. Phosphogypsum (PG) is a by-product from the industry of phosphate fertilizer. Approximately, 5 tons of PG are generated for the production of per ton of phosphoric acid. The pile up of WDC and PG lead to severe risks of nearby soil and surface water. This paper paid attention to the recycling of WDC and PG as major raw materials in the preparation of construction cushion layer. In the research, physical properties, microstructure, and environmental pollution of the road cushion layer prepared from WDC and PG were investigated. The results show that the physical properties of compactness and unconfined compressive strength are basic meet the China national standard. The WDC cushion layer mainly constitutes of AFt, C-S-H, and plate-like Ca(OH) around the mineral phases. The leaching test revealed that the contaminants in the layer do not exceed the limits allowed by the "National Overall Discharge Standard of Sewage" (GB 8978-1996). This paper therefore outlines the effects that provide an effective way for the utilization of WDC and PG.