Preparation of cement-modified phosphogypsum filler under alkaline excitation conditions

Abstract Phosphogypsum (PG) stabilized with cement can be used as a bed or base course of the road, a novel method to consume solid waste. Meanwhile, using PG filler can also generate economic benefits and social value in engineering. In this paper, mechanical tests and microscopic inspection were used to analyze the performance of PG fillers and the mechanism of the modified process. The test results indicate that 1) When the environmental pH value is 8, the PG filler can be used in roadbed filling. However, the strength of the PG filler forms slowly. Its 7d unconfined compressive strength (UCS) is only 50% of 28d UCS. 2) Sulfate (SO4 2− ) induced AFt, which may fill the meso-voids of solidified PG filler, is an essential manifestation of cement-modified PG in alkaline environments. Therefore, the solidified PG filler seems water-resistant. Once the cement clinker content (mass fraction) is more than 7%, no damage phenomenon that affects the integrity of the specimen can be detected during the 60-day soaking.