Abstract:

Mildew on phosphogypsum products not only poses a threat to human health but also causes significant deterioration of material properties. This study was investigated the influence mechanism of additive types and dosages on the mildew of phosphogypsum， based on commonly using additives in the production of phosphogypsum products. The samples were characterized using XRF， EA， SEM， and static contact angle measurements to preliminarily explore the mildew mechanism of phosphogypsum. The results indicate that a higher dosage of water reducer accelerates the mildew rate of phosphogypsum. At the same dosage， naphthalene-based water reducer is more likely to induce mildew on phosphogypsum compared to polycarboxylate-based water reducer. A higher dosage of waterproofing agent slightly reduces the mildew rate， suggesting that waterproofing agent can improve mildew resistance to a certain extent. Increasing the surface environmental pH of phosphogypsum promotes the growth of the six selected fungal strains， making the material more susceptible to mildew. The carbon （C） element introduced by additives is the primary factor accelerating mildew， followed by nitrogen （N）. Elements such as K， Mg， Al， and P， which are macronutrients required for microbial growth， have a certain influence on mildew， but their effects are relatively minor.

Key words: phosphogypsum, water reducer, waterproofing agent, quicklime, mildew mechanism, mildew rate