Study about the rehydration of phosphogypsum hemihydrate in tropical soil mixtures

ABSTRACT

The objective of this paper is to verify the occurrence of phosphogypsum hemihydrate (PG-HH) rehydration and its influence on the mechanical behaviour in tropical soil mixtures. The studies were carried out in mixtures with lateritic clay, PG and Portland cement. Were carried out microstructural and mineralogical analyses with scanning electron microscopy and X-ray diffraction experiments, compaction tests at different setting times and unconfined compressive strength tests on saturated samples subjected to weathering. This study showed that PG-HH can rehydrate when it is in contact with water. This fact changes its crystals’ shape and impacts the mechanical behaviour of tropical soil mixtures. Saturated samples exposed to weathering presented strength reduction. However, the strength of mixtures with PG-HH, even when rehydrated, is superior to the strength of mixtures with PG-DH. The incorporation of PG-HH in mixtures with tropical soil and cement in geotechnical works is possible despite its rehydration.

KEYWORDS:

• Chemical stabilization
• byproducts
• mechanical behaviour
• saturation
• weathering

Acknowledgments

The authors are thankful for the technical support given by laboratories in Federal University of Goias (CRTI, LabGeo, LabMic) and in University of Brasilia (geotechnical laboratory).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

All authors contributed to the study conception and design. Funding acquisition and project administration were conducted by M.M.A.M. and L.R.R. Material preparation, data collection and analysis were carried out by M.V.S., T.L.S., L.F.M.R and K.C.S. K.A. Formal analysis were performed by M.M.A.M, M.V.S., T.L.S. and K.C.S. K.A. Writing – original draft preparation were executed by M.V.S., T.L.S. K.C.S. K.A. and M.M.A.M. Writing – review and editing were performed by M.V.S., T.L.S, M.M.A.M, L.F.M.R. and L.R.R. All authors read and approved the final manuscript.

Additional information

Funding

This research was funded by Brazilian Research Agencies (Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq, process [408756/2016-0] and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES, Finance code 001) and CMOC International Brazil.