# Optimization of Microbial-Induced Carbonate Precipitation Parameters for Strength, Durability, and Environmental Safety of Phosphogypsum Road Base Materials

**Authors:** Peiyao Sun, Xiaodi Hu, Jiaxi He, Quantao Liu, Pan Pan

PMC · DOI: 10.3390/ma19040817 · Materials · 2026-02-20

## TL;DR

This study explores how to optimize a microbial process to strengthen and stabilize road materials made from phosphogypsum, while ensuring environmental safety.

## Contribution

The study identifies optimal parameters for microbial-induced carbonate precipitation to enhance the strength and durability of phosphogypsum road base materials.

## Key findings

- Optimal mechanical strength was achieved with 2.0 mol/L cementation solution and a 2:1 bacterial/cementation solution ratio.
- MICP improves durability by coating phosphogypsum particles and filling voids with calcium carbonate.
- Toxic leaching of F− and PO43− was significantly reduced in treated mixtures.

## Abstract

This study investigates the mechanical properties, moisture stability, and environmental safety of microbial-induced carbonate precipitation (MICP)-treated phosphogypsum (PG)-based mixtures (MPGT) for road base utilization. Optimal cementation solution concentrations and bacterial-to-cementation solution ratios were determined via unconfined compressive strength (UCS), California bearing ratio (CBR), and splitting tensile strength tests. Durability was compared with untreated mixtures, and enhancement mechanisms were analyzed using XRD, SEM, and FTIR. Additionally, toxicity leaching tests evaluated environmental safety. Results indicated optimal parameters of 2.0 mol/L cementation solution and a 2:1 bacterial/cementation solution ratio for maximum mechanical strength. Under these conditions, MPGT durability significantly improved compared to untreated mixtures. Mechanism analysis revealed that MICP-generated calcium carbonate coats PG particles and fills voids, enhancing strength and durability. Furthermore, F− and PO43− leaching concentrations were significantly reduced. In summary, MICP improves the mechanical performance, durability, and environmental safety of PG-based mixtures, promoting PG recycling in road engineering.

## Linked entities

- **Chemicals:** F− (PubChem CID 24524), PO43− (PubChem CID 1061), calcium carbonate (PubChem CID 10112)

## Full-text entities

- **Diseases:** Toxicity (MESH:D064420), injury to (MESH:D014947)
- **Chemicals:** CO32- (-), Si (MESH:D012825), PG (MESH:C077769), S (MESH:D013455), SiO2 (MESH:D012822), Cr (MESH:D002857), phosphoric acid (MESH:C030242), urea (MESH:D014508), ettringite (MESH:C501337), Na2O (MESH:C096707), OH- (MESH:C031356), Pb (MESH:D007854), K2O (MESH:C068440), quartz (MESH:D011791), oxide (MESH:D010087), Ca (MESH:D002118), heavy metals (MESH:D019216), lime (MESH:C016538), CaCO3 (MESH:D002119), NaCl (MESH:D012965), Carbonate (MESH:D002254), P (MESH:D010758), phosphate (MESH:D010710), Calcium Phosphates (MESH:D002130), O (MESH:D010100), ammonium (MESH:D064751), nitrogen (MESH:D009584), Water (MESH:D014867), NiCl2 (MESH:C022838), F (MESH:D005461), CaF2 (MESH:D002124), fluoride (MESH:D005459), CaCl2 (MESH:D002122), gypsum (MESH:D002133), HCl (MESH:D006851), NaOH (MESH:D012972)
- **Species:** Bacteria Latreille et al. 1825 (Bacteria stick insect, genus) [taxon 629395], Homo sapiens (human, species) [taxon 9606], Sporosarcina pasteurii (species) [taxon 1474]

## Full text

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## Figures

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## References

46 references — full list in the complete paper: https://tomesphere.com/paper/PMC12941396/full.md

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Source: https://tomesphere.com/paper/PMC12941396