Fig 1.
Schematic drawing of procedure of microbial-induced calcite precipitation (MICP).
Fig 2.
Schematic illustration of microbially induced calcium salt deposition.
Table 1.
Contribution summary.
Table 2.
Physical and chemical properties of original desert soil.
Fig 3.
Grain size distribution curve of the tested soil.
Y-axis represents the cumulative percentage of particles passing through the sieves.
Fig 4.
Physical morphology of raw palm fiber before mixing, showing typical yellowish-brown surface texture and fibrous bundle structure.
Table 3.
Physical and mechanical properties of palm fiber used in this study.
Fig 5.
Surface appearance of MICP-treated sand sample after 7-day curing with 0.15% palm fiber content, demonstrating crust formation and structural integrity.
Table 4.
Composition and labeling of desert sand.
Fig 6.
Micro-penetration test device used to evaluate bearing capacity-Measure the soil penetration resistance.
Table 5.
The parameters of the vernier calipers.
Fig 7.
The instrument of freeze-thaw test.
Fig 8.
Bearing capacity.
Fig 9.
Crust thickness.
Table 6.
The calcium carbonate content and the crust thickness of the sample.
Fig 10.
Crust thickness and calcium carbonate content.
Fig 11.
The relationship between calcium carbonate content and cementation solution concentration.
Fig 12.
Freeze-thaw cycle test loss of bearing capacity.
Fig 13.
Freeze-thaw cycle test loss of weight.
Fig 14.
SEM analysis of the sample (a).
Fig 15.
SEM analysis of the sample (b).
Fig 16.
Mechanism of sand solidification by combining palm fiber and microorganisms.
(a) Palm fiber enhances microbial colonization; (b) Colonizing microorganisms facilitate urea hydrolysis and calcium carbonate formation; (c) Calcium carbonate strengthens the interface between palm fiber and silica sand.
Fig 17.
EDS acquisition parameters and microscopic image scale. Instrument parameters: MAG 500x magnification, HV 15 kV acceleration voltage (optimal for light elements and thin samples) WD 15 mm working distance (balancing resolution and signal strength), 0.23 μm pixel resolution, 50 μm scale bar for feature size measurement, Technical note: 15 kV sufficiently excites medium-Z elements (Fe Kα) but may require higher voltage (>20 kV) for heavy elements (Zr L/M lines).
Fig 18.
Elemental composition and quantitative results.
Detected elements (ordered by energy): C, O, Na, Mg, Al, Si, Cl, K, Ca, Fe, Zr, Light elements (C, O): Potential sample constituents or surface contaminants, Na-Al-Si group: Typical of silicates or aluminum alloys, Fe-Zr: Possible alloy components or ceramic phases (e.g., ZrO₂), Quantitative data: Dual values represent weight % and atomic % (e.g., 1.5 wt%/ 3.9 at%), Local variations (1.7%/2.6%) indicate phase heterogeneity.
Fig 19.
Elemental mapping. Spatial distribution visualization: Color-coded intensity (warm=cold colors for high-low concentration), 50 μm scale matching SEM image, Critical parameters: 1-5 ms/pixel dwell time for optimal SNR, Peak deconvolution applied for overlapping signals (Zr L/Cl Kα).
Fig 20.
Spectral characteristics: X-axis: X-ray energy (keV), Y-axis: counts, Identified peaks (e.g., Fe Kα at 6.4 keV), Quantitative analysis: ZAF-corrected peak integration, Background subtraction for net counts, This integrated presentation demonstrates: Parameter optimization for multi-element detection, Spatial correlation between chemistry and microstructure, Rigorous quantification accounting for atomic number, absorption, and fluorescence effects, Comprehensive characterization of [observed features/phases] through combined SEM-EDS methodology.
Fig 21.
XRD analysis.
Fig 22.
FTIR analysis.
Fig 23.
Schematic diagram of the mechanism of microbe-induced deposition.