A synergistic approach to rapid stabilization and immobilization of crude oil-contaminated clayey sand using calcium chloride and sodium silicate
Bibliographic record
Abstract
The immobilization and stabilization of crude oil-contaminated soils pose significant challenges in geotechnical engineering, particularly in clayey matrices prone to hydrocarbon adsorption and structural degradation. This study evaluates a two-step synergistic grouting technique using calcium chloride (CaCl2) and sodium silicate (Na2SiO3) to enhance strength recovery and immobilize contaminants simultaneously. Laboratory experiments simulated field conditions on sand and sand-clay mixtures containing 1 %, 3 %, and 5 % bentonite under both clean and crude-oil-polluted conditions. Direct shear results revealed strength improvements of 28-120 %, with polluted clayey soils showing the most substantial gains. Cohesion increased from 29 kPa to 64 kPa, and the friction angle rose by 4-7°. In some cases, treated polluted samples outperformed untreated clean soils. Morphometric analysis confirmed microstructural enhancement: average pore area decreased by 37-52 %, major-to-minor axis ratio fell by 13-35 %, and eccentricity dropped from 0.83 to 0.66. These changes reflected the formation of calcium silicate hydrate (C-S-H) gels, which bridged particles and reduced void spaces. They created denser, more isotropic fabrics, improving load-bearing capacity, lowering permeability and limiting further hydrocarbon migration. The results showed that oil-polluted soils, which typically suffer pronounced mechanical deterioration, can be effectively rehabilitated using this method, in some cases exceeding the performance of untreated clean soils. Cost and carbon analyses confirmed the sustainability of the CaCl2-Na2SiO3 system, indicating significant reductions of 56 % in cost and 97 % in carbon emissions compared with Portland cement stabilization. Furthermore, hydraulic conductivity and leakage tests on polluted sandy soils indicated reductions of more than 90 % in conductivity and nearly 100 % in leakage for soil containing 5 % clay, confirming the method's effectiveness as both a stabilizer and a barrier. The results demonstrate that a two-step synergistic chemical grouting technique is effective for stabilizing petroleum-affected foundations, slopes, and containment barriers. Field trials are recommended to evaluate the material's long-term durability and environmental performance.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".