X-ray studies of lime-bentonite reaction products

Glenn, George Rembert

doi:10.31274/rtd-180816-1030

Cited by 2 publications

(2 citation statements)

References 3 publications

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“…Soil treatment with lime addition is certainly one of the most widespread methods used worldwide to improve the geotechnical properties of land soil waste, mainly clayey soils. This technique appears to be very effective [1][2][3][4][5][6][7][8][9][10][11][12] and durable [13][14][15][16] for the reuse of soils that are not suitable for earthworks in their natural state. During the construction of large infrastructure and geotechnical works, the surplus of unsuitable soil is a common occurrence leading to the serious problem of disposing of excavated material in dedicated areas.…”

Section: Introductionmentioning

confidence: 99%

Peculiar Features of Lime-Treated Pyroclastic Soils through a Multi-Scale Experimental Investigation

Cecconi,

Russo

2024

Minerals

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Soil-improvement techniques with binders are used in several geotechnical engineering applications as a sustainable solution for the reuse of waste soils. Due to their inherent complexity and their mechanical behaviour, pyroclastic soils are generally considered waste geomaterials in their natural state. Lime treatment of pyroclastic soils can be considered a viable solution for their reuse in geotechnical applications. In this paper, some peculiar features of the chemo-physical evolution and mechanical behaviour of lime-treated pyroclastic soils are evidenced through a multi-scale experimental investigation. While, for clayey soils, the fine fraction is mainly responsible for ion exchange and pozzolanic reactions induced by lime, for pyroclastic soils, pozzolanic reactions are dominant processes due to the low quantity of clay minerals along with the abundance of aluminates and silicates as the main constituents of their amorphous phase. The link between the phenomena detected at the microscale level, the mineralogical composition, and the macroscopic behaviour of two lime treated pyroclastic soils of different origin is explored through a multiscale approach.

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Section: Introductionmentioning

confidence: 99%

Peculiar Features of Lime-Treated Pyroclastic Soils through a Multi-Scale Experimental Investigation

Cecconi,

Russo

2024

Minerals

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“…1−5 A large body of the literature has been devoted to the qualitative understanding of the reactions between lime, cementitious materials, and clay soils, with mechanisms that are now well understood: cation exchange, flocculation, and pozzolanic reactions that form calcium silicate hydrates (CSH) and calcium aluminate hydrates (CAH), similar to those formed in the hydration of Portland cement. 6,7 The formation of CSH and CAH is aided by the alkaline pH (exceeding 12.4) created by lime and cement and by the acceleration in the dissolution of clay minerals in alkaline conditions that release alumina and silica in solution. For a kaolinite−lime system, the following reactions may be written 8,9 + + Ca(OH) (s) Ca (aq) 2OH (aq) The formation of the reaction products (written as jennite and C 4 AH 13 in the cement nomenclature) drives further dissolution of lime and kaolinite, and the additional release shifts the pH and the stability to form other CAH and CSH products over time.…”

Section: ■ Introductionmentioning

confidence: 99%

Thermodynamic and Kinetic Modeling of the Lime–Kaolinite System

Ahmadullah,

Chrysochoou

2023

ACS Earth Space Chem.

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A thermodynamic and kinetic model of kaolinite mixed with 5% lime was developed in this study in order to inform the long-term prediction of the system composition and its influence on the geotechnical properties of lime-stabilized clays. For model calibration, pore solution analysis of lime–kaolinite-compacted monoliths was performed for up to 2 years of curing time. The model showed that there are three stages in the evolution of the pozzolanic reactions that correspond to a progressive decrease in the rate of kaolinite dissolution. In the first stage (0–180 days of curing), portlandite is consumed rapidly, and kaolinite dissolution proceeds at the highest rate. From the model prediction, the phase assemblage during this stage is amorphous jennite, C4AH13, and SO4-AFm, which control Al and Si in solution at very low values and result in rapid strength development. In the next stage (180–360 days), portlandite is consumed and kaolinite dissolution slows down. Si and Al in solution increase rapidly, and the phase assemblage shows transformation to stratlingite first and then a small amount of gibbsite and tobermorite-II also starts forming. The last stage is marked by a further decrease in the dissolution rate and transformation of stratlingite to tobermorite-II and gibbsite, with every component in the solution plateauing except Si, which is predicted by the model to increase. The phase transformation is related to a reduction in strength from 360 to 720 days of curing. The model also predicts a last drop in pH and Al when stratlingite is completely depleted and equilibrium is reached, which was not observed in the experiments terminated at 720 days.

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X-ray studies of lime-bentonite reaction products

Cited by 2 publications

References 3 publications

Peculiar Features of Lime-Treated Pyroclastic Soils through a Multi-Scale Experimental Investigation

Peculiar Features of Lime-Treated Pyroclastic Soils through a Multi-Scale Experimental Investigation

Thermodynamic and Kinetic Modeling of the Lime–Kaolinite System

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