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Book ChapterDOI

Durability of Cementitious Phases in Lime Stabilization: A Critical Review

TL;DR: In this paper, the degradation nature of the soil-lime composites under adverse conditions like moisture ingress and carbonation is evaluated for their long-term performance, and the type of reaction products and their chemical composition, which is a function of the mineralogy of soil, will determine their durability in adverse conditions.
Abstract: Soil–lime interactions involve concomitant short-term and long-term alterations of the fine-grained soil resulting in the formation of a workable material bonded by various pozzolanic compounds. These pozzolanic compounds being cementitious in nature are expected to hold the soil particles together and bring long-term strength and stability to the soil–lime composites. However, the durability of cementitious phases formed due to pozzolanic reactions is highly subjective owing to the variations in the moisture and physiochemical factors like pH under diverse environmental conditions. The relative humidity and presence of atmospheric gases like carbon dioxide have a significant impact on the performance of the stabilized system. Carbonation of reaction products, as well as the effects of seasonal moisture fluctuations, can cause the decalcification of the cementitious phases and further degradation in the stabilized system. However, the type of reaction products and their chemical composition, which is a function of the mineralogy of the soil, will determine their durability in adverse conditions. The present study attempts to review the chemistry of reaction products formed in view of its inherent mineralogy. In addition, the degradation nature of the soil–lime composites under adverse conditions like moisture ingress and carbonation is evaluated for their long-term performance.
Citations
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Journal ArticleDOI
TL;DR: In this paper , the average unconfined compressive strength (UCS) was estimated by multivariate regression analysis using the stepwise approach, and the results indicated that the lime content significantly influenced the average UCS, followed by the water content and dry density.

3 citations

Journal ArticleDOI
TL;DR: In this article , the effect of carbonation on a one-year atmosphereherically exposed lime-treated soil structure is investigated, which involves analyzing the chemical characteristics and pore-structure modifications of several specimens sampled up to 12 cm depth perpendicular to the surface.

2 citations

Proceedings ArticleDOI
17 Mar 2022
TL;DR: In this article , the effects of carbonation on the compressive strength of lime-stabilized compacted expansive soil by varying the dosage of lime content and curing period were investigated using a thermogravimetric analyzer, Fourier transform infrared spectrometer, and mercury intrusion porosimeter.
Abstract: Carbonation is a chemical reaction that occurs invariably throughout the service life of lime-stabilized soil. Carbonation results in densification owing to the precipitation of reaction product calcite within the pore structure. However, the pore structure of lime-stabilized soil varies during curing due to the progressive surface modifications and pozzolanic reactions. Given this, the present study investigates the effects of carbonation on the compressive strength of lime stabilized compacted expansive soil by varying the dosage of lime content and curing period. The chemical, molecular, and microstructure changes upon carbonation were assessed using a thermogravimetric analyzer, Fourier transform infrared spectrometer, and mercury intrusion porosimeter. Results showed that the porosity of lime stabilized soil increased with initial lime content and curing period. Also, the permeation of gas and consequent changes in the mechanical performance upon carbonation is observed to be highly dependent on the availability of macropores and residual lime in a stabilized expansive soil.

1 citations

Journal ArticleDOI
TL;DR: In this article , the authors used the resistivity plate loading device to assess the physical and stiffness properties of compacted quicklime-stabilized subgrade instantaneously and simultaneously for compaction quality control.
Abstract: Quicklime-mixing in soil stabilization applications for subgrade construction is crucial to its engineering performance and controlling quicklime and water content. Modern construction quality control devices and methods have improved construction quality control substantially. Certain devices, meanwhile, still need to be studied more thoroughly. This study used the resistivity plate loading device to assess the physical and stiffness properties of compacted quicklime-stabilized subgrade instantaneously and simultaneously for compaction quality control. The Taguchi L 9 orthogonal array was used to design the experiment considering the dry density, test time, quicklime, and water content at various input factor levels. The pH, cation exchange capacity, conductivity, X-ray diffraction analysis (XRD), and scanning electron microscope (SEM) tests were further conducted. Analysis of the Taguchi experiment shows that the average soil electrical resistivity responses increased with dry density, test time, and quicklime content, and were highest at low water content. Whether the dry density, quicklime content, and test time are positively or negatively related to the average subgrade reaction modulus depends on the level of the water content. Regression equations are proposed to predict the average subgrade reaction modulus and soil electrical resistivity. The tested soils’ pH, conductivity, and cation ion exchange capacity properties were directly related to the test time, water, and quicklime content. The XRD showed nearly similar X-ray diffraction peaks. The SEM analysis confirmed marked changes in the microstructure of the samples that explained the changes in electrical resistivity and subgrade reaction modulus responses. The test results show that the resistivity plate loading device efficiently assesses compacted quicklime’s stiffness and physical properties at ease and instantaneously.
References
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Journal ArticleDOI
Warda Ashraf1
TL;DR: In this article, the authors summarized the existing knowledge regarding the carbonation of cement-based materials and identified the areas which require further investigations, including the potential of CO 2 storage in concrete and the newly developed carbonate binders.

311 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of decalcification under saturated conditions on the dimensional stability of cement paste were investigated, and it was found that the decalcation shrinkage is due initially to these structural changes in C3S-H at Ca/Si ´1.2 and eventually to the decomposition of C−S−H into silica gel.

281 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of lime stabilization on these soils was evaluated through determination of geotechnical properties such as liquid limit, plastic limit, swell, compressive strength, mineralogy, and microstructure.
Abstract: Lime generally improves the performance of soils. However, some cases reported an adverse effect. To develop an understanding of the underlying mechanisms, a systematic study covering a wide range of plasticity and mineralogy of soils was carried out. Six different soil samples were reconstituted using two extreme types of soils, in other words, a montmorillonite rich expansive soil and a silica-rich non-expansive soil. The influence of lime stabilization on these soils was evaluated through determination of geotechnical properties such as liquid limit, plastic limit, swell, compressive strength, mineralogy, and microstructure. An optimum lime content beyond which the strength improvement decreased was found. This phenomenon is more prominently observed with silica-rich soils that form silica gel. As the silica gel is highly porous, when formed in large scale the strength gain from cementation is substantially countered by the strength loss from gel pores, giving rise to a visible reduction in ove...

228 citations

Journal ArticleDOI
TL;DR: In this article, phase and morphology evolution of CaCO3 precipitated during carbonation of lime pastes via the reaction Ca(OH)2+CO2→CaCO3+H2O has been investigated under different conditions.
Abstract: Phase and morphology evolution of CaCO3 precipitated during carbonation of lime pastes via the reaction Ca(OH)2 + CO2 → CaCO3 + H2O has been investigated under different conditions (pCO2 ≈ 10−3.5 atm at 60 % RH and 93 % RH; pCO2 = 1 atm at 93 % RH) using XRD, FTIR, TGA, and SEM. Simulations of the pore solution chemistry for different stages and conditions of carbonation were performed using the PHREEQC code to investigate the evolution of the chemistry of the system. Results indicate initial precipitation of amorphous calcium carbonate (ACC) which in turn transforms into scalenohedral calcite under excess Ca2+ ions. Because of their polar character, $$ \left\{ {21\bar{3}4} \right\} $$ scalenohedral faces (type S) interact more strongly with excess Ca2+ than non-polar $$ \left\{ {10\bar{1}4} \right\} $$ rhombohedral faces (type F), an effect that ultimately favors the stabilization of $$ \left\{ {21\bar{3}4} \right\} $$ faces. Following the full consumption of Ca2+ ions and further dissolution of CO2 leading to a pH drop of the pore solution, $$ \left\{ {21\bar{3}4} \right\} $$ scalenohedra are subjected to dissolution. This eventually results in re-precipitation of $$ \left\{ {10\bar{1}4} \right\} $$ rhombohedra at close-to-neutral pH. This crystallization sequence progresses through the carbonated depth with a strong dependence on the degree of exposure to CO2, which is controlled by the carbonated pore structure governing the diffusion of CO2. Both the carbonation process and the scalenohedral-to-rhombohedral transformation are kinetically favored under high RH and high pCO2. Supersaturation plays a critical role on the nucleation density and size of CaCO3 crystals. These results have important implications in understanding the behavior of ancient and modern lime mortars for applications in architectural heritage conservation.

194 citations

Journal ArticleDOI
TL;DR: In this paper, the long-term stability characteristics of FoCa bentonite soil (FoCa represents the first two letters of the two towns between which this type of soil is excavated: Fourgues and Cahaignes) using 4% lime treatment were examined taking into account the influence of wetting-drying and freezing-thawing cycles on key engineering properties.
Abstract: There are several questions that are not well understood with respect to the long-term stability characteristics of lime-treated expansive soils in spite of being used as a conventional technique to improve the properties of expansive soils. This paper examines the long-term stability characteristics of FoCa bentonite soil (FoCa represents the first two letters of the two towns between which this type of soil is excavated: Fourgues and Cahaignes) using 4% lime treatment. The long-term stability characteristics referred to as durability in the paper were interpreted taking into account the influence of wetting–drying and freezing-thawing cycles on key engineering properties which include swelling and strength behavior of both untreated and lime-treated FoCa. In addition, leaching tests were carried out to study the Ca2+ ions and pH concentration changes of the percolating water from both treated and untreated compacted expansive soil specimens analyze the permanence of the clay treatment. Finally, to highl...

151 citations