Lime Modification Research Articles

Investigation of phosphogypsum-based cementitious materials: The effect of lime modification

Phosphogypsum-based cementitious material (PBC) is acknowledged as a low-carbon green composite material. The addition of lime to modify PBC has been found to significantly enhance PBC utilization rate. This study investigates the effects of varying lime contents in PBC on mechanical properties, volume expansion, hydration products, micromorphology, and pore structure of modified Phosphogypsum (PS). The results demonstrate that lime effectively counteracts the retarding effect of water-soluble impurities in PS, thereby reducing setting time. Additionally, the 7 days and 28 days strength of PBC initially increases and then decreases with increasing lime content, with the 28 days compressive strength of B0 (0.5%) reaching 48 MPa. A 0.5% lime-modified PS proves beneficial in promoting PBC hydration, reducing pore size, densifying the microstructure, and enhancing mechanical properties. Moreover, the volume expansion results highlight the significant influence of the alkaline environment on both the generation and distribution of ettringite, consequently impacting PBC expansion.

Effect of Glass Cullet Size and Hydrated Lime—Nanoclay Additives on the Mechanical Properties of Glassphalt Concrete

In this study, the use of glass waste as aggregate in asphalt mixtures was investigated. Maximum glass aggregate size options of 0.075, 2.00, 4.75 and 9.5 mm. were selected. Conventional bitumen, nanoclay-modified bitumen and hydrated lime-modified bitumen were used. Dense graded asphalt mixtures were designed according to the Marshall method. Mixtures were evaluated for low-temperature cracking, resistance to water damage, fatigue, and permanent deformation behavior with repeated creep, indirect tensile strength, indirect tensile fatigue, modified Lottman and Hamburg wheel tracking tests. Increasing glass aggregate size reduced the water damage resistance of asphalt mixtures because of the smooth surface of the glass particles and nanoclay and hydrated lime modification improved the mechanical properties of the asphalt mixtures. Using 2.00 mm sized maximum glass aggregate showed relatively less water damage and deformation properties due to higher internal friction which is due to the greater angularity of the glass particles. In addition, there was a significant correlation between repeated creep test, modified Lottman methods and Hamburg Wheel tracking test from the viewpoint of deformation and water damage assessments.

Permeability of Expansive Soils Modified/Stabilized with lime (Review Paper)

The aim of this paper was to review the mechanism of the expansive soil-lime reactions: short term and long-term reactions in both lime modification and lime stabilization. The focus of the study was the effect of curing time for a certain centigrade 25C curing temperature in both lime modification / stabilization-expansive soils on the coefficient of permeability. Peer reviewed articles published between 2000- and 2019 were collected and relevant data were extracted. Results of this review study showed that the coefficient of permeability of expansive soils modified with lime increased during the first 7 days of curing time at curing temperature 25C and it remains constant or slightly decreased for longer curing time periods. However, for expansive soils stabilized with lime, it was found that the coefficient of permeability increased during the first 7-day curing time at curing temperature 25C, then decreased during the longer curing time periods (pozzolanic reaction). It is also noted that even though the coefficient of permeability decreased during pozzolanic reaction, it remains higher than that of the untreated soils

Study on the effect of hydrated lime content and fineness on asphalt properties

Hydrated lime is known to be an effective moisture damage additive, and it can also reduce the chemical ageing of the bitumen and stiffen the mastic. However, the optimum content and fineness of hydrated lime used in asphalt have been rarely studied. In order to determine the effect of lime content and fineness on hydrated lime modified asphalt and select the optimum lime content and fineness, XD90 asphalt, granite and 200 mesh, 300 mesh and 400 mesh lime with different lime content were chosen as experimental materials. At first, according to surface free energy method, the adhesion work Wa was chosen as the main index to evaluate the adhesion between asphalt and granite, and the asphalt surface free energy components after hydrated lime modification were tested. After that, basic technical properties of hydrated lime modified asphalt were studied to refine lime content and fineness. Finally, multiple stress creep and recovery and linear amplitude sweep tests were carried out respectively to study rheological properties of hydrated lime modified asphalt. The results showed that the asphalt adhesiveness increased with the increase of lime fineness, and the optimum lime content for asphalt adhesiveness was around 10%. Moreover, hydrated lime could raise the asphalt viscosity and stiffen asphalt. To make ductility meet the specification requirements, the lime content should be controlled below 10%. When lime content was around 3%–10%, hydrated lime modified asphalt had relatively good rheological properties compared with base asphalt. Meanwhile, the high temperature performance together with the ability to resist permanent deformation was improved apparently. In conclusion, taking into account the adhesion, rheology and basic properties of hydrated lime modified asphalt, the optimum lime content and fineness could be finally determined.

Effect of water content on lime additive content in vacuum preloading with PVDs

Dredged slurry is composed of a great quantity of fine soil particles, which accumulate around prefabricated vertical drains during vacuum preloading. The addition of hydrated lime as a flocculent can improve the permeability and vane shear strength of dredged slurry. A series of experiments showed that lime exists in the lime modification optimum as a flocculent. This study was aimed at analyzing the relationship between a given amount of lime additive and different water contents according to lime flocculation combined with a vacuum preloading test. For this, parameters, including the pore water pressure, discharged water, post-test water content, and vane shear strength, were monitored. Based on a given amount of lime additive in optimum water content, a function was derived, which could provide theoretical guidance for similar studies in the future.

Rutting performance of hydrated lime modified bituminous mixes

Hydrated lime has conventionally been used in bituminous mixes primarily for improving the moisture damage resistance of bituminous mixes. Most of the available literature is about studies conducted on mixes in which lime was added as filler. The present study explores the effect of different proportions of hydrated lime added by two different methods (wet and dry) on the rutting performance of bituminous mixes. The rutting characteristics of unmodified and lime modified binders were evaluated in terms of superpave binder rutting parameter (G∗/sinδ) and non-recoverable creep compliance (Jnr). Mix rutting performance was measured in terms of E∗, E∗/sinφ, flow number and accumulated strain measured in dynamic creep test. Rutting performance of mixes improved significantly by lime modification. Wet method of addition of lime has significantly higher beneficial effect than the dry method. Flow number determined at 60 °C demonstrated the beneficial effect of lime more distinctly compared with the dynamic creep test conducted at 40 °C. It was also observed in this study that the beneficial effect of lime addition in reducing rutting (which is a high temperature phenomenon) was realized more at higher mix temperatures.

Development of bio-cemented constructional materials through microbial induced calcite precipitation

Microbial induced calcite precipitation (MICP) is an environmentally friendly technology to bond sand particle together to form sandstone like materials. In this paper, MICP-treated bio-specimen was developed through MICP. The property of bio-specimen was compared with beams or bricks made through lime modification and cement modification. Ottawa sand was used in MICP-treated bio-specimen preparation. The proportion of lime or cement was in the range of 10–40% by weight of dry sand. The four-point bending tests, brick compression tests and unconfined compression tests were conducted. The test results indicated that flexure strength of MICP-treated bio-specimen was 950 kPa which was similar to flexure strength of 20–25% cement-treated sand beams, but was much higher than flexure strength of 30% lime-treated sand beams. The brick compression strength of MICP-treated bio-specimen achieved 500 kPa, which was similar to brick compression strength of 30% lime-treated sand bricks. The unconfined compression test results showed that the unconfined compression strength (UCS) of MICP-treated bio-specimen (1300 kPa) was higher than UCS of 10% cement-treated specimen (900 kPa), and much higher than UCS of lime-treated sample (around 140 kPa). The relative uniformity of precipitated CaCO3 distribution was achieved through the sample immersing preparation method. SEM images showed that failure pattern of MICP-treated, cement-treated and lime-treated specimens were bond-particle failure.

Combination of vacuum preloading and lime treatment for improvement of dredged fill

Numerous land reclamation projects that utilise dredged fill are currently being executed in the eastern regions of China to cater to the demands of economic development and address the land shortage problem. However, the dredged fill has high water content, low shear strength, and mainly consists of fine-grained particles. A long period is thus normally required for the treatment of dredge fill by vacuum preloading, and clogging always occurs around the prefabricated vertical drains (PVDs), resulting in insufficient consolidation of the soil. To address this issue, combination of vacuum preloading and lime treatment is proposed in this paper. In this method, a certain percentage of hydrated lime (Ca(OH)2) is added into the dredge fill slurry before vacuum preloading, to enhance the engineering properties of the fill, such as the shear strength and permeability. The added hydrated lime would induce cation exchange on the clay surface and flocculation of the fine soil particles. As a result, this method would significantly mitigate the risk of clogging around the PVDs with the enhanced soil permeability, thereby improving the consolidation efficiency. In this study, dredged slurry with a water content of approximately 187% was utilised. Lime modification optimum (LMO) was first determined using the vacuum preloading method, and a comparison test was then conducted to verify the effectiveness of the proposed method. It was found that, compared to the conventional vacuum preloading method, the proposed method significantly increased the vane shear strength of all the soil layers, especially the deep soil layers, and afforded a higher consolidation rate.

石灰与水泥改性花岗岩残积土耐久性的对比评价

花岗岩残积土粘聚力小，水稳定性差，遇水易崩解，应用时需进行土体改性。其中在土体中掺入水泥或石灰是最常用的化学改性方式。展开室内试验，分别将石灰及水泥掺入花岗岩残积土进行土体改性，从CBR强度、崩解特性和水稳性三个方面对比评价石灰与水泥改性花岗岩残积土耐久性。结果表明，在最佳掺加量下，水泥改性后的各项指标基本均优于石灰改性，水泥改性花岗岩残积土的耐久性更优。 Granite residual soil has little cohesive force and poor water stability. It is easy to disintegrate in water, and soil modification is needed in application. The incorporation of cement or lime in the soil is the most commonly used chemical modification. The lime and cement were mixed into granite residual soil for soil modification, and the durability of lime and cement modified granite residual soil was evaluated from CBR strength, disintegration characteristics and water stability. The results show that under the optimal dosage, the indexes of cement modification are better than lime modification, and the durability of cement-modified granite residual soil is better.

Effect of aging on fatigue performance of hydrated lime modified bituminous mixes

Hydrated lime has traditionally been used as filler primarily for its ability to improve the moisture resistance of bituminous mixes. However, studies carried out in the past showed that the addition of hydrated lime is also useful in improving the resistance of bituminous mixes to rutting, fatigue and aging. The effect of lime in increasing the stiffness of the mix can be beneficial to thicker bituminous pavements, which will be in stress control mode of fatigue. The reduction in the rate of aging due to lime can also benefit the performance of mixes due to reduction in brittleness and improvement in the healing characteristics. The present work explores the effect of hydrated lime modification of bituminous mixes on their fatigue performance. The effect of two different methods of lime addition, wet and dry, was investigated. The influence of short-term and long-term aging of the mixes on the fatigue characteristics of bituminous mixes was examined. Ten different combinations of mixes with two virgin binders, four lime modified binders and four mixes with lime added as filler were considered in the investigation. The results of laboratory tests conducted for determination of the moduli of elasticity of mixes and the fatigue performance models obtained for different mixes, under two different aging conditions, combined with the mechanistic analysis of typical bituminous pavement sections established the beneficial effect of lime in improving the fatigue lives of bituminous layers, especially for thicker pavements.

Experimental assessment regarding leaching of lime-treated silt

Durability of lime-treated soil structures, such as earth dams, dikes or river levees, is related to stability, or long term physicochemical evolution of soils in their service environment. The present work aims at (i) providing information on the long term physicochemical behaviour of lime-treated soils subjected to leaching, and (ii) assessing if leaching could be detrimental to the durability of lime-treated soils.Lime addition improves the unconfined compressive strength (UCS) of silt by formation of secondary cementitious phases (C-A-S-H, C-A-H,…) and carbonation of lime. The UCS increases with the lime added. Leaching induces a leaching of these secondary phases, as recorded by the evolution of the chemistry of the leachates. The results obtained indicate that addition of lime up to soil lime modification optimum (LMO at 1% lime) is not sufficient to maintain long term durability of lime-treated soils. Addition of important lime contents extends the resistance of materials, but the UCS decreases. However, leaching of cementitious phases has no effect on the hydraulic conductivity of materials.

Relative efficiencies of electrolytes in stabilization of an expansive soil

Sequential permeation of calcium chloride and sodium hydroxide solutions into the soil mass leads to the formation of lime in the in-situ soil mass owing to chemical reactions. Previous studies have demonstrated that the lime precipitation modifies the expansive soil properties both by lime modification and pozzolanic reactions. However, the independent contributions of either calcium chloride solution or sodium hydroxide solution in stabilizing the expansive soil are not known. Therefore, an attempt is made in the present investigation to examine the relative efficiencies of calcium chloride solution, sodium hydroxide solution and lime precipitation in stabilizing the expansive soil by comparing the physico-chemical and index properties, oedometer swell potentials and unconfined compressive strength of treated specimens. The present investigation also brings out the relative efficiencies of hydrated lime and precipitated lime in stabilizing the expansive soil. The experimental results showed that treating the expansive soils with calcium chloride and sodium hydroxide solutions independently promoted only the short-term reactions whereas the sequentially treating the expansive soil with calcium chloride and sodium hydroxide solutions resulted in the formation of lime precipitation, which could mobilize both short-term lime-modification reactions and long-term soil-lime pozzolanic reactions.

Laboratory Investigations of In Situ Stabilization of an Expansive Soil by Lime Precipitation Technique

AbstractThe present investigation examines the efficiency of an in situ lime precipitation technique in stabilizing expansive soil through laboratory-scale model tests. Expansive soil was compacted in a cylindrical mold and sequentially permeated with CaCl2 and NaOH solutions into the expansive soil through a central hole filled with coarse sand. Successive permeation of CaCl2 and NaOH solutions into the compacted expansive soil resulted in precipitation of lime in the expansive soil mass. The precipitated lime reduced the plasticity index, controlled the swell–shrink potentials, and increased the unconfined compressive strength of the expansive soil by both strong lime modification reactions and soil–lime pozzolanic reactions. The results are corroborated with microfabric studies on lime precipitation treated specimens, which showed the formation of cementation bonds.

Behaviour of Lime Treated Cured Expansive Soil Composites

Expansive soils have the tendency to undergo volume change behavior and cause large uplift pressures and upheaval of structures built on them. Avoiding expansive soil in most of the cases is not practically possible, hence stabilization practices are undertaken to treat them. Chemical stabilization through lime is the most sought after treating method. In this study, soil from an expansive soil site, Siruseri near Chennai, was treated with lime to understand the microstructural changes taking place and its influence on the macro structural properties. X-ray diffraction, SEM and microporosimetry were the techniques used to understand the microstructural properties of lime treated soils. The expansive soil was treated with different percentage of lime, 2, 4, 6, and 8 % and cured for 3, 7, 14, and 28 days. The concept of lime modification optimum (LMO) was used as a reference to understand the progression of lime reactions. The change in the physical properties of the soil was determined through UCC, chemical batch testing, pH and chemical conductivity. The lime addition higher than the LMO brings about more permanent pozzolanic reactions which cause tremendous increase in strength. The time dependency of the reactions was observed through the change in pH values, conductivity and batch test results. At the microstructural level, lime addition reduces the specific surface area and increases the pore size. The SEM results also revealed larger clusters and aggregation of the clay particles.

Quick Lime Modification and Coagulation Performance of Nano-Inorganic Polymer Coagulants from Oil Shale Ash

The nano-inorganic polymer coagulant, poly-ferric-aluminum-silicate-sulfate (PFASS) modified by quick lime were prepared from oil shale ash, which were evaluated by treating sewage. The following results are discovered: The samples contain (CaO)xSiO2•zH2O, Fe2(SO4)2(OH)•5(H2O), NaAl(SO4)2•(H2O)6 and other crystal; PFASS are complicated compounds by iron, aluminum, silicon and other ions rather than simple mixtures of raw materials. The optimal coagulant dosage is about 80-100 mg/L for the turbidity removal, and the range of the suitable dose is wider for COD removal, the optimal dose of quick lime is 2.5 g for turbidity removal and 3 g for COD removal.

The mechanisms of hydrated lime modification of asphalt mixtures: a state-of-the-art review

Although already known for a long time, hydrated lime (HL) attracted a strong interest as an asphalt additive during the 1970s in the USA, when moisture damage and frost became some of the most pressing pavement failure modes of the time. Given its extensive use in the past 40 years, HL is known to be more than a moisture damage additive: it is an “active filler” that also reduces the chemical ageing of the bitumen and stiffens the mastic more than a normal mineral filler above room temperature. These properties impact durability, and HL is now seen as an additive that increases asphalt mixture durability. This article is a literature review on the fundamentals of the effect of HL on asphalt mixtures. The reasons for it being so effective lie in the strong interactions between both the aggregate and the bitumen and a combination of four mechanisms, two on the aggregate and two on the bitumen. HL modifies the surface properties of the aggregate, allowing for the development of surface composition and roughness more favourable to bitumen adhesion. Then, HL can treat the existing clayey particles adhering to the aggregate surface, inhibiting their detrimental effect on the mixture. Also, HL reacts chemically with the acids of the bitumen, which in turn slows down the age hardening kinetics and neutralises the effect of the “bad” adhesion promoters originally present inside the bitumen, enhancing the moisture resistance of the mixture. Finally, the high porosity of HL explains its stiffening effect above room temperature.

Performance-based mix design of unmodified and lime-modified hot mix asphalt

This paper presents the performance evaluation of unmodified and lime-modified hot mix asphalt (HMA) mixtures at varying asphalt content using asphalt mixture performance test developed from National Cooperative Highway Research Program project 9-19 and 9-29 and the viscoelastic continuum damage finite element analysis. Test methods adopted in this study are the dynamic modulus test for stiffness, the triaxial repeated load permanent deformation test for rutting, and the direct tension test for fatigue cracking. The findings from this study support conventional understanding of the effects of asphalt content and lime modification on the fatigue cracking and rutting performance. Finally, the optimum asphalt content for both lime-modified and unmodified mixtures are proposed based on the knowledge gleaned from the performance-based mix design methodology. With additional validation and calibration, the comprehensive methodology described in this paper may serve as the foundation for a performance-based HMA mix design and performance-related HMA specifications.

In-situ stabilization of an expansive soil in desiccated state

This paper examines the efficiency of in-situ stabilization of expansive soil by lime slurry technique in desiccated state through laboratory and field experimental studies. The laboratory and field studies consists of permeating 34% hydrated lime slurry into the desiccated soil through vertical holes and measuring the physico-chemical, index and engineering properties before and after treatment at different radial distances. The distinct changes in the physico-chemical and index properties of the expansive soil indicate the occurrence of lime modification reactions and pozzolanic reactions on lime migration into the inter-connected shrinkage cracks. The lime slurry treatment increased the soil <i>pH</i> (≍ 12) to the levels that are conducive for the pozzolanic reactions to occur. The soil-lime reactions reduced the swelling potential and increased the unconfined compressive strength of lime slurry treated expansive soil. The test results encourage the application of lime slurry technique to expansive soil deposits during dry season upon development of shrinkage cracks.

Case Studies and Benchmark Examples for the Use of Grading Entropy in Geotechnics

The grading entropy concept can be adapted to the field of geotechnics, to establish criteria for phenomena such as particle packing, particle migration and filtering, through a quantified expression of the order/disorder in the grain size distribution, in terms of two entropy-based parameters. In this paper, the grading entropy theory is applied in some geotechnical case studies, which serve as benchmark examples to illustrate its application to the characterisation of piping, softening and dispersive soils, and to filtering problems in the context of a leachate collection system for a landfill site. Further, since unstable cohesive (dispersive) soils are generally improved by lime, the effect of lime addition is also considered, on the basis of some measurements and a further application of the grading entropy concept, which allows evolutions in the entropy of a soil to be considered as its grading is modified. The examples described support the hypothesis that the potential for soil erosion and particle migration can be reliably identified using grading entropy parameters derived from grading curve data, and applied through an established soil structure stability criteria and a filtering rule. It is shown that lime modification is not necessarily helpful in stabilizing against particle migration.

Use of the Methylene Blue Stain Test to Evaluate the Efficiency of Lime Treatment on Selected Clayey Soils

AbstractThe methylene blue (MB) stain test was used to determine the efficiency of lime modification of clay soils and to define the percentage of lime required to reach the stabilization field. Montmorillonite and kaolinite, mixed in variable proportions with quartz sand, were treated with differing percentages of lime, and the MB test was performed on both untreated and treated soils. Results show that the test can determine whether a soil is prone to efficient modification, follows the evolution of clay minerals in the lime modification field, and it also determines the quantity of lime necessary to enter the stabilization field. X-ray powder diffraction, thermal analyses, and electron microscopy observations of the montmorillonite-richer sample showed its crystal chemical evolution in the modification field. Mineralogical results match the outcome of the MB test, defining the same lime percentage for best modification (4%) and confirming that the test can be used for preliminary and ongoing analyses o...