Initial Consumption Of Lime Research Articles

Mix optimization and mechanical properties evaluation of lime-fly ash-stabilized loess in various engineering applications

Determining a rational mix ratio for lime-fly ash-stabilized loess (LFSL) can achieve multiple benefits of economy, environmental protection, and engineering quality improvement. This research was designed to optimize the mix ratios of LFSL applied in the pavement structure, subgrade, slopes, and foundations by conducting the unconfined compressive strength (UCS) test, California bearing ratio (CBR) test, resilient moduli (MR) test, triaxial test and uniaxial consolidation test on LFSL and lime-stabilized loess (LSL). Combined with the initial consumption of lime (ICL) test result and relevant specifications, the optimized mix ratios are as follows: 2% lime + 11.82% fly ash and 2% lime + 3.95% fly ash can reach the strength requirement of road base and subbase, respectively; 2% lime + 3.84% fly ash in building foundations and subgrade and 2% lime + 3.55% fly ash in slopes can reach the equal improvement effect of the LSL with 8% lime content. Three-factor comprehensive models were established and fitted in well with the experimental results of the LFSL with 2% lime content. Moreover, the development of correlations between UCS and other mechanical indices offers a shortcut for engineering property estimation. Finally, based on the abundant literature on LSL, another approach to estimating engineering quality was proposed for the LFSL with 2% lime content, which enhances the universality and practicability of the estimation models further.

Stress-Strain Characteristics and Mineralogy of an Expansive Soil Stabilized Using Lime and Phosphogypsum

The study involved the utilization of an industrial waste product, Phosphogypsum (PG) as an additive to lime for the stabilization of soil. Three lime dosages, viz. initial consumption of lime (ICL), optimum lime content (OLC) and less than ICL (LICL) were adopted for stabilizing the soil. The study investigated the stress-strain characteristics of soil composites stabilized with these three lime contents modified with optimum dosages of PG. Mineralogical studies were performed on the spent samples used for a series of determinations of unconfined compression strength tests with various combinations of lime and optimum PG content. The addition of an optimum dosage of PG resulted in an early strength gain of 8.8%, 14.1% and 13.9% and a delayed strength gain of 9.9%, 19% and 19.7% for 3%, 5.5% and 7% for the lime-stabilized soil, respectively. It was found that the addition of PG to the lime resulted in enhanced stiffness, residual strength and reduced brittleness due to the PG amendment of the stabilization reactions. However, in terms of the overall improvement of soil properties, the most favorable benefit was obtained by optimal PG modification of ICL rather than OLC. Microanalysis of the X-ray diffraction scatter also supported the results revealed through stress-strain characteristics. ICL with its optimal PG dosage showed a better progression of pozzolanic reactions when compared to the other two in terms of reduction of peaks of soil minerals and increase in peaks of CSH.

Effects of Lime Addition on the Plasticity of Tropical Clay Soils with Different Mineralogical Composition

The influence of hydrated lime on the plasticity of six tropical soils from Sudan having different mineralogical composition and constituents has been studied. The mineral constituents of the clay fraction of these soils vary from predominantly montmorillonitic, predominantly kaolinitic to mixed minerals. Lime has been added in varying percentages by weight and Atterberg limits have been determined for the untreated and lime treated soils. The test results have shown that on treatment with lime the Liquid Limit (LL) has decreased, the Plastic Limit (PL) has increased and the Plasticity Index (PI) has subsequently decreased for all the soils. The Optimum Lime Content (OLC), the Initial Consumption of Lime (ICL) and the Lime Fixation Point (LFP) have been defined and determined. A very good relationship between ICL and the Activity of the untreated soils (Ae) has been found out. The drop in PI and LL upon treatment with OLC is directly proportional to PI and LL, respectively. Montmorillonitic clay soils react faster with lime compared to kaolinitic clays. The OLC is higher for montmorillonitic clays compared to kaolinitic clays.

Pengaruh Subtitusi Bubuk Cangkang Telur terhadap Batas-batas Konsistensi Tanah Lempung yang Distabilisasi dengan Kapur

This study aimed to investigate the use of eggshell powder (ESP) to replace lime in soil-lime stabilization. Calcite was found in significant quantities in the ESP. The soil consistency limits are commonly used to evaluate the workability and estimate the mechanical properties of stabilized soil. The pH test was used to determine the initial Consumption of Lime (ICL), which was 8%. Several test variations were performed to investigate the effect of ESP replacement on the consistency limits of soil-lime stabilization soil, substituting ESP for a portion or all of the lime content required for stabilization. Soil-lime stabilization decreases the liquid limit, plasticity index, and linear shrinkage of the soil. With lime stabilization, the plasticity index reduced by 60% - 55%. The more lime content was substituted with ESP The greater the plasticity index. However, when all lime content was replaced with ESP, the soil plasticity index reduced by 29% compared to untreated soil. The shrinkage limit of untreated soil was 10.43%; after stabilization with 8% eggshell powder, the shrinkage limit increased by 26% to 13.22%. The shrinkage ratio, volumetric shrinkage, and linear shrinkage, on the other hand, are not significantly reduced. Lime types (hydrated lime and quicklime) have nearly identical behavior in terms of changes in soil plasticity. The eggshell powder can be used for soil stabilization and can affect soil plasticity. However, the changes in plasticity are not as significant as those seen with lime stabilization.

Valorization of phosphogypsum as a road material: Stabilizing effect of fly ash and lime additives on strength and durability

Phosphogypsum is a by-product from the phosphoric acid industry following the wet process. Known for its low cost, this process generates large amounts of phosphogypsum, the management of which has so far remained problematic due to the impurities it contains including heavy metals, radionuclides and acidic residuals. It is above all, its acidic nature that hinders its use as a road material since it increases its solubility which in turn makes it sensitive to water variations. This paper presents an investigation on the stabilization of Moroccan phosphogypsum, through neutralizing acidity, while considering both techno-economic and environmental constraints. To this end, mixtures of phosphogypsum and fly ash were prepared then activated with varying quicklime additions (beyond Initial Consumption of Lime) to develop different combinations of phosphogypsum (40–80%), fly ash (20–60%) and lime (4–20%). These have been tested for their mechanical and mineralogical properties at different curing periods (7, 28, 90, 180 days) besides durability against Wetting/Drying cycles, in order to evaluate the stabilizing effect of fly ash and lime. Results from Unconfined Compressive Strength (UCS) tests showed a strength increase with fly ash and lime addition with increasing the curing time. The UCS at 180 days varied between 1 and 3 MPa for formulations containing 4% lime (ICL) while those with 12–20% lime reached 4–7 MPa (12 times higher than UCS at 7days). As for durability, these showed weight losses of up to 10% upon W/D cycles, a strength loss of up to 56% and high porosity compared to formulations with higher lime content which rather gained up to 264% in strength. The influence of curing time and mixture composition on the mineralogy of the prepared composites was assessed through XRD and TGA analyzes highlighting the formation of ettringite as main hydration product responsible for strength development.

WETTING AND DRYING RESISTANCE OF LIME-STABILIZED EXPANSIVE SOILS MODIFIED WITH NANO-ALUMINA

Weak soil at construction sites necessitates ground improvement. Chemical stabilization is typically carried out using either lime or cement. The primary objective of this study was to assess the strength and durability of lime-stabilized soils modified with nano-alumina (NA). This study adopted the scientifically established initial consumption of lime (ICL) content for soil stabilization. In addition, nano-alumina was added in varying percentages as an auxiliary additive. It was observed that 0.5 % of nano-alumina was optimal with respect to the ICL for maximizing the soil stabilization. The stabilized soils were cured for 0, 7, 14, and 28 days. Post-curing testing revealed that the strength increased sixfold for the optimal combination, compared with the virgin soil. To understand the durability behavior of the optimal combination, the stabilized soil specimens were subjected to wetting and drying cycles after 28 days of curing. The optimal combination was nearly as durable as that of the lime-stabilized soil subjected to five cycles of wetting and drying.

Proposal for a Methodology Based on XRD and SEM-EDS to Monitor Effects of Lime-Treatment on Clayey Soils

The aim of this paper is to present the results of X-ray diffraction (XRD) tests and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analyses on a natural and lime-treated clay, in order to determine the percentage of lime able to stabilize soil. For this reason, XRD test analyses have been conducted on natural soil (TQ0) and on two different mixtures (TQ3 and TQ5): The former with 3% and the latter with 5% by mass of quicklime. These mixtures have been analyzed at different curing times: At the addition of lime (0 d), and after a mellowing period of 7 and 28 d. The obtained results show that 3% of CaO is the percentage of quicklime able to modify the material (initial consumption of lime (ICL)) and 5% of CaO is the percentage able to stabilize it (lime stabilization optimum (LSO)). Finally, SEM images allowed for the monitoring of the process of reactions between the soil and lime during the mellowing period, while EDS analyses validated the XRD results in terms of chemical composition of the examined soil. For the examined natural clay, statistical analysis of the obtained EDS results identified a linear regression curve between the added quicklime and the after-treatment Ca content. The proposed approach could be adopted to calculate the content of calcium after the treatment and verify the in situ-added CaO during roadworks or at the end of them.

Effect of compaction time delay on compaction and strength behavior of lime-treated expansive soil contacted with sulfate

Application of lime as an additive for controlling the volume change behavior and improving the strength of expansive soils has been in use over several decades. However, the contamination of lime-treated expansive soil with sulfate always results in the deterioration of treated expansive soil. Therefore, this paper highlights the effect of sodium sulfate solution on compaction and strength behavior of lime-treated expansive soil. Further, the effect of compaction time delay and contact period of sulfate solution with lime-treated soil is also brought out in this paper. To bring out the above effects, the lime contents corresponding to the initial consumption of lime (ICL) and ICL ± 1% were used along with sulfate solutions of 5000, 10,000 and 20,000 ppm. The experimental study showed that upon mixing the lime-treated expansive soil with sulfate solutions, the maximum dry unit weight decreased and optimum moisture content increased with increase in concentration of sulfate solutions when compacted without any compaction delay. With compaction time delay, the lime-stabilized soils mixed with distilled water led to the formation of flocs and aggregation of clay particles and decreased the maximum dry unit weight and optimum moisture content. However, the effect of compaction time delay was negligible on maximum dry unit weight as the formation of flocs and aggregation of clay particles were inhibited in lime-treated soil mixed with sulfate solutions. These changes in dry unit weights and soil structure were reflected on the strength of lime-treated expansive soil as well.

Influence of Blended Lime-GGBS Slag on the strength of Laterite

Residual soils are referred to soils that formed through process of physical and chemical weathering of in-situ rocks. Reactions of various physical and chemical weathering agents had resulted in physical and chemical variability of residual soil and site dependent. The structure and minerals of in-situ rock were degraded physically and chemically and thus making its less resistance to load compared to un-weathered parent rock. Hence, it is important to stabilize the residual soil. Different ratios of blended hydrated lime and Ground Granulated Blast Furnace Slag (GGBS) namely 10:0, 9:1, 8:2 and 5:5 were utilized in this study. The percentage of admixtures was set at 10% with respect to its dry mass of soil. Unconfined compressive strength of treated soil specimens were determined after 7 days, 14 days and 28 days of humid curing. The water contents of the specimens were found to decrease slightly with an increment of curing periods while the strengths of the stabilized specimens were increased with curing periods. The highest unconfined shear strength at 28 days was recorded as 321.74 kPa with 8.18% axial strain. Thus, it showed that the use of blended lime and slag can improve the strength of residual soil. However, the treated samples failed to achieve the minimum strength increment of 345 kPa to be considered as an effective stabilization as stated in ASTM D4609. Some other factors namely curing temperature and Initial Consumption of Lime (ICL) should be considered to optimize the strength of the stabilized materials.

Pozzolanic benefit of fly ash and steel slag blends in the development of uniaxial compressive strength of lime stabilized soil

This investigation involved the examination of pozzolanic benefits that resulted from the amendment of lime stabilization of a soil by using a combination of two industrial wastes viz. Fly ash (FA) and Steel Slag (SS). Two lime contents (6% and 8%), which represented the control specimens, were selected for stabilizing the soil, one above the Initial Consumption of Lime (ICL) and the other above the Optimum Lime Content (OLC), respectively. The lime to total solid waste ratio was maintained as 1:1, and the FA/SS ratio varied within the total solid waste content adopted for amending lime stabilization. The unconfined compressive strength (UCS) of the stabilized samples were determined by casting UCS specimens of 38 x 76 mm and cured for 2 hours, 7, 14 and 28 days. After curing, the specimens were strained until failure, to study the pozzolanic benefits of adding FA-SS. The results revealed that the addition of FA and SS improved the pozzolanic strength, ranging from 3.5% to 15%. The optimal dosage of FA and SS also varied with the lime content adopted. For the 6% lime content, a FA/SS ratio of 1:1 was found to be optimal, whereas for the 8% lime content, a FA/SS ratio of 3:1 was found to develop the maximum strength. The amendment of lime stabilization with FA/SS clearly brought about the difference in lime stabilization stages, unseen when only lime was adopted as stabilizer.

Strength and microstructure of micro ceramic dust admixed lime stabilized soil

The use of micro ceramic dust (CD) as an additive to lime in soil stabilization has been analysed in this study. CD was obtained by crushing and sieving of waste ceramic tiles from construction debris. The initial consumption of lime (ICL) for soil modification was determined using Eades and Grim pH test. In order to study the effect of lime content on soil stabilization, three different lime contents (below ICL, ICL and above ICL) were used for stabilizing the soil. These three lime contents were amended with various amounts of CD to study its effect on the strength of the stabilized soil. Unconfined compression strength (UCS) tests were carried out on the stabilized soil specimens of dimensions 38mm x 76mm at different ages of curing. The spent UCS samples were crushed and sieved to carry out Atterberg limits and free swell tests followed by x-ray diffraction (XRD) and scanning electron microscopy (SEM) tests for determining changes in microstructure. The results indicated that the addition of CD resulted in a marginally negative influence on the early strength of the stabilized soil at three days of curing whereas it enhanced the delayed strength of the soil at 28 days of curing, gaining between 12-14% strength. The effect of CD on the plasticity and swell-shrink of lime stabilized soil indicated a further reduction in plasticity and swell-shrink nature. The mineralogy of the amended soil revealed the formation of CSH and CAH minerals responsible for strength gain. SEM images used to analyse the microstructure of the virgin and stabilized soil, indicated the formation of a dense and compact microstructure. Finally, it was concluded that CD can be adopted as an auxiliary additive to lime in stabilization of expansive soil with provision of sufficient curing and the delayed onset of early strength due to CD can be overcome by using higher lime content in stabilization.

Bagasse Ash as an Auxiliary Additive to Lime Stabilization of an Expansive Soil: Strength and Microstructural Investigation

The study dealt with the effect of addition of sugarcane bagasse ash (BA) on the strength development of a lime stabilized expansive soil. Unlike previous investigations with combinations of lime and BA, this study compares the effect of lime contents determined by scientifically established procedures and the effect of BA on the stabilization of lime at different proportions with additional microstructural investigations. The minimum lime content required for stabilization known as initial consumption of lime (ICL) was determined using the Eades and Grim pH test as 5.5%. The optimum lime content (OLC) was determined using unconfined compression strength (UCS) tests as 7%. Another lime content less than ICL was randomly adopted as 3%. The three lime contents were mixed with 0.25%, 0.5%, 1%, and 2% BA. UCS samples of dimension 38 mm × 76 mm were prepared at a fixed dry density and moisture content and cured for periods of 2 hours (0 days), 3, 7, 14, and 28 days to study the development of strength and effect of BA. Mineralogical and microstructural analyses were performed on the pulverized UCS samples after failure. The results revealed that the addition of BA increased the immediate, early, and delayed strength of lime stabilized soil further, even when the lime content was lower than ICL. Addition of BA produced maximum immediate, early, and delayed strength gains of 58.3%, 20.7%, and 32.7%, respectively. Higher proportion of BA was required when lime content was above ICL, for maximum strength. Addition of BA resulted in better utilization of quartz in lime‐soil reactions leading to formation of CSH and CAH minerals. A dense compact matrix was seen on analyzing the microstructure of the stabilized soil composite.

Soil stabilization using lime precipitation technique

Many relevant studies on lime stabilization have been done with regard to swell-shrink behaviour of expansive soils. Sequential lime mixing technique was also proven to be effective in limiting the swell shrink behaviour. But, strength and deformation are generally the most important parameters in assessing the effect of soil stabilization in pavement and other geotechnical practices. Therefore, the impact of these modification techniques has to be studied in terms of unconfined compressive strength of lime-treated soft clays. Such studies would definitely imbibe confidence in the practitioners to take up these advanced stabilization techniques which would in turn make our designs more robust and safer. In this regard, the current investigation is taken up to examine the efficiency of lime precipitation technique by sequential mixing of sodium hydroxide (NaOH) and calcium chloride (CaCl2). The lime precipitated in expansive soil is likely to change the basic properties by short term modification reaction and long term pozzolanic reactions between soil and lime. In expansive soils, Initial Consumption of Lime (ICL) was established based on the experiment proposed by Eades and Grimm. All the laboratory tests were done by maintaining these moisture and compaction conditions. Lime precipitation was employed on the mixes and its time dependent impact on physico-chemical behaviour of expansive soil and formation of various cementation products were studied. The study discusses the effect of these reactions on Particle size, Unconfined Compressive Strength (UCS) and California baring ratio (CBR). The soil-lime modification reactions had significant impact on the index properties and Particle size of the expansive soil. Due to strong short time modification reactions and long term pozzolanic reactions, a notable increase in the CBR and UCS values of the expansive soil was observed

The identification and treatment of poor durability Karoo dolerite base course aggregate - evidence from case studies

The Karoo Supergroup covers approximately 57% of South Africa's surface area and the sedimentary rocks therein generally do not yield acceptable pavement aggregates. The Karoo Dolerite Suite (intrusions) present in these sedimentary units have successfully been used as pavement aggregate sources, but numerous cases of premature pavement failure due to alleged rapid degradation of the dolerite have been reported. Durability tests are included in basic or mafic igneous rock aggregate specifications, but rapid pavement failures continue to occur. A study was recently undertaken to identify cases where degradation of Karoo dolerite was the cause of pavement failure. A secondary objective of the study was to determine if any observed degradation could have been identified using currently specified or alternative testing methods. Three such case study sites are presented in this article and the properties of their materials compared to those from five non-problematic dolerite materials. It is shown that the poor performance of the case study materials was likely due to the poor durability of the materials, manifesting as a reduction in resistance to abrasion and attrition. The identification of the observed poor durability could not have been performed accurately using only the currently specified test specifications. Alternative tests that allow an accurate differentiation to be made were, however, identified and, based on the results, tentative limits set. Additionally it was shown that modification of problematic Karoo dolerite base course materials, by applying lime at a rate less than the initial consumption of lime, can be successful in preventing further rapid pavement failures.

Plasticity, Swell-Shrink, and Microstructure of Phosphogypsum Admixed Lime Stabilized Expansive Soil

The study involved utilization of an industrial waste, Phosphogypsum (PG), as an additive to lime stabilization of an expansive soil. Three lime dosages, namely, initial consumption of lime (ICL), optimum lime content (OLC), and less than ICL (LICL), were identified for the soil under study for stabilizing the soil. Along with lime, varying doses of PG were added to the soil for stabilization. The effect of stabilization was studied by performing index tests, namely, liquid limit, plastic limit, shrinkage limit, and free swell test, on pulverized remains of failed unconfined compression test specimens. The samples were also subjected to a microstructural study by means of scanning electron microscope. Addition of PG to lime resulted in improvement in the plasticity and swell-shrink characteristics. The microstructural study revealed the formation of a dense compact mass of stabilized soil.

Stabilization of Artificial Organic Soil at Room Temperature Using Blended Lime Zeolite

Organic content in soil is believed to inhibit formation of reaction products in lime stabilization which resulted in low gain of strength when dealing with organic soils. Zeolite, a kind of pozzolan with high CEC capacity is proposed to be use in this study in order to improve lime stabilization of organic soil. The effectiveness of blended lime zeolite in stabilization of organic soils was investigated by using two types of artificial organic soils with predetermined organic contents. Artificial organic soils were formed by mixing inorganic soil (commercial kaolin) with organic matter (commercial humic acid) at specific ratio. Initial consumption of lime for organic soils was determined in order to determine the minimum percentage of stabilizer required for each soil. Potential influencing factors that might affect the strength such as organic contents, contents of stabilizer, and curing periods were studied. The findings of the study showed that high organic contents and low lime contents resulted in lower gain of strength. However, it is found that slight replacement of lime with zeolite works well with low organic soil at long curing period which resulted in highest strength among all the mixes. Overall, longer curing periods will increase the strength of the soil in the order of 56 days > 28 days > 7 days. Nevertheless, the percentage of strength increment over curing periods is linear with the lime contents, which proved that lime is required for pozzolanic reaction.

Soil Stabilization by Chemical Agent

Soil treatment is commonly resorted in order to improve the strength, stiffness properties of road foundations, and reduce the swelling potential of expansive soils. In Jordan, considerable amount of construction activity is carried out at relatively shallow depths where soil is likely to be unsaturated and subjected to low stresses level. Road damage is frequently observed when it is founded on weak sub-grade in Karak. Therefore, chemical stabilization of the base course, sub base course and sub-grade is essential. The soil will be treated by using sodium silicate and lime with different percentages. An experimental program was designed to study the behavior of soil as the percent of additive agent changes. The results showed that; the geotechnical properties have been improved when soil is treated by mixing lime and sodium silicate. The initial consumption of lime is of 4 and 2 % for sodium silicate. The reaction time is a significant parameter where strength improves as time increases.

Effect of Humic Acid on Physical and Engineering Properties of Lime-Treated Organic Clay

The study of lime stabilisation has been established for a long time and its implementation in geotechnical engineering has improved regularly. The present work deals with the stabilisation of organic clay using hydrated lime, which resulted in three favourable combinations of artificial organic clay. The idea of using artificial organic clay is to reduce possible inconsistencies that may happen during testing and to ensure the repeatability of the results of the test. This is vital for comparative study that involves varying additive contents and curing periods. Due to the complex nature of natural soils, a series of experiments was carried out using the manufactured kaolin which represents the clay mineral and different commercial humic acid contents (0.5%, 1.5%, and 3%), which are the main constituents of organic matter that impede the lime stabilisation process. The amount of hydrated lime (5%, 10% and 15% based on dry weight of soil) was taken beyond the initial consumption of lime (ICL) value. Results are presented in three aspects: (1) behaviour of physical properties, (2) shear strength development and (3) microstructure changes due to shear strength. Results produced by physical testing show that the presence of humic acid has a drawback effect on untreated and limetreated organic clay. The decrease in specific gravity value is accompanied by a decrease in dry density and strength of kaolin prepared with higher humic acid content. Plasticity of untreated organic clays also decreases with increased humic acid content. Some notable increases in shear strength at 7 days curing period were observed in the limetreated sample for up to 5% lime content. However shear strength of lime-treated organic clay decreased at longer curing periods. A slight decrease in shear strength occurred for samples treated with 0.5% and 1.5% humic acid. The significant decrease in shear strength can be observed at 3% humic acid content. Thus it can be concluded that lime stabilisation is not effective with the presence of more than 1.5% humic acid at longer curing periods. A microstructure analysis was carried out on untreated and limetreated specimens at OLC (5%) with 1.5% and 3% humic acid content at a 14 days curing period, which represent the duration of the modification process. The findings reveal that the fabric of untreated organic clay for both specimens prepared at different humic acid contents reveals no apparent aggregations. More pore spacing was clearly observed for lime-treated clay minerals with 1.5% humic acid than for 3% humic acid soil structure. Flocculating structure was more visible at lower humic acid contents with particles dispersed by large openings.

LIME MODIFICATION OF CLAY SOILS FOR CONSTRUCTION EXPEDIENCY.

Lime modification has the potential to reduce greatly the delays to construction projects caused by wet weather. The initial consumption of lime (ICL) test, currently used as an indicator of how much lime to use, is shown to produce results that can be both inconsistent and excessively conservative. Interpretation based on the full pH against lime addition curve is suggested. Changes in plasticity with both time after mixing and lime content are examined for four British clays, comprehensive Atterberg limit testing being shown to be adequate for design. The points at which full modification occurs are interpreted from these changes and complement well those determined by the modified ICL test. Changes in plasticity caused by smaller lime additions are shown to be adequate in many cases to improve site workability. (A)