Dry Lime Research Articles

Investigation of Weathering Resistance and Damage Manifestations of Mortar Formulations for Heritage Structures in Saline Environment

ABSTRACT Salt, moisture, wind, relative humidity, and temperature fluctuations accelerate the deterioration of heritage masonry mortars. The salt entering the structure crystallizes on water evaporation, resulting in efflorescence and cryptoflorescence. As the conservation of built heritage primarily focuses on protecting the structure’s functionality, durability, and compatibility with the materials, salt weathering resistance must be emphasized when choosing a repair material for conservation. This study investigates the resistance of five different mortar compositions to salt exposure. Mortar cubes of size 50 mm were cast using five different binder compositions — dry hydrated lime, lime aged for one month, lime aged for one year, lime mortar with 20% Ordinary Portland Cement by weight and lime mortar with 50% Ordinary Portland Cement by weight. Alternate wetting and drying cycles were simulated by immersing the cubes in a 10% anhydrous sodium sulphate solution followed by drying. Physicomechanical characterization of the mortar was conducted before weathering. X-ray diffraction and Scanning Electron Microscopy provided the mineralogical and morphological alterations of the mortar specimens with weathering, respectively. Along with the microstructural assessment, observations on the mass change during the weathering cycles indicated that the partial replacement of lime with cement improved the weathering resistance of the mortar by changing the pore structure of the matrix. However, salt weathering resistance was unaffected by the changes in the ageing duration of lime. The study provides options for alternative lime-based systems with enhanced salt weathering resistance and investigates the role of the compositional differences and their impact on the pore structure and strength of the matrix, which in turn governs the salt weathering resistance.

The influence of the pre-addition of semi-dry and dry slaked lime during the purification of flue gas on the subsequent chelation and solidification treatment of MSWI fly ash

Incineration is a main way to dispose the municipal solid waste (MSW) in China, but municipal solid waste incineration (MSWI) fly ash will negatively impact the environment and human health as containing high content of heavy metals. This study aimed to investigate the influence of the pre-addition of dry/semi-dry slaked lime during the purification of flue gas on the subsequent chelation and solidification treatment of fly ash. This study has found that semi-dry slaked lime had more effect on the solidification rate of heavy metals in MSWI fly ash compared to the pre-addition of the dry slaked lime. As the dosage of semi-dry slaked lime increased, the solidification rate of Zn and Ba increased to 100 %, while the solidification rate of Cr decreased to as low as 0 %. However, the effect of the dosage of semi-dry slaked lime on the other heavy metals (Cu, Pb, Cd, Ni) showed a complex trend. This study underscores the importance of the pre-addition of slaked lime during the purification of flue gas in influencing subsequent chelation and solidification treatment of MSWI fly ash. It provides valuable insights into optimizing lime dosage to enhance heavy metal stabilization, contributing to more effective and sustainable waste management practices.

The Effect of Nano-Hydrated Lime on the Durability of Warm Mix Asphalt

Premature failure in asphalt concrete pavement has been the main concern for pavement construction companies and engineers in recent years because of the large rise in traffic volume and loads and the temperature extremes in the summer and winter. The use of modifiers in asphalt concrete mixtures has attracted much attention to increase the performance and lifespan of pavements. As nanotechnology developed, several researchers concentrated on how these materials can help increase pavement serviceability by minimizing rutting and moisture damage. This study evaluates the Hydrated Lime (HL) effect by two methods (wet and dry hydrated lime) on the durability of the warm mix asphalt. The first method, HL, has been supplemented to the asphalt binder with three ratios (0.5%, 1%, and 1.5%) by weight of asphalt (Wet HL). Then, the second method was added via the aggregate weight as a replacement filler using three percentages (1%, 2%, and 3%) (Dry HL). The mechanical qualities, including Marshall Mix design, moisture susceptibility, and permanent deformation, were evaluated through experimental tests. Results showed that the mechanical characteristics and the fineness of the HL particle sizes are positively correlated.

Dynamic CFD modeling of calcination in a rotary lime kiln with an external dryer

Mid-kiln ring formation is a problem in lime kilns that may be related to fluctuations in the start location of calcination. To calculate fluctuations in bed and gas temperature profiles within a lime kiln with an external dryer, a dynamic two-dimensional (2D) axisymmetric computational fluid dynamics (CFD) gas model with a methane burner implemented in ANSYS Fluent, coupled by mass and heat balances to a one-dimensional (1D) bed model, was developed. The dynamic model was used to calculate changes in the location where calcination starts with fluctuations in operational conditions using pulp mill data. This model simulates radiative, convective, and conductive heat transfer between the gas, wall, and bed to determine the axial bed temperature in the kiln. The calcination reaction is described using a shrinking core model that allows for the prediction of the location at which calcination begins and the degree of calcination achieved. The solid motion within the kiln is modeled using Kramer’s equation modified for transient response. Steady-state and dynamic simulation results were compared to data from an industrial dry lime kiln, and good agreement was found. A sensitivity analysis was also performed to provide insight on how operating conditions and model variables impact the calcination location and degree of calcination. Of the variables examined, the fuel rate and the feed temperature had the largest impact on both the calcination location and degree of calcination in the kiln. Model predictions of a period of ring formation in the industrial kiln showed that the start location of calcination fluctuated by more than 2 m on either side of the mean of regular operation, warranting further investigation of the importance of these fluctuations on mid-kiln ring formation.

Additive Based on Synthetic Aluminosilicates for Dry Lime Construction Mixtures

The possibility of increasing the durability of coatings based on lime dry construction mix by introducing an additive containing synthetic aluminosilicates is substantiated. The regularities of the structure formation of the lime composite in the presence of an additive containing synthetic aluminosilicates, which additionally consists of a formation of calcium–sodium hydrosilicates and minerals of the zeolite group, an increase in the amount of chemically bound lime by 8.74%, are revealed. X-ray diffraction analysis and thermodynamic calculations have established that the mineralogical composition of the crystalline phase of the additive based on synthetic aluminosilicates is represented by thenardite, gibbsite, and the minerals of the zeolite group. It is shown that the content of the amorphous phase is 77.5%. It was found that the additive based on synthetic aluminosilicates is characterized by high activity, which is more than 350 mg/g. It was also found that the introduction of an additive based on synthetic aluminosilicates into the formulation of a lime dry mixture accelerates the curing of coatings and increases the compressive strength after 28 days of air-dry hardening by 1.9 times.

Use of Taguchi method to evaluate the unconfined compressive strength of quicklime stabilized silty clayey subgrade

For practical deployment of lime-stabilized subgrade in the engineering field, laboratory and field-based pavement design studies highlight the significance of simpler preparation and maintenance techniques. In this article, sets of samples were prepared using Taguchi L9 orthogonal array to quantify and assess the dry density, lime, and water content's effect on the unconfined compressive strength (UCS). Scanning electron microscope analysis and X-ray diffraction test were further conducted on prepared samples. The average UCS was estimated by multivariate regression analysis using the stepwise approach. Test results suggested that the lime content significantly influenced the average UCS, followed by the water content and dry density. In addition, whether the dry density is positively or negatively related to the average UCS depends on the level of the water content and lime content. A statistical regression model considering the interaction terms is proposed to predict the average UCS during the design of pavement foundations and evaluate the UCS. The stabilized soils’ variations in lime content, water content, and dry density nearly showed similar x-ray diffraction peaks. However, a marked change in the microstructure of the tested samples confirmed the results of the UCS test. The proper understanding and characterization of the effect of dry density, lime, and water content on soil strength and stiffness are vital for an enhanced design of pavement foundations. The dry density, lime, and water content should be carefully controlled during construction to realize design objectives.

Determination of Properties of Loose and Granulated Organic Fertilizers and Qualitative Assessment of Fertilizer Spreading

Precise and environmentally friendly fertilization is one of the most effective agrotechnical measures to improve crop yield, crop quality, and environmental sustainability. The aim of this study was to determine the uniformity of spreading of organic fertilizers on the soil surface at different flows by evaluating the influence of the physical and mechanical properties of the fertilizers. The physical properties of organic fertilizers have been found to have a significant impact on the uniformity of fertilizer distribution. The investigation of fertilizer properties showed that the average moisture content of meat and bone meal granular fertilizers was 8.6 ± 0.2%, of cattle manure granular fertilizers—14.9 ± 1.5%, of dry lime—9.4 ± 0.1%, of wet lime—17.0 ± 1.1%, and of manure—66.7 ± 6.9%. It was found that the granules of cattle manure were more evenly spread on the soil surface (Gaussian coefficient 0.46) than the granules of meat and bone meal (g2 = 7.11). At the same time, manure was found to be most evenly distributed on the soil when dry lime was spread more evenly than wet. Simultaneously, it was revealed that the physical properties of the fertilizer, such as higher moisture, lower mass, granule length, and width, affected the uniformity of fertilizer distribution on the soil surface.

РАЗРАБОТКА СОСТАВА СУХОЙ ШТУКАТУРНОЙ СМЕСИ НА ОСНОВЕ ИЗВЕСТИ

There is a renewed interest in limebased plaster coatings due to their optimal vapour permeability and bioproofness. This article discusses the possibility of producing dry lime plaster mix based on the lime-sand mixture of plants for the production of silicate bricks. Additionally improve the technological and operational characteristics of the lime dry plaster mix is proposed by using additives - redispersible polymer powder and cellulose ether.

The Influence of Dry Hydrated Limes on the Fresh and Hardened Properties of Architectural Injection Grout.

Dry hydrated lime is an air binder often used in architectural injection grouts. This study compared the influences of three commercially available dry hydrated limes on the injection grouts’ workability and mechanical properties. The main differences between the limes were in their chemical and mineralogical composition and Blaine specific surface area. The grouts were composed of dry hydrated lime, finely ground limestone filler, water, and super plasticiser. Subsequent results obtained revealed that the Blaine specific surface area is not directly related to the fresh grout properties. Grain size distribution and shape of lime particles and their aggregates in the water suspension are key parameters influencing the following fresh grout properties: fluidity, injectability, the mixture’s stability, and water retention capacity. However, the lime injection grouts’ mechanical strengths were higher in relation to an increase in the content of portlandite and the Blaine specific surface area of the dry hydrate.

Assessment the Behavior of Stone Columns under Confined Compression

The emphasis of current work is on assessing the settlement improvement ratio, which is described as the ratio between the settled soils treated with a stone column and the settlement of the non-treated soil (Sr = Streated/Suntreated). The research was conducted using a 300 mm diameter and 300 mm high stone-column container testing model. On 14 modeled stone columns made only from crush stones and using various backfill content, model tests including static axial compression tests were performed. The substance used in the stone backfill column had been changed by sand or lime or cement percentages. The shear strength prepared by the containers varied between 5.5 kPa and 13.5 kPa. Results show that the settlement ratio values, Sr achieved with crush stone, crushed stone +50% sand, crushed stone +5% dry lime, crushed stones +10% dry lime, crushed stone +2.5% cement +5.0% crushed stone +5.0% cement, respectively, was 0.23, 0.12, 0.16, 0.15 and 0.09. In other words, there is a drop in the settlement from 77% to 91%.

Assessing the influence of the mixing method on porosity and durability of NHL-based renders based on key parameters

Natural hydraulic lime (NHL) is a common binder material in historic mortars and becomes increasingly used in recent restoration works for the preservation of cultural heritage. These plasters, renders and masonry mortars are suitable for applications, where elevated water permeable characteristics are required. At the building site different workmanship methods may be used, which can be simulated by e.g. different mixing times. Hence, within the present study two NHL-based recipes using hydrated lime of different origin (dry powder and lime putty suspension) were evaluated with regard to the effect of different mixing methods and water content on fresh and hardened mortar characteristics based on a comprehensive experimental program. Additionally, the porosity was evaluated by direct and indirect methods for assessing the water transport behaviour. Although durability and the underlying water transport properties are strongly related to porosity, this study focused primarily on this essential interrelation described by key parameters found in literature and evolved within this study. The results revealed that the mixing method and its associated water content as well as the type of hydrated lime affect strongly the fresh and hardened mortar properties. The pore structure characteristics that resulted from different fresh mortar treatment are crucial for the developing of durability. The observed interrelation between the aforementioned characteristics is essential for a deeper understanding of NHL-based systems. Generally, a longer treatment time leads to a higher durability against e.g. like frost-thaw and salt exposure. Considering the evaluated characteristics, it is possible to apply a prediction model based on the introduced key parameters to obtain information about the estimated resistance of NHL-based renders against damaging processes. Thus, the gained insights are beneficial for a comprehensive scheduling of restoration approach with specified framework requirements and arranged general material selection.

Molybdenum, phosphorus, and pH do not constrain nitrogen fixation in a tropical forest in the southeastern Amazon.

High rates of biological nitrogen fixation (BNF) are commonly reported for tropical forests, but most studies have been conducted in regions that receive substantial inputs of molybdenum (Mo) from atmospheric dust and sea-salt aerosols. Even in these regions, the low availability of Mo can constrain free-living BNF catalyzed by heterotrophic bacteria and archaea. We hypothesized that in regions where atmospheric inputs of Mo are low and soils are highly weathered, such as the southeastern Amazon, Mo would constrain BNF. We also hypothesized that the high soil acidity, characteristic of the Amazon Basin, would further constrain Mo availability and therefore soil BNF. We conducted two field experiments across the wet and dry seasons, adding Mo, phosphorus (P), and lime alone and in combination to the forest floor in the southeastern Amazon. We sampled soils and litter immediately, and then weeks and months after the applications, and measured Mo and P availability through resin extractions and BNF with the acetylene reduction assay. The experimental additions of Mo and P increased their availability and the lime increased soil pH. While the combination of Mo and P increased BNF at some time points, BNF rates did not increase strongly or consistently across the study as a whole, suggesting that Mo, P, and soil pH are not the dominant controls over BNF. In a separate short-term laboratory experiment, BNF did not respond strongly to Mo and P even when labile carbon was added. We postulate that high nitrogen (N) availability in this area of the Amazon, as indicated by the stoichiometry of soils and vegetation and the high nitrate soil stocks, likely suppresses BNF at this site. These patterns may also extend across highly weathered soils with high N availability in other topographically stable regions of the tropics.

IMPACT OF DEHYDRATION METHODS ON THE YIELD AND QUALITY OF LIME PEELS PECTIN

Following the extraction of juice from lime fruits, the peels are dried and utilized in the production of pectin. Different dehydration methods are used to dry lime peels. These methods have great impact on the yield and the quality of the resultant pectin. The aim of this study was to investigate the effect of drying methods (hot air oven, microwave and Instant Controlled Pressure Drop (DIC) on the chemical composition of lime peels, and the extracted pectin. The results showed that DIC dried lime peels had the highest moisture content (12.80%), ash content (4.58%) and fiber content (26.83%). The highest pectin yield (25.77%) was obtained from the DIC dehydrated lime peels. The ash content of pectin samples ranged from 2.61% to 3.0%. Pectin extracted from DIC dried peels (DP) had the highest galactuornic acid content (86.82%). Degree of esterification of extracted pectin was 69.18%, 67.90% and 68.50% for oven dried lime peels (OP), microwave dried lime peels (MP) and DIC dried lime peels (DP), respectively. Therefore, all pectin samples were classified as high ester pectin. The extracted pectin samples were used to make strawberry jam and compared to commercial pectin. The results showed also that viscosity values of jam made by extracted pectin were higher than jam made by commercial pectin. The highest value of viscosity was found in jam made with oven pectin (OP) being 480 cp, thenjam with DIC pectin (DP) being 472 cp, and then jam with microwave pectin (MP) being 450 cp. Sensory evaluation of jam samples showed that jam made with (DP) had the highest score in respect to colour and texture. Strawberry jams made with OP and DP were characterized by the highest score in respect to odour, taste and over all acceptability.

Performance analysis of an online lime separation system in a refuse incineration plant

This study aims to examine the effect of an online lime separation system with the semi-dry scrubber and dry lime injection system in a refuse incineration plant. Fine powder was used to prepare different concentrations of lime slurry to remove four combinations of boiler outlet acid gas. Results show that the lime separation can reduce the particle size (D90) of the hydrated lime from 31 to15 μm. The removal rate of HCl and SO2 remains over 98% and 90%, respectively. If the SO2 concentration in the gas is maintained below 200 mg/Nm3 via judicious refuse mixing, the consumption of lime will be most economical. Herein, the payback period of the facility will be approximately three years, and the online lime separation system can enhance the quality of hydrated lime, improve the emissions quality, reduce the consumption of lime, and achieve economic benefits.

Tobacco use and oral health status among adolescents visiting patliputra medical college and hospital, Dhanbad

Introduction: Tobacco use is one of the main risk factors for a number of chronic diseases, including cardiovascular diseases, lung cancer, and oral cancer. Tobacco epidemic is one of the public health threats killing nearly six million people yearly. Tobacco use also contributes to poor oral health causing staining, bad breath, and tooth decay. Different studies in India are suggestive of upward trend in the use of tobacco even in adolescents.Objectives: The objectives of this study are to find the prevalence of tobacco use among adolescents in an urban slum and to assess the oral health status among them.Materials and Methods: This cross-sectional study was carried out as a part of oral health assessment camp conducted in an urban slum. All adolescents attending the camp were recruited in the study after due informed consent, the final sample size is 130.Results: The overall tobacco use among adolescents was found to be 95.8% adolescent boys and 27.6% among adolescent girls. The most common reasons cited for tobacco use were peer pressure followed by parent's influence. Smokeless tobacco (dry tobacco, lime, and gutkha) was consumed by 39.13% boys and 19% girls. Smoking was prevalent among 16.7% boys and 8.6% girls. However, 41.7% adolescent boys consumed both forms of tobacco. The prevalence of dental caries was high in both boys (77.7%) and girls (55.2%). The presence of tartar was found in 47.3% boys and 22.4% girls. Bleeding gums was found in more number of girls (29.3%) as compared to boys (25%). The other morbidities found on examination were ulcer (16.7% boys and 3.5% girls) and oral submucous fibrosis (27.8% boys and 3.5% girls).Conclusion: Appropriate intervention is required because adolescence is a tender period where these risk factors such as tobacco consumption and oral hygiene could be modified by awareness and counseling.

Relatively Large-Scale Experimental Study on Behavior of Compacted Lime Mortar (CLM) Columns: Influence of Moisture Content

Various materials have been utilized for ground improvement techniques based on geoenvironmental compatibility. The application of lime mortar in soil has been catching the attention of researchers and engineers. However, there is a lack of research on the variation of moisture content in soil affecting the mechanical behavior of lime mortar. In this study, large-scale laboratory tests were conducted on approximately thirty specimens to evaluate the size effect on stiffness and load bearing capacity of compacted lime mortar (CLM) columns and clayey soil under different saturation conditions. In addition, approximately forty small-scale laboratory tests were carried out on dry clay, dry CLM column and lime mortar specimens to evaluate the unconfined compressive strength (UCS). According to results, UCS of CLM column under small-scale condition was higher than that of the large-scale. Moreover, high moisture content had a significant influence on the stiffness of improved ground and the bearing capacity of CLM columns. Finally, validation of results indicated that numerical model predictions are in agreement with experimental results.

Durability of reclaimed asphalt pavement–coal fly ash–carbide lime blends under severe environmental conditions

The sustainable use of industrial residue in enhancing the long-term performance of reclaimed asphalt pavement (RAP) has been proven to be effective under freeze–thaw and wet–dry conditions. This study focuses on coal fly ash (FA) and carbide lime (CL) as the enhancing agents. It evaluates how the durability and long-term performance of compacted RAP–FA–CL mixtures are impacted by dry unit weight and lime content. The tested mixture’s specimens were moulded in three layers through static compaction inside a cylindrical mould. Several single-level variables were used in the stabilisation process. Among these were: FA content of 25%, optimum water content of 9% (modified effort) and seven days of curing. Additionally, three target dry unit weights (17, 18 and 19 kN/m3 – the last of which was determined using the modified Proctor energy) and three percentages of lime content (3%, 5% and 7%) were used for a comparative analysis. The tested specimens’ accumulated loss of mass (after wetting–drying and freezing–thawing cycles) and splitting tensile strength were both evaluated as a function of the porosity/lime index. The experiments revealed that compacted RAP–coal FA–CL mixtures performed noticeably worse when subjected to freezing–thawing cycles than when subjected to wetting–drying cycles. These results indicate an increase in the breadth of the porosity/lime index, as it is shown to control the long-term performance of compacted RAP–coal FA–CL mixtures, in addition to controlling their mechanical response.

Effects of lime treatment on the hydraulic conductivity and microstructure of loess

Lime treatment of loess in foundation engineering modifies the soil structure, leading to changes in mechanical and hydraulic properties of soil, which in turn will affect the flow of water and transport of contaminants in the loess. In light of this, it is essential to identify the dominant effects of different lime treatments on hydraulic conductivity, and to ascertain the optimum lime treatment. For this purpose, we investigated the effects of dry density and lime content on changes in hydraulic conductivity and microstructure of loess in Yan’an City, China. The results indicate that hydraulic conductivity has a log negative correlation with dry density, and lime addition can result in a decrease of hydraulic conductivity of loess at the same dry density. Under a given degree of compaction, however, lime addition can lead to a decrease in dry density due to an increase in flocculation and aggregations. The significant decrease of dry density leads to an increase in hydraulic conductivity when lime content (in mass percentage) is lower than 3%. Nevertheless, when lime content is higher than 3%, the reactions between loess particles and lime will be intensified with an increase in lime content, and become the primary factors affecting pore characteristics. These reactions can further decrease the hydraulic conductivity of lime-treated loess, and the lowest hydraulic conductivity was obtained for lime-treated loess with 9% lime content. The excess lime (above 9% lime content) dramatically increased pore size, leading to a significant increase in hydraulic conductivity. Therefore, 9% is the optimum lime content for loess treatment, and the degree of compaction in engineering should be higher than 95%. In addition, statistical analysis of microstructure of lime-treated loess shows that the distribution trends of macro- and meso-pores coincided with that of saturated hydraulic conductivity, which indicates that lime content affects saturated hydraulic conductivity of lime-treated loess by changing the soil structure, especially the properties of pores larger than 8 µm.

A multi-scale homogenization approach for the effective thermal conductivity of dry lime–hemp concrete

Lime–hemp concrete is an environmentally friendly material that is used more and more in building construction. This study develops a multi-scale homogenization approach to model the effective thermal conductivity of this bio-based material. The developed model dedicated to non-compacted and compacted hemp concrete takes into account the shape and the orientations of pores of hemp particles as well as imperfect particle-binding interfaces. Unknown properties of the solid phase of hemp particles and binding, and that of the particle-binding interface are calibrated by inverse analysis using available experimental data. The model is then used to carry out a sensitivity analysis to study the effect of the porosities of hemp particles and binding, the volume fraction of hemp particles, density and temperature on the overall thermal conductivity of hemp concrete. Analytical solution proposed can be used for a fast estimation and optimization of the thermal conductivity of hemp concrete, which is very useful for the building design.

THE USE OF SYNTHETIC ZEOLITES AS MODIFYING ADDITIVES IN THE FORMULATION DRY MIXES ON CEMENT AND LIME BASIS

Ponte Academic JournalFeb 2017, Volume 73, Issue 2 THE USE OF SYNTHETIC ZEOLITES AS MODIFYING ADDITIVES IN THE FORMULATION DRY MIXES ON CEMENT AND LIME BASISAuthor(s): Zhegera C. V. ,Loganina V. I., Sadovnikova M. A.J. Ponte - Feb 2017 - Volume 73 - Issue 2 doi: 10.21506/j.ponte.2017.2.17 Abstract:It was suggested that in the dry construction mixtures on the basis of cement and lime as a modifying additive may be used synthetic zeolites. Are presented of the chemical composition of the obtained additive on the basis of zeolites. The presented the technology of preparation of the additive based on zeolites. Are presented of data on the effect of additives on the basis of synthetic zeolite on the properties of composites on basis cement and lime. Investigated the effect of additives on the kinetics of curing composites on basis cement and lime. Are presented of the experimental data of the kinetics of the strength of cement in air-dry conditions and shows the experimental data of the kinetics of the strength of lime samples hardening in air-dry conditions. Examined of the characters changes the rheological properties of cement and lime putty. Established the water-retaining properties additives based on the synthetic zeolites. Are presented data of the influence of additives on the basis of synthetic zeolites and additive methylcellulose grade FMC 2094 on the water retention capacity of the solution based on the cement and lime. Download full text:Check if you have access through your login credentials or your institution Username Password