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In this study, the replacement of raw rice husk, fly ash, and hydrated lime for fine aggregate and cement was evaluated in making raw rice husk-concrete brick. This study optimizes compressive strength, water absorption, and dry density of concrete brick containing recycled aggregates via Response Surface Methodology. The optimized model's accuracy is validated through Artificial Neural Network and Multiple Linear Regression. The Artificial Neural Network model captured the 100 data's variability from RSM optimization as indicated by the high R threshold- (R > 0.9997), (R > 0.99993), (R > 0.99997). Multiple Linear Regression model captured the data's variability the decent R2 threshold confirming- (R2 > 0.9855), (R2 > 0.9768), (R2 > 0.9155). The raw rice husk-concrete brick 28-day compressive strength, water absorption, and density prediction were more accurate when using Response Surface Methodology and Artificial Neural Network compared to Multiple Linear Regression. Lower MAE and RMSE, coupled with higher R2 values, unequivocally indicate the model's superior performance. Additionally, employing sensitivity analysis, the influence of the six input parameters on outcomes was assessed. Machine learning aids efficient prediction of concrete's mechanical properties, conserving time, labor, and resources in civil engineering. [ABSTRACT FROM AUTHOR]

This work reports a new means of preparing graphene tubes (GTs) without relying on chemical vapor deposition (CVD) and it's template-free. Surprisingly, we found that under the action of calcium oxide (CaO) and after 1500 °C heat treatment, a large amount of GTs grew on the surface of polyimide (PI). These nanotubes have a maximum diameter of about 600 nm and a length of up to millimeters, and some nanotubes even have a branching structure. We propose a simple, effective and green method which exhibits prospects for large-scale production of GTs using polymeric materials. [ABSTRACT FROM AUTHOR]

Urea is recognized as one of the most frequently used adulterants in milk to enhance artificial protein content, and whiteness. Drinking milk having high urea concentrations which causes innumerable health disputes like ulcers, indigestion, and kidney-related problems. Therefore, herein, a simple and rapid electroanalytical platform was developed to detect the presence of urea in milk using a modified electrode sensor. Calcium oxide nanoparticles (CaO NPs) were green synthesized and used as a catalyst material for developing the sensor. Synthesized materials formation was confirmed by different techniques like FTIR, UV–visible, XRD, SEM–EDX, and Raman spectroscopy. The carbon paste electrode (CPE) was modified using the CaO NPs and used as a working electrode during the analysis followed by cyclic voltammetry and differential pulse voltammetry (DPV) techniques. The fabricated calcium oxide modified carbon paste electrode (CaO/CPE) successfully detected the presence of urea in the lower concentration range (lower limit of detection (LLOD) = 0.032 µM) having a wide linear detection range of 10–150 µM. Adsorption-controlled electrode process was achieved at the scan rate variation parameter. The leading parameters like the selectivity, repeatability, and stability of the CaO/CPE were investigated. The relative standard deviation of sensor was ± 3.8% during the interference and stability study. [ABSTRACT FROM AUTHOR]

Adding different materials to soil can improve its engineering properties, but traditional materials such as cement, lime, fly ash, etc., have caused pollution to the environment. Recently, biopolymers have shown many advantages, such as economy and environmental protection, which make them applicable to geotechnical engineering. This study summarizes the effects of biopolymers on soil's engineering properties and the main directions of current research. Firstly, the advantages and disadvantages of a variety of widely used biopolymer materials and their effects on the specific engineering characteristics of soil (i.e., water retention characteristics, strength characteristics, permeability characteristics, microstructure) are introduced, as well as the source, viscosity, pH, and cost of these biopolymers. Then, based on the theory of unsaturated soil, the current research progress on the water retention characteristics of improved soil is summarized. The key factors affecting the strength of biopolymer-treated soil are introduced. Due to the actual environmental conditions, such as rainfall, the permeability and durability of biopolymer-treated soil are also worthy of attention. In summary, it is necessary to study the variation laws of the engineering properties of biopolymer-treated soil in the full suction range, and to predict such laws reasonably. The relevant results are conducive to the safer and more scientific application of biopolymers in geotechnical engineering practice. [ABSTRACT FROM AUTHOR]

Strontium (Sr) substituted wollastonite bioceramics were prepared by a modified sol-gel technique using bio-wastes such as eggshell as calcium oxide source and rice husk as silica source. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) were used to perform structural analysis. Bioactivity was examined by testing the apatite mineralization ability in vitro by immersing the ceramic pellets in simulated body fluid (SBF) for various time periods. Degradation assay was performed in Tris buffer solutions by following the protocol in ISO 10993-14 standard. Cytocompatibility and cell proliferation were analyzed at different concentrations using osteoblast like MG 63 cells by MTT assay. The results show that the addition of Sr increases the density and mechanical properties of wollastonite but decreases with SrO above 2.5 mol.%. Pure and Sr containing wollastonite possessed excellent apatite formation ability with continuous degradation under physiological conditions. The results of cell culture studies revealed that all prepared ceramics were non-toxic to osteoblast-like cells at different doses (0–1000 μg/mL), and wollastonite ceramics containing Sr also enhanced cell proliferation. [ABSTRACT FROM AUTHOR]

The ultra-high lime aluminum method (UHLA) is a method that can effectively adsorb chloride ions in a solution. Calcium oxide (CaO) and sodium aluminate (NaAlO2) were mixed and added to the sodium chloride solution. After the reaction lasted for some time, the content of chloride ions in the solution was significantly reduced. Through the experiment of chloride ion adsorption, it was found that when the mass ratio of calcium oxide to sodium aluminate was m(NaAlO2):m(CaO) = 1:2.5, the reaction temperature was 25°C, and the stirring time was 60 min, the adsorption effect on chloride ion was the best. The adsorption rate can reach 93.3% in a 100 mg/L sodium chloride solution. With the increased sodium chloride concentration, the time required to reach adsorption equilibrium becomes longer. In a 2,000 mg/L sodium chloride solution, this method's unit adsorption mass of chloride ion can reach 63.5 mg/g. Through SEM and XRD analysis, calcium oxide and sodium aluminate react in solution to form Ca4Al2(OH)14 with a layered structure. The OH- between the layers can exchange with external chloride ions. After Ca4Al2(OH)14 adsorbs chloride ions, the product is Friedel's salt (Ca4Al2Cl2(OH)12) with the same layered structure. [ABSTRACT FROM AUTHOR]

Bearing capacity of reinforced footing clearly depends on the characteristics of interface between geosynthetic and soil. A suitable solution for increasing the bearing capacity is to treat the geotextile surface by various additives. This study reported the results of plate load test on square model footing resting on reinforced sand with and without treated geotextiles to survey the effects of the treatment of geotextile on settlement and bearing capacity. The treated geotextiles were made using additives onto the surface, with a layer of sand located on the top. Geotextile sides were treated in the same way. Different additives including the lime, cement, emulsion, and the effect of the number of layers were considered. The bearing capacity ratio values (BCR), improvement ratio values (IR) and variation of load-settlement ratio obtained from the treated models were presented. The results showed that the treatment of geotextile has a great effect on the behavior of reinforced sand and thus bearing capacity. Also, the test results indicated that lime-treated geotextiles provided better improvement than other additives. The maximum improvement in the bearing capacity of square footing supported on treated geotextiles was found to be 75% compared with the pristine geotextiles. [ABSTRACT FROM AUTHOR]

• Phosphogypsum decomposes at high temperature with carbon monoxide. • The main products of this decomposition are calcium oxide and calcium sulfide. • High carbon monoxide partial pressure enhances the calcium sulfide formation. • Sulfur dioxide is formed with calcium oxide and recycled in the sulfuric acid plant. Phosphogypsum (PG) is a co-product of the phosphoric acid industry. To reduce the environmental impact and land occupation caused by PG disposal, researchers are trying to integrate it into building materials, agriculture, etc. Herein, PG decomposition with carbon monoxide (CO) was studied with i) thermogravimetric analysis (TGA), ii) induction heated fluidized bed reactor (IHFBR), and iii) thermodynamically using FactSageTM. Experimentally, PG starts decomposing around 600 °C and produces mainly calcium sulfide (CaS) at high CO partial pressure, above 50 %, and mainly to calcium oxide (CaO) at lower CO partial pressure (<20 %). At 1000 °C and above, CaSO 4 was completely converted to CaS, CaO, and minor co-products due to the presence of impurities in PG. Elemental and XRD analyses were adopted to understand the reaction mechanisms of PG decomposition. Thermodynamic simulations confirmed the full conversion of calcium sulfate (CaSO 4) above 600 °C for a CO/CaSO 4 ratio above 6.81 (mol/mol), whereas only 60 % conversion would be achieved at 1500 °C and lower ratio (<0.49 (mol/mol)). As a result, CaS and CaO may be produced, depending on the temperature and CO partial pressure. [ABSTRACT FROM AUTHOR]

Nanotechnology has been employed to provide solutions to the problems arising in the design, construction, and utilization of functional structures with at least one dimension measured in nanometres. The outstanding features of nanomaterials include high functional density, high sensitivity, special surface effects, large surface area, high strain resistance and catalytic activity. This article is aimed to provide a comprehensive understanding of the application of nanomaterials in the field of pavement engineering (in asphalt binders and mixtures) based on an exhaustive review of the literature. The current review work can be broadly classified into three segments. The first segment deals with the (a) basic definition of asphalt binder (b) definition of nanomaterials (c) different types of nanomaterials used in the field of pavement engineering (with their characteristics). The second segment deals with functional characteristics of the asphalt modified with nanomaterials that are (a) mixing of nanomaterials with asphalt binders (b) characterization of nanomaterial modified binders (c) the difficulties encountered in achieving nanomaterial modified binders. The third segment deals with the effect of nanomaterials (a) on the properties of asphalt binder (b) on the properties of asphaltic mixtures (c) comparison of nanomaterials with other asphalt modifiers. The role of certain nanomaterials (which include carbon nanotubes, nanoclays, nanosilica, nano titanium dioxide, nano zinc oxide, nano aluminium oxide, nano iron oxide, nanophosphor, nano hydrated lime and graphene) in the field of pavement engineering has been highlighted in the present review work. Usually, nanomaterials have a positive influence on binder properties which include viscosity, rutting resistance, fatigue resistance, temperature susceptibility and ageing resistance. Unlike polymer modified binders, nanomaterial modified binders, exhibit storage stability at higher temperatures. Not only this, nanomaterials are effective in enhancing the high-temperature storage stability of Polymer Modified Binder. Nanomaterials are also responsible for improving the properties of asphaltic mixtures which include rutting resistance, fatigue resistance, Marshall Stability, indirect tensile strength, resilient modulus and moisture stability. After thorough research on nanomaterials modified binders, it can be established that among the various nanomaterials, extensive studies have been carried out on carbon nanotubes, nanoclays and nanosilica. They can be categorized as the most effective nanomaterial modifiers. Still, there is immense scope for exploring the properties of other nanomaterials, especially Graphene. [ABSTRACT FROM AUTHOR]

One of the ways to modify selected parameters of lime mortars is the use of biopolymers of animal origin, such as bone glue, skin glue, bovine blood, eggs, and casein. These are protein-based biopolymers. Casein is an example of an organic polymer produced from cow's milk. The aim of the work was to investigate the possibilities of improving selected properties of mortars based on hydrated lime and metakaolin. The mixture was modified with powdered technical casein in amounts of 0.5%, 1.5%, 1%, 1.5%, and 2% as a partial mass replacement for the binding mixture. Additionally, the influence of increasing the amount of water on the properties of the mortar with a casein admixture of 2% was checked. This study examined consistency, shrinkage, water absorption, capillary action, porosity, flexural, compressive strength, and Young's modulus. The admixture of casein influenced the properties of the mortar, but not in all cases, and it was possible to determine a clear trend related to the variable amount of casein. Strength properties deteriorated as the amount of casein increased. When air bubbles were introduced into the mortar after the casein was dissolved, the porosity increased as the amount of admixture increased. The moisture properties improved; namely, casein led to a reduction in water absorption and water absorption caused by capillary action. No relationship was observed between the amount of casein and the drying shrinkage. Increasing the amount of water in the mixture led to the expected effects, i.e., an increase in porosity, shrinkage, and water absorption, and a decrease in mechanical strength. [ABSTRACT FROM AUTHOR]

Attempts have been made to extract nickel from ores and nickel-containing wastes using the chlorination method. However, the use of gaseous chlorinating agents is limited due to their toxicity. High-temperature chlorination of nickel oxide using calcium chloride is analyzed in this study. The volatilization percentage is positively correlated to temperature and CaCl2 dosage and negatively correlated to oxygen partial pressure. The apparent activation energy is calculated to be 142.91 kJ/mol, between 1173 K and 1323 K, which suggests that the high-temperature chlorination of nickel oxide using calcium chloride is controlled by a chemical reaction. [ABSTRACT FROM AUTHOR]

Stone matrix asphalt (SMA) mixtures are the most resistant type of asphalt mixtures today in which the aggregate skeleton bears the bulk load. In this study, the effect of nano hydrated lime (NHL) on the moisture sensitivity of SMA mixtures was investigated. To examine the effect of NHL, the surface free energy (SFE) method and the dynamic modulus (DM) test were applied under wet and dry conditions on mixtures constructed with limestone and granite aggregates. The SFE results indicated that the granite aggregates had a greater polar component and limestone aggregates had a higher non-polar component which shows their higher moisture resistance. The adhesion free energy (AFE) results showed that the adhesion of base bitumen and limestone aggregate was higher, and using NHL improved the AFE values. The results of DM tests indicated that as the load cycles raised, the wet to dry DM ratio reduced and using NHL increased this ratio. The reduction slope of the DM ratio in samples constructed with granite aggregates showed a faster trend compared to limestone aggregates, and using NHL improved the resistance of SMA mixtures constructed with granite aggregates to moisture more than limestone aggregates. [ABSTRACT FROM AUTHOR]

This paper studies the response of unreinforced masonry (URM) members made of hydraulic lime mortar and fired clay bricks, commonly found in heritage structures, strengthened with textile reinforced mortar (TRM) overlays. The investigation includes URM and TRM-strengthened diagonal compression tests on square panels, and relatively large-scale wall specimens subjected to combined gravity and lateral cyclic loads. Complementary compression, tension, and interface material tests are also carried out. The diagonal panel tests show that the TRM effectiveness depends in a non-proportional manner on the overlays, render thickness, and substrate strength. The enhancement in stiffness, strength, and ultimate shear strain, using one to four mesh layers on each side, is shown to vary in the range of 49–132%, 102–536%, and 300–556% respectively. It is shown that strut crushing typically governs the response of such low-strength URM masonry elements confined by TRM overlays. The cyclic tests on the comparatively larger walls show that the TRM is effective, shifting the response from URM diagonal tension to rocking, and enhancing the stiffness, strength, and ultimate drift capacity by more than 160%, 30%, and 130%, respectively. It is shown that analytical assessment methods for predicting the response of TRM-strengthened and URM members in terms of stiffness, strength and load-deformation can be reliably adapted. The cumulative contribution of the URM and TRM components, in conjunction with a suitable fibre textile strain, is also found to offer an improved prediction of the shear strength compared to codified procedures. The findings enable the evaluation and improvement of analytical models for determining the main inelastic response parameters of TRM-strengthened masonry and provide information for validating future detailed nonlinear numerical simulations. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to report the effect of different content of calcium oxide on the process of electromelting magnesia. Design/methodology/approach: The process of molten magnesia was analyzed by finite element simulation and proved by scanning electron microscope. Findings: The results show that with the increase of CaO content, the maximum temperature appreciation increases from 3,616°C To 3,729°C, showing an approximate nonlinear evolution. Low thermal conductivity and low specific heat of CaO result in higher temperature. With the increase of CaO content and temperature, the maximum flow velocity of MgO slag increases from 0.043 to 1.34 mm/s. Under different initial CaO contents, the distribution trend of CaO volume fraction is basically the same, and the CaO volume fraction is evenly distributed between 50 and 225 mm in the furnace. Originality/value: The influence of different contents of impurity calcium oxide on the process of electromelting magnesia was analyzed and a theoretical system was established. [ABSTRACT FROM AUTHOR]

The biodiesel production catalyzed by naturally derived catalysts such as calcium oxide (CaO) and sulfonated carbon catalysts achieved high biodiesel yield at moderate operating conditions. However, very few studies were conducted to evaluate the economic feasibility of industrial‐scale production of biodiesel catalyzed by both green catalysts of CaO and sulfonated carbon catalysts. The current study aims to assess the technical competency and economic feasibility of industrial‐scale production of biodiesel catalyzed by two processes 1.) CaO catalyst and 2.) sulfonated carbon catalyst. Process simulations via Aspen Hysys were carried out to perform material and energy balances for both process configurations designed earlier with respect to the base catalyst (CaO) and acid catalyst (sulfonated carbon) used. Economic analysis was initiated after the equipment sizing and costing had been carried out. Total capital investment, total manufacturing cost, and key performances of the rate of return, payback time, breakeven point, and net profit after‐tax rate were calculated for each process. Based on the economic analysis, the computed return on investment (ROI) is 105.36%, and it has a low payback period of 0.94 year to offset its original investment. The discounted cumulative profit (NPV) analysis shows that breakeven was achieved in the 3rd year. On the other hand, for the plant that utilizes sulfonated carbon in the transesterification reaction, the computed ROI is 14.02% with a payback period of 7.13 years, and the breakeven was achieved in the 9th year. In conclusion, the manufacturing plant of transesterification reaction catalyzed by CaO catalyst appeared as the most promising pathway either technically or economically. [ABSTRACT FROM AUTHOR]

To address the global requirement for a phosphorus-free fire-extinguishing agent, this study elucidated the ability of calcium acetate to extinguish cup-burner flames. The inhibition efficiency of calcium acetate powder (<50 μm) was compared with that of silica-uncoated ammonium dihydrogen phosphate (<50 μm), a chemical contained in agents used in typical ABC fire extinguishers. Calcium oxide and calcium carbonate powders were also used to investigate the suppression mechanisms of calcium acetate. The cup-burner experiments demonstrated that (i) calcium acetate, calcium hydroxide, and ammonium dihydrogen phosphate could extinguish cup-burner flames; (ii) calcium carbonate could not extinguish cup-burner flames; and (iii) the fire-suppression ability of calcium acetate was higher than that of ammonium dihydrogen phosphate, which was in turn higher than that of calcium hydroxide. Thermogravimetric analysis (TG) and X-ray diffraction measurements revealed that, although the calcium-compound powders decomposed and produced calcium oxide during flame extinction, significant differences existed among the fire inhibition efficiencies of the calcium compounds. TG and particle-size measurements proved that the high fire-suppression ability of calcium acetate resulted from the high ability of calcium acetate to generate inert gases during its decomposition, which diluted the oxygen concentration, thereby extinguishing the fires. [ABSTRACT FROM AUTHOR]

In this work, ASPENplus was used to simulate biogas upgrading by sorption-enhanced methanation in a dual interconnected bubbling fluidized bed configuration using inexpensive, abundant, and eco-friendly CaO to remove H2O from the reaction environment. The chemical looping scheme consisted of two reactors: a methanator/hydrator, where the catalytic reactions occurred on a catalyst with 20% Ni supported on alumina as well as the steam removal by CaO, and a regenerator, where the Ca(OH)2 was dehydrated back to CaO. The simulations were carried out to identify possible reactant compositions (H2 and biogas), CaO amount, and the methanation temperature able to produce an outlet gas matching the specifications for direct grid injection. When considering a stoichiometric gas feed ratio at the methanator inlet, the unwanted CaO carbonation worsened the process performance, subtracting CO2 from the desired methanation reaction. However, optimal conditions were found with hydrogen-lean gas feedings, balancing the limited H2 amount with the capture of CO2 due to the sorbent carbonation. Thermodynamic considerations pointed out the possibility of solid carbon formation induced by sorption-enhanced methanation conditions, especially for H2 sub-stoichiometric feedings. [ABSTRACT FROM AUTHOR]

Since the grinding and chemical reagents required for flotation are expensive, coarse particle flotation reduces grinding costs and makes the subsequent process more accessible and cheaper. Recent studies suggest that the flotation of coarse particles using microbubbles has some advantages. However, a thorough analysis of the effectiveness of various flotation parameters and the impact of their interactions on the recovery of coarse particles in the presence and absence of microbubbles has yet to be fully understood. In the current study, the two-level factorial and Box-Behnken experimental designs were performed to characterize, assess, and optimize the implications of seven numerical (sodium oleate, collector; calcium oxide, activator; MIBC, frother; impeller speed; froth depth; pulp concentration; fine particles) and one categorical (microbubbles) independent parameters on the coarse quartz particles. Characterization revealed that froth depth did not significantly affect the flotation recovery of coarse particles in the mechanical laboratory cell. The effects of the variables in the presence of microbubbles revealed that sodium oleate and impeller speed significantly impacted recovery, followed by calcium oxide and fine particles, both of which had a medium influence, and MIBC and pulp concentration, which had a minimal impact. The recovery of coarse particles increased by 92.714% when microbubbles were used, compared to the estimated maximum recovery under ideal conditions of 62.258% without them. From this, it can be concluded that a high coarse particle flotation recovery is possible by optimizing the hydrodynamic conditions and the chemical environment using microbubbles. [ABSTRACT FROM AUTHOR]

This study reports the synthesis of calcium oxide nanoparticles supported activated carbon from the algal–bacterial activated sludge by using eco-friendly and non-toxic reagents. The prepared activated carbon was employed as competent material for the antibiotic compound ciprofloxacin (CIP) removal from the liquid phase. The synthesized activated carbon has been characterized by using Brunauer–Emmett–Teller, scanning electron microscopy–energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray powder diffraction analysis. The sol–gel method was used to synthesize calcium oxide nanoparticles utilizing white chicken eggshells as the calcium source. Neem (Azadirachta indica) leaf extract was used as the promoter during the synthesis. The adsorption studies show that the pH of the solution has a substantial impact on the adsorption of CIP. Maximum CIP removal of 89.5% was obtained at pH 4.0. The Langmuir adsorption isotherm was found to be well fitted to the experimental results. It was observed that the maximum adsorption capacity was 8.1 mg/g. The adsorption kinetics were best described by a pseudo-second-order kinetic model. The most plausible CIP removal mechanisms involved cation exchange, cation–π interaction, hydrophobic effect, and hydrogen bonding. [ABSTRACT FROM AUTHOR]

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Micro-arc oxidation is a technique used to modify the surface of metals by anodic oxidation. The process changes the material's surface characteristics to improve its wear, corrosion, and tribocorrosion resistance. Additionally, the technique allows for incorporating elements that contribute to osseointegration when the material is intended for biomedical applications. The main objective of this study is to enhance the surface of the Ti-25Ta binary alloy, which has the best mechanical compatibility among the alloys of the Ti–Ta system, by using the micro-arc oxidation method. The surface treatment was performed to promote the incorporation of calcium, phosphorus, and magnesium, followed by heat treatments to modify the crystalline phases of the coating to increase the hardness of the oxide layer, improving adhesion and wear resistance. The structural and microstructural characterization, performed by X-ray diffraction and microscopy (scanning electron and confocal), showed that ceramic coatings are initially composed of TiO2 (anatase and rutile) and calcium carbonate (CaCO3). Increasing the heat treatment temperature to 600 ℃ induced rutile formation. For temperatures above 600 ℃, the calcination of the CaCO3 compound occurs, forming calcium oxide and calcium titanate in the form of perovskite (CaTiO3). Regarding the morphology, the high temperatures increased the crystallinity, decreased the number of surface pores and thickness of the MAO layer, and increased the hardness value of the coating, consequently improving the wear resistance of the Ti-25Ta alloy. [ABSTRACT FROM AUTHOR]

The objective of this work was to improve the thermal stability, flame resistance, and surface properties of black poplar (Populus nigra L.) wood via different impregnation methods. The impregnation methods were employed through two distinct modalities: vacuum impregnation and immersion impregnation. Here, poplar wood was impregnated with calcium oxide solutions (1%, 3% and 5%). Fourier-transform infrared spectroscopic analysis revealed a shift in the typical peaks of cellulose, hemicellulose, and lignin depending on the impregnation method and solution ratio. Thermogravimetric analysis and the limiting oxygen index indicated that the samples impregnated with lime solutions exhibited higher thermal stability than the unimpregnated wood. Both impregnation methods caused a decrease in water absorption and thickness swelling of the sample groups. Using a scanning electron microscope, the effect of the impregnation process on the structure of the wood was examined. In terms of surface properties, it was determined that the surface roughness value increased. On the contrary, it was observed that the contact angle value also increased. A significant difference emerged between the applied methods. In conclusion, the applied lime minerals are suitable substances to increase the flame resistance and thermal stability of black poplar wood. [ABSTRACT FROM AUTHOR]

This study examined the index properties, strength, and swelling pressure by mixing the Quicklime with five soil samples taken from the Meki-Abossa road section part of the Modjo- Hawassa highway. The main goal of this study was to provide more insight into the effects of Quicklime stabilization on the Atterberg limit like (LL, LP, and PI), OMC, MDD, CBR, and CBR swell percent of subgrade soil along the selected route alignment. Five disturbed samples were collected from the Meki-Abossa Road section to achieve the objectives. The samples were collected using the open pit sampling method with an average 1-1.5 m depth. Laboratory works were carried out for natural sub-grade soil and soil mixed with Quicklime. The natural sub-grade soil was classed as A-7-5 (38) by AASHTO and MH & CH by USCS, with a maximum LL of 75, PI of 41.6, MDD of 1.59, and OMC of 28, with CBR values less than five and CBR swell > 2%. The recommended lime (4%, 6%, and 8%) was mixed with the subgrade material. The result shows that the soil treated with Quicklime 4%, 6%, and 8% improved or lowered the untreated expansive soil plasticity index by 18.5%, 28.9%, and 23.8%, respectively, and increased OMC by 15.2% and reduced MDD by 18.23%. On the other hand, CBR values of the treated soil were increased by an average of 56.9%, with lower swelling potential decreases by 93.3%, higher workability, and stabilized soils were feasible to be used as subgrade material. [ABSTRACT FROM AUTHOR]

The only way to dispose of municipal solid waste (MSW) in Oman is in engineered landfills without pre-treatment. An effective waste management system requires a reliable database of solid waste composition, properties, and energy content. Although investigating waste in landfills in Muscat Governorate is challenging and complex, it is essential. In this study, MSW from Muscat Governorate landfills is examined. The MSW samples were collected et al. Amerat and Barka landfills in 2020 in order to determine some of the importance of their physiochemical properties and the ratio of materials (food, plastic, and paper). It was found that approximately 50% of the weight of the disposed waste was recyclable. There were high levels of biodegradable organic material in MSW. In terms of moisture content, MSW ranged from 21.5 to 43.3%. Both the volatility and loss of ignition of MSW were high. It was found that the total oxide ratios ranged from 12.4 to 44.06%. The elemental analysis of Muscat MSW resulted in six chemical formulas for MSW with and without sulfur. Silica is the most influential oxide, followed by calcium oxide. The findings of this study indicate that almost half of Muscat's municipal solid waste can be recycled. Solid waste can be recycled to create renewable materials that can replace oil as a by-product of the recycling industry. Additionally, Muscat MSW has a high moisture content, which enables it to be composted and biodegraded. Moreover, waste-to-energy technologies are feasible due to their high-energy content. [ABSTRACT FROM AUTHOR]

Dredged sediments with high water content is difficult to be treated and beneficially reused because of their poor engineering characteristics. To treat those slurry, this paper introduces a novel mechanical-chemical combined method, i.e., vacuum-solidification (VS) combined method, and investigates its performance in dewatering and strength improvement. Corresponding model tests using vacuum-only preloading method and binder-only solidification method, respectively, were conducted. Ground granulated blast-furnace slag, an industrial by-product, activated by hydrated lime, magnesium oxide or carbide slag was used as the binder in the proposed method. The mass of discharged water due to vacuum consolidation was measured during the model test. Soil samples were taken after vacuum preloading for unconfined compression test, permeability test, X-ray diffraction, scanning electron microscopy and mercury intrusion porosimetry to analyze the strength development, hydraulic and microstructural properties of the treated soil. The results indicate that the VS combined method exhibits a remarkable enhancement in both volume reduction efficiency and the strength improvement effectiveness. The type and content of activators have an obvious influence on the performance of the combined method. This study preliminarily revealed the mechanism and effect of using the VS combined method with alkali-activated GGBS as binder to treat high water content dredged mud. [Display omitted] • Vacuum-solidification combined method outperforms single methods in stabilizing mud slurry. • Appropriate amount of binder improves dewatering and strength development efficiency. • Alkali-activated slag is a superior alternative to cement for proposed combined method. • Lime, MgO and carbide slag are sequentially preferred activators for proposed method. • Combined method with green binder is a promising technology to recycle dredged mud. [ABSTRACT FROM AUTHOR]

The absence of calcium decreases the production of peanuts compared to any other element. To investigate the influence of calcium (Ca) applications on the production and seed quality of four diverse peanut cultivars from different regions—USA (NC-7), Egypt (Giza-6) and Nigeria (Samnut-23 and Samnut-24)—under clay soil conditions, two experiments were carried out at the Agricultural Experimental and Research Station, Cairo University, Egypt, during the two seasons of 2016 and 2017. The experimental design was a randomized complete block in a spilt-plot arrangement with three replications. The main plots were allocated to four peanut cultivars (Giza-6, Samnut-23, Samnut-24 and NC-7), and the sub-plots were devoted to calcium applications (soil application in the form of calcium sulfate dihydrate, foliar application in the form of calcium oxide and the control treatment of distilled water). Results indicated that all four peanut cultivars responded differently to the application of calcium fertilizers. The calcium application significantly enhanced peanut growth, yield components, biological, pod, seed, oil yields, seed oil, free fatty acids and seed calcium percentages in different cultivars. Soil calcium application significantly improved peanut production compared to foliar calcium application. NC-7 cultivar treated with the soil Ca application resulted in the maximum values of biological yield (92.9-ton ha−1), pod yield (6.8-ton ha−1), seed yield (4.4-ton ha−1), oil yield (2247.0 kg ha−1), pod index (203.2 g) and seed index (84.1 g). The interaction between the NC-7 cultivar and soil calcium applications is recommended to attain the best combination, leading to the highest yield and seed quality of peanuts. [ABSTRACT FROM AUTHOR]

China's 2022 crude steel production soared to an impressive 1.018 billion tons, and steel slag constituted approximately 10% to 15% of this massive output. However, a notable hindrance to the comprehensive utilization of steel slag arises from the fact that it contains 10% to 20% of free calcium oxide (f-CaO), resulting in volume instability. To address this challenge, our study delved into the dynamic transformation of the interface between lime and slag, as well as the fluctuations in the dissolution rate of lime. An Electron Probe Micro Analyzer, equipped with an energy-dispersive spectrometer, was employed for the analysis. Our findings revealed that the configuration of the reaction interface between quicklime and slag underwent alterations throughout various phases of converter smelting. At a temperature of 1400 °C, several significant transformations occurred, including the formation of a CaO-FeO solid solution, (Ca, Mg, Fe) olivine, and low-melting point (Ca, Mg) silicate minerals. With the gradual reduction in FeO content, a robust and high-melting 2CaO·SiO2 layer emerged, generated through the interaction between CaO and (Ca, Mg, Fe) olivine. Furthermore, for lime with a particle size of 20 mm and a calcination rate of 0%, the thickest layer of 2CaO·SiO2 was observed after 120 s of dissolution in slag A2 at 1400 °C. Overall, the dissolution rates of lime with different particle sizes in slag A1 to A4 showed a gradual increase. On the other hand, the dissolution rates of lime with different calcination rates in slag A1 to A4 exhibited an initial increase, followed by a decrease, and then another increase. The formation of a high-melting point and continuous dense 2CaO·SiO2 layer during the dissolution process hindered the mass transfer between lime and slag. [ABSTRACT FROM AUTHOR]

The initial weight and volume relationships are crucial factors in determining the strength, stiffness, and durability of cement-stabilized soils. The porosity/binder ratio has been widely used as a control parameter for stabilized soil mixtures. However, this approach does not take into consideration the water content used during the stabilization process, which can impact the strength and durability of the final product. To address this issue, this paper introduces the porosity–water/binder relationship as a new parameter to predict the strength, stiffness (Go), and durability against wetting–drying cycles of artificially cemented soils. The strengths, Go, and accumulated losses of mass (ALM) of different stabilized soils were compared based on this new parameter, and the comprehensive results were analyzed to demonstrate its effectiveness. The findings indicate that the new parameter is a suitable design parameter for soil–lime, soil–cement, and geopolymerized soil mixtures. Furthermore, it was determined that the water content has no effect on the splitting tensile strength to compressive strength ratio. The results of this study offer valuable insights into the optimization of stabilized soils and the development of improved soil stabilization processes. [ABSTRACT FROM AUTHOR]

The effect of adsorption of acid gases CO2, SO2, and SO3 on the electron accepting ability of cations on the surface of calcium oxide was studied by low-temperature IR spectroscopy of adsorbed CO. It is shown that the formation of carbonate, sulfite and sulfate anions in the surface layer leads to the appearance of Lewis acid sites, the strength of which, estimated by the shift in the vibration frequency of CO molecules associated with them, increases in the appropriate order, approaching that for calcium-containing zeolites. The results of the calculation of cluster models by the DFT method confirm the observed trends in the variation of the vibrational frequency and the absorption coefficient of CO molecules bound through both the carbon and oxygen atoms, and also demonstrate the dependence of the ability of a cation for CO linkage isomerism on its local environment. [ABSTRACT FROM AUTHOR]

Featured Application: We found that in the areas with high seasonal rainfall, to stabilize clay soils, if the amount of Montmorillonite mineral is greater than a certain amount (for example, in this study, 45%), with any amount of chemical additives, they do not maintain their stability and collapse. Conversely, soils containing certain amounts of Illite and Kaolinite minerals with the smallest amount of chemical additives have the best performance. Although the interaction between clay minerals and lime is the most effective factor in lime stabilization techniques, it has not been deeply evaluated. This research study investigated the microstructural characteristics of lime-stabilized Bentonite and Kaolin soils using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray (EDX) analyses. To consider the variation in clay mineralogy, these soils were mixed at varied ratios, stabilized, and then subjected to a durability process. The microstructural findings showed that the pozzolanic reactions with lime did not occur or occurred at a low level for Bentonite soil. However, they occurred at a very high level for Kaolin soil. The durability test confirmed the microstructural results and showed that the samples in which Bentonite soil had a share of 40 to 100% by dry weight of the soil did not last with any percent of lime. When the Kaolin soil content reached 100% by dry weight of the soil, the specimens lasted in the best possible way, even with 4% of the lime. This study concluded that the determination of optimum lime content based on the amounts and types of soil clay minerals is an important innovation for geotechnical projects and may be very cost-effective. [ABSTRACT FROM AUTHOR]

This paper aims to assess the behavior of the unconfined compressive strength (UCS) of polypropylene fiber (PF) reinforced natural pozzolana-lime-stabilized expansive grey clayey soil (GS) contaminated by sulfates. Lime (0--8%), natural pozzolana (NP) (0--20%), and PF (0--3%) by dry weight of soil were used. GS was contaminated by different sulfate contents (0-6%) and UCS was assessed at various curing periods (7--120 days). Results showed that adding 8% lime alone or with 20% NP considerably improved UCS. Including 1% or 2% PF as reinforcement without sulfates in lime-stabilized GS transferred stress from GS to PF due to bonding. However, increasing PF beyond 2% formed lumps, reducing contact and friction coefficient, thus decreasing UCS. This means that the optimum PF dosage was found to be 2%. The UCS of GS increased with PF content up to 2% and then decreased. The UCS significantly increased with higher calcium sulfate content and curing period due to observed cementing agents in X-ray diffraction (XRD) and scanning electron microscopy (SEM). Adverse effect of ettringite mineral on UCS caused by sodium sulfate addition was suppressed with the combination of 20% NP and 2% PF in lime-stabilized GS. Binding forces from lime and NP resisted to ettringite expansion. Sensitivity of UCS to sulfate effect was more pronounced with sodium sulfate than calcium sulfate. In addition, NP--PF mixture in lime-stabilized GS was more effective, improving the strength of expansive soil, especially with sodium sulfate. In conclusion, reinforcement of NP-limestabilized expansive soils with PF is an effective method. [ABSTRACT FROM AUTHOR]

The present study addresses the characterization of long-term and durability properties for employment in road subgrade construction of geopolymer-treated sediments. Four mixtures are presently selected based on a previous study: untreated sediment, sediment treated with 2% hydraulic lime (L) and 7% ordinary Portland cement OPC, and two geopolymer-treated mixtures using 5% and 10% of ground granulated blast furnace slag/sodium silicate-based geopolymers. Long-term properties are investigated through unconfined compressive strength and tensile strength tests. The resistance of designed materials to weathering conditions is tested through freeze–thaw cycles, humidification–drying cycles, and immersion in water. Sediments treated using 10% geopolymer binder are resistant to weathering conditions and showed long-term properties superior to those of sediments treated using an L/OPC mixture. [ABSTRACT FROM AUTHOR]

Subgrade filling materials affect the settlement in expressway widening projects with a soft soil foundation. On-site monitoring and finite element simulation are used to analyze and compare the settlement and lateral displacement of a lime soil subgrade and mixed gravel and lime soil subgrade. The results show that the trends of the foundation surface settlement, the lateral displacement of the new subgrade foundation at the slope foot, and the newly widened subgrade layered settlement are the same for the two subgrade types. However, the settlement and lateral displacement values are larger for the mixed gravel and lime soil subgrade than for the lime soil subgrade. Moreover, the foundation surface settlement difference between the two subgrade types increases with the distance from the slope foot of the new subgrade. The lateral displacement difference changes during the post-construction period with the depth from the foundation surface and operation time, and the subgrade layered settlement difference changes with the subgrade's longitudinal depth and lateral position. The research results provide information on the subgrade settlement during expressway widening projects. [ABSTRACT FROM AUTHOR]

The demand for lithium is constantly increasing due to its wide range of uses in an excessive number of industrial applications. Typically, expensive lithium-based chemicals (LiOH, LiCl, LiNO3, etc.) have been used to fabricate adsorbents (i.e., lithium manganese oxide) for lithium ion (Li+) adsorption from aqueous sources. This type of lithium-based adsorbent does not seem to be very effective in recovering Li+ from water from an economic point of view. In this study, an innovative nanocomposite for Li+ adsorption was investigated for the first time, which eliminates the use of lithium-based chemicals for preparation. Here, calcium oxide nanoparticles (CaO-NPs), silver-doped CaO nanoparticles (Ag-CaO-NPs), and surfactant (polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS))-modified Ag-CaO (PVP@Ag-CaO and SDS@Ag-CaO) nanocomposites were designed by the chemical co-precipitation method. The PVP and SDS surfactants acted as stabilizing and capping agents to enhance the Li+ adsorption and recovery performance. The physicochemical properties of the designed samples (morphology, size, surface functionality, and crystallinity) were also investigated. Under optimized pH (10), contact time (8 h), and initial Li+ concentration (2 mg L−1), the highest Li+ adsorption efficiencies recorded by SDS@Ag-CaO and PVP@Ag-CaO were 3.28 mg/g and 2.99 mg/g, respectively. The nature of the Li+ adsorption process was examined by non-linear kinetic and isothermal studies, which revealed that the experimental data were best fit by the pseudo-first-order and Langmuir models. Furthermore, it was observed that the SDS@Ag-CaO nanocomposite exhibited the highest Li+ recovery potential (91%) compared to PVP@Ag-CaO (85%), Ag-CaO NPs (61%), and CaO NPs (43%), which demonstrates their regeneration potential. Therefore, this type of innovative adsorbents can provide new insights for the development of surfactant-capped nanocomposites for enhanced Li+ metal recovery from wastewater. [ABSTRACT FROM AUTHOR]

Chemical stabilization is used to enhance and increase the strength characteristics of soft and problematic soils. In this research, Gaussian Process Regression (GPR) is employed to estimate the unconfined compressive strength (UCS) and the Young's modulus (E) of lean clay soils stabilized with iron ore mine tailing (IOMT) and hydrated lime (HL) percentage. In this regard, four inputs including the moisture content (MC), IMOT percentage, HL percentage, and curing time (CT) were used. The value of R2 for estimating the UCS and the E were 0.9825 and 0.9633 for all data, respectively. The RMSE for predicting the UCS and the E were 0.1875 and 19.868 for all data, respectively. The result of the sensitivity analysis demonstrated that MC, CT, HL, and IOMT percentage have the highest contribution to the UCS of the stabilized lean clay, respectively. Also, MC, HL, IOMT percentage, and CT have the highest impact on the E of the stabilized lean clay, respectively. The parametric study also revealed that increasing the HL content and the curing time led to an increase in the UCS and the E of stabilized lean clay, while IOMT content and the moisture content has an inverse relationship with the UCS and the E of stabilized lean clay soils. [ABSTRACT FROM AUTHOR]

Aim: The aim of this scoping review is to highlight the effect of nanoparticles (NPs) when incorporated as an intracanal medicament to direct imminent research to understand the efficiency of NPs in clinical scenarios. Methods: A PubMed, Scopus, EBSCO host, and manual search were performed April 18, 2022. Inclusion criteria were set that had to be met by each study for it to be selected for the review. "The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews Checklist." Results: Ten in vitro studies that fulfilled the inclusion criteria were included in this review. Six studies evaluated silver NPs, one study with bioactive glass NPs, one study with chitosan-propolis NPs, one study with zinc oxide NPs, two studies with calcium hydroxide NPs, and one with calcium oxide NPs. In endodontics, materials such as zinc oxide and silver NPs disturb biofilm and lessen bacterial load within biofilm. The small size of the particles allows them to readily penetrate greater depths into dentinal tubules, resulting in an amplified antimicrobial action on root canal pathogens. Conclusion: According to the included studies, the findings indicate that the antibacterial efficacy of intracanal medicament was higher in groups containing NPs and provide a basis for future studies to be conducted in vivo and direct future research on NPs and its various unexplored applications. [ABSTRACT FROM AUTHOR]

The manganese silicate and calcium ferrite commonly generated during the treatment process of manganese ore results in difficult separation of manganese and iron. In this study, the migration behaviors of ferromanganese spinel and gangue compounds in a microwave field were explored by examining the corresponding phase and microstructural evolutions. Different from the traditional process, the interface reactions depend on the diffusion of Mn2+ and Fe2+ towards the surface of the gangue particles, owing to the microwave absorption ability of ferrite being better than that of calcium oxide. Compared with manganese, iron more easily combined with silicon oxide to form silicates. CaO induced the lattice transformation of the ferromanganese spinel to calcium manganese ferrite. The migration rate of manganese was faster than that of iron in the microwave field. The appropriate mass ratio (m(CaO)/m(SiO2)) reduced the negative impact of gangue components on the reduction process of ferromanganese. [ABSTRACT FROM AUTHOR]

Waste biomass-derived carbon materials are an attractive eco-friendly material. Biomass-derived carbon materials have received increasing attention due to the demand for renewable energy. In this work, abundantly available waste eggshell membrane was converted into carbon material and activated by KOH. The eggshell membrane-derived activated carbon (EgC) was mixed with calcium bismuth oxide (CBO) to form a composite material (EgC/CBO). Various characterization techniques were used to confirm the synthesized materials, including x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and Raman spectroscopy. The electrochemical properties of the synthesized materials EgC, CBO, and (EgC/CBO) were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The EgC/CBO electrode material exhibited a good specific capacitance value of 222F/g at 1 A/g. The composite material also exhibited a long cyclic stability, up to 5000 cycles at 5 A/g. The present study clearly confirms that the EgC/CBO material can be employed as a potential electrode material for electrochemical supercapacitor energy storage applications. [ABSTRACT FROM AUTHOR]

This research aimed at developing a process optimization of biolubricant production that will be environmentally eco-friendly. Greater concern has been focused on the use of solid-base catalysts, such as calcium oxide from limestone, for the transesterification of vegetable oils. Limestone was pretreated and calcined to 900 °C for 5 hours to obtain calcium oxide (CaO). The tropical almond seed oil was extracted from the tropical almond seeds using the soxhlet extraction method with a yield of 53.91%. The biolubricant was produced via double transesterification of tropical almond seed oil with methanol and trimethylolpropane (TMP) under reflux at different reaction conditions. Optimization of process parameters for the transesterification of tropical almond seed oil was determined using a response surface based on Box-Beinkhen design. The optimum yield of the biolubricant, 81.9%, was achieved at a temperature of 150°C, catalyst dose of 0.75 %wt and reaction time of 3 hours, respectively. [ABSTRACT FROM AUTHOR]

The increasing demand for silicate-based inorganic materials, depleting mineral resources and a growing desertification phenomenon force us to expedite the industrial application of desert sand for environmentally sustainable development. In the present study, the mineralogy, microstructure, phase composition, and thermogravimetric characteristics of Algerian Sahara sand were deeply examined using X-ray diffraction (XRD), Fourier transforms infrared (FTIR), X-ray fluorescence (XRF), Scanning electronic microscope (SEM/EDX) and Thermal analysis (ATG/DTA). The XRD results show that sand samples are very rich in a-quartz with a low content of calcite (CaCO3) and Albite (NaAlSi3O8), and the quartz crystallite size was in the range of 136-227 nm with high crystallinity. Furthermore, the FTIR, EDX, and XRF analysis demonstrate the dominance of silicon dioxide (90-95 % SiO2), besides a low ratio of calcium oxide (0.93-3.48 % CaO), and other oxides such as Al2O3, and Fe2O3. As well as Sahara sand particles were not uniform, which exhibited a variety of morphology and microstructure. ATG/DTA analysis confirms these findings and indicates that this sand was stable at high temperatures. These properties are beneficial in understanding the process and controlling the synthesis and characteristics of the Sahara-sand materials. [ABSTRACT FROM AUTHOR]

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Soil contaminated with petroleum substances is classified as hazardous, i.e., particularly harmful to the proper functioning of environmental ecosystems. It is therefore necessary to take measures to restore the homeostasis and ecological potential of degraded areas. The study aim was to determine the impact of bentonite, compost, and calcium oxide (CaO) on trace element content in the maize grown on diesel oil (DO)-contaminated soil. Increasing doses of the petroleum substance increased the accumulation of chromium (Cr), lead (Pb), copper (Cu), nickel (Ni), manganese (Mn), cobalt (Co), and cadmium (Cd) in maize. The largest increases were found for Cu (by 76%), Co (by 73%), and Pb (by 42%). All soil amendments proved useful for in situ stabilization of anthropogenically transformed soils. Bentonite reduced Cr (by 94%), Cu (by 84%), and Mn content (by 53%), while compost reduced the contents of Cu (by 75%), Mn (by 44%), and iron (Fe—by 29%) in maize. CaO significantly reduced the levels of Cr (by 94%), Cu (by 84%), Ni (by 66%), Mn (by 32%), Co (by 72%), zinc (Zn—by 30%), and Cd (by 22%) in maize. The effects of compost and bentonite on maize chemical composition were smaller than that achieved with CaO, and the direction of changes in elements content depended on the DO dose and the element type. [ABSTRACT FROM AUTHOR]

The unstable substances in steel slag are the main substances that affect its stability, which limits the large-scale resource utilization of steel slag. Most of the current methods for stabilizing electric arc furnace (EAF) slag are time-consuming and cannot be completely stabilized. In view of this, this study aimed to explore the feasibility of microbial-induced calcium carbonate precipitation (MICP) technology for stabilizing EAF reducing slag, and this was to be achieved by using the reaction between carbonate ions and free calcium oxide (f-CaO) in reducing slag to form a more stable calcium carbonate to achieve the purpose of stabilization. The test results showed that, when the EAF reducing slag aggregates (ERSAs) were immersed in a Sporosarcina pasteurii bacteria solution or water, the f-CaO contained in it would react such that stabilization was achieved. The titration test results showed that the f-CaO content of the ERSAs immersed in the bacterial solution and water decreased. The expansion test results of the ERSAs that were subjected to hydration showed that the seven-day expansion of ERSAs after biomineralization could meet the Taiwan regulation requirement of an expansion rate less than 0.5%. The thermogravimetric analysis showed that both the experimental group and the control group might contain calcium carbonate compounds. The results of the X-ray diffraction analysis showed that the CaCO3 content in the ERSAs that were immersed in the bacterial solution was significantly higher than those that were immersed in water. Moreover, the compressive strength test results of concrete prepared with ERSAs showed that the compressive strength of the control group concrete began to decline after 28 days. In contrast, the experimental group concrete had a good stabilization effect, and there was no decline in compressive strength until 180 days. At 240 days, the surface cracks of the experimental group were particularly small, while the surface of the control group showed obvious cracks. These results confirmed that a mineralization reaction with S. pasteurii bacteria could be used as a stabilization technology for ERSAs. [ABSTRACT FROM AUTHOR]

Waste management practices are vital for human health and the environment in a world where natural resources stress is expected to increase with the growth of population. Our study aimed to evaluate the potential use of crop-livestock residue as a bulking agent associated with the ideal level of hydrated lime for the stabilization and sanitization of urban sewage sludge through the alkalization-composting process. Therefore, we determined the alkalization efficiency on the heavy metal concentration in urban sewage sludge, quantified the viable eggs of helminths in pure and alkalized sludge, and measured the rate of earthworms (Eisenia fetida) surviving in the vermicomposting process using different levels of alkalized urban sewage sludge associated with crop-livestock residue. Four sequential trials were carried out in a completely randomized design with three replicates. The lime alkalization reduced the levels of Ba, As, Pb, Cu, Cr, Mo, Ni, and Zn compared to the pure urban sewage sludge. Using 30% w/w of lime in the urban sewage sludge (SS-30) for composting process reduced the viable helminth eggs by 71, 72, and 69% for sugarcane bagasse (Saccharum officinarum; SB), fresh chopped Napier-grass (Pennisetum purpureum; NG), and bovine ruminal content (BR), respectively. The ideal level of hydrated lime for stabilization and sanitization of urban sewage sludge was found to be 30%, which was able to reduce the heavy metals. The residues have the potential as a bulking agent for the composting of urban sewage sludge when associated with alkalization. The lime alkalization decreases the total number of helminth eggs and the number of viable eggs. The possibility of starting a vermicomposting using the mixtures is promising, evidenced by the earthworm survival in composting urban sewage sludge mixed with crop-livestock residues after 45 days of composting. The earthworm survival is maintained by an association of at least 80% of the crop-livestock residues. [ABSTRACT FROM AUTHOR]

The main aim of this research was to investigate the effectiveness of liquid antistrips (LASs) as compared with mineral admixtures such as lime and cement in treating moisture sensitivity of asphalt concrete (AC) mixtures produced with aggregates that are severely susceptible to moisture damage. The study involved evaluating the moisture susceptibility of four mix designs that featured two aggregate sources, two asphalt binder types, and both cement and lime as mineral admixtures. Five different liquid antistripping additives were evaluated. Liquid antistrips were directly added to the binder, and the mineral admixtures in the mix were replaced with mineral filler. The experimental plan involved a volumetric assessment of the mixtures after the filler adjustment and baseline characterization of aggregates and mixtures used in the study. A multipoint moisture sensitivity assessment protocol with a moisture conditioning procedure that includes multiple freeze-thaw cycles was used. Moisture susceptibility was evaluated using a fracture experiment and its parameters in addition to the standard indirect tensile strength. The replacement of both mineral admixtures led to a considerable increase in the air voids and the voids in mineral aggregates for all four mixes. Cement and lime were shown to be effective in retaining strength and fracture energy after several conditioning cycles. The performance of the mixtures containing liquid antistrips showed sensitivity to the additive used. While one of the additives showed overall significant deterioration in strength and fracture energy after the first freeze-thaw cycle, a different additive retained 70% of its initial properties after up to three freeze-thaw cycles. Overall, it was shown that a compatible LAS can aid asphalt mixtures' moisture resistance but not to the same efficiency of lime or cement for the mixtures included in the study. [ABSTRACT FROM AUTHOR]

In order to promote the resource utilization of steel slag, based on the stability evaluation of steel slag, using lime as alkali activator, the unconfined compressive strength test, X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to study the effects of different alkali-activated slag mix ratios and alkali-activated slag content on the compressive strength of slag-stabilized steel slag mixture. The hydration products and strength enhancement mechanism of slag-stabilized steel slag mixture was discussed. The research showed that the strength of the mixture increased first and then decreased with the increase of lime content, and the optimal mix ratio of lime and mineral powder was 1 ∶4. 2. Under this mix ratio, the 7 d strength of the mixture with 4. 5% alkali activated mineral powder content reached 6. 27 MPa, which met the technical requirements of high-grade pavement. With the increase of alkali-activated slag content, the compressive strength of the mixture increased, the elastic section of the load-deformation curve increased gradually, the plastic section and the descending section decreased, and the plastic deformation capacity decreased. Lime can better stimulate the potential activity of the slag-steel slag system. The hydration products included hydrated calcium silicate, hydrated calcium aluminate and Jennite. The internal honeycomb and fibrous cementitious structure made the internal structure of the mixture denser and improved the macroscopic strength and volume stability of the mixture. [ABSTRACT FROM AUTHOR]