Laboratory Mixtures Research Articles

Comparing Ground Tire Rubber, Styrene-Butadyene-Styrene, and GTR-SBS Hybrids as Asphalt Binder Modifiers

This technical note evaluated hybrid asphalt binders modified with a combination of styrene-butadyene-styrene (SBS) and postconsumer ground tire rubber (GTR). These hybrid blends were evaluated in laboratory mixture experiments against more traditionally modified binder using either SBS or GTR. Mechanical properties measured during laboratory experiments were supplemented with a literature review, followed by a discussion of trade-offs between these modification options within the context of a sustainability triple bottom line of environment, economics, and social well-being. This technical note also discussed test sections containing hybrid binders and how some state departments of transportation have incorporated hybrid binders into their specifications. Overall, this work suggests that performance leans toward SBS, sustainability leans toward GTR, economics sometimes leans toward GTR, and social well-being benefits from consideration of all these factors simultaneously. A hybrid binder containing 1%–2% SBS and 3%–8% GTR should allow for high-temperature grading increases and the use of GTR in a wider range of mix types than have historical approaches.

Development and Validation of Stability-indicating RP-HPLC Method for Estimation of Pranlukast Hydrate in its Laboratory Mixture.

Pranlukast hydrate is an anti-asthmatic drug and used in the treatment of acute asthma. Stability-indicating RP-HPLC method for pranlukast hydrate has been developed and validated. The reverse phase high performance liquid chromatographic method was developed using Shimadzu Column: Kromosil 100 C18 (150mm×4.6mm×5μm) and mobile phase Acetonitrile: 0.1% Glacial acetic acid (85: 15% v/v). Eluent was monitored with UV-detector at 262nm with a flow rate of 0.5mL/min, temperature maintained at 30°C. Stress testing was carried out in acidic, alkaline, oxidative, photolytic and dry heat degradation conditions. The method was validated as per the International Conference for Harmonization guidelines and includes specificity, accuracy, precision, linearity and limit of quantitation and detection parameters. A relative standard deviation <2% indicates the developed method was precise. The accuracy of the method was represented by recovery studies ranging between 99.41 and 99.72%. In acid, alkaline, oxidative stress conditions, pranlukast hydrate degrades significantly and in photolytic, dry heat, hydrolytic conditions remain stable. This proposed method is suitable for the analysis of pranlukast hydrate in its laboratory mixture.

Composite laser claddings for corrosion protection of outer surfaces of storage containers for spent nuclear fuel in underground repositories

The present contribution examines the structures of and corrosion processes in copper-basalt composite laser claddings on a steel substrate. The cladding material was a laboratory mixture of the following components: Oerlikon METCO 55 (Cu &gt; 99.9 %) + basalt dust. In this investigation, metallographic structures of copper-basalt composite laser claddings were studied using optical and scanning electron microscopy. The adhesion of the claddings to the substrate was testing using the non-standardized Mercedes test. A potentiodynamic corrosion test in artificial mine water was performed on a specimen of the composite laser cladding. The test results were compared against those for a reference high-purity copper standard and AISI 304 steel. The findings were interpreted in terms of the potential of using copper-basalt composite laser claddings as corrosion protection coatings on steel components in nuclear power generation.

Finite element viscoelastic simulations of rutting behavior of hot mix and warm mix asphalt overlay on flexible pavements

The implementation of warm mix asphalt and chemical compaction aids is becoming more widespread. A growing number of contractors are using warm mix asphalt technologies to reduce mixing and compaction temperatures, reduce fuel consumption, improve compatibility, and increase economic and environmental value. In 2009, three pavement overlay projects were constructed in the state of Iowa using both hot mix aphalt and warm mix asphalt mixes to compare their performance. A series of dynamic modulus tests were conducted using field and laboratory mixtures of hot mix asphalt and warm mix asphalt. For each project, twelve specimens, including six hot mix asphalt specimens and six warm mix asphalt specimens, were tested to determine dynamic modulus and phase angles. These results were used as input parameters for designing each pavement in the mechanistic-empirical pavement design guide (MEPDG) and in finite element viscoelastic simulations to predict the performance behavior of warm mix asphalt and hot mix as phalt. A step-by-step framework to convert dynamic modulus results to Prony series to use in finite element simulation models was developed and is detailed for one mixture. This research compared predicted rutting damage by MEPDG design, estimated rutting from finite element simulations, and measured rutting in the field. The results show that MEPDG based on linear elastic theories may overestimate the rutting of pavements while the finite element based on viscoelastic theory accurately predicted the rutting of pavements. Therefore, a series of proposed calibration coefficients from this research can be useful for industrial applications and design engineers to modify and correct MEPDG overlay design thicknesses on top of hot mix asphalt, and jointed plain concrete pavement surfaces with either hot mix asphalt and warm mix asphalt mixtures.

Моніторинг концентрацій газів, розчинених у трансформаторному маслі, під час експлуатації силового трансформаторного обладнання

The peculiarities of application of stationary gas analyzers of power oil of filled equipment in main and distribution networks, as well as at power generation enterprises are analyzed. The problem of discrepancies in the values of concentrations of gases dissolved in oil obtained from stationary gas analyzers in the mode of continuous monitoring and obtained by the results of tests of transformer oil samples performed by laboratory chromatographers is investigated. A comparative analysis of different principles for measuring gas concentrations based on two groups of methods: chromatography method and infrared spectroscopy methods by Bouguer–Lambert–Beer law. The features of application, advantages and disadvantages of the main methods of infrared spectroscopy are considered. The results of the laboratory comparison of the analysis of the mixture of reference gases and the analysis of gases obtained from oil-filled transformer equipment, which is in operation, conducted by a stationary gas analyzer and laboratory. It is established that both laboratory devices and stationary gas analyzers have similar errors in determining gas concentrations in prepared laboratory mixtures. The coefficients of linear regression, constructed as a function of dependence of the indications of a stationary gas analyzer on the indications of a laboratory device, are given, when analyzing the same oil samples. Conclusions were made about the main reasons that affect the discrepancy of the obtained results, which allowed to determine the feasibility of using stationary gas analyzers, on the basis of spectroscopy, as devices capable of fixing the trend of increasing gas concentrations, and to make decisions on unscheduled oil samples for laboratory analysis based on their indications.

Simultaneous Determination of Curcumin and Berberine in their Pure Form and from the Combined Extracts of Curcuma Longa and Berberis Aristata

A simple, rapid, accurate, precise, reliable and economical first derivative spectro- photometric method has been proposed for the simultaneous determination of curcumin (CUR) and berberine (BER) in pure form and in combined methanolic extracts of Curcuma longa and Berberis aristata without any prior separation or purification step. The developed methods show best results in terms of linearity, accuracy, precision, limit of detection (LOD) and limit of quan- tification (LOQ) for standard laboratory mixtures of pure compounds and methanolic extracts of the drugs. The linearity range for curcumin (CUR) and berberine (BER) were found to be 2 to 8 µg mL -1 and 6 to 12 µg mL -1 respectively. The values of LOD were 0.039 µg mL -1 and 0.025 µg mL -1 and the values of LOQ were found to be 0.13 µg mL -1 and 0.08345 µg mL -1 for curcumin (CUR) and berberine (BER) respectively. By this method, C. longa and B. aristata showed 4% w/w curcumin and 2.8% w/w berberine respectively in combined methanolic extracts of the two herbal drugs. The method was validated as per ICH guidelines.

Chemo-metric assisted UV-spectrophotometric methods for simultaneous estimation of Darunavir ethanolate and Cobicistat in binary mixture and their tablet formulation

Darunavir ethanolate (DRV) and Cobicistat (CBS) is a combination of antiretroviral drugs used for the treatment of human immunodeficiency virus (HIV) infections. Two Chemo-metric assisted UV-spectrophotometric methods were developed for simultaneous estimation of DRV and CBS in tablet dosage form, namely; partial least square (PLS) and Classical least square method (CLS). The proposed methods were successfully applied for simultaneous determination of DRV and CBS in a laboratory mixture and their tablet formulation to achieve maximum sensitivity and lowest error. The applied methods were validated as per ICH guidelines and found to be linear in the concentration range of 5-30μg/mL for DRV and 5-30μg/mL for CBS. The developed methods were statistically comared with reported UPLC method where no significant difference was found relating to both accuracy and precision. Thus, the proposed methods can be effectively utilized for the routine quality control assessment of these drugs in commercial tablet dosage form.

Univariate and Chemometrics-Assisted Spectrophotometric Methods for Determination of Flibanserin in a Recently Released Dosage Form

Five simple, selective, and rapid spectrophotometric methods are developed for the determination of flibanserin (FL) in the presence of its oxidative degradation products (ODPs). Stress studies are performed according to the International Conference on Harmonization (ICH) guidelines to assess the behavior of FL against oxidative, thermal, and acidic conditions. FL was stable against thermal and acidic conditions, while it was susceptible to oxidative degradation. Three of the spectrophotometric methods were univariate methods, namely, third derivative (D3), ratio difference of ratio spectra (RD), and first derivative ratio of spectra (D1R), while the other two methods were multivariate methods, namely, partial least square (PLS) and principal components regression (PCR). No preliminary separation steps were required in these methods. The chemical structures of the ODPs were confirmed using mass spectrometry and 1H NMR spectroscopy. The proposed methods were developed and validated according to the ICH guidelines. The linearity, accuracy, and precision were determined, and the selectivity was assessed by analyzing synthetic laboratory mixtures containing different ratios of FL and its ODPs. Statistical comparisons were applied to the five spectrophotometric methods, and no significant differences were found. The validated methods could be applied for routine testing and quality control.

Reflectance study of ice and Mars soil simulant associations – I. H2O ice

The reflectance of water ice and dust mixtures depends, amongst other parameters, on how the components are mixed (e.g. intimate mixture, areal mixture or coating). Therefore, when inverting the reflectance spectra measured from planetary surfaces to derive the amount of water ice present at the surface, it is critical to distinguish between different mixing modes of ice and dust. However, the distinction between mixing modes from reflectance spectra remains ambiguous. Here we show how to identify some water ice/soil mixing modes from the study of defined spectral criteria and colour analysis of laboratory mixtures. We have recreated ice and dust mixtures and found that the appearance of frost on a surface increases its reflectance and flattens its spectral slopes, whereas the increasing presence of water ice in intimate mixtures mainly impacts the absorption bands. In particular, we provide laboratory data and a spectral analysis to help interpret ice and soil reflectance spectra from the Martian surface.

Failure Mode Critical Effect Analysis and Design of Experiment-Based Robust Chromatographic Method for Simultaneous Estimation Lornoxicam and Eperisone Hydrochloride.

Failure mode critical effect analysis and design of experiment-based high performance thin layer chromatography (HPTLC) method has been developed for simultaneous estimation of lornoxicam (LOC) and eperisone hydrochloride (EPR). Failure modes were identified on the basis of prior knowledge and experimental data with the help of Ishikawa diagram for the development of method. The criticality of failure mode was assessed by giving risk priority number and criticality rank on the basis of preliminary experimental trials. The identified critical failure modes were analyzed for their effect by design of experiment (DoE)-based Plackett-Burman screening design. From 11 critical factors, the volume of methanol and modifier in mobile phase composition were found as critical failure modes. Critical failure mode was further analyzed by DoE based on central composite design for study of their relationship with resolution of both drugs. Quadratic model suggested by design was further used for failure mode risk control and navigation of design space for a resolution of both drugs more than 1.5. Failure mode risk control strategy was set for robust HPTLC method for simultaneous estimation of both drugs in laboratory mixture. Developed and validated HPTLC method was applied for assay of LOC and EPR in their laboratory mixture and assay values were found in good agreement with a spiked amount of drugs.

Proposing the use of fine stone cutting factory as recycled materials in concrete and study of design economy and environmental protection

During the past years, extensive studies have been performed on concretes containing rice husk ash and recycled aggregates, which have shown the advantages of those concretes. Comparison of recycled concrete materials from the aggregates of quarrying plants for use in laboratory mixtures is the difference between this study and previous studies in this field. In addition to mechanical tests and evaluation of the performance of recycled concrete and comparison of ordinary concrete, the evaluation of the design economy and environmental protection are also examined. The main purpose of this study is to achieve and introduce the most optimal conditions for the use and application of recycled stone materials in concrete production. Evaluate and compare the effectiveness of each of the hardened concrete parameters such as mechanical properties and engineering properties (compressive and tensile strength) as a result of using recycled aggregate replacement values, as well as conserving environmental resources that are non-renewable in many industries. Or renewed over very long periods of time, reducing construction waste and environmental pollution, creating employment and economic benefits are other goals pursued in this study.

Field and simulated rutting behavior of hot mix and warm mix asphalt overlays

Research implementing new pavement technologies often focuses on material characterization; however, expanding the research to study and validate how new technologies influence pavement design is needed for continual improvement. Numerical analysis approaches use laboratory mixture data to predict field performance. This study compares predicted rutting by MEPDG design, estimated rutting from Finite Element (FE) simulations, and actual rutting performance in the field. Ten years ago, warm mix asphalt research was underway to measure the effect of warm mix asphalt (WMA) additives and lower production temperatures on performance. WMA benefits include reduced mixing/compaction temperatures, reduced fuel consumption, and improved compatibility. In 2009, three asphalt overlay projects were constructed in Iowa using both hot mix asphalt (HMA), and WMA mixes to compare their performance. A series of dynamic modulus tests were conducted to determine dynamic modulus and phase angles of HMA and WMA mixtures. The dynamic modulus results were used to develop FE viscoelastic simulations to predict the rutting of HMA/WMA pavement sections. Iowa’s pavement management system provided field rutting of WMA/HMA sections. Also, pavement sections were evaluated using mixture input parameters in the Mechanistic-Empirical Pavement Design Guide (MEPDG). The results showed MEPDG based on linear elastic theories might overestimate the rutting of asphalt pavements, especially overlays placed on Jointed Plain Concrete Pavement (JPCP). In contrast, the FEM based on viscoelastic theories more accurately predicted the rutting of pavements. Calibration coefficients are proposed by this study, which may be useful for design engineers and industrial applications to correct and modify MEPDG overlay design thicknesses for HMA/WMA mixes placed on HMA and JPCP surfaces.

Estimation of critical nitrogen contents in peach orchards using visible-near infrared spectral mixture analysis

The aim of this study was to predict the critical nitrogen (N) content in peach trees using spectrometric measurements. A nutrient-controlled hydroponics experiment was designed for this purpose. Peach saplings were grown under three N conditions: deficient, sufficient, and excessive. The reflectance values of a plant leaves were measured using a handheld field spectroradiometer fitted with a plant probe. The N contents of leaves were determined in the laboratory and Gaussian mixture discriminant analysis (GMDA) was used to estimate N levels in the leaves from reflectance values. The N levels were categorized for each of the three different N conditions. The wavelengths at 425 nm, 574 nm, 696 nm, and 700 nm were found to be diagnostic of the different N levels. The model developed here classified the experimental plants with high accuracy for NDeficient, 89.28%; NSufficient, 96.30%; and NExcess, 71.42% with 85.71% coefficients. The reliability of the model was also tested under field conditions using 96 peach trees representing the three different N status. Leaves were analyzed by reflectance at 425 nm, 574 nm, 696 nm, and 700 nm, which functioned in real N, percentage classes determined based on the laboratory analyses of the orchard samples, and the data were categorized as NDeficient, NSufficient, and NExcess with a similarity ratio of 77.78%, 80%, and 67.74%, respectively with the general correct classification rate of 75%. The study findings showed that the model developed using hyperspectral reflectance data can discriminate different N nutritional status in plants with an accuracy of ≥70% and can be applied under field conditions. The results of this research provide a new perspective for future studies by showing that GMDA with hyperspectral remote sensing may be useful for the classification of different plant nutrient contents.

Optimal conditions for extraction and simultaneous determination of sulfamethoxazole and trimethoprim in pharmaceuticals by micellar electrokinetic capillary chromatography

A micellar electrokinetic capillary chromatography was performed at 25°C and 30 kV (under pressure of 15 mbar), with 30 mM borate buffer (pH 9.0), 60 mM sodium dodecysulfate, and 10% (v/v) ethanol as background electrolyte for the determination of sulfamethoxazole and trimethoprim. UV detection was at 205 nm. Recoveries were optimal and acceptable after extraction with ethanol/deionized water (1:1, v/v) for both investigated compounds from laboratory mixtures of standards. The method was shown to be specific, accurate (recoveries were 99.9 ± 0.4% for sulfamethoxazole and 99.8 ± 0.3% for trimethoprim), linear over the tested ranges (correlation coefficients ≥ 0.9990) and precise (RSD below 0.6%). The method was applied to determine sulfamethoxazole and trimethoprim in tablets, powder for cutaneous use and solution for infusion.

“Sniffing” Toxic Methanol in Laced Beverages By a Fully-Integrated and Portable Analyzer

Introduction In July 2019, more than 20 people died in Costa Rica due to methanol-tainted alcohol of registered and unregistered brands [1]. Similar outbreaks have been reported in India [2] (95 deaths, February 2019), Iran [3] (768 cases, 2018) or Cambodia [4] (237 cases, 2018). In fact, 5400 intoxications and 1500 deaths were reported due to methanol-tainted alcohol within the last two years [5]. Apparently, cheap methanol is intentionally added to alcoholic beverages to increase their potency and profit. In the human body, methanol is converted to formaldehyde and formic acid, which can interfere with the human metabolism leading to blindness or even death [6]. Therefore, handheld analyzers or sensors to screen beverages are urgently needed to prevent such intoxication. These could be applied by tourist or even first responders.However, compact gas sensors either suffer from insufficient detection limit (legal limit of 0.09 vol% in fruit distilled spirits [7]), cannot distinguish methanol from the chemically similar ethanol present at much higher concentration or have not been validated with real beverages. Here, we present a stand-alone, inexpensive and miniaturized analyzer for screening of potential safety hazards in beverages. Methods The handheld device consists of a printed circuit board with integrated microcontroller and circuitry to operate metal-oxide gas sensors (Figure 1a). A miniaturized pump (12 g) is used to guide the sample through a sorption filter for analyte pre-separation to a highly sensitive and flame-made Pd-doped SnO2 sensor [8]. The sample was obtained from the headspace above liquors. The device was calibrated with laboratory mixtures containing methanol and ethanol in ultra-pure water at concentrations ranging from 0.01 – 10 vol% and 5 – 80 vol%, respectively. Subsequently, the device was tested with real beverages including beer, sake, Baileys, Arrack, pear spirit and Stroh rum. The drinks were chosen to cover a wide range of ethanol concentrations (5 – 80 vol%) and flavors that might interfere with the detector. The methanol concentration of the pure drinks was determined by liquid chromatography. To generate higher methanol concentrations, the pure beverages were spiked with methanol up to 10 vol%. Results and Conclusions In laboratory mixtures, methanol (1 vol%) and ethanol (5 vol%) passed through the separation column with retention times of 1.6 and 5.3 min, respectively, that can be detected subsequently (thus selectively) by the Pd-doped SnO2 sensor. Thereby, the effective separation of methanol and ethanol is crucial. This was evaluated by comparing the retention time of methanol to the breakthrough time of ethanol. For methanol, the retention time ranged from 1.25 – 1.5 min depending on concentration, from 0.01 to 10 vol%. Importantly, the breakthrough time of ethanol was always larger than 2.2 min. This enabled reliable and simultaneous detection of methanol and ethanol, even at their lowest and highest concentrations, respectively.For all alcoholic beverages, no interference originating from the different flavors was observed on the methanol and ethanol quantification. Most importantly, the device predicted methanol and ethanol with average error of 21.9 and 13.4% (with respect to the actual concentration), when tested in 43 pure and methanol spiked beverages (Figure 1b). Also, the performance was reproducible and stable for at least 107 days. As a result, the validated device could readily be applied by laymen (e.g. tourists) or first responders to screen beverages for toxic methanol and prevent severe health damage.

High‐Temperature HCl Evolutions From Mixtures of Perchlorates and Chlorides With Water‐Bearing Phases: Implications for the SAM Instrument in Gale Crater, Mars

AbstractEvolved hydrogen chloride (HCl) detected by the Sample Analysis at Mars (SAM) instrument's evolved gas analysis (EGA) mode on board the Mars Science Laboratory Curiosity rover has been attributed to oxychlorines (i.e., perchlorates and chlorates) or chlorides in Gale crater samples. Previous laboratory EGA studies of oxychlorines have been unable to reproduce the high‐temperature (&gt;600 °C) HCl evolutions observed in most Gale crater samples. The objective of this work was to reproduce these high‐temperature HCl releases from laboratory mixtures of perchlorates and chlorides with phases that evolve water upon heating. Magnesium and sodium perchlorate and chloride were mixed with saponite, nontronite, and a basaltic glass and analyzed in a laboratory thermal evolved gas analyzer configured to operate similarly to the SAM instrument. Na perchlorate and chloride evolved HCl only when mixed with all three water‐producing phases. Mg perchlorate and chloride evolved a mid ‐temperature HCl release (~450–550 °C) and evolved an additional high‐temperature HCl release (~810–820 °C) when mixed with saponite. This work demonstrated that chlorides, either originally present or from perchlorate decomposition, evolved high‐temperature HCl when reacting with water from water‐producing phases. The HCl release temperature was dependent on the mixture's mineralogy and chemical composition. HCl releases detected by SAM were consistent with oxychlorines and/or chlorides in the presence of water‐producing phases. Additionally, this work provided constraints on the presence of oxychlorines or chlorides and their cation types, which has implications for past aqueous and diagenetic processes, the potential for past life, and detection of organics by EGA.

Development and Validation of UV-Spectrophotometric and HPLC Method determination of Dofetilide in Formulation

A new, simple, specific and economic UV Spectrophotometric method and HPLC method for the estimation of Dofetilide content in bulk and laboratory prepared mixture. UV spectrophotometric detection was carried out at absorption maxima (λmax) at 231nm using methanol as a solvent. The quantitation of drug was carried out using A1% 1cm at 231nm and Beer’s law was obeyed in the concentration range of 2.5-20 μg/ml, with correlation coefficient value less than 1.The chromatographic separation was carried on a C-18 (250 mm × 4.6 mm, 5μ) column using an isocratic mode with a mixture of Acetonitrile:Phosphate Buffer (pH-7) in the ratio of 55:45% v/v as a mobile phase. The flow rate was 1.5ml/min, temperature is maintained at ambient and detection was made at 231 nm using Photodiode array (PDA) detector. The developed method was validated according to ICH guidelines and different analytical parameters such as linearity, precision, accuracy, specificity, limit of detection, limit of quantitation were determined. The percent amount of drug estimated was nearly 100%, found to be a good agreement with label claim of prepared laboratory mixture. The proposed method was validated for its accuracy, precision, robustness, ruggedness, linearity, limit of detection, limit of quantitation and was found to be in range (% RSD&lt;2.0 and SD &lt;±2.0). Both methods were validated and found to be simple, sensitive, accurate, and precise. The results of the study and statistical data proved the applicability of the present method in routine analysis of Dofetilide in bulk as well as laboratory prepared mixture.

Characteristics and catalytic activity of zeolite-a synthesized from rice husk silica and aluminium metal by sol-gel method

In this research, sol-gel process was applied to synthesize zeolite-A from rice husk silica and aluminum metal. For preparation of the zeolite, the specified amount of rice husk silica and aluminum metal was separately dissolved in NaOH solution, and both solutions were transfered in to a laboratory mixture for complete mixing and production of gel. The gel was converted into solid zeolite precursor by oven drying of the gel for 24 hours. The precursor was transformed into zeolite by subjecting to different calcination temperatures, and then characterized using different techniques. The zeolites were also tested as catalyst for transesterification of Ricinius communis oil. Development of structure of the zeolite was confirmed using FTIR and XRD techniques analyses, while SEM analysis revealed the characteristic of the samples as porous and multiphasic materials. The zeolites were found to exhibit good catalytic activity as revealed by the results of transesterification of Ricinius communis oil. Appreciable catalytic activities were also demonstrated by the reaction yields achieved which are in the range of 68 to 82%.

Application of multiple reaction monitoring for quantitation of sweeteners in food products

A coupled UPLC-MS/MS method has been developed and validated for the simultaneous quantitation of food sweeteners stevioside (STV) and aspartame (ASP). Good chromato-graphic separation was achieved on a Hypersil gold 50×2.1 mm (1.9 μm) column, using a gradient flow of 10 mM ammonium acetate, pH = 2.9 adjusted with formic acid, and 10 mM ammonium acetate in acetonitrile:water (95:5, v:v) as the mobile phase. The eluate was introduced to ESI-Mass spectrometer and scanned using multiple reaction monitoring (MRM). The method was robust, reproducible and easy to use and was validated according to ICH guidelines for the accuracy and precision giving acceptable ranges. The utilization of multiple reaction monitoring improved the selectivity of detection. Method was linear in the ranges of 2-250 ng/mL for STV and ASP. Application of this method on laboratory mixtures of the selected sweeteners was successful. The using of mass spectrometry make the method selective and measurement did not affect the presence of impurities, additive and other ingredients of detection due to the simplicity and sensitivity of this method allows the utilization of method in quality control of STV and ASP.

Stabilisation of soft clay by deep cement mixing (DCM) method – A case study

Soft ground under the sea often presents challenges for supporting seawall or reclamation without treatment if no dredging is implemented. Ground treatment is often required to improve the engineering properties of weak soils to enhance bearing capacity for supporting the intended structures. Deep soil mixing with addition of binder is one of the ground treatment methods that has been widely used in Asia and worldwide. This method was recently adopted by the authors for a practical ground improvement project in Hong Kong. This paper presents the characteristics of cement-soil mixture in the laboratory environment as well as performance of the field mixed soil using the same binder material. A detailed test programme was developed to evaluate the strength and other properties of the cement-soil mixtures by using various amounts of binder and water to binder ratios. A series of unconfined compressive strength (UCS) of the laboratory mixture were performed. The relationship of strength of the cement-soil mixture with binder dosages is developed. Test results of laboratory mixed soils were compared with those of field mixed soils. The relationship of strength between laboratory mixed soils and field mixed soils was derived. Field installation of deep mixing for the project is discussed.