Carbonation study and determination of cement to sand ratio in hardened cement mortar by X-ray photoelectron spectroscopy

The determination of cement and sand content in an aged cement mortar is a challenging problem for civil engineers. Techniques like x-ray diffraction (XRD), thermogravimetric analysis (TGA) and electrochemical impedance spectroscopy (EIS) are well established, which can give some insight of the hydrated products. The present study is an attempt to use x-ray photoelectron spectroscopy (XPS) technique for the evaluation of ordinary Portland cement (OPC), sand (aggregate) composition and carbonation study in hardened cement mortar. Carbonation analysis and cement to sand ratio for all mortar compositions has been determined and studied in detail in the present work. The C 1s spectra of cement mortar with ratios 1:1, 1:3 and 1:6 shows carbonate formation on the surface with 21, 40 and 32 atomic percent, respectively. An increase in SiO₂ content corresponding to sand is observed for all three mortar mix. The formation of silica gel due to carbonation has not been observed in the mortar samples. The cement to sand ratio for all three mortar mixes is found to be in 20–30 percent error limit due to the heterogeneous nature of the mortar system.     

Magnetic normalization of particle size effects in a heavy metal pollution study of intertidal sediments from the Yangzte Estuary

Magnetic, granulometric and geochemical analyses were conducted on an intertidal sediment core from the Yangtze Estuary to evaluate the possibility of normalizing samples for particle size effects in a heavy metal pollution study by means of magnetic proxies. It has been found that the magnetic parameter XARM, indicating fine grained ferrimagnetic minerals, correlates well with the clay content and organic matter concentration of the sediments. XARM also shows significant relationship with heavy metals. Therefore XARM is proposed as a proxy for clay content in the sediments, and can be used to compensate for the particle size effect in sedimentary heavy metal records, where magnetic minerals are not subject to significant post-depositional alteration.     

Crystal chemistry of clay minerals in bottom sediments of the Sea of Okhotsk as a paleoclimatic indicator

X-ray diffraction and infrared spectroscopy were used to study the mineral composition of bottom sediments of the Sea of Okhotsk with ages ranging from Holocene (10 My ago) to Pleistocene (10 to ～74 My ago). The concentrations of nonlayered minerals (quartz, plagioclase, carbonates, and biogenic silica) were determined from IR spectra, which made it possible to estimate the actual abundance of the clay component in test samples. Calibration curves used in the calculation were plots of the optical density in the maximum of the analytical absorption band of the analyzed component versus its concentration in the sample. These curves were constructed for standard mixtures of known compositions. The crystal-chemical parameters and quantitative ratios of clay minerals were elucidated by the computer simulation of X-ray diffraction profiles; clear correlations were found between these parameters and paleoclimatic changes. Our results show that the clay minerals from the bottom sediments of the Sea of Okhotsk can serve to search for paleoclimatic events in the North-Eastern Asia.     

The archaeometry study of the chemical and mineral composition of pottery from Brazil’s Northeast

Chemical and mineralogical analysis was performed on ceramics and clay samples from Barracão archaeological site located in Baixo São Francisco River by means of instrumental neutron activation analysis (INAA) and by differential scanning calorimetry (DSC). The data set was studied by means of cluster analysis (CA) and discriminant analysis (DA). The results showed that the raw material used in ceramics is not local. By using DSC it was possible to discover that the principal minerals in the samples are quartz, feldspars, mica and kaolinite.     

Magnetic normalization of particle size effects in a heavy metal pollution study of intertidal sediments from the Yangzte Estuary

Magnetic, granulometric and geochemical analyses were conducted on an intertidal sediment core from the Yangtze Estuary to evaluate the possibility of normalizing samples for particle size effects in a heavy metal pollution study by means of magnetic proxies. It has been found that the magnetic parameter_ϰARM, indicating fine grained ferrimagnetic minerals, correlates well with the clay content and organic matter concentration of the sediments._ϰARM also shows significant relationship with heavy metals. Therefore_ϰARM is proposed as a proxy for clay content in the sediments, and can be used to compensate for the particle size effect in sedimentary heavy metal records, where magnetic minerals are not subject to significant post-depositional alteration.

     

Continuous microwave-assisted extraction, solvent changeover and preconcentration of monophenols in agricultural soils

An automatic extraction, preconcentration and clean-up module for the extraction of phenolic compounds from soils was developed; the separation and quantitation of each phenol is accomplished by GC-MS. The sorption-desorption of thirteen phenols on soils containing variable amounts of organic carbon (0.05-3.4%) and clay minerals (2-43%) at pH 5.7-8.6 was investigated. For this purpose, uncontaminated soils were spiked with 5 or 20 microg of each phenol per g of soil; the soils were then stored at 4 degrees C for at least 3 months prior to analysis in order to simulate analyte-matrix interactions other than material losses and environmental degradation in actual contaminated soils. The organic carbon content in acid and alkaline soils affects the sorption of chlorophenols but not that of alkylphenols. On the other hand, alkylphenols are preferentially sorbed by neutral soils, the process being influenced by the clay mineral content. Based on the results, alkylphenols interact more strongly with agricultural soils than do chlorophenols; also, both types of compound are less strongly sorbed by loamy sand soils owing to their increased sand contents.     

Photoacoustic infrared spectroscopy of Syncrude post-extraction oil sand

Rapid- and step-scan photoacoustic (PA) infrared spectra of three fractions of a Syncrude post-extraction oil sand were analyzed in detail in this work. The rapid-scan spectra showed that the samples were comprised primarily of kaolinite, quartz, silica, siderite, and residual hydrocarbons, and that the proportions of these constituents were different for each fraction. Depth profiling of the three post-extraction oil sands was accomplished using both rapid- and step-scan PA infrared spectroscopy. The results confirmed that kaolinite is more abundant in the near-surface region, whereas quartz and hydrocarbons are concentrated at greater depths. The modulation frequency dependence of the PA intensities for all three fractions was consistent with a model in which the samples are thermally thick; in other words, the thermal diffusion length (roughly equal to the sampling depth) was less than the particle sizes of all three samples. The results of this study are consistent with published reports on the PA infrared spectra of fine tailings generated during bitumen extraction and the spectroscopic and thermophysical characterization of clay soils and an appropriate model clay.     

DTA and TG studies of paleocene bituminous rocks from EL Iusr oil deposit — Egypt

The organic and mineral composition of selected samples from boreholes P-24, P-27 and P-26 of the oil deposit El Iusr, in the Suez Channel region, were characterized by DTA and TG supplemented by X-ray and luminescence-bituminous studies. It was established that the content of bitumens in sandstones is higher than in clays and their compositions changes with the depth of the borehole. A slight vertical and lateral migration of hydrocarbons in the first clay member of the lateral migration of hydrocarbons in the first clay member of the Iusr article was observed. The content of light hydrocarbons rises with the increase of the proportion of clay minerals. It was found that montmorillonite is more effective in retaining light hydrocarbons than kaolinite.     

Molecular and elemental characterisation of mineral particles by means of parallel micro-Raman spectrometry and Scanning Electron Microscopy/Energy Dispersive X-ray Analysis

The “fingerprinting” of a molecular structure obtained by micro-Raman spectroscopy (MRS) can be successfully complemented by means of X-ray spot analysis through the application of scanning electron microscopy equipped with an X-ray detector (SEM/EDX). The elemental composition revealed by SEM/EDX is essential for a correct interpretation of the collected Raman spectra. The results presented here illustrate how the two techniques can be combined to characterize geological samples, especially in the case of individual particles. The samples involved in the experiments were Zr- and Ti-bearing sand from South Africa (with major minerals such as zircon and rutile) and U mine tailings from Hungary (rich with feldspars, quartz and sulphate minerals). Mineral phases detected by MRS were identified according to their respective main Raman shifts, with a spatial resolution up to 1 μm, depending on the parameters set. Some unusual and sometimes inexplicable Raman activity was observed, which was ascribed to and rationalized by the presence of accompanying elements as detected with EDX. The relocation of a particle by means of the two instruments was facilitated with TEM grids. Although the limitations of the sequential use of SEM/EDX and MRS, such as different beam sizes, probing depth and surface topography, should be considered in their application to the analysis of individual geological particles, the two methods appeared to be complementary. Not only do they provide correlated chemical information about the sample, but also enable chemical characterization that would be otherwise incomplete when analyzed on a stand-alone basis.     

Mineralogical analysis with the firing temperature of limestone and clay mixture from Dominican Republic using Mössbauer spectroscopy and X-ray powder diffractometry

The study of a limestone and clay mixture using Mössbauer spectroscopy, and X-ray powder spectrometry (XRD) for different firing temperatures are presented. This type of mixture is used in raw minerals in order to obtain industrial clinker. This study permits to know the changes of the iron present during the clinkerization process, its mineralogical transformation with the temperature, and the minimal temperature necessary to obtain a good quality clinker.     

Retention of tannic acid and condensed tannin by Fe-oxide-coated quartz sand

This paper intends to shed light on the interactions between tannin and mineral soil particles. For that purpose, aqueous solution of condensed tannin (CT) (derived from Black pine (Pinus nigra var. maritima)) and commercially available tannic acid (TA) were added to purified quartz (Qtz) sand and quartz sand coated with either goethite (Gt) or ferrihydrite (Fh). After solvent removal by evaporation the samples were extracted by water. The extracts were analysed for organic carbon, total phenolics and CT. The extractability of the two tannins was small and increased in the order Qtz-Fh < Qtz-Gt < Qtz. For all mineral samples, TA was more extractable than CT. Bonding of tannins to the mineral samples and the partial peptisation of the Fe oxide coatings upon the binding resulted in complex tannin release curves. Our results suggest that the inextractability of tannins from natural soils and the absence of tannins in soil leachates might be caused by strong adsorption on soil minerals such as Qtz and Fe (oxy)(hydr)oxides. The results of competition experiments with mixtures of both tannins demonstrate that the CTs, and TA in particular, can release large amounts of Fe (oxides), suggesting that the tannins are excellent metal-mobilising agents. We therefore suggest that the fate of tannins in the mineral soil environment is highly dependent on the abundance of weakly bonded secondary oxides.     

Mössbauer spectroscopy of some volcanic glasses from the Pampa Region,Córdoba,Argentina

Mössbauer spectroscopy has been applied to the study of volcanic glasses and closely associated clay minerals which were carefully separated from the sediments of the Pampe Region, Córdoba, Argentina. The parameters of volcanic glass samples show the presence of a high content of Fe²⁺ in octahedral coordination and some Fe³⁺ in tetrahedral and octahedral coordination. No remarkable difference has been found with a pure volcanic glass sample taken as a reference. In the clay samples, the only clay mineral found was illite.     

Taphonomy of prehistoric bark in a salt environment at the archaeological site in Hallstatt,Upper Austria – An analytical approach based on FTIR spectroscopy

Taphonomy of subfossil bark was assessed in Hallstatt, Upper Austria. Samples from the Bronze Age were compared with recent corresponding material from the same site. Preservation of the prehistoric samples was caused by storage in a salt and clay mixture. FTIR spectroscopy was used to determine differences in material chemistry. Principal Component Analysis was applied to display the segregation of the data set according to the different factors and to display the strength of the effects. Results revealed that deacetylation processes dominated aging processes. Focusing on two band regions at around 1730 and 1230 cm⁻¹ a clear separation was achieved. Additionally some samples were selected for further analyses to investigate the influence of the inorganic matrix. Thermal analyses demonstrated an ash content of more than 15%_mass. X-ray diffractometry revealed the presence of salt (dominant), gypsum, pyrite, quartz, and calcite minerals.     

用蒙脱土酸处理法制备洗用4A沸石过程中石英问题的探讨

目前我国洗涤剂用４Ａ沸石实现半工业化的是采用以水玻璃、氢氧化铝为起始原料的全合成法[1],以该法生产沸石的产品质量较稳定,但生产成本较高。而以蒙脱土为原料的合成４Ａ沸石,生产成本可以大大降低［２－４］,但是蒙脱土中往往含有石英杂质,如果不设法去除,必将影响产品的纯度,使其质量指标（白度、粒度、钙离子交换量）难以达到洗涤剂行业标准［５］,而且洗衣粉中含有石英也会磨损衣物。 本文将重点讨论石英这一问题,包括如何测定石英杂质含量和如何在用蒙脱土生产洗涤剂用４Ａ沸石过程中去除石英杂质。１实验部分１．１实验样…     

Chemical modification of natural clays

Natural clay samples and calcined clay varieties treated with hydrochloric acid of various strengths were characterized by X-ray diffraction, positron annihilation spectroscopy, and IR spectroscopy. The specific surfaces and pore sizes were determined by nitrogen adsorption. The constituent phases of the clay were found to be nontronite, muscovite, quartz, and hematite; after calcination, quartz, muscovite, hematite, and an amorphous phase remained in the samples. The Brilliant Green adsorption properties and tribotechnical properties of the modified clays were studied. The natural clay was surface-modified chemically by means of consecutive exposure to 36.5% hydrochloric acid and an alkaline hydrolyzate of rice hulls. Calcination at 700°С destroyed the amorphous phase to a greater extent; exposure to acid provided a greater recovery of aluminum and iron ions from the surface of calcined samples. Native clay composites with an alkaline hydrolyzate of rice hulls were shown to have enhanced tribotechnical characteristics.     

Determination of Gold Content in Geological Samples by Atomic Absorption Spectrometry Method Applied after Separation of Gold by Tellurium or MIBK

Research has been carried out for the application of AAS method to determine gold content in geological samples. These samples usually contain mainly metal sulfides and quartz. Gold usually occurs in the samples as native gold in free state or in joints of some other minerals. The gold grain size is usually below 0.01 mm to over 1 mm and the gold content varies from some ppb to some tens of g/t.     

Étude des propriétés mécaniques des géomateriaux argileux associant la décoction de Parkia Biglobosa (néré)

Researches for non-energy intensive construction products, that are durable and cheaper is today of global concern because of the limited resources (energy, financial, etc.). To address this issue, the present work presents the combination of the decoction of pods of Parkia Biglobosa (néré) that is rich in tannins compounds including gallic acid, epicatechin gallate and epigallocatechin, with a clay-sand mixture. The clay used is referenced KORO and contains montmorillonite, illite, quartz, albite, orthoclase, kaolinite and goethite. The study of the mechanical properties of geomaterials formulated from the mixture shows that they have values of mechanical resistance higher and that their behavior becomes viscoplastic. This is due to the formation of chemical complexes from carboxylic groups of tannins macromolecules with the iron oxy-hydroxide in the interlayer spacing of clay minerals. This process is enhanced by the sorption of tannins on the surface of clay minerals.     

Determination of trace elements in beach asphalts by neutron activation analysis

The feasibility of using trace multielement data obtained from neutron activation analysis to identify the source of crude oil residues was recently demonstrated. This paper presents the concentrations of Br, Co, Cr, Sb, Sc, Zn, and V/Ni, for 30 crude oil residues collected from beaches (beach asphalt), using 1 g samples. The method does not require chemical separation or post-irradiation concentration. The average standard deviation for the V/Ni ratio was ±0.39.     

A mineralogical study of some west indian soil-clays

Identification of primary clay minerals species and mixtures of secondary layer-silicate minerals and of allophane have been made on some West Indian Soils. These soils are high in kaolinite, low in gibbsite, and contain montmorillonite, illite, vermiculite, quartz, allophane and chlorite. Some soils, however, are composed essentially of organic materials.     

Solid-state transformation mechanisms of associated minerals to aluminosilicates

Thermochemical and mechanochemical transformation mechanisms of associated minerals in clay (quartz, calcite, Al and Fe oxyhydroxides) are comparatively examined. The phase transformation sequence resulting from heating and, on the other hand from dry grinding of each of the associated minerals, depends on the structure and physicochemical properties of the starting materials.Grinding treatments may cause local heating and local pressure effects in some selective metal oxides and in calcite, respectively, accounting for their structural conversions.Dedicated to Dr. Robert Mackenzie on the occasion of his 75th birthday