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This paper looks at the changes in urban air quality and the effect on building materials, particularly concerning their deterioration arising from pollution due to vehicles. The paper aims to review basic information on the likely effect of ozone on calcareous building materials (limestone, marble, dolomite, and calcareous cemented sandstone). Controlling factors in the reaction and oxidation of sulphite to sulphate is the type and porosity of the stone. The level of humidity, is effected by the nature of the oxidants and to a lesser extent the presence of other extraneous reactants, e.g. metal oxides, chlorine and ammonia salts. [ABSTRACT FROM AUTHOR]

This paper addresses the issue of environmental noise from mining operations, focusing on the specific case of a quarry located in the municipality of Trebejov, Slovakia. The study aims to demonstrate an effective approach to reducing noise pollution through the implementation of mobile noise barriers. The research was motivated by the negative impact of noise from the processing line on the wellbeing of the population residing in the vicinity of the facility. The study involved conducting extensive noise measurements at various locations surrounding the quarry. The collected data were analyzed to assess the existing noise levels and identify the areas of highest noise exposure. Based on the findings, the implementation of mobile noise barriers was proposed as a solution. The results of the study demonstrated that the mobile noise barriers successfully reduced the noise levels below the legal limits, significantly improving the well-being of the population living near the quarry. The case study opens up the possibility of using mobile noise barriers in other areas and operations with high noise exposure. [ABSTRACT FROM AUTHOR]

Copyright of Rudarsko-Geolosko-Naftni Zbornik is the property of Faculty of Mining, Geology & Petroleum Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thermal spallation drilling is an alternative technology expected to be suitable for the development of oil and gas in hard rocks. In this paper, experiments on six types of rocks were performed to analyze characteristics of rock spallation and spall distribution. Additionally, a specific energy model for thermal spallation drilling was established. The analytical temperature results were compared with experimental values for validation. Finally, the specific energy of granite was compared with those of other rock breaking methods. Results show that it is important to control the lowering velocity of the coiled tubing (recommended in field application) to obtain the optimal penetration rate during spallation drilling. The degree of heterogeneity of rock may play an important role in the spall-ability. The shale has the largest average aspect ratio (diameter/thickness) of 30.97, with the following sequence being dolomite, limestone, granite and sandstone. The granite shows the highest penetration rate, while the limestone has the lowest. The specific energy values for sandstone, granite, shale and limestone are approximately 1000 MPa. Compared with other rock breaking methods, thermal spallation has advantages when drilling hard rocks (e.g., granite). All results in this paper can provide important implications for further study on the thermal spallation drilling. [ABSTRACT FROM AUTHOR]

This paper analyses the possibility of using tannery shavings as a basis for new composite materials with specified properties. The new material was made by combining tannery shavings with an adhesive medium. Mineral additives, such as dolomite, kaolin and bentonite were used in an amount of 5% and 10% of the total mass of shavings as a filler. In order to point out the influence of mineral additives on the final composite structure, some physico- -mechanical properties, such as tensile strength and elasticity were examined with the use of static tensile tests. The second part of the investigation involved the analysis of wetteability by immersion, because this property depends on several aspects, such as surface roughness and the material structure. Thus, changes in wetteability values can provide information about the impact of mineral additives on the material properties of composites. With regard to physico-mechanical and sorption properties obtained on the basis of experimental results, it was possible to define areas of possible applications of these materials in comparison with current methods. [ABSTRACT FROM AUTHOR]

Diagenetic heterogeneities are difficult to predict in the subsurface. Nevertheless, such heterogeneities can be crucial in hydrocarbon exploration. Diagenetic processes can significantly alter petrophysical properties of reservoir rocks, especially in carbonate rocks because of the reactive nature of the carbonate minerals. Dolomitization [i.e., the transformation of calcite (limestone: Lmst) into dolomite] is a common diagenetic process in carbonate rocks. Resulting dolomite bodies have a different pore network than the original Lmst and respond also differently to tectonic stress causing different fracture networks than in the original Lmst. The paper presents an overview of the learning outcomes gained by studying fracture-related dolomite in outcrops of Oman and subsequent laboratory analysis conducted over the last 4 years. A combined structural, petrographic, and geochemical approach was taken to study three dolomite systems occurring in different stratigraphic host-rock (HR) intervals. Structurally controlled dolomitization (i.e., dolomitization along faults and fractures) typically occurs in burial conditions, and the resulting strong permeability anisotropies caused by the dolomite textures can cause major challenges for hydrocarbon exploration. Dolomite bodies in the Precambrian Khufai formation are related to N/S to NNE/SSW fractures, whereas dolomite bodies that mainly occur in the Jurassic HRs occur along reactivated WNW/ESE normal faults. These fracture-related dolomite bodies are generally less than 15 m wide, but can be up to a few hundred meters long. Late-diagenetic dolomite bodies were also recognized in Permian HRs, where they occur at or close to the contact between Permian Lmst and early-diagenetic dolomite. This late-diagenetic dolomite system can be traced laterally for at least hundreds of meters and occurs in wadis that are approximately 40 km apart. Our data indicate that there were several dolomitization events in the geological history of the succession, generating dolomite bodies with different characteristics. This paper highlights the need to understand timing and structural setting of dolomite bodies in the subsurface to improve reservoir management. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of recycled gravel obtained from low (Gl) or medium (Gm) concrete grade on fresh property of concrete (slump), mechanical properties (compressive-splitting tensile strength) and mass transport properties (ISAT-sorptivity) of concrete containing dolomite as a natural coarse aggregate. Concrete specimens were prepared with cement, water, sand and dolomite admixed with recycled gravel. The percentage of recycled gravel/dolomite was 0:100, 25:75, 50:50 and 75:25 at w/c = 0.50, 0.55 and 0.60. The effect of silica fume and bonding admixture at w/c = 0.55 on concrete properties were also considered. The results indicated that, increasing the percentage of recycled gravel/dolomite led to decreasing the slump. All mechanical properties of concrete discussed were inversely affected by increasing percentage of recycled gravel/dolomite from low and medium concrete. Adding 10% SF or bonding admixture increased the mechanical properties of concrete. Mass transport properties of concrete (ISAT-sorptivity) were enhanced by decreasing the percentage of recycled gravel/dolomite. The optimum percentage of recycled gravel/dolomite = 25%. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing is an extensively used technique for development of oil and gas resources. In the shale reservoir, rock brittleness plays an important role during hydraulic fracturing. In this paper, a numerical code known as RFPA (Rock Failure Process Analysis) is introduced and the embedded digital-image-based (DIB) technique is illustrated in detail. Based on this integration, the effects of rock brittleness on the failure mode and stress-strain characteristic of the shale specimens are numerically investigated. It is found that the brittle shale specimen is more likely to rupture with multi crossed failure planes while the ductile specimen is more likely to rupture with a penetrating failure plane, from which we deduce the brittle shale is easier to develop more natural fractures than the ductile shale. The influence of natural fractures on complex hydraulic fracture network is further investigated through numerical simulation and the positive effect of rock brittleness is indirectly verified. It is found that hydraulic fractures are preferable to propagate in brittle minerals, i.e. the hydraulic fractures always choose the brittle minerals as the favorite path to propagate or choose a thin or weak part of ductile minerals to penetrate and is blocked by the ductile minerals. Moreover, the hydraulic fractures generated in the brittle shale are tortuous and appear with multi branches, which is much beneficial to form hydraulic fracture network in contrast to the smooth hydraulic fracture generated in the ductile shale. This is probably one of the causes of that the required treatment pressure in ductile shale layer is higher than that in brittle shale layer. [ABSTRACT FROM AUTHOR]

In this paper, a novel composite material for methylene blue (MB) removal was successfully synthesized from dolomite and graphene oxide. The graphene oxide/calcium magnesium silicate composite (GO/Si-Ca-Mg) was prepared through in-situ functionalizing silicates on the surface of GO. Briefly, metal ions (Ca 2+ or Mg 2+ ) were anchored by oxygen-containing functional groups on the GO and acted as growth centers of silicates. Properties of the material were characterized by XRD, FT-IR, SEM-EDS and TEM, and spectral results implied that silicates were successfully in-situ functionalized on the GO. During the preparation process, experimental factors were studied to investigate the optimum conditions. The adsorption capacity for MB could reach 230 mg/g. Thermodynamic and kinetic studies were also carried out to investigate the adsorption characteristics of the composite. This work came up with a feasible method to synthesize GO/silicate composite, which pleasantly avoided the severe aggregation of silicates in synthesis process. [ABSTRACT FROM AUTHOR]

The paper considers the applicability of magnesia building materials based on mining wastes as an alternative material for the stowing mixtures production. The main advantages of such mixtures in comparison to the well-known Portland cement mixtures are shown. I is found out that low water resistance of magnesia binding materials hampers its use in this field. The authors examine the ways of improving water resistance of magnesia binding materials from man-made dolomite in order to create a qualitative stowing mixture on this basis. The effect of various mineral admixtures on properties of dolomite is studied. The comparative analysis of strength and water resistance of the obtained dolomite with these additives is conducted. The phase constitution of the obtained compositions is examined with the help of X-ray analysis. The influence of additives on water resistance and regularity of dimensional change in case of dolomite hardening is determined. Based on the research results the most efficient admixture, i.e. nickel slag and its dosage for obtaining dolomite binders, which meet the requirements imposed for water resistance of stowing mixtures, is chosen. The optimal composition of the stowing mixture with the required water resistance and maximum environmental efficiency is developed. [ABSTRACT FROM AUTHOR]

In this investigation, a novel mesoporous silicate material (MS) was successfully synthesized from dolomite and applied for removal of hazardous dye Methylene Blue (MB). Properties of the material were characterized by XRD, FT-IR, BET, SEM-EDS, TEM, and TG-DSC. During the adsorption process, conditions like contact time, dye concentration, temperature and pH were studied to investigate the adsorption characteristics of the material. The adsorption capacity for MB could reach 111.65 mg/g. Thermodynamic and kinetic studies were also carried out in this paper. Moreover, a relative reasonable adsorption mechanism was revealed by XPS analysis. The results showed that the electronic induction between calcium and magnesium ions is advantageous to enhance the MB adsorption. [ABSTRACT FROM AUTHOR]

This paper presents the static and dynamic experimental characterization of dolomite subjected to static unconfined compressive strength test and dynamic split Hopkinson pressure bar (SHPB) tests. The dynamic compression tests on rock samples are performed at strain rates from 500/sec to 1500/sec. It is observed from the results that the rocks exhibit significant strain rate sensitive behaviour and the peak stress increases with increasing strain rate. In the present work, the force equilibrium at the incident and transmission bar ends of the rock samples has been studied. Dynamic increase factor ( DIF ), i.e. the ratio of the dynamic to static peak stress has been calculated at different strain rates. Based on the calculated DIF values, an empirical correlation equation has been proposed for the DIF of the rock with the strain rate induced. [ABSTRACT FROM AUTHOR]

Copyright of Contributions. Section of Natural, Mathematical & Biotechnical Sciences is the property of Macedonian Academy of Sciences & Arts (MANU) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Some dolomite aggregates exposed to a wet environment may decompose. The presence of sodium, magnesium, calcium and sulfate ions in the corrosive medium and the higher temperature can increase the rate of aggregate decomposition. The results of a study on the impact of defined environmental exposition to a H 2 O, Mg(OH) 2 , MgSO 4 , Na 2 SO 4 solutions in various temperature conditions on the susceptibility to dedolomitisation processes of cement concrete made with selected dolomite aggregate are presented in the paper. The observation of linear extension as well as changes in compressive strength and surface alteration due to corrosive exposition conditions were the key diagnostic features adopted for this examination. [ABSTRACT FROM AUTHOR]

Some dolomite aggregates exposed to a wet environment may decompose. The presence of sodium, magnesium, calcium and sulfate ions in the corrosive medium and the higher temperature can increase the rate of aggregate decomposition. The results of a study on the impact of defined environmental exposition to a H2O, Mg(OH)2, MgSO4, Na2SO4 solutions in various temperature conditions on the susceptibility to dedolomitisation processes of cement concrete made with selected dolomite aggregate are presented in the paper. The observation of linear extension as well as changes in compressive strength and surface alteration due to corrosive exposition conditions were the key diagnostic features adopted for this examination. [ABSTRACT FROM AUTHOR]

Centering on the mechanism of reactive acid transport in fractured two-mineral carbonate rocks, this paper established a two-mineral model for fractured media with the extended finite element method based on the two-scale continuum model. A series of examples are presented with the numerical model, the numerical results show that the variation of volume fraction of dolomite, the surface reaction constant of dolomite as well as the diffusion coefficient can alter the dissolution morphology and dissolution performance. As the volume fraction of dolomite increases or surface reaction constant of dolomite decreases, the dissolution patterns would transform form wormhole to uniform dissolution. And the bedding distribution and porphyritic distribution of dolomite will cause a fragmentation phenomenon for the dissolution morphology. Besides, the bedded dolomite can bring about an increased acid consumption. It can be inferred that the reaction rate difference between limestone and dolomite is the key factor that affects the dissolution morphology, and the retarded acid with a low reaction rate in dolomite rocks does not perform well. • A two-mineral model for simulating acid transport in carbonate reservoirs was developed. • The reaction mechanism of two minerals in carbonate rocks was analyzed. • The dissolution morphology characteristics in two mineral carbonate rocks were discussed. • The effect of dolomite distribution characteristics on acid transport was investigated. [ABSTRACT FROM AUTHOR]

• Salt precipitation in dual- and multi-porosity systems compared to monomodal systems. • Permeability reduction of up to three orders of magnitude observed. • Capillary-driven transport between micro- and macro-porous system responsible for permeability reduction. • Volumetric ratio of micro to macro porosity and water salinity and saturation are controlling parameters. Drying of geological formations by supercritical gas injection and the associated precipitation of salts from the formation water may have serious consequences for upstream operations in terms of injectivity/productivity impairment. The potential effect on the formation permeability near the injection well is controversially discussed in literature with some studies finding a strong and others no impairment. In an earlier publication (Ott et al., 2014), we argue that this is related to the microscopic pore structure and capillary-driven brine transport therein, and that in well sorted sandstone reservoirs, permeability may be less affected than in dual- or multi-porosity systems. In the present paper, we investigate the consequences of dolomite-formation drying due to the injection of under-saturated supercritical CO 2 into samples from a Middle-East dolomite formation. Compared to earlier reported results on sandstone, the experiments show a complex behavior with a much larger effect on permeability. A permeability reduction of up to three orders of magnitude has been found. This is explained by a simple numerical model on local capillary-driven flow of water from micro- to the macro-porous regions at low brine saturation where evaporation dominates desaturation. The model suggests salt precipitation in the CO 2 conductive macropores, which impacts the effective CO 2 permeability. The volumetric ratio of micro to macro porosity, the capillary pressure contrast and water salinity and saturation are identified as the controlling parameters. [ABSTRACT FROM AUTHOR]