Papers by Keyword: Sandstone

Abstract: Due to climate and environmental changes, the coral reef ecosystem has undergone severe degradation, leading to widespread bleaching, coral death, and a significant decline in live coral coverage. As a result, coral cultivation has become an urgent task, and the establishment of horticultural nurseries and the implementation of sexual reproduction for coral transplantation have emerged as crucial methods to address the scarcity of coral sources for transplantation. However, the selection of suitable attachment stones remains a challenge, as it significantly impacts the survival rates of transplanted corals. It is essential to choose appropriate base stones that not only align with the restoration of the original environment but also offer economic viability. The South China Sea coastline is abundant in sandstone, which possesses dense structure, large blocks, high porosity, and excellent water absorption characteristics, making it an ideal choice as a base stone for coral cultivation. Furthermore, these base stones can be shaped into familiar story scenes or characters, allowing for the creation of underwater coral gardens that serve as both a means of sustainable funding and a platform for scientific popularization and aesthetic education.By integrating these elements, a coral restoration and cultivation system can be developed, promoting a sustainable model that combines science education, aesthetic appreciation, and self-sustaining financial resources. This holistic approach not only addresses the pressing need for coral cultivation but also contributes to the preservation and revitalization of coral reef ecosystems.

Abstract: This study investigated the effect of rock-water interaction on microstructural properties of various weathering grade sandstone. Sandstone samples were acquired from the Sor-Range coal mine area, Pakistan, and were investigated using a tabletop scanning electron microscope (SEM). The characteristics of microstructures from micrographs were obtained using ImageJ software. According to the findings an increase in wet and dry cycles significantly affects the microstructures (pore spaces and microcracks). The porosity and microcracks density of sandstone increases with the number of wet and dry cycles. Furthermore, the length of microcracks increases as the weathering grade increases. As variation in rock macroscopic mechanical characteristics is directly associated with the deterioration of microstructures. Therefore, analyzing the effect of water-rock interaction in various weathering grades of rock can offer a more accurate reference index for assessing the stability of geotechnical structures.

Abstract: The improved oil recovery (IOR) is a way of enhancing the reservoir properties with the use of nanomaterials to detach the oil molecule from the trapped zone. The polarization effect on reservoir sandstone under an electric double layer is one of the major research interests. The nanoparticles agglomeration such as graphene nanofluid due to poor dispersion in reservoir zone can be a major challenge that can lead to low reservoir permeability are well elucidated. This study investigated the influence of graphene nanofluid on the ionic polarization under an electric double layer in reservoir sandstone. Saturated Berea sandstone was used to investigate the interaction of ionic species on reservoir sandstone with the aid of Field-emission microscopy (FESEM), Energy dispersive X-ray mapping (EDX), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectral analysis, and Core flooding experiment. This research gives information on the adsorption of ions within an electric double layer and its polarization mechanisms. It was revealed from the experimental result that ionic polarization occurs at 9.97 GHz with a 5.8nm wavelength shift which improves the mobility of the reservoir and in turn increases oil recovery factors. Graphene nanoparticles show a positive effect on both reservoir oil viscosity and stabilization characteristics of drilling fluids, wettability alteration, interfacial tension, and improving the emulsion Keywords: Nanomaterials, Sandstone, Electric double layer, Graphene

Abstract: The article considers and evaluates the impact of dispersed reinforcement of heavy concretes manufactured by means of vibration and centrifugation, various types of fibers on their strength-density ratio. The options of applying different types of heavy-weight aggregates for these concretes: crushed stone, limestone and sandstone are considered. The highest strength-density ratio is registered in centrifuged crushed stone fibrous concretes, and all types of centrifuged concretes has the ratio higher than vibrated concretes with the same composition of the studied fibers. The highest growth of the strength-density ratio for the centrifuged crushed stone fibrous concretes as compared with the vibrated ones was identified in case of dispersed reinforcement with steel fiber.

Abstract: This work presents results of experimental researches of influence of various high-temperature thermomechanical treatment (HTMT) modes in 35KhGSA steel – material applied in rock-destroying cutters – on hardness and wear rate for the most common abrasive rock in mining operations – sandstone. It has been found out that HTMT leads to increase of steel hardness and reduction of wear rate compared to heat treatment applied at manufacture of cutters. The maximal increase of hardness (by 23%) and reduction of wear rate (by 38%) corresponds to the mode of distortion accumulation of ~1,5 at 900 °С at water quenching and tempering at 230 °C. A conclusion that thermomechanical treatment is an effective way to increase the wear resistance of steels applied in the conditions of abrasion wear has been drawn.

Abstract: In this paper, the researcher synthesis a super-hydrophobic nanosilica to alter the wettability of the sandstone surface from hydrophilic to super-hydrophobic. Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were used to test the characterization of the products, and the wettability were examined by contact angle measurement, glass capillary tube rise measurement and spontaneous imbibition tests. The results shows that the water contact angle is over 150°,the liquid level is down to-42mm and the spontaneous volume is only 0.025mL after the surface modified with super-hydrophobic nanosilica which means the surface wettability is altered to be super-hydrophobic.

Abstract: Within the solution of the research project GAČR P105/12/G059 a detailed diagnosis of the stone railway bridge on the railway line Plzeň - Tachov was performed. The bridge is created by two parallel vaulted tubes made from sandstone where a frequented road of second category goes through under one of them and Myslinsky brook flows under the second. The bridge was built approximately in 1978 and in 2006 a reinforced concrete frame structure was built to the bridge portal. Length of both tubes is about 45.5 m, width about 5.7 m, height of the tube above the road is about 6.0 m and above the brook 7.8 m. The arch is made as an annular vault. On the basis of the diagnostic works the structure is evaluated from the point of view of moisture, amount of water soluble salts, strengths of sandstone and there is also a visual observation of a condition of the structure itself performed. In the end there recommendations for a consequent procedure in case of the revitalization are stated.

Abstract: Present paper is focused on the experimental assessment of three sandstones from different quarries. Mechanical testing was carried out besides water absorption test and determination of frost resistance what is the crucial material parameter for all types of porous rocks. Gradual deterioration due to action of frost was monitored using non-destructive testing – ultrasonic pulse method. Obtained results well describe failure mechanism of studied sandstones of different basic physical properties. It was conducted that main part of deterioration was performed at the beginning of the freeze-thaw cycling.

Abstract: Redevelopment of wet masonry by additional creating of hydroinsulating screens by injection gels is nowadays one of the most widespread methods in treating old damaged structures, which would not withstand any other more damaging method of redevelopment. One of the biggest advantages of this method is its quick and relatively easy application, excellent efficiency and low impact on buildings statics. This articles main object is observing penetration rate and final functionality of hydroinsulating injection gels in sandstone building materials.

Abstract: The flood in 2002 affected salinity and microflora of surface layers of the sandstone blocks of the Charles Bridge in Prague. The microbial decomposition of the organic contaminants causes a significant decrease of pH value which resulted in the chemical denitrification and, consequently, also in the microbial denitrification of nitrites and nitrates on the sandstone block surface.