Papers by Keyword: Granite

Abstract: Six Portuguese magmatic ornamental stones were submitted to Soxhlet experiments during 10,000 hours (approximately 416 days) in order to evaluate how the rain water affects the rock behavior as a dimension stone. Macroscopic alterations were observed in the rock fragments and chemical analysis of leaching water solutions revealed how major elements were mobilized from rock-forming minerals allowing to compare weathering susceptibilities between different natural stones.

Abstract: A silica-based nanoproduct - UCAT-10P© - developed and patented by the TEP-243 (Molecular sieves and other nanomaterials) group of the Cadiz University (UCA) is applied on two stone materials – granite and marble – from the stage front of the Roman theater of Merida, World Heritage by UNESCO (1993). Marble shows firstly scaling as the main decay form, and granite, grain-disintegration, which, at the same time, favor an acceleration of their deterioration condition due to physical, mechanical, chemical and biological processes. That is the reason of assessing the efficiency and durability of a multifuncional nanoproduct, with both consolidating and hydrophobing effects. The performance of this product has been evaluated in terms of the appearance of the stone surfaces (color and roughness), the consolidating role (hardness and ultrasound velocity) and the hydrophobing achievements (capillarity and water contact angle). The most distinctive feature of this research is the in situ testing of the stone blocks, the use of mostly non-destructive and portable techniques, and the monitoring of the product performance of the treatment at a short (1 month) and mid-term (12-15 months), proving the efficacy of the product, although its behavior changes with time.

Abstract: The waste generated in granite processing has caused great social and environmental concern due to the release of its solid effluents into landfills and other places. The recycling and reuse of waste from different industrial processes as new raw materials has been the object of various researches. The use of hydrocyclone in the treatment of residues can represent a very efficient tool for separation and purification of the granite residue. This work aims to characterize and analyse the technological properties of the granite sawdust residues submitted to the hydrocyclone process in comparison with the same residue without going through the hydrocyclone process. The results indicate that the material resulting from this process presented different characteristics from the material without the process, mainly in terms of granulometric distribution and technological properties.

Abstract: This study deals mainly with the mix proportions using granite and unwashed gravel as coarse aggregate for self-compacting concrete (SCC) and its workability, by considering the water absorption of unwashed gravel aggregate. Mix proportions for SCC were designed with constant cement and fine aggregate while coarse aggregates content of granite-unwashed gravel combination were varied in the proportion 100%, 90%/10%, 80%/20%, 70%/30%, 60%/40%, 50% /50%, represented by SCC1, SCC2, SCC3, SCC4, SCC5 and SCC6. 100% granite (SCC1) serves as the control. The workability of the samples was quantitatively evaluated by slump flow, T₅₀₀, L-box, V- funnel and sieve segregation tests. Based on the experimental results, a detailed analysis was conducted. It was found that granite and unwashed gravel with SCC1, SCC2 and SCC3 according to EFNARC (2002) standard have good deformability, fluidity and filling ability, which all passed consistency test. SCC1, SCC2 and SCC3 have good passing ability while all mixes were in the limit prescribed by EFNARC (2002). It can be concluded that the mix design for varying granite-unwashed gravel combination for SCC presented in this study satisfy various requirements for workability hence, this can be adopted for practical concrete structures.

Abstract: In order to study the relationship between the fractal dimension of rock fracture surface and temperature, uniaxial compression experiments on the granite rock and scanning electron microscopy experiments on the rock fracture surface were carried out after different temperatures. The fractal dimension was calculated by using scanning electron microscopy images. The results are as following: (1) The cracks show intergranular damage like rock candy, rivers and so on at the temperature from 25°C to 200°C. The fractal dimension are volatile, the fractal dimension reach the maximum at 200 °C, it can be inferred that the granite rock burst the most energy consumption at 200 °C; (2) From 200°C to 800°C, the cracks transform from stepped cleavage, intergranular fracture gradually to grain crushing, transgranular cracking damage with the rise of temperature. When the temperature is above 800 °C, the cracks transform from the transgranular cracks, shear slip bands gradually to dimples and microporous points. The cracks of rock surface transform from irregular crack structure to homogeneous pore structure gradually at high temperature, the weakening of rock heterogeneity is the basic reason for the decrease of fractal dimention of rupture surface, the fractal dimension is reduced from 1.634 at 200 °C to 1.595 at 1200 °C, the margin of reduction is 2.39%. At the same time, the energy consumption of rock rupture decreases with the rise of temperature, rock transforms from brittle to plastic gradually.

Abstract: Because of their widely application of tantalum, niobium and lithium in industry, the occurrence modes of tantalum-niobium tailing mine in Yichun city was investigated by SEM, XRD, XRF measurement. Some interesting results are obtained, which is useful for the next flotation process and for the comprehensive utilization of lepidolite resources in Jiangxi province.

Abstract: The escalating interest of researchers to use industrial waste materials in the manufacture of ceramic products is growing. This work is aimed at studying the properties of granite waste (GW) upon incorporation in ceramic bodies. Initially, the GW was characterized in terms of chemical and mineralogical compositions. Then, the GW was added (in the range 40-60 wt.%) to a ball clay. Firing was carried out at 1100°C to1200°C and then the properties of the fired specimens were determined. The results showed that specimens with GW 50 wt.% fired at 1150°C exhibited the best properties, i.e. minimum water absorption of <0.36%, the best bulk density (2.48 g/cm³) and strength (21.34 MPa). This showed that GW can act as a fluxing agent and reduces the firing temperature of the ceramic body with additional advantages in terms of cost and reuse of waste materials.

Abstract: Two coarse-grained granitic rocks - charnockite and biotite granite were studied with the aim of estimating their unconfined compressive strength from simpler non-destructive test values. The simpler tests were the ultrasonic pulse velocity, the Schmidt hammer rebound, and the specific gravity. Another test carried out was the moisture absorption. The rocks had compressive strength in the range 115-250 MPa, Schmidt hammer rebound number or index of 35-55, and pulse velocity of 3.4-5.5 km/s. The correlation coefficients between the uniaxial compressive strength and the rebound number were 0.86 and 0.81 for the biotite granite and the charnockite, respectively. Products of the rebound index and the pulse velocity and the specific gravity improved the correlation coefficients to 0.94 and 0.91 respectively. The high correlation factors implied that the compressive strength can be estimated using the simpler tests parameters. These simpler parameters also relate indirectly to geomechanical properties of the rocks such as drillability, boreability and machine tool wear. The moisture absorption alone and its combination with the rebound number correlated inversely and poorly with the compressive strength. The correlation coefficient ranged between 0.45 to 0.67. The moisture absorption therefore proved to be a poor predictor of the uniaxial compressive strength of the rocks.

Abstract: Grinding test was carried out to study the grinding of granite with single diamond grain. Forces were measured to investigate the mean normal and tangential forces acted on the diamond grain. The relationship between the forces and either spindle speed or the maximum thickness of the undeformed chip produced by a diamond grain was discussed. The digital models of granite were constructed by discrete element method. Based on the model, two-dimensional and 3-D analysis was carried out to simulate the grinding process with the single diamond grain. The simulation results were compared with experimental data, and some useful conclusions were obtained: the 3-D results agree well with the experiment data at the sameand largeas well as the sameand large; the 3-D and 2-D results are comparable to the experiment data at other machining parameters..

Abstract: Based on orthogonal experiment of machining the irregular surface of Wulian red granite (G3768) with diamond profiling wheel, the relations between the fractal dimensions of cutting forces with machining parameters are studied. Cutting speed, feed speed and cutting depth are considered as the process parameters. The cutting force in machining granite operation are measured and the fractal dimension are calculated using using the algorithm of correlation dimension. From main effect plots the fractal dimensions of three directions of cutting forces are reduced with the increase of cutting speed and increased with the increase of feed speed and cutting depth. The mathematic models of fractal dimension of cutting force are developed by analysis of regression. The results of the ANOVA show that cutting speed and feed speed have remarkable influence to fractal dimension D_x, D_y and D_z.