Papers by Keyword: Brittleness Index

Abstract: Geopolymer concrete (GPC) is the most advanced form of concrete amongst the various types of concrete developed so far. This paper aims at investigating the feasibility of using Ground Granulated Blast furnace Slag (GGBS) as a base material for geopolymer concrete. Effect of dolomite, which is a by-product from rock crushing plant on GGBS based GPC, was studied. Maximum compressive strength was obtained when GGBS and dolomite were proportioned at 70:30. Steel fibres were added to geopolymer concrete (SFGPC) to improve the ductile behaviour and its brittleness index was compared with Ordinary Portland Cement (OPC) concrete. Strength and behaviour of GGBS-Dolomite GPC and SFGPC flexural member subjected to cyclic loading are explained in this paper. Steel fibres are added at 0.25%, 0.5% and 0.75% volume fraction of concrete. Properties such as load deflection behaviour, ultimate load, crack width and ductility were compared with OPC concrete beams.

Abstract: In our country there is plenty of CBM (coalbed methane), but the state of CBM itself, unique output mechanism and low saturation, low permeability, low reservoir pressure and high gas content, et al. determine the low efficiency of it, so in order to improve CBM recovery, combined with the successful experience of north American shale gas reservoir by SRV(stimulated reservoir volume), the writer summarizes the implementation of SRV, deeply analyzes effectiveness and limitations of this new technology in CBM development. The results of practical research and theoretical analysis show that SRV in the coal reservoir can achieve the desired effect on the condition that there are great quantity of natural fractures, joints and bedding, weak structure surface development in the reservoir, the rock brittleness index is greater than 40 and horizontal principal stress difference is relatively smaller. Finally, simulating a well’s condition by the MEYER software, the result shows that SRV is feasible in coal reservoir, which will create important guiding significance and practical value for the exploration of CBM.

Abstract: The efficient development of tight oil exploration and development domestic and foreign has been a difficult, hot issues, using conventional reservoir reconstruction process, the yield increase is limited. Ordos Basin in the Chang 7 layers of tight oil reserves on behalf of a large scale, widely distributed, in order to reinforce to achieve fifty million tons of Changqing Oilfield stable long-term strategic objectives of the resource base and improve the tight oil well production, faced with enormous challenges. For Changqing Oilfield tight reservoir geological features, learn from foreign experience in tight oil development success, positive change in Changqing Oilfield reservoir reconstruction,approach to volume fracturing as a concept, greatly contributed to the Chang 7 represented tight reservoir of cost effective development, the effect is significant, strategic breakthrough.

Abstract: Abstract. Through the uniaxial compressive test, the mechanical parameters and the complete stress-strain curves were obtained, which presented a brittle failure of the mudstone samples of the No.2₁ coal seam in West Henan. Soft rock was regarded as no brittle in its failure usually, but in fact it was exactly. It showed that yield failure occurred in some areas and tension occurred inside the specimens because of the samples’ inhomogeneous deformation. The comprehensive decision method of mining surrounding rock’s brittleness was suggested: the brittleness index was more than 25; the strain of rock at failure was less than 3%, and there was brittle stress drop in the complete stress-strain curve.

Abstract: A series of large scale consolidated drained shear triaxial tests were performed on geotechnical grille reinforced sand-gravel specimens, the aim was to study influence of elongation and strength characteristic of geotechnical grille on initial modulus, peak strength, residual strength, brittleness index, volumetric strain and shear strength of reinforced sand-gravel. The results show that: the elongation of geotechnical grille used in the sand-gravel specimens has great influence on residual strength, brittleness index and cohesion of reinforced sand-gravel, but the initial modulus, peak strength and volumetric strain are affected slightly.

Abstract: This paper investigates the effect of fly ash content on unconfined compressive strength, cleavage strength and resilient modulus of cement-fly ash stabilized crushed stones. The relationships between mechanical parameters were also studied. The results show that with fly ash content increasing, the unconfined compressive strength and cleavage strength were increasing firstly but decreased then, and the resilient modulus were decreasing. The brittleness index was increased by the increment of fly ash content. It can be concluded that the optimal fly ash content in cement-fly ash stabilized crushed stones is between 10% and 15%, and increment of fly ash content can improve its crack-resistance.

Abstract: 43 Φ50mm × 100mm column stress - strain curve tests are completed through RMT-201, which studied the compressive stress - strain curves of recycled aggregate concretes at distinct confining pressures under conventional triaxial stress state. This article, has analyzed the influence of different water-cement ratios, confining pressures on the curves, and raised constitutive equations of triaxial compression stress - strain curves for the different strength of recycled aggregate concretes.The brittleness indexes for recycled aggregate concrete under distinct confining pressures were analyzed contrastively. The result showed that: the failure modes of recycled aggregate concrete specimens are similar to those of ordinary concretes, but the final failure patterns of recycled aggregate and ordinary aggregate are quite different; with the increase of lateral pressure, the peak stress and peak strain of recycled aggregate concrete show linear growth; recycled aggregate concrete compressive stress - strain curves under the uniaxial and triaxial stress states are similar to ordinary aggregate concrete, yet peak strain shows signs of larger growth; with the increase of lateral pressure, the brittleness of recycled aggregate concrete reduces. The brittleness index of high-strength recycled aggregate concrete is larger wholly than that of ordinary recycled aggregate concrete and with confining pressure reaching a certain value, the brittleness index remains stable.

Abstract: Different crystalline phases (tetragonal zirconia, titanite, celsian, diopside, anortite, zircon, scheelite, casiterite, gahnite and spodumene) have been devitrificated into a transparent ceramic glaze by addition of oxides that acts as crystallisation agents. Microstructure, wear resistance and gloss of glass ceramic surface obtained on fired modified glazes are studied. All crystalline phases diminish the brittleness index of the original transparent glaze. Anortite stands out among reinforcing phases that produces dull surfaces associated with high roughness. On the other hand, zircon stands out among the phases that improve gloss surface together wear resistance.

Abstract: This paper analyse the wear resistance of high reflective metal oxide films of TiO2 (anatase), Fe2O3 (hematite), ZrO2 (Zirconia) and SnO2 (Casiterite) deposited by screen printing over a conventional ceramic glaze (molar composition 0,2CaO.0,15ZnO.0,05K2O.0,1Al2O3 0,45SiO2.0,05ZrO2). All oxide coatings increase the gloss of the substrate producing a lustre effect. Anatase films stand out for their high gloss valour and low roughness Ra. Likewise, all lustres improve the wear resistance of the glaze substrate. Hematite and casiterite coatings stand out for their relatively high wear resistance maintaining relatively high reflectivity.