Papers by Keyword: Compaction

Abstract: A dark reddish-brown lateritic soil collected from existing borrow pit abandoned by Reynold Construction Company Ltd behind New WAZOBIA Market on Latitude 08008′N and Longitude 04014′E along Ogbomoso-Ilorin Express road, Ogbomoso, Oyo State. Nigeria was treated with cement kiln dust (CKD), a by-product of long wet kiln, obtained from West African Portland Cement Organisation (WAPCO), Ewekoro, Ogun State, Nigeria, under varying moulding water content.The results show gradual reduction in the plasticity index of the samples, decrease in the maximum dry densities (MDD) with corresponding increase in the optimum moisture contents (OMC) of the treated soil samples. The unconfined compressive strength (UCS) of the treated samples increases with both increase in the treatment content as well as compactive effort from British Standard (BS) to West African Standard (WAS) however, there was reduction in the UCS with varying moulding water content as the water content increases and decreases relative to optimum moisture content. The maximum UCS was obtained at optimum moisture content.Cement kiln dust though regarded as waste can therefore serve as potential material in the stabilization of the lateritic soil when compacted at moisture content within its OMC.

Abstract: This article deals with the presentation of modern applications for processing powdered, primarily hazardous, waste to an agglomeration form appropriate for subsequent processing by classical methods, for example in the construction, automotive and consumer goods industries. The aim of the research work was to set appropriate operating conditions in order to appreciate currently non-processable wastes resulting from the intensive production of often extremely expensive materials. Technologies which enable returning powder waste back into the primary production cycle were developed and experimentally tested, thus saving raw material resources. When necessary for the fixing of fine airborne particles with a problematic compacting curve (hard to compress, repulsive due to the surface charge) extrusion processes using a patented technology enabling controlled modification of shear forces in the extrusion zone were successfully applied. A new type of axial extruder allows the elimination of the liquid phase and as a result prevents the clogging of the extrusion chamber. In the case of need for granulation of sensitive materials (for example pharmaceuticals not allowing the addition of any kind of agglomerating fluid or reacting strongly in the contact of the two phases), a process of compaction between rolls with different profiled surface was successfully applied. The developed high technologies and the resulting products thus represent a major contribution to environmental protection in the context of not only the work but also the communal environment.

Abstract: A powder metallurgical process was used to fabricate Metal Matrix Composites (MMCs). A 2124 aluminium alloy was reinforced with 5 and 10 vol.% of Al₂O₃ (40-70nm) to form Metal Matrix Nano Composites (MMNCs) as well as 10 and 15 vol.% of SiC (1-10µm) to fabricate low micron MMCs. It was observed that the nano-sized Al₂O₃ particles were evenly dispersed in the aluminium matrix while a lot of loose SiC particles settled on the grain boundaries in the low micron MMCs. The relative density of all the composites increased due to sintering, however full densification was not achieved. This result was attributed to the hindered motion of dislocations, grains and grain boundaries by reinforcing particles. The 2124-Al/10%-SiC composite was cold extruded and the extruded part fractured. A metallographic evaluation was carried out and it was deduced that the mode of failure was intergranular cracking. Hardness tests performed after sintering indicated that hardness increased with an increase in volume fraction of reinforcement in the matrix. Annealing of the extruded part resulted in a decrease in hardness.

Abstract: In the present research, the combined utilization of fly ash (FA), derived from a lignite-fed power station, along with scrap-soil (SS), a steel industry by-product, is investigated, for the development of eco-friendly ceramics, thus enhancing innovation and sustainability. The valorization of these low price and largely available industrial secondary resources as 100% the raw materials mixture in ceramic industry arises interesting technological, environmental and economical benefits. FA and SS were mixed in various proportions (0-70%wt. in SS), cold compacted at 20 tn load using an automated hydraulic press to form a series of 5 cm diameter disc-shaped specimens, and finally sintered at three different peak temperatures (1000oC, 1100oC and 1140oC) for 3h. Then, the specimen microstructure and physico-mechanical properties were characterized. According to the experimental results, a sintering temperature increase from 1000°C up to 1140oC significantly improves specimen densification, thus sharply enhancing the diametral tensile strength (DTS), from 0.5 MPa up to 12.8 MPa respectively for a 50-50%wt. FA-SS mixture. Mechanical strength also varies with the SS percentage in the raw materials. Physico-mechanical properties seem to be constant for specimens containing SS up to 60% at 1140oC.

Abstract: Direct shear tests by laboratory to study the red sandstone aggregate mixture under the action of water intensity decay law, got red sandstone aggregate mixture, fill high subgrade compaction experimental study, tests showed that dynamic compaction compacted earth and rock mix fill embankment feasible, Rayleigh Wave test results show that the effect of dynamic compaction compaction good.

Abstract: A good understanding of the compaction mechanisms of pharmaceutical powders allows accurate prediction of tablet quality and facilitates design of tablet formulations. In this area of research, a common practice is to examine the response of particles towards the pressure applied during compaction. To ensure accurate and reproducible experimental results, it is prudent to have an in depth understanding of the fundamental background and potential applicabilities of the compaction process. This article reviews methods that are widely employed to study the compaction process, such as mathematical models, compaction energetics, statistical analysis methods and mechanical element simulations. In view of the complex nature of the compaction process and current research gaps in understanding the compaction characteristics, particularly of pharmaceutical powder blends, some suggestions will be proposed as well.

Abstract: The potential to control the final properties, as measured by density, strength and microstructure, of press-and-sintered titanium and master alloy Ti-6Al-4V is investigated by designing and evaluating bimodal particle size distributions of the relevant powders. Ratios of 1/3, 2/3 and 1/1 by volume of coarse to fine powders, as determined by particle size peaks, were blended from -200 and -100 mesh commercially pure titanium powders and -200 mesh 60Al-40V master alloy powder, in the case of Ti-6Al-4V. The powder blends were uniaxially compacted at 350, 400 and 450 MPa, and the green specimens were sintered under high vacuum for two hours at 1300°C. The results support theoretical prediction of green and sintered density based on the ratio of the volume percentage of coarse to fine powder; green density increases as the ratio of coarse powder increases for both the pure and alloy titanium, while the sinter density similarly decreases for the pure titanium. Microstructural observations of the sintered specimens show that the pore size decreases, and the pore shape becomes more rounded, as the ratio of fine powder increases. In order to extend the study to find the optimal packing ratio, and potentially the optimal blend for densification, further refinement of the initial powder particle size distributions is needed.

Abstract: In this study, an attempt has been made to develop solid lubricant cutting tool material with the aid of powder metallurgy technique. Chosen tungsten carbide, cobalt and calcium fluoride were milled in the planetary ball milling, followed by uniaxial compaction and sintering in a tube furnace. Materials were milled at various hours of milling and compaction pressure to understand the effect of relative density and hardness of sintered specimens. It is found that the relative density of compacted and sintered specimens found to increase with the compaction pressure but decreased with milling time after particular time. From the investigation, 40 hr of milling and 400 MPa compaction pressure found to be suitable for the development of proposed material. In this work, sample density was measured by the Archimedes’ method and hardness was measured by Rockwell hardness tester.

Abstract: Combined with dynamic consolidation Caofeidian area of land reclamation project examples, Vibration transmission mechanism of dynamic consolidation and reclamation of the foundation were explored, obtaining acceleration attenuation law, and studying and analyzing the impact of strong vibrating composite foundation. Research provide important theoretical basis to guide Dynamic Consolidation coastal reclamation foundation design and construction.

Abstract: In this paper, we exploded the technology of Sanhetu based on the historical records and previous studies. Mixing technology, molding pressure, W/S, curing time and curing method were investigated to increase the compressive strength of the imitating samples. XRD, FTIR and SEM were used to analyze the composition and consolidation mechanism. The results show that the compressive strength of the imitation could exceed 50 MPa, when molding pressure is 20 MPa, W/S is 0.49 with mixing technology A. Pozzolanic reaction is significant in strength development. And the reaction product, CSH gel, is the main factor in strength gain. Sufficient inner water of the imitating samples could contribute to the pozzolanic reaction. And increasing temperature could accelerate the reaction. The study confirms the possibility of the imitation for Sanhetu.