Papers by Keyword: Compaction

Abstract: Effect of glass fines and cement as a composite mixture on the geotechnical properties of a poor lateritic soil obtained from a borrow pit at Aroje, Ogbomoso, Nigeria was investigated as a reuse method of managing wasted glass. Glass fines up to 12% at intervals of 4% by mass of the soil sample were added to the lateritic soil stabilized with cement of 0, 2, 4, and 6% by mass of the soil sample. Sieve analysis, Atterberg limit, British Standard (BS) Compaction, California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) tests were conducted on the stabilized soil specimens. Results showed that Liquid Limit (LL), Plastic Limit (PL) and Plasticity Index (PI) decreased while compaction and UCS of the lateritic soil increased from 0 to 8% addition of glass fines. The CBR of the soil increased continuously from 0 to 12% glass contents. However, addition of cement increased the LL and PI while it decreased the PL between 0 and 4% but increased beyond this range. The compaction, UCS and CBR of the stabilized soil increased significantly with increasing cement content. Hence, the soil can be stabilized with the addition of 8% glass fines and 6% cement content to be used as improved subgrade material for construction of light trafficked pavement.

Abstract: In this paper, obtaining by PM of aluminum based materials, characterization of them and Finite Element Analysis (FEA) of compaction were investigated. Sintered aluminum alloys (Al-Cu and Al-Mg-Si) were tested from physical and mechanical point of view and the obtained experimental results were compared with those of sintered bronze powder materials. We studied the compressibility and densification mechanism of Al-Cu mixed powders and for prediction of compaction behavior we used FEA. The data was obtained on the stress distribution in the compacted material and on the deformations occurring throughout the mixed metal powder of the compacted samples. The results of FEA were compared with those obtained experimentally

Abstract: This BC Soil are expansive in nature and are problematic because of low shear strength and high compressibility. Review of literatures have proven that addition of lime imparts high strength with a corresponding reduction in swell of BC soils. In addition, Bio-enzymes have also been found to play a key role as activators in improving the characteristics of clayey soils such as BC soil. Development and use of non-traditional ground improvement techniques such as bio-enzymes in combination with lime for soil stabilization helps to reduce the cost and the detrimental effects on the soil environment. In the present study lime and bio-enzymes were used as soil stabilizing agents. Compaction test results on BC soil admixed with different percent of lime indicated that 3% addition lime gives higher maximum dry density of 17kN/m3 with OMC of 21% compare to other addition of lime percentages. Keeping 3% of lime as optimum lime content(OLC), BC Soil was admixed with different dosages of Bio-enzymes 25ml/m3, 50ml/m3, 100 ml/m3,150ml/m3, and 200ml/m3 along with OLC was tested for compaction and unconfined compressive strength(UCC). Further UCC test was carried out for different curing period of 0, 7, 15, 30, and 60 Days to analyse the long term effect of BC soil admixed with bio-enzymes with and without lime content. Morphological and chemical analysis was done by using XRD and SEM analysis, from all the test results it was found that 3%OLC + 75ml/m3 of bio-enzymes for 7 day of curing gives higher UCC of 450 kPa. From the SEM it was found that better bond between particles found to develop in bio-enzyme+ lime admixed BC soil in comparison with lime alone admixed BC soil. XRD studies indicated morphological changes in crystallinity and structure of stabilized BC soil in comparison to BC soil alone.

Abstract: The use of shallow and surface foundations without changing the properties of the active (seasonally thawed) layer is impossible. The ground of the active layer may be improved for used as a base in the cryolitozone. To reduce the thaw settlement ability and avoid active layer frost susceptibility a well-known technique of ground compaction by tamping may be used. This paper presents the peculiarities and possibility the properties of the active layer improvement.

Abstract: Ceramic matrix composites (CMCs) are known to have high hardness, temperature and corrosion resistance, while being comparatively lightweight. One of many external factors that influence the mechanical properties of CMC is the compaction pressure given during fabrication process. Generally, greater amount of applied compaction pressure will result in improved final product density and bending strength. In this research, a type of CMCs was fabricated using Al₂O₃, SiC, and ZrO₂ powder mixed with Nb₂O₅ additive of 81Al₂O₃-10SiC-5ZrO₂-4Nb₂O₅ wt. % composition. Fabrication was done through mixing, compacting, and sintering process. Compaction was performed at 257, 308, and 359 MPa and finished with sintering process at 1400 °C for 4 h. Final samples were characterized by density measurement, 3-point bending strength testing, XRD for phase investigation, and microstructure observation using SEM-EDS. Results showing that samples with 308 MPa compaction pressure possessed the highest density and bending strength of 3.29 gr/cm³ and 14.91 MPa, respectively. These numbers however, declined on samples with higher compaction pressure of 359 MPa due to the formation of porosities caused by entrapped gas that failed to exit the sample of which compaction pressure was considered to be overwhelmingly high.

Abstract: The paper is based on dynamic modeling research and experimental results obtained for freshly compacted concrete under stationary vibration. Thus, computational relationships and laws for vibration parameters and dissipated energy will be presented. In correlation with the dissipated energy, it will be evidenced by the evolution of the compaction degree and the resistance of the concrete depending on the vibration duration. It is noted that significant correlations have been established between the displacement curve of the dissipated energy and the loop hysteresis area for several vibration frequencies specific to the dynamic compaction regime

Abstract: This article presents the results of the binder jetting technology application for the silicon nitride ceramics production. A modified version of the Plan-B 3D printer with an epoxy-based binder was used for silicon green bodies preforming. Silicon powder was pre-coated with epoxy resin, and the curing agent was added during 3-D printing of green bodies using a standard cartridge. Curing and removal of organics was carried out during the high-temperature vacuum drying of the printed preforms. Reaction-bonded silicon nitride was obtained by using pressureless sintering. An additional compaction of green bodies is proposed to reduce the porosity of green bodies and sintered ceramics. It is shown that the proposed methods allows to improve the mechanical properties of sintered specimens.

Abstract: Transverse compaction is an important pattern of deformation during the composite resin transfer molding (RTM) process. Reasonable compaction rate is related to both the composite mould design and the fiber volume fraction of the final composite. In this paper, a mesoscopic geometry model based on CT scanning of 2.5D preform reinforcements is presented. Applying this model to the FEM simulation of transverse compaction, we prove the validation on simulating transverse compaction property of 2.5D preform by comparing to results of compaction test. Orientation angle during the progressive compaction is studied. Using this geometry structure, we build internal and surface RUC respectively then combining together to predict the in-plane mechanical property of 2.5D preform composite. Prediction result is acceptable corresponding to the mechanical properties calculated by homogenized method and compressive stiffness tested by combined loading compression (CLC) experiment.

Abstract: Titanium based alloys show very high strength to density ratio, and could be the choice of material for a wide range of applications. By practicing press and sintering for production of Ti components, high materials utilization can be assured, and at the same time costly machining operations can be limited. Difficulties in processing and high cost for powders have been limiting factors for progress, but recent development indicates good possibilities on cost effective use of TiH₂ powder in the press and sintering segment. In this paper, influence of processing parameters and powder properties on final sintered component properties are discussed.

Abstract: It is well known that cement stabilization of granular materials is a cost-effective and environmentally friendly technique for the highway construction. However, the testing and design methods for these stabilized materials have not been sufficiently advanced scientifically, which hinders their full potential application. The proper characterization of the stabilized pavement materials is vital for the successful pavement design and construction. This paper presents the results from an experimental study on the effect of cement stabilization on pavement materials in terms of engineering properties essential for use in mechanistic design of road pavements. The test results from this study revealed that the index and shrinkage properties of the pavement materials are significantly influenced by cement content, and the tensile and compressive resistances of a cement stabilized pavement base layer increase significantly with the increasing cement content and increasing curing period. Based on the test results, it is concluded that the flexural modulus/UCS and the flexural strength/UCS ratios of the cement stabilized pavement materials depend on the material, age of curing, initial stage of the compacted material and laboratory testing practices.