Crushing strength properties of furnace slag-fly ash blended lightweight aggregates

P. Gomathi and A. Sivakumar

Crushing strength of lightweight aggregates depends on the efficiency of production, type of binder used and size of the aggregate formed. Fly ash based slag pellets were produced in the present study by pelletization process. The pellets consist of fly ash and furnace slag as binder substituted at 10%, 20% and 30% by the weight of fly ash. A disc pelletizer was set to an angle of 36º with a speed of 55 rpm and pelletization duration of 10 minutes and 15 minutes was adopted. Hardening of cold bonded fly ash aggregate was carried out in hot air oven at 100ºC. The crushing strength of different size ranges of cold bonded aggregate was tested at different ages. Test results showed that the strength gain of pellet depends on the percentage of binder added and pelletization duration. A significant strength improvement is noticed at higher duration (15 minutes) (mix combination of 80% fly ash and 30% furnace slag added with concentration of 10M of NaOH) compared to 10 minutes pelletization duration. Also, the strength reduction was noticed with the increase in the size of pellets; due to size effects. The crushing strength of smaller size pellets (6 mm diameter, 30G2) exhibited higher strength (43.88%) than the larger size aggregate (16 mm diameter, 30G2) and a significant reduction in strength was noted for bigger sized aggregates due to size effect.

In this article, an investigation on bi-directional carbon fiber composite INDCARF manufactured in India - to study remaining life assessment-RLA- of the composites to enable one to design suitably. But since composites are made of different materials bonded and reinforced with fibres, they develop distress in the form of cracking and damage while in service and there is a need to assess their performance in terms of strength and stiffness for the remaining portion of their life. The cracking/damage under different conditions is simulated in the form of hair-line cracks, introduced on the surface of the coupons used for testing. Based on coupon test results, analytical studies using non-linear finite element model were carried out to assess the influence of different characteristics of damage on failure and remaining life. The cracking parameters were identified as initiation, spread and inelastic material behavior using elastic-plastic material model. The samples were evaluated by tensile tests according to the ASTM D3039.

Effect of the lime content in marble powder for producing high strength concrete

V. M. Sounthararajan and A. Sivakumar

Marble powder is a by-product obtained during the quarrying process from the parent marble rock; which contains high calcium oxide content of more than 50%. The potential use of marble dust can be an ideal choice for substituting in cementitious binder as the reactivity efficiency increases due to the presence of lime. In this research work, the waste marble powder upto 10% (passing through 45 microns) by weight of cement was investigated for hardened concrete properties. Furthermore, the effect of different percentage replacement of marble dust on the compressive strength, splitting tensile strength and flexural strength were evaluated. It can be noted that the influence of fine to coarse aggregate ratio (F/C) and cement-to-total aggregate ratio (C/TA) had higher influence on the improvement in strength properties. A phenomenal increase in the compressive strength of 46.80 MPa at 7 days for 10% replacement of marble powder in cement content was noted and also showed an improved mechanical property compared to controlled concrete.

A survey on energy conservation techniques in wireless sensor networks

In the last years, the research community and actual users have enabled to increase the attention of Wireless Sensor Networks. The lifetime of the sensor node is based on battery powered devices. Several authors discussed the different energy consumption techniques for different layers. Consolidated efficient energy consumption techniques are missing.  This paper provides a detailed study about all the existing energy conservation techniques and also explains about limitations available in the techniques. In this paper, the energy conservation approaches and its algorithms for computing the optimal transmitting ranges in order to generate a network with desired properties are discussed. Finally this paper concludes with insights for research techniques about energy conservation in Wireless Sensor Networks.

Abstract:

Due to the combination of excellent mechanical properties, high chemical stability and appropriate biocompatibility, the Ni-based alloys find large application in implantology and dentistry. The traditional metallurgical synthesis methods of these alloys have some difficulties leading to inconstancy of the composition, degradation of properties and escalation of the product price. Here we show how to overcome the disadvantages of the traditional methods of synthesis and production of Ni-based alloys for medical application using combination of mechanochemical and powder-metallurgical routes. The structural properties of the products were studied using SEM/TEM and XRD methods. It was shown that the mechanically assisted synthesis allows obtaining nanosized Ni-Ti alloy with mean particle size of 20-30 nm at significantly lower temperature in comparison with the traditional metallurgical high-temperature alloying. It was also shown that after 40 hours of intense mechanical treatment of the starting Ni and Ti powders, a direct synthesis of Ni-Ti alloy proceeds. The product has excellent sinterability which allows producing bodies with controlled structural properties appropriate for application in implantology. Using standard mechanical tests and structural examinations it was demonstrated that the Ni-Cr dental alloys obtained by mechanically assisted sintering and casting possess excellent mechanical, technological and aesthetic properties. These alloys are suitable as dental restoration materials and production of porcelain veneered constructions like crowns and bridges using the so called metal-to-ceramic technique.

Influence of perforations on flexural strength of aluminium 8090alloy sheets

Abstract:

Reliable knowledge about flexural strength of sheet metals is very important for sheet metal bending process. Young’s modulus and cross sectional area determine the flexural strength of sheet metals. For perforated sheet metals, the presence of holes reduces the cross sectional area and hence the flexural strength is affected. In this paper, an attempt is made to study the influence of presence of holes on flexural strength of Aluminium 8090 alloy sheets. Experiments are conducted to study the influence of hole size, percentage of open area and hole arrangement pattern.

Selective assembly to minimize clearance variation in complex assemblies using fuzzy evolutionary programming method

Jeevanantham A.K. and Kannan S.M.

Selective assembly is an economic method to obtain perfect precision assemblies by using the components manufactured with wide tolerance specifications. The mating component’s tolerances are divided into equal number of groups. The manufactured components are segregated according to these groups and the components from the corresponding groups are assembled interchangeably in the conventional method. The required clearance can be achieved at this assembly method that is tighter than those achieved at the normal fabrication method with lowest total cost. Still there are more variations in the clearance range. In this paper, a new optimization method is proposed to find the best combination of the selective groups to minimize assembly variation for the complex assemblies. A case example is analyzed for piston, cylinder and piston ring assembly. Fuzzy evolutionary programming (EP) method is used to obtain the best combination of the selective groups to control the assembly variation. Selective assembly is successfully applied for a piston and cylinder assembly using fuzzy EP method to achieve minimum clearance variation without sacrificing the benefit of wider tolerance in manufacturing.

Abstract:

The continuous increase in road traffic couple with an insufficient degree of maintenance due to shortage of funds has caused an accelerated and continuous deterioration of the road network in Nigeria. To alleviate this process, several types of measures are reported to be effective, for instance, securing funds for maintenance, improved roadway design, use of better quality of materials and the use of more effective construction methods. Improving the quality of materials used in road construction had been shown to improve road service performance in the wake of the increase usage. Practical experiences over the last four decades have shown that the modification of the bituminous binder with polymer additives offers several benefits in asphalt concrete and has been tested in a number of countries around the World. The use of polythene materials for pure water sachet in the country has received a great boost due to its abundant supply and high resistance to insects, fungi, animals, as well as molds, mildew, rot and many chemicals. However the disposal of the waste polythene materials in large quantities has been a problem all over the country. This study was therefore designed to investigate the effect of polythene as contained in pure water sachet in the asphalt concrete properties. Polythene was added in grinded state as binder modifier. It was introduced to the mixture by melting it in the bitumen used in preparing the asphalt concrete mix. Marshall Mix design method was used, first to determine the optimum bitumen binder content and then further to test the modified mixture properties. In total, 17 samples were prepared (10 samples were used to determine the binder content and the remaining samples were used to investigate the effect of modifying the asphalt mixtures). The optimum asphalt content was 7.0%. Six proportions of polyethylene by weight of the optimum binder content were selected to be tested (2.5, 5.0, 7.5, 10, 12.5 and 15%). The properties tested include bulk density, stability and flow of the concrete mix. The obtained optimum proportion of the modifier is 12.5% by the weight of the optimum bitumen content. It is found to increase the stability, reduce the density and slightly reduce the flow of asphalt concrete specimen. Findings from this study suggest that polythene modifier offers better engineering properties and its usage as bitumen modifier could serve as a means of managing the waste menace.

Study the effect of externally and internally ply drop-off in composite laminate analysis

Abstract:

Tapered laminated structures, which are formed by dropping off some of the plies at discrete positions over the laminate, have received much attention from researchers because of their structural tailoring capabilities, damage tolerance, and their potential for creating significant weight savings in engineering applications. The inherent weakness of this construction is the presence of material and geometric discontinuities at ply drop region that induce premature interlaminar failure at interfaces between dropped and continuous plies. In the present work the finite element analysis of composite laminates with externally and internally ply drop-off is presented. The effect of different lay-ups and different ply drop-off ratio Th/L (where Th is total thickness of ply drops and L is ply drop of length) under tensile load is study. The finite element analysis is carried out using ANSYS software.

Abstract:

This paper presents the study on the effect of fly ash (FA), silica fume (SF) and microwave incinerated rice husk ash (MIRHA) as cement replacement material (CRM) on the mechanical and fresh properties of self-compacting Concrete (SCC). Some of the CRM materials are supposed to enhance the properties of SCC by avoiding the Bleeding at fresh stage and increase the strength in the long term at hardened stage, in addition of that CRM can reduce the total cost of mixing depends on the replacement percentage. The experimental work included the workability test as well as mechanical test of SCC. Workability test determined the flowability, filling ability and segregation resistance by slump flow, slump T50, L-box and V-funnel testes. The mechanical properties by applying compressive strength, splitting tensile strength and flexural strength were investigated. There were a total of nine mixes created with different CRM contents. The result showed that the MIRHA needded more water as compared to SF to achieve the similar fresh properties, similarly concrete with 5% SF showed about 9.70% highest compressive strength after 90 days, 5.10 MPa high tensile strength and 10.12 MPa flexural strength when compared with other mixes.

Abstract:

Flow measurement in open channel is important to support the system management. An experimental study in a laboratory flume is carried out to study flow over a sharp crested weir and under gate in combined structure as flow measurement device. Four different oblique angles to the longitudinal axis of the channel and four different heights of gate opening were used. The basic principles of statistical analysis are employed to correlate between the hydraulic and geometric dimensionless parameters with the discharge coefficient. Different relationship models with acceptable significance are suggested. It was found that the major parameters effecting significantly on discharge coefficient are (h/d, α, L/d, P/d), and value of C_d range from 0.623 to 0.403, with Standard Error 0.0047. Within the limitations of the present experimental work two different discharge equations were predicted. The first equation Which assumed that the coefficient of discharge is the same for weir and gate with R² of o.972, and  the second which assumed that there is different  percent of discharge for each weir and gate with R2 of 0.997.