Civil Engineering

Concrete is the major construction material which plays a vital role in the development of current civilization. Construction and demolition waste is one among the various types of waste materials which can be reused in concrete production. Construction wastes are obtained during construction, renovation and demolition of a building. Dumping of these wastes to landfill causes serious environmental issues. The major factor that affects the quality of recycled coarse aggregate which is obtained from construction and demolition waste is the large amount of cement mortar that remains on the surface of it. Hence, it is essential to determine the properties of concrete containing construction and demolition waste as recycled coarse aggregate (RCA). The objective of this study is to develop the equations in order to predict compressive strength of concrete for different cement content with varying water cement ratio using RCA.

Concrete columns confined by single layered stirrup are commonly used for increasing the strength and ductility in seismic areas. Recent experiments have developed hope in the use of double stirrup confinement technique in enhancing the strength and ductility of the columns. In the present study, 12 numbers of double confined concrete square column specimens of high strength concrete, of size 150x150x450 (mm), were cast and tested under uni-axial compression. The columns were reinforced with 6 mm and 10 mm diameter of 500 MPa grade as transverse and longitudinal reinforcements respectively. Varied shapes of inner transverse reinforcement such as square, diamond, circular and spiral with square shaped outer layer stirrup, have been studied. The findings reveal that variation in shapes, contributed to greater compressive strength and better ductility of double layered stirrup confined concrete columns.

Accurate rainfall prediction is of great interest for water management and flood control. In reality, physical processes influencing the occurrence of rainfall are highly complex, uncertain and nonlinear. In this paper, we present tool for modeling and predicting the behavioral pattern in rainfall phenomena based on past observations. The aim of this paper is to predict the seasonal rainfall of (Iran) khozestan using artificial neural network (ANN) model. In order to evaluate the prediction efficiency, we made use of 33 years of seasonal rainfall data from year 1983 to 2015 of Khozestan Province (Iran). The model were trained with 28 years of seasonal rainfall data. The ANN approache is applied to the data to derive the weights and the regression coefficients respectively. The performance of the model was evaluated by using remaining 5 years of data. The study reveals that ANN model can be used as an appropriate forecasting tool to predict the rainfall.

Achklun and Amgala are located in the North and South of Abéché, region of Ouaddaï (Eastern Chad). In Achklun and Amgala crop out, granites which are cross cut by diaclases and veins. Petrographic investigation of rocks shows that granites are of two types: (1) fine grains biotite granites constituted of quartz, orthoclase, plagioclase biotite andopaque minerals and (2) coarse grains amphibole biotite-granites made up of quartz, orthoclase, plagioclase biotite amphibole and opaque minerals. Structural feature investigated are diaclases and veins. Diaclases are observed in biotite granite and amplibole biotite-granite. They display NE-SW trend direction. Veins are observed in amplibole biotite-granite. They have granitic composition and pegmatitic texture. Veins display NE-SW dominant trend direction. The NE-SW trend direction suggests that their emplacement benefited from diaclase network. Geotechnical studies indicate that fine grains biotite granite is more resistant than amphibole biotite-granite. The resistant may vary from one station to another in the same rock type. This variation is due to mineral composition grain sizes and the intensity of fractures (diaclases). Base on field observations laboratory investigation the present work permitted to select the granite more adapted for various building.

Lots of research and developments have been made in accepting the behavior of engineering materials when machining at higher cutting conditions. Developments attained from research and development activities in this area have particularly enhanced the machining of difficult-to-cut titanium alloys that have traditionally exhibited low machinability due to poor thermal conductivity, high strength at elevated temperature, resistance to wear and chemical degradation, etc. These alloys are used extensively where the strength-to-weight ratio and corrosion resistance are of the utmost significance. Even though there have been prodigious developments in the development of cutting tool materials which have significantly improved the machinability of a large number of metallic materials, including cast irons, steels and some high temperature alloys such as nickel-based alloys, no equivalent development has been made for cutting titanium alloys due primarily to their abnormal characteristics. A worthy accepting of the cutting tool materials, cutting conditions and functionality of the machined component will lead to efficient and economic machining of titanium base super alloys. This paper evaluation the main problems associated with the machining of titanium as well as tool wear, the mechanisms responsible for tool failure. Step growth in productivity, hence lower manufacturing cost, without contrary result on the surface finish and surface integrity of the machined component. It was found that the straight tungsten carbide (WC/Co) cutting utensils remain to maintain their superiority in almost all machining processes of titanium alloys, whilst CVD coated carbides and ceramics have not replaced cemented carbides due to their reactivity with titanium and their relatively low fracture toughness as well as the poor thermal conductivity of most ceramics. Cubic Nitride Boron (CBN) outfits are also normally used for machining harder alloys such as titanium and nickel alloys. The implements are expected to endure the heat and pressure developed when machining at higher cutting conditions because of their high hardness and melting point. An effort has been made to debate special machining methods, such as Rotary cutting, High pressure coolant delivery, Cryogenic cooling, Minimum Quantity Lubrication and the use of ledge tools, which have shown some success in the machining of titanium alloys.

The present investigation makes an attempt to study the modulus of elasticity of concrete , concrete in which M-sand is used as a partial and full replacement for natural sand. E is an important parameter reflecting the ability of concrete to deform elastically.M20 and M25 grade of concrete was investigated by replacing natural sand by M-sand at replacement levels of 25%, 50%, 75%, sand 100%. The results revealed that there is an increase in the value modulus of elasticity of concrete as the percentage of m sand increases also it is observed that the stress-strain behavior exhibits non-linear variation

Biomass is currently considered as an emerging technology to develop ecological sources of energy. Several studies have shown that and it is feasible to use biomass in concrete production. This paper presents results about the characterisation of the biomass rice husk ash (RHA) derived from combustion of an agricultural solid residue rice husk. The implementation of biomass in concrete will indirectly advance the renewable energy production and the economic development by decreasing CO2 emission from cement industry and saving energy as well. The results also indicate that up to 20% of RHA incorporation could be advantageously blended with cement without adversely affecting the strength properties of concrete.

Analysis of earth dams Stability, and their arching phenomenon, is one of the most important issues in geotechnical engineering. Arching dam, you can use one or more methods are analyzed. The main factor of instability dams, gravity effect, but other factors can, intensify or provoke them to be effective. To understand the factors intensifying landslide, could contribute significantly to the experts, and the stability of the dam dirt, and prevent the arching. The purpose of this paper is to examine the phenomenon of arching in the bathroom tight barrier with finite element method, and compared with studies of dam instrumentation, numerical analysis by finite element software PLAXIS, has been made. Analysis, using behavioral models Mohr-Coulomb, is done. On the other hand, we can say that, numerical methods in the analytical methods is very rapid, reliable and accurate, and therefore these methods, able to perform parametric studies, the boundary conditions are complex. So in this study, AH stresses dam Tang-e Hamam, has been studied, and then perform parametric studies, it was concluded that increasing the angle of internal friction shell dam, the dam will lead to increased confidence. However, by changing the geometry of the dam core, core thickness miles to miles and increase confidence rises Dam. Also, the arching, the barrier height is variable, and strongly arching and the maximum arching, core thickness depends on the height of the dam.

The environment of Dhaka city is depraving gradually day by day because of unplanned urbanization, destruction of greeneries by increasing building and economical activities areas to meet the demand of migrated people. This scenario is enhancing the negative change in climate gradually. It is one of the main causes of Buriganga river pollution because of climate change impact. Dhaka city, a capital of Bangladesh, which largely depends on the Buriganga River’s water for drinking, fishing, carrying merchandise and transportation.. The quality of water in this river was very poor and the average DO, BOD5, COD, Nitrate and Phosphate concentration in mg/L were 1.11, 82.3, 148.45, 5.92 and 5.83 respectively. This study mainly focused the climate change impact in term of rainfall on Buriganga River and disclosed it that decreasing the rate of rainfall affect the discharge of river because of climate change and increasing the rate of waste water because of incremental economical activities in industries both affects the dilution rate of Buriganga River simultaneously and this scenario will be also big concern in future for increasing climate change impact on rainfall in Dhaka City. In this study, we also discussed about pollution status of this river and finally the way to mitigate or minimize the pollution of Buriganga River.

For the efficient design of structure it is necessary to do the exact analysis of the elements. There are several methods of analysis broadly classified into classical and approximate method classical methods give exact solution but has its own constraints like magnitude of structure & specific geometrical dimensions. To overcome this and for rapid processing approximate methods are adopted. One such method is finite element method. Even though the results are said to be approximate but with keen consideration the variance is as good as negligible.The aim of this dissertation work is to find out the factors like shape & size of elements for gaining more accurate analytical result. The work over here is done by considering a plate with various shape & size & comparative results are depicted in the observation tables. It is clear that accuracy in the result can be obtained with refined meshing and considering Triangular shape element.