Civil Engineering

The plastic strain accumulation in sub grade soils under repeated loading is an important parameter to be considered for the Mechanistic empirical Pavement Design purposes. This paper investigates the critical stress limits in locally available red earth soil which is used as the subgrade layer for large extent of pavements. The soil was tested for permanent deformation with servo-controlled cyclic triaxial equipment under six varying stress levels. To find the sensitivity of permanent deformation accumulation to moisture content, samples were tested at OMC, 110% OMC and 120% OMC. Observed test results show that the permanent strain rate increases with increasing water content and deviator stress levels. Korkiala-Tanttu model was used to find out the accumulation of permanent strain with number of load repetitions and applied stress.

This paper aims at establishing the influence of acidic and alkalinepore fluids on the swell behaviour of an expansive soil. Aseries of laboratory one dimensional free swell tests were performedto study the behaviour of soil in acidic and alkaline environment.Three different concentrations of sodium hydroxide andsulphuric acid solutions were used as pore fluids to understandthe influence of variable concentrations on the swell behaviourof soil. Results showed that, the swelling of soil that interactedwith sodium hydroxide solution initially increased at lower concentrationand then decreased with increase in concentration.In contrast, the swelling initially decreased at lower concentrationof sulphuric acid and then increased with increase inconcentration of solution. The complexity in the swell behaviourof contaminated soil was assessed by thoroughly investigatingthe mineralogy and microstructure alterations by carrying outX-ray diffraction analysis, Scanning electron microscopy andE...

Alkali contamination of soils results in repeated structural failure when exposed. Though the effects of alkali on different soils have been investigated in recent years, a systematic research approach aimed at establishing swell behavior in non-swelling kaolinitic clays when exposed continuously with varying concentrations of alkali solution as pore fluid and its micro-level investigation is not well documented. Series of one-dimensional free swell tests and micro-level studies (XRD, SEM) have been carried out to investigate the alkali induced swell in nonswelling kaolinitic clays. Naturally available red earth and two commercial clays, namely ball clay and china clay, which predominantly contains kaolinite mineral are selected for the study. The swell test results showed that all three clays exhibited high swelling with alkali solutions (0.1 N, 1 N, 4 N, 8 N) when compared with water. The magnitude of swell observed in clays interacted with alkali solution ranged from a minimum of 8% to maximum of 56% depending upon the concentrations exposed. China clay showed a minimum swell of 8% with 8 N alkali solution to a maximum swell of 22% with 4 N alkali solution and red earth showed a minimum swell of 18% with 8 N alkali solution to a maximum of 27% with 0.1 N alkali solution. Whereas, ball clay showed a minimum swell of 12% with 0.1 N alkali solution and maximum swell of 56% with 8 N alkali solution. The resulted magnitude of alkali induced swell in clays is attributed to dispersion of clay particles and new mineral formations. To explore the formation of new minerals and morphological transformations a micro-level investigation is carried out on representative samples collected at the end of free swell tests. The formation of zeolite minerals viz. sodalite and cancrinite were evidenced from XRD results and rosette type structures were observed from SEM studies.

Internal curing of high performance concrete (HPC) by pre-saturated lightweight aggregates is a wellestablished method of counteracting self-desiccation and autogenous shrinkage. However, by introducing the internal water reservoirs strength and durability properties can be injured. Tests by the widely accepted methods of durability assessment, such as resistance to chloride penetration, air permeability, water absorption, autogenous and drying shrinkage and mass loss, were conducted on HPC mixes made at water to cement ratios in the range of 0.21-0.33. The effect of internal curing on the durability related properties of high-performance concretes as a function of water to cement ratio is reported.

We present the Kinetic Model (KM) as an alternative to combat the computational barrier posed by state-of-the-art evacuation modeling and simulation approaches. Instead of tracing individual agents, the KM simulates a coarse measure, namely the local occupant density. The two-phased approach tracks two distinct kinds of traffic, namely individual motion in "rarefied" (i.e. non-congested) regions and vacancies left by individual motion in "dense" (i.e. congested) regions. The dynamics of the phase boundary is governed by the balance of individuals moving from the "rarefied" region and vacancies moving from the "dense" regions across the boundary, making the approach intrinsically computationally efficient. The paper presents the theoretical formulation of the KM and comparisons of the model predictions of occupancy during evacuation with that from higher fidelity ABM. The KM computations are nearly 3 orders of magnitude faster than the ABM simulations with minimal degradation of prediction accuracy.

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BiEuO 3 (BE) and BiGdO 3 (BG) are synthesized by the solid-state reaction technique. Rietveld refinement of the X-ray diffraction data shows that the samples are crystallized in cubic phase at room temperature having Fm3m symmetry with the lattice parameters of 5.4925(2) and 5.4712(2) Å for BE and BG, respectively. Raman spectra of the samples are investigated to obtain the phonon modes of the samples. The dielectric properties of the samples are investigated in the frequency range from 42 Hz to 1.1 MHz and in the temperature range from 303 K to 673 K. An analysis of the real and imaginary parts of impedance is performed assuming a distribution of relaxation times as confirmed by the Cole-Cole plots. The frequency-dependent maxima in the loss tangent are found to obey an Arrhenius law with activation energy $ 1 eV for both the samples. The frequency-dependent electrical data are also analyzed in the framework of conductivity formalism. Magnetization of the samples are measured under the field cooled (FC) and zero field cooled (ZFC) modes in the temperature range from 5 K to 300 K applying a magnetic field of 500 Oe. The FC and ZFC susceptibilities show that BE is a Van Vleck paramagnetic material with antiferromagnetic coupling at low temperature whereas BG is an anti-ferromagnetic system. The results are substantiated by the M-H loops of the materials taken at 5 K in the ZFC mode.

Ba 2 CoWO 6 (BCoW) has been synthesized in polycrystalline form by solid state reaction at 1200 ˚C. Structural characterization of the compound was done through X-ray diffraction (XRD) followed by Rietveld analysis of the XRD pattern.The crystal structure is cubic, space group Fm-3m (No. 225) with the lattice parameter, a = 8.210. Optical band-gap of the present system has been calculated using the UV-Vis Spectroscopy and Kubelka-Munk function, it's value being 2.45 eV. A detailed study of the electronic properties has also been carried out using the density functional theory (DFT) techniques implemented on WIEN2k. Importance of electron-electron interaction between the Co ions leading to half-metallic behavior, crystal and exchange splitting together with the hybridization between O and Co, W has been investigated using the total and partial density of states.

Nano-sized La 1/2 Nd 1/2 FeO 3 (LNF) powder is synthesized by the solegel citrate method. The Rietveld refinement of the X-ray diffraction profile of the sample at room temperature (303 K) shows the orthorhombic phase with Pbnm symmetry. The particle size is obtained by transmission electron microscope. The antiferromagnetic nature of the sample is explained using zero field cooled and field cooled magnetisation and the corresponding hysteresis loop. A signature of weak ferromagnetic phase is observed in LNF at low temperature which is explained on the basis of spin glass like behaviour of surface spins. The dielectric relaxation of the sample has been investigated using impedance spectroscopy in the frequency range from 42 Hz to 1 MHz and in the temperature range from 303 K to 513 K. The ColeeCole model is used to analyse the dielectric relaxation of LNF. The frequency dependent conductivity spectra follow the power law. The magneto capacitance measurement of the sample confirms its multiferroic behaviour.

The glassy behavior of the phase segregated state in the layered cobaltite La 2 À x Sr x CoO 4 has been studied. The role of the inter-cluster interactions as well as the disordered spins at the paramagneticferromagnetic interface, behind the observed glassy behavior have been investigated. The disordered spins at the interface appear to be strongly pinned, and they contribute little to the observed glassy behavior. On the other hand, the inter-cluster interactions play the key role. Both the Co 4 þ and Co 3 þ ions are in the intermediate spin state.

This paper deals with the study of impact resistance and flexural performance of reinforced ferrocement specimens with layers of welded mesh and varying percentages of steel fibers. The main objective of this work is to study the effects on specimens casted by using single and double layers of welded mesh and varying percentages of steel fibers 0.5%, 1 %, 1.5%, 2%. Mainly concentrated on energy absorption properties and flexural performance of ferrocement specimens. The size of impact test specimens is 500x500x25mm and the flexural test specimens is 700x300x25mm.Flexural specimens were tested under two point loading system in UTM machine and impact specimens were tested by conducting a low velocity impact test. The results indicated that impact energy increases with increase in steel fibers and flexural strength increases with increase in number of mesh layers and percentage of steel fibers (0.5%-2%).

The Study investigated to acquire an overall idea about risk and its consequences in construction field and the process required for its management. The effect of risk on assessment of a project is discussed along with the tools and methods adopted to manage risk in construction industry. The objective of the research topic " Risk Management in Construction Industry " is to explore the effective way for implementation of risk management in construction industry, to consider the different types of risk management techniques applied to alleviate risk, to identify the use of implementation of the risk management, to determine the factors that can influence the applications of risk management in the project life cycle, wherein to categorize the principles adopted in Risk Management. I have conducted a survey on the following aspects of it, a) Identify, characterize, and assess threats involved in the construction industry b) Assess the vulnerability of critical assets to specific threats. c) Determine the risk (i.e. the expected consequences of specific types of attacks on specific assets). d) identifies ways to reduce those risks. e) Prioritize risk reduction measures based on a strategy.

Concrete is a construction material consisting of cementitious material, fine aggregate, coarse aggregate and water. Now a days the cost of these materials are increased so, we need to look at a way to reduce the cost of building materials especially cement. One of the recent advancement in construction industry is replacement of materials in concrete. The replacement of materials offers cost reduction, energy savings and protection of environment. To achieve the above objective we are partially replacing the cement with waste marble powder (WMP) produced from marble industries. The present investigation is aimed to study the fresh and hardened properties of concrete when cement is partially replaced by waste marble powder. The work is focused on M 20 , M 30 , M 40 grades of concrete. The percentage of Waste marble powder that replaced cement in this investigation are 0%,5%,10%, 15% and 20% .The fresh proprieties are workability and hardened properties are compressive strength at the age of 7,28 days of curing, split tensile strength, and flexural strength of concrete are at the curing age of 28days are to be determined. Results shows that the workability and compressive strength, flexural, and split tensile strengths of concrete are increased with partial replacement of cement by waste marble powder between 10% to 15%.