School of Civil and Mechanical Engineering

The geothermal piles are dual functional geostructures which provide sub-structural support to the building and also fulfill the energy demands in terms of its climate control. For efficient design of geothermal piles, it is necessary to evaluate the thermo-mechanical behavior of geothermal piles. The purpose of this study is to evaluate the behavior of geothermal heat exchanger pile installed in sand, subjected to a coupled thermomechanical loading. Initially, in this study a full scale field test is simulated and results are compared. In the second phase, parametric study by varying mechanical and thermal loading on the geothermal pile placed in dense sand, is performed. In this study, the sand and geothermal pile are simulated as axis-symmetrical models, where pile is considered to be thermo-elastic in nature and sand is considered as Mohr-Coulomb elastic-plastic material. Coupled Temperature-Displacement analysis is applied in order to simulate the observed experimental results. It is shown that the simulated model is able to reproduce the major thermo-mechanical effects for the selected full scale model approximately. Stress and strain behavior along with the depth of energy pile induced by thermo-mechanical loading has been reported. It was concluded that when mechanical load value is comparatively low, the thermal variation influences the induced axial stress while at higher mechanical load the stress behaviour is nearly constant at different temperature variation.

Riverbank erosion is a global problem with significant socio-economic impacts. Microbially induced calcite precipitation (MICP) has recently emerged as a promising technology for improving the mechanical properties of soils. The present study investigates the potential of selectively enriched native calcifying bacterial community and its supplementation into the riverbank soil of the Brahmaputra river for reducing the erodibility of the soil. The ureolytic and calcium carbonate cementation abilities of the enriched cultures were investigated with reference to the standard calcifying culture of Sporosarcina pasteurii (ATCC 11859). 16S rRNA analysis revealed Firmicutes to be the most predominant calcifying class with Sporosarcina pasteurii and Pseudogracilibacillus auburnensis as the prevalent strains. The morphological and mineralogical characterization of carbonate crystals confirmed the calcite precipitation potential of these communities. The erodibility of soil treated with nativ...

This study evaluated the impacts of future climate change on the hydrological response of the Richmond River Catchment in New South Wales (NSW), Australia, using the conceptual rainfall-runoff modeling approach (the Hydrologiska Byrans Vattenbalansavdelning (HBV) model). Daily observations of rainfall, temperature, and streamflow and long-term monthly mean potential evapotranspiration from the meteorological and hydrological stations within the catchment for the period of 1972e2014 were used to run, calibrate, and validate the HBV model prior to the streamflow prediction. Future climate signals of rainfall and temperature were extracted from a multi-model ensemble of seven global climate models (GCMs) of the Coupled Model Intercomparison Project Phase 3 (CMIP3) with three regional climate scenarios, A2, A1B, and B1. The calibrated HBV model was then forced with the ensemble mean of the downscaled daily rainfall and temperature to simulate daily future runoff at the catchment outlet for the early part (2016e2043), middle part (2044e2071), and late part (2072e2099) of the 21st century. All scenarios during the future periods present decreasing tendencies in the annual mean streamflow ranging between 1% and 24.3% as compared with the observed period. For the maximum and minimum flows, all scenarios during the early, middle, and late parts of the century revealed significant declining tendencies in the annual mean maximum and minimum streamflows, ranging between 30% and 44.4% relative to the observed period. These findings can assist the water managers and the community of the Richmond River Catchment in managing the usage of future water resources in a more sustainable way.

The application of two distinctively different hydrologic models, (conceptual-HBV) and (distributed-BTOPMC), was compared to simulate the future runoff across three unregulated catchments of the Australian Hydrologic Reference Stations (HRSs), namely Harvey catchment in WA, and Beardy and Goulburn catchments in NSW. These catchments have experienced significant runoff reduction during the last decades due to climate change and human activities. The Budyko-elasticity method was employed to assign the influences of human activities and climate change on runoff variations. After estimating the contribution of climate change in runoff reduction from the past runoff regime, the downscaled future climate signals from a multi-model ensemble of eight global climate models (GCMs) of the Coupled Model Inter-comparison Project phase-5 (CMIP5) under the Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 scenarios were used to simulate the future daily runoff at the three HRSs for the mi...

Acknowledgment iv Table of contents v List of acronyms vii List of notations ix List of tables x List of figures xi List of publications xiv Chapter I vi 2.6 Influence of stabilizer or long term retarder (LTR) on hydration of clinker and cement 34 2.7 Summary 27 Chapter III Methodology 3.1 Introduction 3.2 Experimental plan 3.3 Constant factors 3.4 Variable factors 3.5 Response variable 3.6 Experimental procedure 3.7 Materials 3.8 Phase I-Determination of setting time 3.9 Phase 2-Effect of stabilizer on efflux time with increased stabilize time 54 3.10 Phase 3-The effect of stabilizer on temperature rise during hydration 56 3.11 Phase 4-Effect of stabilizer on plastic and mechanical properties of concretes 57 3.12 Phase 5-Plastic and mechanical properties of 32MPa stabilized concrete upgraded to 40MPa 59 Chapter IV Results and discussions 62 4.1 Introduction 4.2 Setting time without stabilizer 4.2.1 OPC 4.2.2 Blended cement containing 35% OPC and 65% slag 4.2.3 Blended cement containing 75% OPC and 25% fly ash 64 4.2.4 Discussion on setting time without stabilizer 64 4.3 Results and its validation with Marsh cone 67 4.3.1 Ordinary Portland cement 67 4.3.2 Blended cement containing 35% OPC and 65% slag 4.3.3 Blended cement containing 75% OPC and 25% fly ash 72 4.3.4 Discussion on Marsh cone results 74 4.4 Results and its validation with heat of Hydration-Coffee Cup Method 75 vii 4.4.1 Effects of stabilizer on heat of hydration on ordinary Portland cement grout 4.4.2 Effects of stabilizer on heat of hydration on blended cement grout 35% OPC and 65% slag 77 4.4.3 Effects of Stabilizer on Heat of Hydration of blended cement grout containing 75% OPC and 25%fly ash 79 4.4.4 Discussion on Coffee Cup Method 81 4.5 Correlation between dosage of stabilizer with holding time and heat of hydration 4.6 Effects of stabilizer on workability of concretes 4.6 Effect of stabilizer on workability on workability of concretes 4.6.1 OPC concrete 86 4.6.2 Blended cement (35% OPC and 65% slag) concrete 4.6.3 Blended cement (75% OPC and 25% fly ash) concrete 4.7 Effects of stabilizer on setting time of concrete 4.8 Effects of stabilizer on unit weight of harden concrete 4.9 Effects of stabilizer on temperature of plastic concrete 4.10 Effects of stabilizer on compressive strength of concrete 4.11 Effects of stabilizer on drying shrinkage of concrete 4.12 Studies of upgrading 32MPa stabilized concrete to 40MPa Chapter V Conclusions 106 5.1 Introduction 106 5.2 Summary 107 5.3 Recommendations for further studies 108 References 110 Appendix A 117 Appendix B 123 viii LIST OF ACRONYMS AS Australian Standard ASTM American Society for Testing Materials C 3 A Tricalcium Aluminates C 4 AF Tetracalcium alumino-ferrite C 2 S Dicalcium Silicate C 3 S Tricalcium Silicate CH Calcium Hydroxide CAH-Calcium Aluminate hydrate CSH Calcium Silicate Hydrate FA Fly Ash GB General blended cement (75% OPC and 25% fly ash) GP General Portland Cement ISM Blended Cement (85%OPC and 15% slag) LH Low heat cement (35% OPC and 65% slag) LTR Long-Term Retarder NRMCA National ReadyMixed Concrete Association OPC Ordinary Portland cement PBTC Phosphonobutane tricarboxylic acid GGBS Ground Granulated iron Blast-furnace Slag SCM Supplementary Cementitious Materials ix LIST OF NOTATIONS MPa Megapascal = N/m 2 (1Newton per square meter) µƐ-Shrinkage measured in microstrain x LIST OF TABLES 2.1 Hydration characteristics of cement compounds 2.2 Variability of adiabatic and semi-adiabatic test results 2.3 Overview of experiment with clinker phases clinkers and cement 3.1 General chemical constituents of OPC and FA and GGBS 3.2 Mix proportion of concrete containing OPC and blended cement 3.3 Mix proportion and correction of cement and cementitious materials for Phase 5 xi LIST OF FIGURES 2.1 Determination of set times 2.2 Effect of cement type and temperature on set times 2.3 Effect of fly ash replacement and temperature on set times 2.4 Effect of fly ash type and temperature on set times 2.5 Cement hydration process 2.6 Temperature increase of mass concrete under adiabatic conditions 2.7a Hydration rate of cement compounds-in pastes of pure compounds 2.7b Hydration rate of cement compounds-in type I cement paste 2.8 Effect of C 3 A content (C 3 S ≈ Constant) on heat of hydration 2.9 Effect of C 3 S Content (C 3 A ≈ Constant) on heat of hydration 2.10 Heat of immediate hydration with SO 3 varied 2.11 Heat of hydration with specific surface varied 2.12 Effect of w/c ratio on the heat evolution 2.13 Effect of curing temperature on hydration 2.14a Effect of Class F fly ash on heat generation 2.14b Effect of Class C fly ash on heat generation 2.15 Effect of slag on hydration 2.16 Heat evaluation at 20°C (1) 40% coarse slag (400m 2 /Kg) (2) 40% fine slag (592 m 2 /Kg) (3) OPC. 2.17 Total heat of blended cement with slag at different temperatures 2.18 Effect of Superplasticizer on cement hydration 2.19 PBTC-deprotonated 2.20 Effect of LTR on hydration of Portland cement clinker without or with non-optimized supply of CaSO 4 , (K II-2) 2.21 Effect of LTR on hydration of Portland cement with optimized supply of CaSO 4 , (Z II-2) 2.22 Dosage-Set time curves for stabilized concrete 3.1 Experimental process flow chart 3.2 Cross section of flow cone 3.3 Coffee Cup test setup 4.1 Initial and final setting time OPC 4.2 Initial and final setting time of OPC 35% and slag 65% cementitious 4.3 Initial and final setting time of OPC 75% and FA 25% cementitious 4.4 Holding time required to achieve 35 seconds flow for OPC grout with and without water reducer xii xiv LIST OF PUBLICATIONS 1. Shaikh, F.U.A., and Mali, S. (2015) Properties of stabilized recycled plastic concrete made with three types of cement. Structural concrete

Having a precise vulnerability discovery model (VDM) would provide a useful quantitative insight to assess software security. Thus far, several models have been proposed with some evidence supporting their goodness-of-fit. In this work we describe an independent validation of the applicability of these models to the vulnerabilities of the popular browsers Firefox, Google Chrome and Internet Explorer. The result shows that some VMDs do not simply fit the data, while for others there are both positive and negative evidences.