By optimizing the packing of the combined aggregate gradations, the cement paste content needed to make concrete can be reduced, improving sustainability, cost, performance, durability, and workability. Optimization can be achieved using theoretical and empirical techniques, or waste concrete material as an intermediate size fraction. However, the potential for improvement is currently limited by prescriptive grading specifications that require meeting individual requirements for fine and coarse aggregates. From this study, using various optimization techniques, it was found that by inclusion of an intermediate sized aggregate material, a reduction in cement paste up to 16% is possible for 35 MPa and 50 MPa mix designs typically used in Ontario bridge decks. The aggregate materials used were a natural sand, and two crushed limestones of 19.0 mm and 6.7 mm maximum size. From these findings, recommendations are made for improving the current Ontario Provincial Standard Specification (OPSS) 1002 used for concrete aggregates.

By optimizing the packing of the combined aggregate gradations, the cement paste content needed to make concrete can be reduced, improving sustainability, cost, performance, durability, and workability. Optimization can be achieved using theoretical and empirical techniques, or waste concrete material as an intermediate size fraction. However, the potential for improvement is currently limited by prescriptive grading specifications that require meeting individual requirements for fine and coarse aggregates. From this study, using various optimization techniques, it was found that by inclusion of an intermediate sized aggregate material, a reduction in cement paste up to 16% is possible for 35 MPa and 50 MPa mix designs typically used in Ontario bridge decks. The aggregate materials used were a natural sand, and two crushed limestones of 19.0 mm and 6.7 mm maximum size. From these findings, recommendations are made for improving the current Ontario Provincial Standard Specification (OPSS) 1002 used for concrete aggregates.

Historical lead in tap water data from the City of London and the City of Ottawa were examined for trends and correlations over time. Factors such as the sampling protocol, temperature, and pH were analyzed to determine their specific impacts on lead. Linear and logistic regression models were also developed to predict lead concentrations in tap water based on different water quality parameters. Finally, a physical mass transfer and flow model (zonal model) was validated with the lead data from the two municipalities. Results indicate the potential use of the regression and zonal models to predict a range of lead concentrations for a number of homes in a Canadian city based on the field data. These methods may allow municipalities to determine the impact of a corrosion control strategy such as a pH increase without having to sample for lead in people's homes.

Historical lead in tap water data from the City of London and the City of Ottawa were examined for trends and correlations over time. Factors such as the sampling protocol, temperature, and pH were analyzed to determine their specific impacts on lead. Linear and logistic regression models were also developed to predict lead concentrations in tap water based on different water quality parameters. Finally, a physical mass transfer and flow model (zonal model) was validated with the lead data from the two municipalities. Results indicate the potential use of the regression and zonal models to predict a range of lead concentrations for a number of homes in a Canadian city based on the field data. These methods may allow municipalities to determine the impact of a corrosion control strategy such as a pH increase without having to sample for lead in people's homes.

The purpose of this project was to evaluate two types of concrete surfaces and analyze the effect of each finish on the air content, paste content, aggregate fraction and rate of absorption at various depths from the surface. For this project, nine concrete mixtures were evaluated with varying cement, water and air contents. Slabs were cast and two types of finishes were considered: a trowel-finished made with a magnesium trowel and a form-finished from the plywood molds used. Cores were taken from the slabs and tested at 0, 5, 10, and 20mm below the surface.

The purpose of this project was to evaluate two types of concrete surfaces and analyze the effect of each finish on the air content, paste content, aggregate fraction and rate of absorption at various depths from the surface. For this project, nine concrete mixtures were evaluated with varying cement, water and air contents. Slabs were cast and two types of finishes were considered: a trowel-finished made with a magnesium trowel and a form-finished from the plywood molds used. Cores were taken from the slabs and tested at 0, 5, 10, and 20mm below the surface.

Master of Science / Department of Civil Engineering / Hayder A. Rasheed / The development of column interaction diagrams for unconfined concrete is a standard analysis procedure. However, the need to develop analysis tools for the actual ultimate capacity of columns is evident. Modern codes and standards are introducing the need to perform extreme event analysis. In previous studies, various models were implemented to assess the ultimate confined capacity of columns under concentric axial loads. On the other hand, the effect of confinement in case of the eccentric axial load and the corresponding bending moment are not investigated in such models. So it is demanded to relate the strength and ductility to the degree of confinement utilization in a new model. The more the eccentricity the less the confinement engaged till the effect of the confinement vanishes at pure bending. Accordingly, the ultimate confined strength and the maximum strain range between the fully confined values (at zero eccentricity) and the unconfined values (at infinite eccentricity) depending on the level of eccentricity. Radial loading with constant eccentricity is followed in the nonlinear moment of area concept that considers the finite layer procedure and the secant stiffness approach, to achieve equilibrium points up to failure. Three different comparisons are made to ensure the accuracy of the analysis. The first is to compare the unconfined analysis results with the well-known software (CSI-Section Builder). Secondly, the ultimate capacity of the confined section is compared with experimental data. Finally, the new eccentricity model is compared with the widely used Mander model, which is applicable to concentric columns, to examine the accuracy versus safety.

Energy derived from biomass has been proposed as a means to attain various environmental, economic and social goals. However, bioenergy production and utilization may also result in undesirable environmental and social consequences. This thesis investigates, from a life cycle perspective, environmental and cost implications of near-term bioenergy applications in the transportation and electricity sectors. Key tradeoffs related to the attributes of the systems are elucidated. Three case studies are conducted to consider the site-specific nature of bioenergy systems. The first two studies analyze the environmental and cost implications of displacing coal with biomass for electricity generation in Ontario’s coal generating stations. The third study examines implications of replacing gasoline with ethanol for use in California’s light-duty vehicle fleet to meet the State’s Low Carbon Fuel Standard (LCFS). The Ontario studies show that, relative to coal-based electricity generation, electricity generated from co-firing 10% (energy input) biomass with coal reduces greenhouse gas (GHG) emissions by 8% at a cost of $22/tonne CO2 equivalent for agricultural residues ($50/dry tonne residues delivered), and by 9% at a cost of $70-$84/tonne CO2 equivalent for wood pellets ($160/tonne pellets delivered), on the basis of one kWh of electricity generated (all costs are in U.S. dollars). One hundred percent pellet firing reduces GHG emissions by 91% compared to the coal system; however, the cost of GHG reduction is $99-$106/tonne CO2 equivalent. Displacing a portion of gasoline with ethanol is a feasible option to meet California’s LCFS, which calls for a 10% carbon intensity reduction of the State’s transportation fuels by 2020. Assuming current production methods and an indirect land use change effect of 30 g CO2/MJ, average Midwest corn ethanol is ruled out as an option to meet the LCFS. Using lignocellulosic ethanol to meet the LCFS is more attractive than using Brazilian sugarcane ethanol due to lower direct agricultural land requirement, dependence on imported energy, projected ethanol cost, required refuelling infrastructure modifications, and penetration of flexible fuel E85 vehicles. The thesis demonstrates that a life cycle approach is useful for analyzing and comparing different bioenergy applications, and providing insights into tradeoffs necessary in decision making for the development of next generation energy systems.

Recently, treatment plants have adopted biofiltration to compliment conventional treatment and ozonation. Previous literature has focused on passive applications of biofiltration. In this study, several pilot-scale biofiltration trains were designed in parallel to conventional treatment to investigate the impact of nutrient addition (nitrogen and phosphorus), use of hydrogen peroxide, aluminum sulphate (alum), and different filtration media (anthracite vs. granular activated carbon (GAC)) on biofiltration performance. Parameters measured included organic removal, reduction of DBP precursor, improvements in filter runtimes and ultrafiltration (UF) fouling control. Nutrient addition did not improve biofiltration performance. Supplementing hydrogen peroxide (<1 mg/L) decreased headloss, DBP formation potentials while adversely affecting UF fouling. In-line alum addition (<0.5 mg/L) improved biofilter’s ability to control fouling and DBP precursor without adversely impacting headloss. GAC provided superior performance when compared to anthracite. Conventional treatment provided higher DOC, and DBP precursor removal, as well as better UF fouling control compared to biofiltration.

In previous research, ranitidine has formed high yields of the disinfection by-product N-Nitrosodimethylamine (NDMA) upon chloramination. In the current research, bench-scale experiments were conducted to investigate the impact of cations (i.e., Ca2+, Mg2+, and Na+) on NDMA formation from ranitidine in three water matrices (Milli-Q® water, Lake Ontario water, and Otonabee River water) under practical chloramine disinfection conditions. In Milli-Q® water, excess cations did not change the yields of NDMA. NDMA formation kinetic profiles monitored in the lake and river water also indicated that elevating the cation concentrations did not affect the ultimate NDMA formation from ranitidine, but then did affect the observed rates of NDMA formation; the rates underwent an initial decrease and a subsequent increase as the cation concentrations were increased. The lowest reaction rates were observed in the lake and river water samples when they have a hardness level of 240 and 203 mg/L as CaCO3, respectively.