Engineering Commons^™

The Former Asarco Demolition Fallout, A Post Study On Lead Soil Concentrations And Environmental Agents Of Redistribution In El Paso, Texas, Stephanie A. Robinson

Open Access Theses & Dissertations

The former El Paso ASARCO Smelting and Refining Co. operated between 1877 and 1999, the pyrometallurgic activity was estimated to have discharged excess of a 1,000 tons of lead (Pb) into the atmosphere from 1969-71. It was estimated 96 tons of (Pb) were emitted on an annual basis from the standing ore and fluid beds. The Environmental Protection Agency (EPA) determined that lead (Pb) is the heavy metal of the highest concentration within the vicinity of the smelter. After the smelter production ceased, flash flooding common to the southwest, such as the 2006 historic flood, increased transportation of superficial contaminants …

Studies Of Air Pollutants And Their Impact On Respiratory And Cardiovascular Diseases In The El Paso Del Norte Region With Emphasis On Mobile Emissions, Juan Gustavo Arias Ugarte

Open Access Theses & Dissertations

Air pollution may cause different diseases, such as cardiovascular and lung diseases. Traffic is a major source of mobile emissions causing air pollution. Exhaust emissions from mobile sources (Emissions of Carbon Monoxide, Nitrogen Oxides and Hydrocarbons) and Non-exhaust (Brake and Tire) are complex mixtures of gases and dust, including a large number of ultrafine particles, especially in areas with high traffic density. Recent studies have shown high rates of morbidity and mortality in people exposed to these types of emissions because the fine and ultrafine particles can be transported from the respiratory airways to the organs, thus contributing to increase …

Integrating Manufacturing Geometric Imperfections In The Inelastic Behavior Modeling Of Joints Used In Three-Dimensional Structures, Alfonso Andres Garcia

Open Access Theses & Dissertations

Three-dimensional structures follow design practices on the common assumption that joints are either rigid, or pinned. However, the non-linear behavior of engagement of the joints is required to be incorporated into the analysis. This research is intended to incorporate manufacturing geometric imperfections into the mechanical analysis of reticulated space structures jointing systems. Imperfect jointing systems deviate from the as-designed models in such a way that the location of the connecting surfaces does not follow the designed interaction path between the component elements. However, current structural analysis methodologies do not consider manufacturing geometric imperfections and often fail to consider the stresses …

Asset Management Support Tools To Assist Agencies In The Development Of Guardrail Preservation Programs, Sandra N. Gutierrez

Open Access Theses & Dissertations

The purpose of this Thesis is to develop a Guardrail Asset Management Framework and a Condition-Based Model to assist agencies in the development of guardrail preservation programs. Both of the guardrail asset management tools can be incorporated into an existing asset management program to assist agencies in utilizing guardrail inventory to forecast key asset management parameters such as the guardrail condition, funds necessary for maintenance and repair, backlogged funding, guardrail system value, and the guardrail sustainability ratio. Each of these parameters is described and determined for a case study involving six scenarios modeling funding and maintenance constraints that can arise …

Quantification Of The Impact Of Asphalt Pavement Conditions On Gas Emissions, Oscar Daniel Gonzalez Calvo

Open Access Theses & Dissertations

This research develops a methodology to quantify the impact of asphalt pavement conditions on vehicular gas emissions based on statistical analysis to correlate the relationship between asphalt pavement roughness and gas emissions. ANOVA (Analysis of Variance) hypoThesis tests were used to compare the factors affecting the results. The roughness was measured with the International Roughness Index (IRI) using a profilometer provided by TxDOT and the gas emissions were measured with a Portable Emission Measurement System (PEMS).

This research also presents the savings obtained in gas emissions using different maintenance and rehabilitation strategies established by TxDOT (Preventive Maintenance, Light Rehabilitation, Medium …

Modeling The Effects Of Manufacturing Geometric Imperfections In The Buckling Analysis Of Three-Dimensional Structures, Juan Carlos Salcido

Open Access Theses & Dissertations

Reticulated three-dimensional structures follow design practices based on the common assumption that joints are either rigid, or pinned. However, the actual non-linear behavior of the jointing system interaction is required to be incorporated into the analysis of the structure to accurately predict its buckling stability. Besides, currently, there is a concern on how manufacturing imperfections of these jointing systems affect the global behavior of three-dimensional structures. This Dissertation incorporates and captures the effect that manufacturing geometric imperfections in the fir-tree jointing system produce in the non-linear buckling behavior of three-dimensional structures.

To understand the effect that initial manufacturing imperfections of …

Impact Of Reclaimed Asphalt Pavement And Recycled Asphalt Shingles On Laboratory And Field Performance Of Texas Asphalt Concrete Pavements, Berenice Salaices Gomez

Open Access Theses & Dissertations

The use of recycled materials in Asphalt Concrete (AC) mixes is highly promoted in the transportation industry. Recycled materials minimize the use of virgin materials, reduce the consumption of resources, and cut costs for new construction or rehabilitation projects. The incorporation of Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingles (RAS) in the AC mixture is promoted as long as equal or improved performance is achieved. The Texas Department of Transportation (TxDOT) is currently placing asphaltic concrete (AC) mixes that are lasting less than their expected performance life when recycled materials are used.

The objective of this Thesis is to …

An In-Depth Evaluation Of Shear Box Compactor For Hot Mix Asphalt, Isaac Jaime Aguilar

Open Access Theses & Dissertations

Asphalt pavement is present in each roadway in every town or city today and it is paramount to properly design pavement to efficiently reduce its deterioration. To determine how pavement fails, pavement specimens prepared in the laboratory undergo performance tests which demonstrate the pavements strength and durability. Performance tests require little variability from compacted specimens, and it is critical to have a compaction method which is similar to field compaction and produces homogenous specimens. Currently, laboratory performance test specimens are obtained with the Superpave Gyratory Compactor (SGC). That device has few similarities to the rolling compactor, which performs the actual …

Evaluation Of Mechanical Parameters Of Contaminated Road Base And Railway Ballast, Prajwol Tamrakar

Open Access Theses & Dissertations

This Dissertation comprises two topics in the area of transportation geotechnics that focus on the evaluation of stiffness parameters of contaminated road base and railway ballast. The abstracts of these two studies are provided in the following two paragraphs.

The performance of a flexible pavement depends on the mechanical characteristics of its unbound granular base layer. The mechanical characteristics such as stiffness and deformation resistance depend on many factors such as the material gradation, fines content, moisture content, physical properties of coarse aggregate and more. The base materials are often contaminated by the excessive fines that is caused by improper …

Cost-Effective Recovery Of Concentrated Cooling Tower Blowdown Using The Cerro Process, Lindsey Nicole Larson

Open Access Theses & Dissertations

The Concentrate Enhanced Recovery Reverse Osmosis (CERRO) process is a seawater-RO unit that can cost-effectively achieve extremely high recoveries from water high in silica, carbonate and sulfate concentrations. This relatively new technology takes advantage of the induction time of potential foulants to recover more water than what is normally achievable with a conventional desalination system. The scope of the project was to evaluate the efficiency of the CERRO process as a pilot study using cooling tower blowdown which varied in water quality parameters daily. It was found that the CERRO pilot could successfully achieve 85% recovery, and the main limitation …