Effects of Aggregate Packing Density on the Mechanical Properties of Ultra-High Performance Concrete

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Description
Cement is a remarkable construction material that allows for the formation of complex geometric forms while still providing adequate strength properties to be used as a structural material. This research focuses on Ultra-High Performance Concrete (UHPC) which is a specialized

Cement is a remarkable construction material that allows for the formation of complex geometric forms while still providing adequate strength properties to be used as a structural material. This research focuses on Ultra-High Performance Concrete (UHPC) which is a specialized class of cementitious material that exhibits exceptional strength and durability properties when compared to standard concrete. UHPC achieves these properties through a combination of high cement content, high particle packing density, low water-to-cement ratio, and the additional of special admixtures such as superplasticizer. These components all serve the purpose of increasing UHPC strength and mechanical properties by helping achieve much high material densities than other forms of concrete.
In this study, aggregate material evaluation and testing was conducted for use in the mix design of the UHPC mixes that were carried out and tested. Each mix employed the same general UHPC mixture design with the only difference being the aggregate proportions of #4, #8, and #10 nominal size aggregates. The purpose of using a UHPC mix design that was independent of aggregate proportioning was to evaluate the effects of varying aggregate particle packing densities. Increased particle packing density of UHPC provide improved mechanical performance by decreasing the distance between particle within cured UHPC, thereby producing significant increases in compressive strength, tensile strength, durability, and service life of UHPC when compared to standard concrete. For this study, particle packing densities of 0.509, 0.521, 0.540, and 0.552 were employed and evaluated on the basis of compressive strength and tensile strength to determine the optimum UHPC mix design.
Date Created
2019-05

The effect of UV-treated plastic reinforcement in cement-based materials

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Description
The preceding paper analyzes the effects of UV radiation in plastic reinforcement and its effects on the fracture properties of cement-based materials. Three point tests were performed on notched beams, which called for the consideration of the Type II Size

The preceding paper analyzes the effects of UV radiation in plastic reinforcement and its effects on the fracture properties of cement-based materials. Three point tests were performed on notched beams, which called for the consideration of the Type II Size Effect. A comparison of the ductility of beams with and without polyethylene plastic powder reinforcement was done through the calculation of the fracture parameters Gf and cf, which represent the initial fracture energy and the characteristic length respectively. Although there was an observed increase in ductile behavior and properties in beams with polyethylene reinforcement, there did not seem to be a significant effect caused by the UV radiation. The hydrophilicity of the polyethylene powder was successfully increased through UV radiation and validated through water retention tests, which showed that the UV-treated polyethylene was retaining more water than the non-treated polyethylene, yet there was no extra increase in ductility of the cement beams compared to using non-treated polyethylene. The Type II Size Effect analysis was performed and compared to the stress analysis results of the experiment. For future research, it is recommended that a higher volume of polyethylene per 1000 grams of cement powder be used, as well as increasing the strength of the UV chamber to achieve a larger increase in the hydrophilicity of the polyethylene. Also, perhaps using more precise equipment to cut the notches in the beams would be helpful in ensuring that all specimens are identical and there is no error in notch depth caused by inaccurate use of the hacksaw or radial saw. Further experiments will be conducted.
Date Created
2019-05
Agent

Ahwatukee Foothills Village Final Residential Structural Report

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Description
This project report contains the design of a low-cost structural model of a residential structure in the City of Phoenix, AZ. The structural unit will be part of a residential area in Ahwatukee Foothills Village located just south of South

This project report contains the design of a low-cost structural model of a residential structure in the City of Phoenix, AZ. The structural unit will be part of a residential area in Ahwatukee Foothills Village located just south of South Mountain. The residential structure is 3600 square feet and consists of three bedrooms (including the master bedroom), two bathrooms (including the master bathroom), a 2-car garage, laundry room, kitchen, dining room, and a living room. There are two elevation options (A & B) for the roof framing plan. Elevation A includes a straight forward truss package consisting of two truss designs with no hip or girder trusses. Elevation B includes a more complex truss package which includes girder trusses, hip trusses, and corner jacks. Within both elevations, the trusses run perpendicular to the ridge of the structure as displayed in the Architectural Floor Plan (see Figure 4) with the exception of the hip trusses and corner jacks in Elevation B.

The design objective is to meet all safety specifications while minimizing the total cost of members and member connections. The design also aims to streamline the construction time and resources by using standard member cross section dimensions. This residential building report is carried out in accordance with the City of Phoenix standards and follows the ASCE7-10 code for the dead and live load combinations and wind pressures. This report also references the National Design Specifications (NDS) 2005 for the column design. HT Consulting Group is excited to create a safe and sustainable development for the residents within Ahwatukee Foothills Village.
Date Created
2019-05
Agent

Supplemental Multimedia Content to Support Effective Engineering Education

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Description
Educational institutions are in a unique position to take advantage of computers and software in new, innovative ways. The Mechanics Project at Arizona State University has done an exceptional job integrating many new ways of engaging students and providing resources

Educational institutions are in a unique position to take advantage of computers and software in new, innovative ways. The Mechanics Project at Arizona State University has done an exceptional job integrating many new ways of engaging students and providing resources that can help them learn course material in a way that they can understand. However, there is still very little research on how to best compose multimedia content for student use.

This project aims to determine what students struggle with in these courses and develop multimedia content to support their education in Dynamics specifically.
Date Created
2019-05

Tendencies of United States Bicycle Commuters: An Analysis of the 2017 National Household Travel Survey

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Description
Approximately 1% of the total working population within the United States bikes as their primary mode of commute. Due to recent increased in bicycle facilities as well as a focus on alternative modes of transport, understanding the motivations and type

Approximately 1% of the total working population within the United States bikes as their primary mode of commute. Due to recent increased in bicycle facilities as well as a focus on alternative modes of transport, understanding the motivations and type of people who bike to work is important in order to encourage new users.
In this project, a literature review was completed as well as data analysis of the National Household Travel Survey (NHTS) in order to find specific populations to target. Using these target populations, it is suggested that advertising and workplace encouragement occur to persuade more people to bike to work. Through data analysis it was found that the most impactful variables were the region of the country, gender, population density, and commute distance. Bicycle commuters statistically had fewer vehicles in their households and drove less miles annually.
There were five main target groups found through this analysis; people who bike for other reasons besides work and live in a city with more than 4,000 people per square mile, young professionals between 19-39, women in regions with separated bicycle facilities, those with low vehicle availability, and environmentally conscious individuals. Working to target these groups through advertising campaigns to encourage new users, as well as increasing and improving bicycle facilities, will help create more new bicyclists.
Date Created
2019-05
Agent

AGE, GENDER, AND TRAVEL SOCIALIZATION EFFECTS ON CHILDHOOD AND ADULTHOOD TRANSIT USE

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Description
The objective of this research paper is to analyze and determine the relationships between childhood and adulthood transit behavior. The study investigates gender differences for each generation regarding childhood transit experiences. Childhood travel socialization was studied to understand its effects

The objective of this research paper is to analyze and determine the relationships between childhood and adulthood transit behavior. The study investigates gender differences for each generation regarding childhood transit experiences. Childhood travel socialization was studied to understand its effects on childhood transit experience and perception. Lastly, childhood transit experience and perception were analyzed to determine their effect on adult transit usage. The variables the study analyzed were childhood peer impression of public transit, parental opinion of the safety of public transit, and the respondents’ childhood public transit experience. These variables were investigated to determine if they had an effect on adult use of public transit. The survey Transit Center’s Who’s On Board: 2014 Mobility Attitudes Survey (WOBMAS) was used to perform these analyses. The results showed that gender equality appears to be increasing in younger generations with respect to their ability to travel alone on public transit. In addition, men were more likely to travel by themselves on public transit when compared to women. There is a direct correlation between childhood travel socialization and childhood transit experience and opinion. However, there appears to be no correlation between childhood travel socialization and a child’s likeliness to travel on public transit alone. Childhood travel socialization had a counterintuitive effect on adult transit usage. On the contrary, it appears that childhood experience is significantly linked to adult transit usage. The data suggests that the earlier a person travels on public transit alone, the more likely they are to ride it as an adult.
Date Created
2019-05
Agent

A Comparison of the Sustainability of Wood and Bamboo as a Structural Material

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Description
With a rapidly decreasing amount of resources for construction, wood and bamboo have been suggested as renewable materials for increased use in the future to attain sustainability. Through a literature review, bamboo and wood growth, manufacturing and structural attributes were

With a rapidly decreasing amount of resources for construction, wood and bamboo have been suggested as renewable materials for increased use in the future to attain sustainability. Through a literature review, bamboo and wood growth, manufacturing and structural attributes were compared and then scored in a weighted matrix to determine the option that shows the higher rate of sustainability. In regards to the growth phase, which includes water usage, land usage, growth time, bamboo and wood showed similar characteristics overall, with wood scoring 1.11% higher than bamboo. Manufacturing, which captures the extraction and milling processes, is experiencing use of wood at levels four times those of bamboo, as bamboo production has not reached the efficiency of wood within the United States. Structural use proved to display bamboo’s power, as it scored 30% higher than wood. Overall, bamboo received a score 15% greater than that of wood, identifying this fast growing plant as the comparatively more sustainable construction material.
Date Created
2019-05

Effective Stabilization of Expansive Soils

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Description
Expansive soils in the United States cause extensive damage to roadways, buildings, and various structures. There are several treatment or methods of mitigation for these expansive soils. These treatments can be physical or chemical treatments that serve to provide more

Expansive soils in the United States cause extensive damage to roadways, buildings, and various structures. There are several treatment or methods of mitigation for these expansive soils. These treatments can be physical or chemical treatments that serve to provide more suitable building qualities for foundations and roadways alike. The main issue with expansive soils, is the volumetric variations, which are known as swelling and consolidation. These behaviors of the soil are usually stabilized through the use of lime solution, Portland Cement Concrete, and a newer technology in chemical treatments, sodium silicate solutions. Although the various chemical treatments show benefits in certain areas, the most beneficial method for stabilization comes from the combination of the chemical treatments. Lime and Portland cement concrete are the most effective in terms of increasing compressive strength and reduction of swell potential. However, with the introduction of silicate into either treatment, the efficacy of the treatments increases by a large amount lending itself more as an additive for the former processes. Sodium silicate solution does not lend itself to effectively increase the compressive strength of expansive soils. The sodium silicate solution treatment needs extensive research and development to further improve the process. A proposed experiment plan has been recommended to develop trends of pH and temperature and its influence on the effectiveness of the treatment. Nonetheless, due to the high energy consumption of the other processes, sodium silicate solution may be a proper step in decreases the carbon footprint, that is currently being created by the synthesis of Portland Cement Concrete and lime.
Date Created
2018-12
Agent

Life Cycle Sustainability Analysis (LSCA) of Enzyme-Induced Carbonate Precipitate (EICP)

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Description
Current practice and a new technology for mitigating fugitive dust on construction sites are compared on the basis of economic, environmental and social impacts for this assessment. Fugitive dust can have serious health impacts, such as repertory illnesses and valley

Current practice and a new technology for mitigating fugitive dust on construction sites are compared on the basis of economic, environmental and social impacts for this assessment. Fugitive dust can have serious health impacts, such as repertory illnesses and valley fever, on affected persons and is regulated by the Environmental Protection Agency and enforced by state and local agencies. Current practice consists of either relatively continuous application of potable water, a valuable resource, or application of expensive polymers, however, water application is considered the best available technology (BAT). The new technology, developed by the Center of Bio-medicated and Bio-inspired Geotechnics at Arizona State University, consists of application of Enzyme-Induced Carbonate Precipitate (EICP) to create an erosion-resistant crust. This crust is considered a "one and done" solution, until it is disturbed, however will last longer and stay more effective than quickly evaporating water. Future work will need to include how much disturbance is required to disturb the crust until ineffective towards mitigating fugitive dust. Results of the comparison show that a single EICP treatment produces 37 times less pollutants, uses 41 times less water and is 1.14 times cheaper than using water treatment to mitigate fugitive dust on a 7 acre site for 2 weeks (14 days). 14 days is the threshold at where EICP treatment becomes less expensive than water application for the purpose of mitigating fugitive dust. The EICP treatment benefits include lowering global warming inducing emissions, providing better air quality, becoming more cost effective, staying constantly effective to mitigate fugitive dust, and saving potable water.
Date Created
2018-12
Agent

Effect of Drought Policies on Los Angeles Water Demand

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Description
From 2007 to 2017, the state of California experienced two major droughts that required significant governmental action to decrease urban water demand. The purpose of this project is to isolate and explore the effects of these policy changes on water

From 2007 to 2017, the state of California experienced two major droughts that required significant governmental action to decrease urban water demand. The purpose of this project is to isolate and explore the effects of these policy changes on water use during and after these droughts, and to see how these policies interact with hydroclimatic variability. As explanatory variables in multiple linear regression (MLR) models, water use policies were found to be significant at both the zip code and city levels. Policies that specifically target behavioral changes were significant mathematical drivers of water use in city-level models. Policy data was aggregated into a timeline and coded based on categories including user type, whether the policy was voluntary or mandatory, the targeted water use type, and whether the change in question concerns active or passive conservation. The analyzed policies include but are not limited to state drought declarations, regulatory municipal ordinances, and incentive programs for household appliances. Spatial averages of available hydroclimatic data have been computed and validated using inverse distance weighting methods. The data was aggregated at the zip code level to be comparable to the available water use data for use in MLR models. Factors already known to affect water use, such as temperature, precipitation, income, and water stress, were brought into the MLR models as explanatory variables. After controlling for these factors, the timeline policies were brought into the model as coded variables to test their effect on water demand during the years 2000-2017. Clearly identifying which policy traits are effective will inform future policymaking in cities aiming to conserve water. The findings suggest that drought-related policies impact per capita urban water use. The results of the city level MLR models indicate that implementation of mandatory policies that target water use behaviors effectively reduce water use. Temperature, income, unemployment, and the WaSSI were also observed to be mathematical drivers of water use. Interaction effects between policies and the WaSSI were statistically significant at both model scales.
Date Created
2018-12