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- Genre: Masters Thesis
Description
Alkali activated mine tailing-slag blends and mine tailing-cement blends containing mine tailings as the major binder constituent are evaluated for their setting time behavior,
reactivity properties, flow characteristics, and compressive strengths. Liquid sodium
silicate and sodium hydroxide are used as the activator solution. The effects of varying
alkali oxide-to-powder ratio (n value) and silicon oxide-to-alkali oxide ratio (Ms value) is
explored. The reactivity of all blends prepared in this study is studied using an isothermal
calorimeter. Mine tailing-cement blends show a higher initial heat release peak than mine
tailing-slag blends, whereas their cumulative heat release is comparable for higher n values
of 0.050 to 0.100. Compressive strength tests and rheological studies were done for the
refined blends selected based on setting time criterion. Setting times and compressive
strengths are found to depend significantly on the activator parameters and binder
compositions, allowing fine-tuning of the mix proportion parameters based on the intended
end applications. The compressive strength of the selected mine tailing-slag blends and
mine tailing-cement blends are in the range of 7-40 MPa and 4-11 MPa, respectively.
Higher compressive strength is generally achieved at lower Ms and higher n values for mine
tailing-slag blends, while a higher Ms yields better compressive strength in the case of mine
tailing-cement blends. Rheological studies indicate a decrease in yield stress and viscosity
with increase in the replacement ratio, while a higher activator concentration increase both.
Oscillatory shear studies were used to evaluate the storage modulus and loss modulus of
the mine tailing binders. The paste is seen to exhibit a more elastic behavior at n values of
0.05 and 0.075, however the viscous behavior is seen to dominate at higher n value of 0.1
at similar replacement ratios and Ms value. A higher Ms value is also seen to increase the
onset point of the drop in both the storage and loss modulus of the pastes. The studied also
investigated the potential use of mine tailing blends for coating applications. The pastes
with higher alkalinity showed a lesser crack percentage, with a 10% slag replacement ratio
having a better performance compared to 20% and 30% slag replacement ratios. Overall,
the study showed that the activation parameters and mine tailings replacement level have
a significant influence on the properties of both mine tailing-slag binders and mine tailing-cement binders, thereby allowing selection of suitable mix design for the desired end
application, allowing a sustainable approach to dispose the mine tailings waste
ContributorsRamasamy Jeyaprakash, Rijul Kanth (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2023
Description
Virtual Reality (VR) has been used in the sphere of training and education in the construction field. Research has investigated the different applications of VR in construction-focused simulations to report its benefits and drawbacks in training and education. Although this is significant, they were not albeit explicitly studied through the lens of accreditation at undergraduate educational levels. The American Council for Construction Education (ACCE) established twenty Students Learning Outcomes (SLOs) that equip students with essential knowledge and industry-oriented technical and managerial skills that maintain quality education in undergraduate construction programs. This paper analyzes the trends in VR literature through reported benefits and unexplored learning outcomes of VR in construction training and education and investigates the ways by which these trends do or do not contribute to the learning experience by targeting the content areas associated with the ACCE’s SLOs. To accomplish this, the author reviewed 59 articles from 2014 to 2023 found through a keyword search for “Virtual” AND “Reality” AND “Construction” AND (“Training” OR “Simulation” OR “Education”) AND “Students”. The learning outcomes of the VR training reported in the 59 articles were mapped to their corresponding content areas from ACCE’s SLO(s). The results demonstrate the content areas of SLOs that were addressed in literature (1, 2, 3, 5, 6, 7, 8, 9, 10, 11, 13, 15, 16, 18, 19, and 20) and the SLOs that were not explored (4, 12, 14, and 17) due to lack of studies in some contexts. This study reveals trends and patterns of VR training, some of which exemplify benefits of addressing content areas of SLOs through virtual on-site immersion, manipulation of time, cost efficiency, and ethical measures, while others indicate unexplored learning outcomes of VR training in targeting content areas of SLOs that involve human interaction, complex quantitative calculations or require construction management tools, delivery method and stakeholders’ management, and risk management. While this research does not seek replacement of traditional trainings, it encourages consideration of VR training under the lens of ACCE’s accreditation. This research’s findings propose guidance to educational researchers on how VR training could address content areas from ACCE’s SLOs.
ContributorsElgamal, Sara (Author) / Ayer, Steven (Thesis advisor, Committee member) / Parrish, Kristen (Thesis advisor, Committee member) / Lamanna, Anthony (Committee member) / Arizona State University (Publisher)
Created2023
Description
Composites are replacing conventional materials in aerospace applications due to their light weight, non-corrosiveness, and high specific strength. This thesis aims to characterize the input data for IM7-8552 unidirectional composite to support MAT213, an orthotropic elasto-plastic damage material model and MAT_186, a mixed mode cohesive zone model used to model delamination. MAT_213 in conjunction with MAT_186 can be used to predict the behavior of composite under crush and impact loads including delamination. MAT_213 requires twelve sets of stress-strain curves, direction-dependent material constants, and flow rule coefficients as input. All the necessary inputs are obtained through the post-processing of a total of twelve distinct quasi-static and room temperature (QS-RT) experiments. MAT_186 is driven by a set of Mode I and Mode II fracture parameters and traction separation laws, a constitutive law that derives the relationship between stresses and relative displacements at integration points of cohesive elements. Obtaining cohesive law parameters experimentally is a tedious process as it requires close monitoring of the crack length during the test, which is a difficult task to achieve with accuracy even after using sophisticated equipment such as Digital Image Correlation (DIC). In this thesis, a numerical inverse analysis method to precisely predict these parameters by using finite element analysis with cohesive zone modeling and response surface methodology (RSM) is proposed. Three steps comprise RSM. The process in Step 1 involves calculating the root mean square error between the finite element and experimental load-displacement curves to produce the response surface. In step 2, the response surface is fitted with a second-order polynomial using the Levenberg-Marquardt algorithm. In step 3, an optimization problem is solved by minimizing the fitted function to find the optimum cohesive zone parameters. Finally, the obtained input for MAT_213 and MAT_186 material models is validated by performing a quasi-isotropic tension test simulation.
ContributorsRaihan, Mohammed (Author) / Rajan, Subramaniam (Thesis advisor) / Neithalath, Narayanan (Committee member) / Hoover, Christian (Committee member) / Yellavajjala, Ravi (Committee member) / Arizona State University (Publisher)
Created2023
Description
In a world where everything is drifting away from the intellectual into materialistic, and where everyone is rushing on the daily basis to provide their basic needs, everything is getting more expensive except the human life’s worth. Construction sites can be some of the clearer examples that show how the technical work, the communication skills, team work and management relate to one another. However, lately, the safety of the labor is neither being prioritized nor considered an important aspect to even consider at sites. Lebanon is, unfortunately, one of the countries where most construction sites are aimed to increase production and decrease cost as much as possible, on behalf of labor safety measurements. The high occurrence of such cases are the result of the lack of government control and accountability, as well as other reasonings.
Similar to the majority of countries, falls are the number one cause of fatalities and serious injuries on construction sites, especially building sites, where working on higher elevations is a must.
This thesis focuses on the topic of “Techniques and technologies for reducing fall hazards in use on Lebanese building construction projects”. The main goal behind it is to shed light on whether there are any traditional, technical or modern mechanisms used for safety on the Lebanese construction sites, however statistically few they might be. On the other hand, Casting the deficiencies, weaknesses and flaws are also discussed by indicating some solutions and pointers on possible methods to improve. Hence, this thesis would demonstrate the high importance of this topic and consequently help construction managers and workers realize that safety should become a priority on all sites in the country.
Researches done and interviews conducted show that fall hazards prevention/protection techniques are only implemented by large scale companies, and totally ignored by other companies which constitute the highest percentage of the active companies in the market now. Several causes are behind this and the result is one: More lives are put in danger due to lack of education, absence of audits and sanctions, and insufficient budgets
ContributorsMdawar, Hikmat (Author) / Gibson, George Edward (Thesis advisor) / El Asmar, Mounir (Committee member) / Sullivan, Kenneth (Committee member) / Arizona State University (Publisher)
Created2022
Description
Vegetative filter strips (VFS) are an effective methodology used for storm water management particularly for large urban parking lots. An optimization model for the design of vegetative filter strips that minimizes the amount of land required for stormwater management using the VFS is developed in this study. The resulting optimization model is based upon the kinematic wave equation for overland sheet flow along with equations defining the cumulative infiltration and infiltration rate.
In addition to the stormwater management function, Vegetative filter strips (VFS) are effective mechanisms for control of sediment flow and soil erosion from agricultural and urban lands. Erosion is a major problem associated with areas subjected to high runoffs or steep slopes across the globe. In order to effect economy in the design of grass filter strips as a mechanism for sediment control & stormwater management, an optimization model is required that minimizes the land requirements for the VFS. The optimization model presented in this study includes an intricate system of equations including the equations defining the sheet flow on the paved and grassed area combined with the equations defining the sediment transport over the vegetative filter strip using a non-linear programming optimization model. In this study, the optimization model has been applied using a sensitivity analysis of parameters such as different soil types, rainfall characteristics etc., performed to validate the model
In addition to the stormwater management function, Vegetative filter strips (VFS) are effective mechanisms for control of sediment flow and soil erosion from agricultural and urban lands. Erosion is a major problem associated with areas subjected to high runoffs or steep slopes across the globe. In order to effect economy in the design of grass filter strips as a mechanism for sediment control & stormwater management, an optimization model is required that minimizes the land requirements for the VFS. The optimization model presented in this study includes an intricate system of equations including the equations defining the sheet flow on the paved and grassed area combined with the equations defining the sediment transport over the vegetative filter strip using a non-linear programming optimization model. In this study, the optimization model has been applied using a sensitivity analysis of parameters such as different soil types, rainfall characteristics etc., performed to validate the model
ContributorsKhatavkar, Puneet N (Author) / Mays, Larry W. (Thesis advisor) / Fox, Peter (Committee member) / Wang, Zhihua (Committee member) / Mascaro, Giuseppe (Committee member) / Arizona State University (Publisher)
Created2015
Description
The need for sustainability in construction has encouraged scientists to develop novel environmentally friendly materials. The use of supplementary cementitious materials was one such initiative which aided in enhancing the fresh and hardened concrete properties. This thesis aims to explore the understanding of the early age rheological properties of such cementitious systems.
The first phase of the work investigates the influence of supplementary cementitious materials (SCM) in combination with ordinary Portland cement (OPC) on the rheological properties of fresh paste with and without the effect of superplasticizers. Yield stress, plastic viscosity and storage modulus are the rheological parameters which were evaluated for all the design mixtures to fundamentally understand the synergistic effects of the SCM. A time-dependent study was conducted on these blends to explore the structure formation at various time intervals which explains the effect of hydration in conjecture to its physical stiffening. The second phase focuses on the rheological characterization of novel iron powder based binder system.
The results of this work indicate that the rheological characteristics of cementitious suspensions are complex, and strongly dependent on several key parameters including: the solid loading, inter-particle forces, shape of the particle, particle size distribution of the particles, and rheological nature of the media in which the particles are suspended. Chemical composition and reactivity of the material play an important role in the time-dependent rheological study.
A stress plateau method is utilized for the determination of rheological properties of concentrated suspensions, as it better predicts the apparent yield stress and is shown to correlate well with other viscoelastic properties of the suspensions. Plastic viscosity is obtained by calculating the slope of the stress-strain rate curve of ramp down values of shear rates. In oscillatory stress measurements the plateau obtained within the linear visco-elastic region was considered to be the value for storage modulus.
Between the different types of fly ash, class F fly ash indicated a reduction in the rheological parameters as opposed to class C fly ash that is attributable to the enhanced ettringite formation in the latter. Use of superplasticizer led to a huge influence on yield stress and storage modulus of the paste due to the steric hindrance effect.
In the study of iron based binder systems, metakaolin had comparatively higher influence than fly ash on the rheology due to its tendency to agglomerate as opposed to the ball bearing effect observed in the latter. Iron increment above 60% resulted in a decrease in all the parameters of rheology discussed in this thesis. In the OPC-iron binder, the iron behaved as reinforcements yielding higher yield stress and plastic viscosity.
The first phase of the work investigates the influence of supplementary cementitious materials (SCM) in combination with ordinary Portland cement (OPC) on the rheological properties of fresh paste with and without the effect of superplasticizers. Yield stress, plastic viscosity and storage modulus are the rheological parameters which were evaluated for all the design mixtures to fundamentally understand the synergistic effects of the SCM. A time-dependent study was conducted on these blends to explore the structure formation at various time intervals which explains the effect of hydration in conjecture to its physical stiffening. The second phase focuses on the rheological characterization of novel iron powder based binder system.
The results of this work indicate that the rheological characteristics of cementitious suspensions are complex, and strongly dependent on several key parameters including: the solid loading, inter-particle forces, shape of the particle, particle size distribution of the particles, and rheological nature of the media in which the particles are suspended. Chemical composition and reactivity of the material play an important role in the time-dependent rheological study.
A stress plateau method is utilized for the determination of rheological properties of concentrated suspensions, as it better predicts the apparent yield stress and is shown to correlate well with other viscoelastic properties of the suspensions. Plastic viscosity is obtained by calculating the slope of the stress-strain rate curve of ramp down values of shear rates. In oscillatory stress measurements the plateau obtained within the linear visco-elastic region was considered to be the value for storage modulus.
Between the different types of fly ash, class F fly ash indicated a reduction in the rheological parameters as opposed to class C fly ash that is attributable to the enhanced ettringite formation in the latter. Use of superplasticizer led to a huge influence on yield stress and storage modulus of the paste due to the steric hindrance effect.
In the study of iron based binder systems, metakaolin had comparatively higher influence than fly ash on the rheology due to its tendency to agglomerate as opposed to the ball bearing effect observed in the latter. Iron increment above 60% resulted in a decrease in all the parameters of rheology discussed in this thesis. In the OPC-iron binder, the iron behaved as reinforcements yielding higher yield stress and plastic viscosity.
ContributorsInbasekaran, Aditya (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2016
Description
This study examines the outcomes of roundabouts in the State of Arizona. Two types of roundabouts are introduced in this study, single-lane roundabouts and double-lane roundabouts. A total of 17 roundabouts across Arizona were chosen upon several selection criteria and according to the availability of data for roundabouts in Arizona. Government officials and local cities’ personnel were involved in this work in order to achieve the most accurate results possible. This thesis focused mainly on the impact of roundabouts on the accident rates, accident severities, and any specific trends that could have been found. Scottsdale, Sedona, Phoenix, Prescott, and Cottonwood are the cities that were involved in this study. As an overall result, both types of roundabouts showed improvements in decreasing the severity of accidents. Single-lane roundabouts had the advantage of largely reducing the overall rate of accidents by 18%, while double-lane roundabouts increased the accident rate by 62%. Although the number of fatalities was very small, both types of roundabouts were able to stop all fatalities during the analysis periods used in this study. Damage rates increased by 2% and 60% for single-lane and double-lane roundabouts, respectively. All levels of injury severities dropped by 44% and 16% for single-lane and double-lane roundabouts, respectively. Education and awareness levels of the public still need to be improved in order for people to be able to drive within the roundabouts safely.
ContributorsSouliman, Beshoy (Author) / Mamlouk, Michael (Thesis advisor) / Kaloush, Kamil (Committee member) / Zhou, Xuesong (Committee member) / Arizona State University (Publisher)
Created2016
Description
Crack sealing is considered one of the least expensive and cost effective maintenance activity used on pavements. In some cases, crack sealing suffers from premature failure due to various material, environmental, and construction issues. A survey that was conducted as part of this study showed that the highest sealant failure year occurring on the second year. Therefore, any attempt to increase the sealants’ service life by addressing and improving the sealant properties and their resistance to failure will benefit the effectiveness of this treatment.
The goal behind this study was to evaluate the potential improvement in performance of hot applied sealant material commonly used in the Phoenix area, and evaluate the performance of using a neat binder modified with crumb rubber (at 5 and 10% by weight of binder) as a low-grade sealing material. The sealants was also modified with crumb rubber at 2.5, and 5% by weight fo the sealant. Six ASTM tests were conducted for the comparison. These tests are the Standard Penetration Test (SPT) and Cone Penetration Test (CPT), Resilience Test, Softening Point Test, Brookfield Viscometer Test, and Dynamic Shear Rheometer (DSR).
The results showed that adding only crumb rubber to a neat binder for its potential use as a crack sealant is inadequate to meet the specifications expected for sealants. However, the modification of the sealant with crumb rubber showed some benefits, such as increased elasticity and decreased temperature susceptibility. A crumb rubber content of 2.5% by weight of the sealant was recommended.
ContributorsThwaini, Talal (Author) / Kaloush, Kamil (Thesis advisor) / Mamlouk, Michael S. (Committee member) / Underwood, Benjamin (Committee member) / Arizona State University (Publisher)
Created2016
Description
The California Department of Transportation (Caltrans) is required to comply
with the National Pollution Discharge Elimination (NPDES) permit, which includes the infiltration of stormwater runoff from highways and implementing soil based best managements practices (BMPs). Stormwater BMPs are in place to prevent pollution in stormwater runoff as well as to facilitate the stormwater discharge from the road. Per this new permit, Caltrans is to install soil based BMPs that can absorb the 85th percentile of a 24-hour stormwater event. In order to absorb the stormwater runoff, the area used is the Clear Recovery Zone (CRZ), which are the road embankments/slopes located adjacent to the roadside. The CRZ must be traversable and recoverable in order to meet roadside traffic safety standards. A major concern for Caltrans is the uncertainty on how these BMPs will affect the safety of a vehicle, if a vehicle were to interact with the soft soils.
In order to provide an insight on the effects of the BMPs, the modeling and simulation of vehicle dynamics under certain interactions between the roadside, soil, and vehicle was completed. The research used computer simulations to quantify the probability of rollover accidents under several different vehicle, driving and ground conditions. The vehicles traversing typical archetype roadsides on soft soil are simulated using MsMac3D software. It was important to model the properties of the vehicle, roadside, mechanical and hydraulic properties of soils realistically in order to obtain an accurate representation of a real-world vehicle and soil interaction.
The outcome was a library of simulations that provided quantifiable data on the effect that soft soils have on the safety and rollover potential of a vehicle traversing the CRZ.
with the National Pollution Discharge Elimination (NPDES) permit, which includes the infiltration of stormwater runoff from highways and implementing soil based best managements practices (BMPs). Stormwater BMPs are in place to prevent pollution in stormwater runoff as well as to facilitate the stormwater discharge from the road. Per this new permit, Caltrans is to install soil based BMPs that can absorb the 85th percentile of a 24-hour stormwater event. In order to absorb the stormwater runoff, the area used is the Clear Recovery Zone (CRZ), which are the road embankments/slopes located adjacent to the roadside. The CRZ must be traversable and recoverable in order to meet roadside traffic safety standards. A major concern for Caltrans is the uncertainty on how these BMPs will affect the safety of a vehicle, if a vehicle were to interact with the soft soils.
In order to provide an insight on the effects of the BMPs, the modeling and simulation of vehicle dynamics under certain interactions between the roadside, soil, and vehicle was completed. The research used computer simulations to quantify the probability of rollover accidents under several different vehicle, driving and ground conditions. The vehicles traversing typical archetype roadsides on soft soil are simulated using MsMac3D software. It was important to model the properties of the vehicle, roadside, mechanical and hydraulic properties of soils realistically in order to obtain an accurate representation of a real-world vehicle and soil interaction.
The outcome was a library of simulations that provided quantifiable data on the effect that soft soils have on the safety and rollover potential of a vehicle traversing the CRZ.
ContributorsPonce, Esai Jonathon (Author) / Neithalath, Narayanan (Thesis advisor) / Underwood, Shane (Committee member) / Khodadaditirkolaei, Hamed (Committee member) / Arizona State University (Publisher)
Created2019
Description
This study evaluates the use of plant-extracted silica solution as a bio-based grout material for improvement of granular soils. Although silicate grout is a very well-established and popular technique in the ground improvement market, efforts have been initiated to replace chemically-synthesized silicate grout with plant-extracted silica grout. This initiative will increase the level of sustainability and consequently improve the existing market acceptability. The silica-rich plant source used for extraction was rice husk, which is an abundantly produced agricultural waste. The extraction method includes acid-leaching, temperature-controlled rice husk ash production and the preparation of an aqueous sodium silicate solution from the ash through an alkaline leachate method. Silica ash was in amorphous form containing 95% of silica content which is suitable for soil treatment. Gelation time was controlled in the absence and presence of sand under different pH values. Bio-based silica grouting showed an improvement of the shear strength of the soil as well as the hydraulic conductivity reduction.
ContributorsSayed Mostafa, Ahmad (Author) / Zapata, Claudia (Thesis advisor) / Khodadaditirkolaei, Hamed (Thesis advisor) / Kavazanjian, Edward (Committee member) / Arizona State University (Publisher)
Created2019