Engineering Commons^™

High Strain Rate Analysis Of 3d Printed Concrete As Compared To Conventionally Cast Concrete, Weston Mcleod Thomsen

Masters Theses

"3D Printed Concrete (3DPC) is a developing method of construction that has advantages over conventional methods, including formwork reduction, complex geometry, and expedited construction. This technology has potential benefits for the military when considering the austere environments that forward operating bases are built in. This study aims to assess 3DPC applications in protective structures that protect critical assets from explosive blasts. These protective structures experience a high-strain rate response during blast loading of the structure, and the effects of this have yet to be analyzed in the literature concerning 3DPC. With the lack of prior research, the focus here will …

Effect Of Radiation On Bond Behavior Between Concrete And Steel Bar: Development Of Experimental Protocol, Mohammed Abdelrahman

Masters Theses

There is a need to assess the effect of radiation on the behavior of bond strength between steel reinforcement and concrete. However, there is geometrical constraints in the cylindrical capsule which limit the size of concrete samples. Thus, developing a protocol to produce pullout sample and a test setup is needed.

A protocol for fabricating high-precision concrete samples with embedded \#2 steel bar has been developed based on the results of an experimental program. A pullout system has also been developed to investigate the bond activity of concrete and steel. This research looks at two different aggregate sizes 3/8 inch …

Projectile Generator Design For Underground Coal Mine Seal Testing, Ethan Allan Steward

Masters Theses

"Underground coal mines have several dangers, one of the most hazardous of which is the possibility of an explosion caused by the ignition of methane gas. To reduce ventilation costs, coal mines have the option to close off abandoned areas that are no longer active with structural seals to keep an explosion from propagating into working areas of the mine. Though seals have been designed to resist the overpressure, none have been evaluated for their resistance to the impact of heavy objects. Underground explosions produce high velocity gasses that, traveling through mine openings, may propel objects in the mine at …

Performance Of Concrete Tunnel Systems Subject To Fault Displacement, Michael Morano

Masters Theses

A Finite Element Analysis (FEA) investigation of concrete tunnel systems traversing seismic faults is carried out to determine how to effectively mitigate the stresses induced in the liner when subject to fault displacement. A parametric study of various fault parameters, both in the damage zone and competent rock, is carried out to determine the site conditions which induce the most stress on the tunnel liner system. Results indicate that friction angle, cohesion, and elastic modulus of fault zones have varying effects on the stresses induced on the liner. The width of damage zone and expected displacements are also investigated and …

Development Of Test Methods For Characterizing Extrudability Of Cement-Based Materials For Use In 3d Printing, Jonathan Thomas Kuchem

Masters Theses

"3D printing is the process of creating three-dimensional objects using an automated additive manufacturing process. The 3D printing process has been used with materials such as metals and polymers, but application with cement based materials for the construction industry has yet to be developed. In this research, two main problems were investigated for printing cement based composite materials: extrudability and tensile reinforcement. Fiber-reinforced concrete (FRC) was studied as an internal reinforcing system to increase tensile/flexural strength. First, FRC was studied to investigate mechanical properties and use of fibers from waste tires as an environmentally friendly option. A reference mixture with …

Projectile Impact Effects On A 50 Psi Plug Type Coal Mine Seal, Bruce Albert Von Niederhäusern

Masters Theses

"The current lack of projectile damage criteria for mine seals is assessed to determine if criteria should be developed. Impact experiments were performed on a full-scale 50 psi mine seal to determine failure modes, dynamic stress state, and assess risk to existing operational mine seals. Test projectiles were selected from common underground coal mine items propelled by means of a black powder projectile generator. Projectile velocities attained in testing ranged from approximately 100 to 650 ft/s (30 to 200 m/s). Dynamic strain was measured on the non-impact face to derive the state of stress and estimate failure criteria. Penetration models …

Numerical And Experimental Analysis Of Local Buckling Of Axially Loaded Steel Tubes Confined By Concrete And Frp, Nicholas Colbert

Masters Theses

“The hollow core Fiber-Reinforced-Polymer (FRP) concrete circular-steel (HC-FCS) column consists of an outer circular fiber reinforced polymer (FRP) tube, an inner thin-walled circular steel tube concentrically aligned, and a concrete shell between them. Research has been performed on the performance of the member as a whole, but to date, there has been no investigation into the behavior of the steel tube confined in the column. 17 small-scale columns were tested under axisymmetric axial compressions applied directly to the steel tube under displacement control. The conducted parametric study examined the effects of diameter-to-thickness (D/t) ratio, concrete unconfined compressive strength, FRP thickness, …

Development Of High Early-Strength Concrete For Accelerated Bridge Construction Closure Pour Connections, Stephanie Castine

Masters Theses

Accelerated bridge construction (ABC) has become a popular alternative to using traditional construction techniques in new bridge construction and existing bridge deck replacement because of the reduction of time spent in field activities. A key feature of bridges built using ABC techniques is the extensive use of prefabricated components. Prefabricated components are joined in the field using small volume closure pours involving high performance materials (steel and concrete) to ensure adequate transfer of forces between components. To date, the materials developed for closure pours have been based on proprietary components, so a need has arisen for development of mixes that …

Bridge Deck Research At The University Of Tennessee: A Summary Thesis, Lindsey Brooke Phelps

Masters Theses

Currently, there has been no compilation of all the research the University of Tennessee has completed on chloride ion penetration in concrete bridge decks. The following thesis is a brief summary of the work that has been completed under Dr. Edwin Burdette’s direction over the last six years along with some additional literature review. The testing consisted of Surface Resistivity and Rapid Chloride Ion Penetration testing. This testing showed that there is, in fact a correlation between the two test methods, though SR testing is much easier to conduct. Considerable testing was completed on bridge decks throughout the state of …

Bonded Anchors In Concrete Under Sustained Loading, Douglas Droesch

Masters Theses

Post installed anchors come in either mechanical anchors that develop their strength purely through mechanical interlock with the base concrete, or bonded anchors that develop their strength by bonding anchor rod to the base concrete. Bonded anchors are either grouted, typically cementitious material, or adhesive, typically a chemical material. This thesis presents a current literature review of post-installed bonded anchors, preliminary testing of adhesive bonded anchors, and details of short term and long term test setups for future testing. The purpose of this thesis was to develop the test setups that will be used for future testing on anchors.

Design And Construction Of A Full-Scale Lateral Impact Testing Facility, Cody Aaron Mitchell

Masters Theses

The goal of this work is to design and construct a full scale lateral impact testing facility that is capable of recreating the damage that would be created by an overheight vehicle collision. This was accomplished by impacting a test specimen with an 8000 lbs. impact cart. The impact cart is raised on an elevated track and allowed to roll down the track with a change in height of 10 ft. This change in height is what provides the impact force necessary to recreate an overheight vehicle collision. The track is constructed out of wood and is designed to withstand …

Advanced Sustainable Concrete Materials For Infrastructure Applications, Kaylea Ann Smith

Masters Theses

"This study was performed to examine the effects of cement replaced by high volumes of Class C fly-ash on durability characteristics of concrete up to 120 days. Specifically, this study investigates possibility of amending American Society for Testing and Materials (ASTM) to allow High Volume Fly-ash (HVFA) concrete to cure until later ages prior to testing instead of 28 days. Five mix designs were compared with varying fly-ash percentages from 0 to 70% (by total cementitious mass). No other additives were present in any of the five mix designs. Water-to-cementitious ratio (w/cm) and total cementitious material remained constant as 0.40 …

Effects Of High Volume Fly Ash And Powder Activators On Plastic And Hardened Concrete Properties, Drew Alexander Davis

Masters Theses

This study was performed to examine the effects of high volumes of Class C fly ash modified by powder activators upon the plastic and hardened properties of concrete. In a companion study, five Missouri area cements and five Class C fly ashes were examined for incompatibilities, with the most and least reactive combinations being scaled up to full scale concrete testing. Two baseline concrete mixtures were examined, the only difference in mixtures being the sources of portland cement and fly ash. Fly ash replacement was examined at 50% and 70% replacement (by total cementitious mass). Three powder activators were used …

Comparison Of Two Methods For The Assessment Of Chloride Ion Penetration In Concrete: A Field Study, Eric William Ryan

Masters Theses

The currently accepted method for assessing the resistance of concrete to penetration of chloride ions is ASTM C1202, commonly known as the “Rapid Chloride Permeability (RCP) Test.” The test is time-consuming, laborious, has rather high variability, and, is to a degree, user sensitive, making it problematic for inclusion in a performance-based specification. A potential alternative to the RCP test is the “Surface Resistivity (SR) Test”, a method which is dramatically easier, faster, and has less variability than the RCP test. The research reported herein was directed toward determining a correlation between RCP and SR test measurements for Tennessee bridge deck …