Engineering Commons^™

Using A Centrifuge For Quality Control Of Pre-Wetted Lightweight Aggregate In Internally Cured Concrete, Albert E. Miller

Open Access Theses

Early age shrinkage of cementitious systems can result in an increased potential for cracking which can lead to a reduction in service life. Early age shrinkage cracking can be particularly problematic for high strength concretes, which are often specified due to their high strength and low permeability. However, these high strength concretes frequently exhibit a reduction in the internal relative humidity (RH) due to the hydration reaction (chemical shrinkage) and self-desiccation which results in a bulk shrinkage, termed autogenous shrinkage, which is substantial at early ages. Due to the low permeability of these concretes, standard external curing is not always …

Durability Of Silane Sealer In A Highly Alkaline Environment, Cameron David Murray

Graduate Theses and Dissertations

Alkali-silica reaction (ASR) is a chemical reaction between siliceous minerals present in certain aggregates and alkalis in the concrete pore solution. The reaction can lead to expansion and severe damage in concrete members. One method to mitigate ASR expansion is to use a penetrating sealer such as silane. A set of columns located in a food preparation facility was treated with silane and a complimentary laboratory study was performed. A cleaning regimen involving application of an alkaline cleaner is employed at the facility, followed by rinsing with hot, pressurized water. The purpose of this research is to evaluate the effectiveness …

Application Of Bamboo For Flexural And Shear Reinforcement In Concrete Beams, Nathan Schneider

All Theses

As the developing world is industrializing and people migrate to cities, the need for infrastructure is growing quickly and concrete has become one of the most widely used construction materials. One poor construction practice observed widely across the developing world is the minimal use of reinforcement for concrete structures due to the high cost of steel. As a low-cost, high-performance material with good mechanical properties, bamboo has been investigated as an alternative to steel for reinforcing concrete. The goal of this research is to add to the knowledge base of bamboo reinforced concrete (BRC) by investigating a unique stirrup design …

Transport Properties Of Nano-Silica Contained Self-Consolidating Concrete, Borhan Moradi

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this research study, transport properties of various self-consolidating concretes (SCCs) containing nano-particles (SiO2) were investigated. Nano-silica replaced a portion of the cementitious materials at different replacement levels ranging from 1.5 to 7.5% by weight. For the purpose of this investigation, flow, bulk, and transport properties of SCCs were studied. The investigated transport properties were absorption, water penetration, rapid chloride permeability, capillary absorption, rapid migration, and chloride diffusion. Transport properties of nano-silica SCCs were also compared to those of equivalent silica fume (micro silica) contained concretes, as well as those of control mixture (concrete without nano or micro silica).

Test …

Failure Mechanisms And Key Parameters Of Frp Debonding From Cracked Concrete Beams, Tayyebeh Mohammadi

Dissertations (1934 -)

Intermediate crack (IC) induced debonding failure of Fiber Reinforced Polymer (FRP)-strengthened reinforced concrete beams starts at the tip of flexural/shear cracks within the shear span and propagates towards the FRP plate termination. In this study, experimental and numerical programs are performed to characterize and predict the failure mechanisms of IC debonding failure, and identify the key parameters affecting such failure. It is found that the bond-slip relation obtained from the pullout test does not represent the bond-slip relation of the FRP/concrete interface in the FRP-strengthened concrete beams, and it cannot be directly used for predicting the load capacity of the …

Retrofitting Of Shear-Deficient Reinforced Concrete T-Girders With Composite-Based Systems, Alaa Ahmad Ata Maali

Theses

This research examines the viability of using different composite-based systems to upgrade the shear resistance of shear-deficient reinforced concrete T-girders. The research comprised experimental testing and analytical investigation. Test parameters included the retrofitting system; externally-bonded carbon fiber-reinforced polymer (EB-CFRP) laminates with or without a mechanical end anchorage (MA) and embedded through depth glass fiber-reinforced (ETD-GFRP) rebars; amount of internal stirrups; no stirrups, limited amount of stirrups with spacing s₁ = 0.6d, higher amount of stirrups with spacing s₂ = 0.375d; and initial shear damage prior to retrofitting; no damage, pre-cracking, and pre-failure.

The shear …

Flexural Behavior Of Reinforced Concrete T-Beams Strengthened With Nsm Composite System Under Accelerated Corrosion., Anes Bouchair

Theses

This research work aims at evaluating the effects of corrosion on flexural response of simply supported reinforced concrete (RC) T-Beams strengthened with near-surface-mounted carbon fiber-reinforced polymer (NSM-CFRP) strips. The research comprised experimental testing and analytical modelling. Test parameters included concrete grade, amount of NSM-CFRP strips, presence of U-wraps along the beam span, and time of corrosion exposure. A total of eighteen reinforced concrete beams with a T-shaped cross section were tested. Fourteen beams were strengthened in flexure and four beams were not strengthened to act as benchmarks. The strengthening regime included installation of either two or four NSM-CFRP strips into …

Reliability Analysis For Shear In Lightweight Reinforced Concrete Bridges Using Shear Beam Database, Danile F. Jensen

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The objective of this report is to analyze and calibrate the reliability indices for shear in reinforced concrete bridge girders. Existing statistical models are based on limited experimental data from only a few research tests. These existing models show that our current procedures for analysis are about 10-15% less conservative for lightweight concrete compared to an analysis for normal weight concrete. Accurate load models are used to find shear and moment envelopes of loads applied to bridges. Analysis is based on different span lengths, span number and girder dimensions. Design calculations are performed using design values and loads calculated from …

Uniform Temperature Predictions And Temperature Gradient Effects On I-Girder And Box Girder Concrete Bridges, Edyson Rojas

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Federal Highway Administration (FHWA) created the Long-Term Bridge Performance (LTBP) program with the objective of acquiring quality scientific data for in-service bridge performance throughout the United States. This information will be used to improve the practices of bridge design and maintenance. To accomplish this objective, a variety of sensors were installed on a bridge south of Sacramento, California and a bridge near Perry, Utah. Data from the sensors is constantly gather and analyzed.

This research analyzed the data from the temperature sensors in order to investigate the effect of temperature changes in the California and Utah bridges over a …

Implementation And Field Testing Of Improved Bridge Parapet Designs, Amy E. Kalabon

ETD Archive

Premature cracking of concrete bridge parapets is a potentially complex problem, with a number of possible causes. Identifying the cause of premature cracking, and avoiding this problem in the future has several benefits, including: a potential cost savings for the district, improving the safety of these structures in future construction, and increasing the overall understanding of parapets. The objective of this study was to analyze the reasons for uncontrolled cracking in order to establish an improved parapet design, and provide recommendations to the Ohio Transportation (ODOT) to prevent such cracking in the future. Previous research carried out a forensic investigation …

Selection Of High Performance Repair Materials For Pavements And Bridge Decks, Alice E. Sommerville

ETD Archive

The Ohio Transportation has identified the need to specify durable, more permanent high performing pavement and bridge deck patching materials. These materials need to allow for expedited pavement and bridge deck wearing surface repair for worker and user safety. Currently, either temporary or generally specified in-kind or like materials are being used to perform pavement patching. Usually, the Department provides generically specified cementitious or cold mix asphalt materials for patching wearing surfaces with varied performance characteristics. Current products used for these repairs are generally those that have been used for many decades for which competition exists. However, new or proprietary …