The inverted T-beam system provides an accelerated bridge construction alternative. The system consists of adjacent precast inverted T-beams finished with a cast-in-place concrete topping. The system offers enhanced performance against reflective cracking and reduces the likelihood of cracking due to time dependent effects. Differential shrinkage is believed to be one of the causes of deck cracking in inverted T-beam systems. The objective of this study was to develop mix designs that exhibit lower shrinkage and higher creep compared to typical deck mixtures, recommend a prescriptive mix design and a performance criterion to VDOT that can be further investigated and used in the inverted T-beam system to combat effects of differential shrinkage. Ten different mix designs using different strategies to reduce shrinkage were tested for their compressive strength, splitting tensile strength, modulus of elasticity and unrestrained shrinkage. The four best performing mixes were selected for further study of their time dependent properties. The test data was compared against the data from various prediction models to determine the model that closely predicts the measured data. It was observed that ACI 209.2R-08 model best predicted the time dependent properties for the four mixes tested in this project. Tensile stresses in the composite cross-section of deck and girder, created due to difference in shrinkage and creep are quantified using an age adjusted effective modulus method. In this analysis, it was observed that mixes with normal weight coarse aggregate (NWCA) developed smaller stresses compared to those of mixes with lightweight coarse aggregate (LWCA). Mixes with fly ash as supplementary cementitious material (SCM) developed smaller stresses at the bottom of deck when compared to mixes with slag as the SCM. / Master of Science / The inverted T-beam system provides an accelerated bridge construction alternative. The system consists of adjacent precast inverted T-beams finished with a cast-in-place concrete deck. The system reduces the likelihood of cracking due to time dependent deformations of concrete – Shrinkage and Creep. The difference in rate of shrinkage of deck and the girder, also called as differential shrinkage, is believed to be one of the causes of deck cracking in inverted T-beam systems. The objective of this study was to develop concrete mix designs that exhibit lower shrinkage and higher creep that can be further investigated and used in the inverted T-beam system to combat effects of differential shrinkage. Studies resulted in the observation that ACI 209.2R-08 – model used to predict concrete behavior, best predicts the time dependent properties of the concrete tested in this project. Also, mixes with normal weight coarse aggregate (NWCA) developed smaller stresses compared to those of mixes with lightweight coarse aggregate (LWCA). Mixes with fly ash as supplementary cementitious material (SCM) developed smaller stresses when compared to mixes with slag as the SCM.

The objectives of this research were 1) to investigate the effects of hydrodemolition treatment timing on chloride concentration profiles in concrete bridge decks for depths of concrete removal below the top mat of reinforcing steel and 2) to investigate factors that influence the occurrence of blow-throughs in concrete bridge decks when hydrodemolition is used. The research results are intended to provide engineers with guidance about the latest timing of hydrodemolition that can maintain a chloride concentration level below 2.0 lb of chloride per cubic yard of concrete at the levels of both the top and bottom mats of reinforcing steel, as well as about conditions that may indicate a higher probability of blow-through during hydrodemolition. The scope of this research included a questionnaire survey of hydrodemolition companies to summarize common practices in the field, numerical modeling of chloride concentration to investigate hydrodemolition treatment timing on typical Utah bridge decks, and structural analysis to investigate factors that influence the occurrence of blow-throughs during hydrodemolition. While some survey respondents indicated that certain parameters vary, the responses are valuable for understanding typical practices and were used to design the numerical experiments. The numerical modeling generated chloride concentration profiles through a 75-year service life given a specific original cover depth (OCD), treatment time, and surface treatment usage. The results indicate that, when a surface treatment is used, the concentration at either the top or bottom mat of reinforcing steel does not reach or exceed 2.0 lb of chloride per cubic yard of concrete after hydrodemolition during the 75 years of simulated bridge deck service life. The results also indicate that, when a surface treatment is not used, the chloride concentration at the top mat of reinforcement exceeds 2.0 lb of chloride per cubic yard of concrete within 10, 15, and 20 years for OCD values of 2.0, 2.5, and 3.0 in., respectively. The numerical experiments generated results in terms of the main effect of each input variable on the occurrence of blow-throughs and interactions among selected input variables. For each analysis, blow-through can be expected when the calculated factor of safety is less than 1.0. The factor of safety significantly increases with increasing values of transverse rebar spacing and concrete compressive strength and decreasing values of depth of removal below the bottom of the top reinforcing mat, orifice size, and water pressure within the ranges of these parameters investigated in this experimentation. The factor of safety is relatively insensitive to jet angle. For both case studies evaluated in this research, the blow-through analysis correctly predicted a high or low potential for blow-through on the given deck.

As the primary cause of concrete bridge deck deterioration in the United States is corrosion of the steel reinforcement as a result of the application of chloride-based deicing salts, chloride concentration testing is among the most common techniques for evaluating the condition of a concrete bridge deck. The objectives of this research were to 1) compare concrete drilling and powder collection techniques to develop a sampling protocol for accurately measuring chloride concentrations and 2) determine the number of chloride concentration test locations necessary for adequately characterizing the chloride concentration of a given bridge deck. Laboratory experiments on concrete drilling and powder collection were conducted to compare current concrete powder sampling techniques, including constant and stepwise drilling methods and spoon and vacuum powder collection methods. In addition, three charts were prepared to determine the number of chloride concentration test locations necessary for adequately characterizing the chloride concentration of a given bridge deck. The number of samples is dependent on reliability, spatial variability in chloride concentration, and an allowable difference between sample and population means. For the experiment on drilling, this research shows that the practice of decreasing the size of the drill bit in a stepwise fashion with increasing sampling depth reduces the possibility of abrading concrete from the sides of the hole above the sampling depth, where the chloride concentrations are higher, during drilling of lower lifts. For the experiment on powder collection, this research demonstrates that representative samples of concrete powder can be collected with either a spoon or a vacuum. Based on the results of this research, the stepwise drilling method and either the spoon or vacuum powder collection method are recommended for application. In addition, the charts developed in this research are recommended for estimating the number of chloride concentration test locations necessary for adequately characterizing the chloride concentration of a given bridge deck. This research will be helpful in effectively assessing the condition of concrete bridge decks with respect to chloride-induced corrosion of the reinforcing steel and prioritizing bridge maintenance and rehabilitation projects.

Infrastructure deterioration is an international problem requiring significant attention. One particular manifestation of this deterioration is the occurrence of sub-surface cracking (delaminations) in reinforced concrete bridge decks. Of many techniques available for inspection, air-coupled impact-echo testing, or sounding, is a non-destructive evaluation technique to determine the presence and location of delaminations based upon the acoustic response of a bridge deck when struck by an impactor. In this work, two automated air-coupled impact echo sounding devices were designed and constructed. Each device included fast and repeatable impactors, moving platforms for traveling across a bridge deck, microphones for air-coupled sensing, distance measurement instruments for keeping track of impact locations, and signal processing modules. First, a single-channel automated sounding device was constructed, followed by a multi channel system that was designed and built from the findings of the single-channel apparatus. The multi channel device performed a delamination inspection in the same manner as the single-channel device but could complete an inspection of an entire traffic lane in one pass. Each device was tested on at least one concrete bridge deck and the delamination maps produced by the devices were compared with maps generated from a traditional chain-drag sounding inspection. The comparison between the two inspection approaches yielded high correlations for bridge deck delamination percentages. Testing with the two devices was more than seven and thirty times faster, respectively, than typical manual sounding procedures. This work demonstrates a technological advance in which sounding can be performed in a manner that makes complete bridge deck scanning for delaminations rapid, safe, and practical.

The Diploma thesis deals with the Diagnostics of Reinforced Concrete Bridge in the village of Luhačovice. This thesis also describes the individual Diagnostic methods and instruments used in purpose to make Diagnosis of bridge constructions. The main aim of the Diagnostics is to determine the current state of the Bridge which consists in verification of the actual road structure, determination of the physical and mechanical parameters of the Concrete (strength, depth of carbonation) and in some parts of the bridge structure to determine the type, number and position of the bending or shear reinforcement. Based on the evaluation of the laboratory tests a static calculation of the selected part of the Bridge structure is performed. The final evaluation is the determination of the load and the subsequent design of the necessary and recommended measures for maintaining or improving the functionality of the bridge structure.

The thesis Building Investigation and Diagnosis of Reinforced Concrete Structure is focused on analyzing two reinforced concrete bridge structures. It discusses different evaluation surveys and its influence on later evaluation of the bridges. In this thesis there is included static evaluation finding supports at one of reinforced concrete bridges. Practical part is complemented by the necessary theoretical part, which deals with exploring bridges, ways of their implementation, and a summary of the most commonly used diagnostic methods for bridges.

The Diploma thesis deals with the road bridge on tfe road 4951 across the D55 highway. Construction is proposed in three variants. The selected design was prestressed board length 67,65 meters, intended as a continuous beam. Calculation is performed by software SCIA. The construction is evaluated according to current standards.

The objective of this research was to investigate the effects of twisted steel micro rebar (TSMR) fibers on 1) the mechanical properties of concrete used in bridge deck construction and 2) the early cracking behavior of concrete bridge decks. This research involved the evaluation of four newly constructed bridge decks through a series of laboratory and field tests. At each location, one deck was constructed using a conventional concrete mixture without TSMR, and one was constructed using the same conventional concrete mixture with an addition of 40 lb of TSMR per cubic yard of concrete. Regarding laboratory testing, the conventional and TSMR beam specimens exhibited similar average changes in height after 4 months of shrinkage testing. The electrical impedance measurements did not indicate a notable difference between specimens comprising concrete with TSMR and those comprising conventional concrete. Although no notable difference in behavior between conventional and TSMR specimens was apparent before initial cracking, the toughness of the TSMR specimens was substantially greater than that of the conventional concrete specimens. Regarding field testing, sensors installed in the bridge decks indicated that the addition of TSMR does not affect internal concrete temperature, moisture content, or electrical conductivity. The average Schmidt rebound number varied little between the TSMR decks and conventional decks; therefore, the stiffness of the TSMR concrete was very similar to that of conventional concrete. Distress surveys showed that the conventional decks exhibited notably more cracking than the TSMR decks. The TSMR fibers exhibited the ability to limit both crack density and crack width. For all of the decks, chloride concentrations increased every year as a result of the use of deicing salts on the bridge decks during winter. However, the chloride concentrations for samples collected over cracked concrete increased more rapidly than those for samples collected over non-cracked concrete. Although TSMR fibers themselves do not directly affect the rate at which chloride ions penetrated cracked or non-cracked concrete, the fibers do prevent cracking, which, in turn, limits the penetration of chloride ions into the decks. Therefore, the use of TSMR would be expected to decrease the area of a bridge deck affected by cracking and subsequent chloride-induced corrosion damage and thereby increase the service life of the bridge deck.

The objectives of this research were to 1) investigate bridge deck condition assessment methods used in the field and laboratory, methods of managing bridge decks, and methods for estimating remaining bridge deck service life using computer models through a comprehensive literature review on these subjects; 2) collect and analyze field data from representative concrete bridge decks in Utah; and 3) develop a decision tree for concrete bridge deck management in Utah. As a result of the literature review performed for objective 1, a synthesis of existing information about condition assessment, bridge deck preservation and rehabilitation, bridge deck reconstruction, and estimating remaining service life using computer models was compiled. For objective 2, 15 bridge decks were strategically selected for testing in this research. Five bridge decks had bare concrete surfaces, five bridge decks had asphalt overlays, and five bridge decks had polymer overlays. Bridge deck testing included site layout, cover depth measurement, chloride concentration testing, chain dragging, half-cell potential testing, Schmidt rebound hammer testing, impact-echo testing, and vertical electrical impedance testing. Two-sample t-tests were performed to investigate the effects of selected bridge deck features, including polymer overlay application, deck age at polymer overlay application, overlay age, asphalt overlay application with and without a membrane, stay-in-place metal forms (SIPMFs), SIPMF removal, internally cured concrete, and use of an automatic deck deicing system. For objective 3, condition assessment methods were described in terms of test type, factors evaluated, equipment cost, data collection speed, required expertise, and traffic control for each method. Unit costs, expected treatment service life estimates, and factors addressed for the preservation, rehabilitation, and reconstruction methods most commonly used by the Utah Department of Transportation (UDOT) were also summarized. Bridge deck testing results were supplemented with information about current bridge deck management practices and treatment costs obtained from UDOT, as well as information about condition assessment and expected treatment service life, to develop a decision tree for concrete bridge deck management. Based on the results of field work and statistical analyses, placing an overlay within a year after construction is recommended. Removing SIPMFs after a deck age greater than 18 years is not likely to be effective at reversing the adverse effects of the SIPMFs on bridge deck condition and is not recommended. Bridge deck construction using internally cured concrete is not recommended for protecting against rebar corrosion. To the extent that excluding an automatic deck deicing system does not compromise public safety, automatic deck deicing systems are not recommended. To supplement the typical corrosion initiation threshold of 2.0 lb Cl-/yd3 of concrete for black bar, a corrosion initiation threshold of 8.0 lb Cl-/yd3 of concrete is recommended in this research for bridge decks with intact epoxy-coated rebar. For chloride concentrations less than 20 lb Cl-/yd3 of concrete as measured between reinforcing bars, an increase of up to 70 percent should be applied to estimate the corresponding chloride concentration of the concrete in direct contact with the rebar. The decision tree developed in this research includes 10 junctions and seven recommended treatments. The junctions require the user to address questions about surface type, degree of protection against water and chloride ion ingress, degree of deterioration, and years of additional service life needed; the answers lead to selection of treatment options ranging from repairing an overlay to full-depth bridge deck reconstruction. Revisions to the decision tree should be incorporated as additional methods, data, treatments, or other relevant information become available.

The purpose of the project is to investigate the difference in performance between ballasted and ballastless railway bridges dedicated to high speed trains by taking into account both static and dynamic requirements. The main questions are: a) whether choosing a ballastless bridge results in a more slender section due to the lower self-weight b) if the design of bridges for high speed trains is governed by the static or by the dynamic requirements. The method followed was to first make a complete static design of a ballasted and a ballastless bridge, and then subject them to a 2D dynamic analyses in order to see if the cross section dimensions must be changed. Some of the bridges required a more thorough dynamic analyses, and for these, a 3D model was developed. The analysed bridge is a simply supported beam with a T section carrying one track. Some variations were also considered, namely a simply supported bridge with a double T section carrying two tracks, as well as a single track bridge in two spans. It was found that all of the analysed bridges are somewhat more slender for the ballastless alternative, and require a 10 -30% less reinforcement. Simply supported bridges carrying one track are governed by the dynamic requirements; the bridges in two spans are for shorter spans governed by the statics and for longer spans by the dynamics. Bridges in double T fulfilled all the requirements according to the 2D analyses, but were found to be greatly affected by the 3 dimensional effects and failed to satisfy the criteria when these were taken into account. Finally, the optimal design according to these analyses is a ballastless bridge in a simple T section. If the bridge constructed should carry two tracks, then it should be constructed as two T beams that are not connected to one another in order to avoid the unfavourable 3D effects.