Gregory Lucier

Jointly, the North Carolina State University School of Architecture (SOA) and Department of Civil, Construction, & Environmental Engineering (CCEE) are seeking multi-year funding from the PCI Foundation to introduce architecture and civil engineering students to precast concrete systems and solutions. This proposal identifies existing courses in which precast concrete is minimally taught or mentioned and proposes an advanced architecture studio course integrated with a civil engineering projects course. Both courses will be dedicated to precast concrete applications. They will begin in Spring 2023, continue for 4 years, and will significantly expand the instruction and knowledge of precast and prestressed concrete for NCSU students and faculty.

Alkali Silica Reaction (ASR) is one of the most ubiquitous deterioration problems and is a major concern for Department of Transportation (DoTs) across the US. Since the first documentation of ASR in 1940 by T.E. Stanton [1], published based on his investigations of cracking of concrete structures in California, a plethora of papers and data have been published in the literature. While a good understanding of ASR has been established today, evaluating aggregates for the potential of ASR remains elusive. The first line of defense against ASR remains avoiding the use of aggregates with a known history of ASR and/or restricting the alkali content of concrete mixes. The use of accelerated test methods are deemed less reliable than the use of historical data and evidence, due to current test methods assessing aggregate reactivity, not concrete mixture reactivity as used in the field. The main challenge with accelerated test methods is that the mechanism of ASR seems to be very sensitive to perturbation and can change depending on the conditions of the test such as increased temperature, concentration of alkalis, and ion leaching from concrete during the test. As a consequence, rapid tests suffer from low fidelity (e.g., ASTM C 1260), and reliable tests (e.g., ASTM C 1293) are often very time consuming and may take up to two years to complete, which in many instances defeats the purpose of running the test to being with (i.e. the project is already constructed by the time the test is completed). The search for accelerated reliable tests for ASR has occupied researcher for decades. Unfortunately, many of the currently available accelerated tests rely on the same length change measurement strategy as traditional tests and expose samples to a highly alkali solution at elevated temperatures. Therefore, common accelerated tests all suffer from the same limitations as traditional tests. Additionally, due to the requirement of measuring very fine changes in length, samples must be prepared in a highly controlled manner in the laboratory. The most common test methods are summarized with relevant information in Table 1.

Abstract: The NSF IUCRC for Integration of Composites into Infrastructure (CICI) is specialized at innovating advanced fiber-reinforced polymer (FRP) composites and techniques for the rapid repair, strengthening or replacement of highway, railway, waterway, bridge, building, pipeline and other critical civil infrastructure. The Center consists of West Virginia University (WVU) as the lead institution in the current Phase II, with North Carolina State University (NCSU), the University of Miami (UM), and the University of Texas at Arlington (UTA) as partner university sites. CICI is currently establishing an international site at the Center for Engineering and Industrial Development (CIDESI) in Queretaro, Mexico, through a collaboration between NSF and the National Council of Science and Technology (CONACYT) in Mexico. The primary objective of the Center is to accelerate the adoption of polymer composites and innovative construction materials into infrastructure through joint research programs between the university sites in collaboration with the composites and construction industries. In Phase III, CICI aims to broaden its scope of research in composites to include: 1) nondestructive testing methods; 2) manufacturing techniques, such as 3D printing; 3) inspection techniques, such as the use of drones with high resolution cameras; 4) in-situ modifications of infrastructure systems, resulting in enhanced durability and thermo-mechanical properties; and 5) cost-effective recycling of high value composites, enabled by the addition of CIDESI.

Sampson County Bridge No. 810003 is a three-span prestressed channel structure built in 1966 on Service Route No. 1933 across Branch Six Run Creek. Six channel beams (12 stems) were retrofit in November of 2020 using a prestressed mechanically fastened fiber reinforced polymer (MF-FRP) system. The retrofit was designed to restore prestressing forces lost due to corrosion of internal steel strands. The retrofit was intended as a temporary measure to keep the bridge open without lowered load postings while a bridge replacement could be designed, bid, and scheduled. Bridge 810003 is scheduled for demolition and replacement in late 2022 or early 2023. The proposed research aims to salvage the six retrofitted channel beams from Bridge 810003 that have been in-service for more than 21 months. In addition, the work proposes to salvage two additional control beams from the bridge that have not been retrofitted. Beams will be identified prior to bridge demolition, carefully removed from the bridge during demolition with the MF-FRP repair systems intact, trucked to Constructed Facilities Laboratory (CFL) in Raleigh, and tested to failure in the laboratory. Samples of the FRP material will be recovered from the tested beams and for material-scale tension testing. Concrete cores will be taken from the beams to determine the concrete compressive strength. The proposed experiments will capture the full response to failure of the retrofit beams, allowing for comparison to analytical predictions and evaluation of the effectiveness and durability of the retrofit. Predications of beam behavior will use the procedures developed as part of previous research project RP2018-16. As justified by the research results, edits to the existing design methods, installation procedures, inspection procedures, ratings spreadsheet, and standard details and specifications will be developed and proposed. This proposed research project presents a unique opportunity to evaluated the performance of in-service girders that cannot be replicated on new concrete girders.

In a recent research project a pipe material selection software was developed. This software enables estimation of the service life of pipes made from different materials based on their anticipated exposure conditions. The linked GIS database is used to automatically compute the anticipated exposure condition corresponding with GPS coordinates input by the user for a given project. The culvert pipe materials commonly used by NCDOT have been included in the software: reinforced concrete, galvanized steel, aluminized steel, cast iron, mild steel, aluminum alloy, and polymeric pipes. Based on conversations with NCDOT, additional scope for the software is desired and identified as follows: i. The developed software selection guide only considers material type and exposure condition in the selection process. It is desirable to integrate NCDOT������������������s structural requirements into the selection process such that NCDOT engineers can use a single software to select pipe materials based on both durability and structural requirements. ii. The current software does not provide an estimate of how service life can be extended by repair and rehabilitation. It is desirable to upgrade the software to account for the additional service life expected from various rehabilitation measures, and to develop a comparative analysis of possible repair methods in terms of expected impact on service life. iii. The current software does not account for the effects of approaches to mitigate adverse subsurface exposure on the service life of installed pipes. Addressing the effects of mitigation is desirable since in many projects, backfill soil is different from native soil. The work proposed herein aims to update the current software to include: (i) An upgraded pipe selection guide software that integrates structural requirements, repair and rehabilitation methods, and mitigation strategies into a unified pipe selection guide, and (ii) provisions accounting for the effects of various repair and rehabilitation methods on the service life of the pipe materials.

The NCDOT is in the process of deconstructing the 56 year old Bonner Bridge. This deconstruction provides an opportunity to evaluate the aged girders of the bridge and to compare their performance to load rating calculations. Such a comparison will provide a better understanding of the accuracy and assumptions associated with prestressing losses and will allow for refinements to the load rating procedures. This project focuses on a complete performance evaluation of the Bonner Bridge girders including full-scale load testing of 9 of the 61 ft. by 45 in. deep AASHTO Type III girders. The load testing will be conducted in the Constructed Facilities Lab (CFL) located at North Carolina State University. The research will provide recommendations for updates to the NCDOT Structures Management������������������s Manual guidelines. These assessments will also include directly evaluating the current amount of stress (after losses) in the girder prestressing steel; the condition, strength and stiffness of the concrete materials; and the location and extent of damage and repair of the girders.

Precast double tees with thin stems are a widely used and highly successful floor member in parking structures and other buildings. Frequently, the end supports are dapped such that the bottom of the double tee is level with the bottom of the inverted tee or ledger beam on which it is supported. The dapped connection detail is especially important at crossovers between spans in parking structures because the overall structural depth and floor-to-floor height need not be increased where the double tee is supported by an inverted tee beam. Double tees with dapped ends are typically 24��������������� to 30��������������� deep and often carry parking loads, however, much deeper tees (48���������������) are becoming more common due to the heavier loads and longer spans needed in data centers and other specialty structures.

TSA: Flexure Capacity of Concrete Beams

A precast concrete sandwich panel is typically comprised of a rigid foam core with a layer of concrete on each face. A wythe connector bridges the insulating core and joins the concrete wythes structurally. Traditionally, solid zones of concrete or steel ties have been used as wythe connections, however, these methods are thermally inefficient. The thermal bridging created is significant, and more thermally efficient wythe ties are needed. Enter a wide variety of proprietary FRP wythe connectors on the market. Carbon fiber grid is one option for wythe connection in precast concrete sandwich wall panels that is both thermally and structurally efficient. The system has been tested extensively under static and cyclic loads. It has not been tested as extensively for creep deformation over time. The experimental plan includes loading several small wall panels with full-scale cross-sections for long durations. Standard ����������������push specimens��������������� will be used and will be tested prior to loading (control specimens) and after sustained loading for 1 year. Various levels of sustained loading will be selected at percentages of the ultimate loads sustained by the control samples.

Jointly, the North Carolina State University School of Architecture (SOA) and Department of Civil, Construction, & Environmental Engineering (CCEE) are seeking funding from the PCI Foundation to study the impact of the NCSU PCI funded studio, Creations in Concrete, on architecture (ARC) and civil engineering (CE) student learning. This study would survey students that have participated in Creations in Concrete and compare those results with surveys of ARC and CE students that did not participate in the studio. The survey would interrogate Creations in Concrete������������������s impact on student learning of precast concrete as a building material, benefits of professional connections, and experiences with collaborating with other disciplines.

A large number of bridge deck rehabilitations are performed each year in North Carolina. Latex Modified Concrete (LMC) and LMC������������������Very Early Strength (LMC-VES) are frequently used in these rehabilitations because these materials provide reasonable installed performance and allow for a rapid return to service. Over the last 5 years, the NCDOT has completed an average of about 25 overlays per year using LMC or LMC-VES materials. The vast majority of these projects are highly successful. However, despite comprehensive NCDOT guidelines and specifications (such as PSP003 and PSP004), substantial cracking is sometimes observed in these overlays shortly after installation. Prior research funded by NCDOT has indicated that if placement and curing follows proper construction procedures, then the primary causes of cracking (such as shrinkage and plastic shrinkage) in LMC and LMC-VES materials are unlikely to develop. However, other secondary mechanisms can potentially cause cracking, including vibration of the structure during casting and curing, temperature changes during casting, and slight differential settlement/deflection of supporting decks as overlay placement progresses across a bridge. These suspected secondary causes of cracking are difficult (or impossible) to mitigate in practice. In practice, it can also be difficult to completely enforce proper construction procedure, which can lead to some shrinkage cracking. For example, fogging above fresh LMC-VES is allowable, but allowing water to accumulate on the material during placement and finishing is not ������������������ the distinction is sometimes difficult to monitor and enforce in the field.

A large number culvert pipes are installed every year in North Carolina. While the loading and structural requirements for these pipes are considered during the selection process, the exposure condition of these culverts receives less attention. Many pipe choices exist including reinforced concrete, galvanized steel, aluminum, aluminized, and various types of plastic. Choosing the right pipe for the right installation is a non-trivial task that carries significant financial impact. Factors such as structural capacity, environmental durability, anticipated life-span, required pipe size, site conditions, and available construction expertise are all important when selecting a pipe. Existing NCDOT selection tables provide some limited guidance, but often result in highly-conservative selections being made, particularly from the perspective of matching pipe materials to site environmental conditions. Selection of the wrong pipe material (or an overly-conservative pipe material) can result in significant excess cost. If materials degrade too quickly, costly re-work is required, and additional costs and risks may be incurred due to reduced performance of the degraded pipe. If high-cost and high-performance materials are selected in areas where they are not needed, then initial construction costs can increase dramatically. For example, in many situations, aluminized corrugated steel pipe can likely provide the same useful service life as corrugated aluminum pipe at a dramatically reduced cost. Aluminum pipe may be justified in regions with salt-water exposure, however, it is likely an over-conservative choice for regions where contact with salt will be incidental. Accounts from NCDOT personnel have indicated widespread use of aluminum pipe in regions where it is likely not needed (i.e., regions with limited salt exposure).

A project focused on the strengthening of reinforced concrete columns under reverse cyclic loading is proposed. Concrete columns will be produced with integrated foundations and will be strengthened with various types of Fiber Reinforced Polymer strengthening systems. The strengthening will be focused on flexural strengthening through confinement and on shear strengthening through external FRP stirrups. All columns will be loaded under reverse cyclic load histories in the presence of axial load. The goal of the program will be to investigate whether various systems can meet building code requirements for FRP strengthening systems.

Prestressed concrete C-channels and cored slabs, and steel beams of various shapes and forms make up a significant percentage of the common bridge superstructure systems used by NCDOT. Many such bridges are in varying states of distress and require retrofit to extend their useful service life prior to major rehabilitation or superstructure replacement. The challenge is to develop retrofit techniques that are durable, easy to install, monitor and maintain, and that may be applied to the range of prestressed concrete and steel beam types. Critically, NCDOT must also be able to rate the proposed retrofit using approved AASHTO methods before it may be applied in the field. In many cases the retrofit may be considered temporary since the bridge may be scheduled for replacement in the near future. Temporary strengthening is intended to provide the ability to maintain a sufficiently high operating rating to keep the bridge functional while replacement is scheduled. In lieu of an acceptable retrofit, the bridge may need to be load posted or closed, often resulting in significant detours and disruption.

North Carolina State University School of Architecture (SOA) and Department of Civil, Construction, & Environmental Engineering (CCEE) is seeking multi-year funding from the PCI Foundation to introduce architecture and civil engineering students to precast concrete systems and solutions. This proposal identifies existing courses in which precast concrete is minimally taught or mentioned, and proposes a new architecture studio course integrated with civil engineering and digital fabrication courses. All three courses will be dedicated to precast concrete applications. They will begin in Spring 2017, continue for 4 years, and will be an incubator to significantly expand the instruction and knowledge of precast and prestressed concrete at NCSU.

The proposed project has an information technology (IT) component that will be coordinated with CICI university partners (UM and NCSU). The following sections highlight the nature of the project������������������s data generation, storage, retention, and sharing components as per NCSU. Expected data This research is expected generate datasets similar to those produced by a typical materials/structures laboratory. The types of data include: ������������������� Experimental measurements from voltage or current measurement devices. These measurements will be converted to useful units through calibration scales. Data will be collected by instruments and sensors such as: strain gauges, load cells, linear variable differential transformers (LVDTs), and displacement transducers. ������������������� Quantitative information in the form of human or machine readouts from measurement devices such as rulers, meter tapes, volume measurement containers, scales, and environmental gauges. ������������������� Qualitative information such as experimental behavior, test conditions, or other significant observations. ������������������� Multimedia data such as photographs, videos, screen captures, audio/video logs captured by cameras, camcorders, or audio recorders, or other multimedia devices. ������������������� Written documents such as progress logs, journal articles, periodic reports, presentations, or any other document detailing progress, results, or outcomes. Data will be collected for the entire duration of this project. In particular, data is expected to be collected during testing preparation, equipment calibration, testing, personnel training, and demonstrations. Data related to the dissemination of information such as written documents or multimedia data, as it relates to publication or sharing of results, creation of manuscripts for archival publication, presentations, and reports, is expected to be generated following significant milestones in the project, and can be expected on a monthly or longer frequency. The project will result in the creation of a software framework for data management, sharing, analysis, and visualization. The code will be managed by graduate students and will be supervised by the PI. The majority of the code will be uploaded to a code repository such as GITHUB, where the code will be made open source under a GNU license.

This research will study the ability of strengthened reinforced concrete columns to resist reverse cyclic lateral load cycles. Control columns and strengthened columns will be tested and specimens will be designed to fail in either flexure or shear. Strengthening systems made of carbon fiber or glass fiber will be applied to selected columns and those columns will be retested to examine the structural performance of the strengthening system.

Traditional concrete protective structures encountered by ground forces typically have unconfined compressive strengths of between 3,000 to 6,000 psi. Recent advances in concrete technology have resulted in new concrete materials with compressive strengths of 30,000 psi or greater. No field instrument currently exists that can simultaneously determine the compressive strength, thickness, and rebar configuration of concrete structures across today������������������s wide range of possible compressive strengths. In STTR Phase I/II efforts, NLA Diagnostics LLC (NLAD) developed a prototype instrument that measures both compressive strength and concrete thickness up to 33,000 psi and 6 ft, respectively. NLAD has also mapped out a technical course to locate rebar within the concrete. This proposed project will take input from military operators to improve packaging of the existing technology and to implement a rebar mapping capability in order to enhance military capabilities to defeat concrete protective structures, accelerate the ability to deploy concrete characterization instruments with operating forces, and reduce the technical risks associated with engaging concrete protective structures in tactical situations.

Membership

TSA - Reverse Cyclic Fatigue of Precast Concrete Sandwich Panels

A large number of bridge deck rehabilitations are performed each year in North Carolina. Latex Modified Concrete (LMC) and LMC������������������Very Early Strength (LMC-VES) are used in these rehabilitations because they allow for a rapid return to service. Despite the comprehensive guidelines and specifications developed by NCDOT (such as PSP003 and PSP004) for quality control, and control of cracking, substantial cracking is observed in these overlays. The observed cracking is mainly attributed to thermal cracking, shrinkage cracking, plastic shrinkage cracking or a combination of them. Cracking of all types substantially reduces the effectiveness and service life of these overlays. To address the cracking issue, the proposed research will investigate whether non-metallic fiber reinforcement can be used to control and reduce cracking in LMC materials. A multi-phased research program is proposed. First, during this project, a number of active overlay projects will be visited. The main goal of these visits is for the researchers to become completely familiar with typical field practices for process of mixing, placing, and curing the overlay. This will help in identifying the best method to add fibers to the mixture and in identifying potential difficulties that addition of fibers might introduce. The researchers will also document observations that will be used to provide guidelines on the best placing and curing practices after addition of fibers. Second, the susceptibility of the LMC to plastic shrinkage cracking will be evaluated using ASTM C1579. The evaluation of plastic shrinkage cracking is important since the type of the fibers needed to control plastic shrinkage cracking is different from the type of the fibers needed for other types of shrinkage cracking and thermal cracking. If LMC is highly susceptible to plastic shrinkage cracking, the effectiveness of an appropriate type of fibers in reducing plastic shrinkage cracking will also be evaluated. Third, the susceptibility of LMC to drying and autogenous shrinkage cracking will be evaluated using restrained ring test. The purpose of this laboratory test is to identify the minimum dosage and an effective type of the fiber in controlling the cracking. Restrained rings with three different degrees of restraint (thickness of the steel ring) will be used. Ring tests will include the test specified by the ASTM specifications. Forth, after identifying the minimum required fiber and the type of fibers, fiber reinforced LMC will be tested on large-scale slabs. For this task the actual volumetric mixer that is used in the field will be employed. Two slabs, one unreinforced and one fiber reinforced LMC, will be cast beside each other using the same equipment and the same crew. The slabs will be cured simultaneously in an environmental chamber that will enable the creation of specific curing conditions. The fiber distribution generated by the volumetric mixer will be quantified using digital image analyses. Finally, if the use of fibers proves unsuccessful or impractical, the researcher will perform a literature review on alternative materials and methods of reducing and controlling cracking that might be feasible and propose those methods to NCDOT for further study.

Memberships

During covert operations, the U.S. Army may be required to breach a concrete structure using a controlled explosion. When choosing the most effective charge size and placement, it is vital to perform a rapid field assessment of the material and structural properties of the target structure. However, recent advances in manufacturing high strength concrete materials may increase the uncertainty of these assessment methods. Therefore, the Army is seeking a non-destructive evaluation (NDE) system which can connect with currently fielded Army systems and identify the following required information: compressive strength of in-situ concrete from 3 ksi to 30 ksi within +/- 3 ksi; wall thickness up to 6 ft with an accuracy of 1 ft; presence and location of metal substructure (such as steel reinforcement) within 1ft from the wall surface; and presence of fiber reinforcement. This project will utilize the commercially available NLA RECON? (manufactured by NLA Diagnostics, LLC), which is rugged, portable, and a field-ready NDE system. The NLA RECON? will utilize ultrasonic pulse velocity, impact-echo, pulse-echo, and ultrasonic attenuation to meet or exceed the Army?s requirements. Tests will be performed on a selected set of large concrete specimens constructed at the Constructed Facilities Laboratory of North Carolina State University, and on in-service structures in the Raleigh, NC, area. The outcome of the project is a handheld system which will utilize an array of transducers to test an appropriately sized area with maximum speed and accuracy. In addition to displaying the material properties and appropriate breaching charge size, the final version will rapidly obtain a two dimensional image of the internal features of the structure. The system could be held against the wall or structure and the proposed tests would be performed automatically. The operator will need very little, if any, NDE expertise to use this equipment. There is vast potential for dual use in numerous applications within the Department of Defense and the commercial sector. For example, state Departments of Transportation could use this all-in-one solution to assess the compressive strength and quality of deteriorating concrete infrastructure. In a similar manner to the Army, the Department of Homeland Security, as well as state and local authorities, could use the technology for breaching concrete structures.

The proposed research topic is related to the design and behavior of precast concrete Ledge Beams.

Prestressed concrete cored slabs are common bridge elements used by the NCDOT for spans up to approximately 60 ft. While cored slabs are structurally efficient, serving as both superstructure and deck, their internal steel reinforcement can be vulnerable to corrosion. Corrosion is of particular concern when structures are located in aggressive environments such as coastal regions or in areas where deicing chemicals are used. The internal steel in cored slabs can corrode when salts and moisture penetrate the concrete from the road surface or are splashed onto the bridge from the bottom or sides. Recent inspections of prestressed concrete cored slab bridges in Carteret County, NC, have brought to light a significant degree of corrosion in the stirrups and prestressing strands of these members. In certain cases, corrosion has compromised layers of longitudinal reinforcement, leading to extensive delamination and spalling of the concrete cover from the soffit of the bridge superstructure. Specifically, the deterioration of the superstructure of Bridge No. 150035 and Bridge No. 150039 are such that they are scheduled for replacement within the next few months. As with most corroded reinforced and prestressed concrete structures, the extent of the deterioration that cannot be visually observed beyond the concrete cover depth is of greatest concern. For example, it is not known to what extent the layers of prestressing strands within the section have deteriorated. The bottom layer of prestressing is clearly deteriorated in several members, however, the condition of the strands above this lowermost layer is unknown. Similarly, the condition of the stirrups and strands behind large areas of delaminated concrete is not known from visual inspection alone. To address this issue a research program has been developed that will (i) critically evaluate existing non-destructive techniques used to quantify the extent of corrosion in existing in-service members, and that can be readily adopted by NCDOT maintenance engineers and contracted bridge inspectors, (ii) undertake detailed field investigations of the two bridges scheduled for superstructure replacement creating a comprehensive photographic record of the degrees and extent of deterioration, (iii) implement the non-destructive techniques on eight deteriorated prestressed concrete cored slab units identified and taken directly from the in-service bridges in order to evaluate their effectiveness and develop protocols for future use, and (iv) test the eight units to destruction in three-point bending to experimentally quantify and observe their failure mode and residual capacity. A unique feature of this research program is the direct correlation that will be established between field measurements (including both visual inspection and non-destructive testing), laboratory testing, and destructive inspection of in-service prestressed concrete cored slab units commonly used by NCDOT that were fabricated with materials common to NC and aged in an environment typical of coastal NC. The outcomes of which will enable NCDOT personnel to assess the residual strength and performance of other similar in-service bridges so that informed decisions may be made regarding maintenance, repair and replacement priorities.

Prestressed concrete cored deck slabs are a common bridge component used by the NCDOT for spans as long as 60 ft. Cored deck slabs efficiently serve as both the bridge superstructure and the deck when placed side-by-side, spanning between bents. Bridges utilizing cored slabs are often subjected to deicing salts, or may be located in the vicinity of saltwater or brackish water. When exposed to moisture and salts, the prestressing and mild steel reinforcement inside any reinforced concrete structure will deteriorate, reducing structural capacity. The problem of corrosion can be exacerbated in cored deck slabs due to the potential for corrosive products to penetrate the cores via the top of the slab, causing corrosion to develop from the interior of the structure. This internal corrosion would not likely be spotted by a visual inspection. Fiber-reinforced polymer (FRP) materials have the potential to improve the durability of cored deck slabs when used as a replacement for traditional mild steel and prestressing strands. FRP strands and bars are a proven non-metallic alternative to steel that have the advantage of being highly corrosion resistant. In addition to their corrosion resistance, FRP materials can offer strengths up to 3-5 times stronger than mild steel at approximately 1/5th the density. The proposed research project will assess the suitability of replacing steel prestressing strands in cored deck slabs with carbon fiber composite cable (CFCC) strands. In addition, the proposed research will investigate using glass fiber reinforced polymer (GFRP) bars as a replacement for conventional mild steel reinforcement in cored deck units (stirrups and supplemental mild steel reinforcement). Producing a cored deck slab with CFCC strands and conventional mild steel transverse reinforcement would negate many of the benefits offered by the CFCC strands. Thus, an all-FRP solution will be developed, validated with full-scale laboratory testing, and documented with design recommendations and examples. Specifically, the research team will: ?h Conduct a detailed literature review to determine available test data, design recommendations, and guidelines that may be relevant for the use of CFCC strands and GFRP reinforcement in cored deck slabs. ?h Develop an approach for designing cored deck slabs using FRP strands and transverse reinforcement. ?h Design several sample cored deck slabs using the developed approach, assuring that all designs remain compatible with conventional production techniques and NCDOT standard details. ?h Develop designs for a series of cored deck slab specimens to be tested experimentally to validate the concept of using FRP for both prestressed and conventional reinforcement. ?h Develop a system for producing FRP-reinforced cored deck slabs using conventional fabrication techniques. In particular, details related to stressing CFCC strands will be implemented. ?h Document the production of full-scale cored deck specimens. ?h Conduct full-scale laboratory testing and analyze the test results. ?h Document the research program in a technical report, including design recommendations and an implementation plan. The outcomes of this research project will provide the NCDOT with the tools required to design and evaluate the performance of FRP-reinforced prestressed cored slabs. The enhanced durability of such systems can be evaluated in life-cycle cost analyses to quantitatively compare alternatives.

Memberships:Precasted double tees with thin stems are a widely used and highly successful floor member in parking structures and other buildings. Frequently, the end supports are dapped such that the bottom of the double tee is level with the bottom of the inverted tee or ledge beam on which it is supported. The dapped connection detail is especially important at cross overs between spans in parking structures because the overall structural depth and floor-to-floor height need not be increased where the double tee is supported by and inverted tee beam. While the title of the research project implies the primary objective is the ?development of rational design methodologies,? the RFP also discusses the need for industry standard details for dapped double tees. Both objectives are appropriate. Rational design methodologies are needed to proportion reinforcement in the dapped end, and standard industry details are needed to assure effectiveness and constructability. Thus, the objective of this research is twofold: 10 develop rational methodologies for proportioning key reinforcements in dapped end double tees, and 2) develop standard details that been rigorously reviewed by industry experts and have proven to be effective by extensive analyses and tests.

During covert operations, the Army may be required to breach a concrete wall or structure using a controlled explosion. To choose the most effective charge size, it is vital to perform an in-the-field estimation of the strength, thickness, and reinforcement locations of the concrete wall. The current methods utilized are based on conventional concrete materials; however, the recent advances (such as Reactive powder concrete materials) in manufacturing of high strength concrete materials may increase the uncertainty of the methods. Therefore, the Army is seeking a non-destructive evaluation (NDE) system which can connect with currently fused Army systems and estimate compressive strength, the wall thickness, existence of metal substructure, and an estimation of the density of reinforcements. Phase I of this project will demonstrate how the portable, rugged, and field-ready NLA Recon® can meet the aforementioned Army requirements using the NDE methods of ultrasonic pulse velocity (UPV), impact echo, pulse echo and ultrasonic attenuation. Using these methods, NLA Diagnostics will demonstrate the ability of the NLA Recon® to detect wall thickness, compressive and tensile strength, presence and density of fiber reinforcement, and location and density of steel bar reinforcement. Experimental program of this project will be performed at North Carolina State University.