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.

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.

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.