Accelerated Determination of ASR Susceptibility During Concrete Prism Testing Through Nonlinear Resonance Ultrasonic Spectroscopy
The alkali-silica reaction (ASR) is one form of deterioration that may significantly reduce the service life of concrete structures. Currently, ASR susceptibility of aggregate sources is most commonly assessed through length change in the concrete or mortar specimens over time while subjected to standardized acceleratory conditions. The standard concrete prism test is considered the most representative of field performance.However, one significant practical drawback of that test is its long duration, which is 1 year to assess aggregate reactivity and 2 years to assess mitigation measures. The standard accelerated mortar bar tests (AMBT) are considerably quicker to perform but have not proven reliable in all cases, leading some agencies and owners to implement alternate test durations and/or expansion limits.
Compression Response of a Rapid-Strengthening Ultra-High Performance Concrete Formulation
Ultra-high performance concrete (UHPC) has garnered interest from the highway infrastructure community for its ability to create strong, robust, field-cast connections between prefabricated structural components. The objective of this research was to evaluate the compressive mechanical response of a rapid-strengthening UHPC formulation exposed to a range of curing conditions. The results of the research effort are provided herein.
Curl and Warp Analysis of the LTPP SPS-2 Site in Arizona
This study examined the roughness and roughness progression of 21 test sections on the LTPP SPS-2 site in Arizona over the first 16 years of the experiment. The site included 12 test sections from the standard experiment and 9 supplemental test sections selected by the Arizona Department of Transportation.
Design and Construction of Field-Cast UHPC Connections
Advancements in the science of concrete materials have led to the development of a new class of cementitious composites called ultra-high performance concrete (UHPC). UHPC exhibits mechanical durability properties that make it an ideal candidate for use in developing new solutions to pressing concerns about higwhay infrastructure deterioration, repair, and replacement. Field-cast UHPC details connecting prefabricated structural elements used for bridge construction have proven to be an applicaiton that has captured the attention of owners, specifiers, and contractors across the country. These connections can be simpler to construct and can provide more robust long-term performance than connections constructed through conventional methods. This document provides guidance on the design and deployment of field-cast UHPC connections.
Provides information regarding material constituents for UHPC matrix designs and detailed procedures for High Performance Concrete
Evaluation of High-Volume Fly Ash Mixtures (Paste and Mortar Components) Using a Dynamic Shear Rheometer adn an Isothermal Calorimeter
The primary objective of this study was to develop a rationale for using a dynamic shear rheometer and an isothermal calorimeter as practical, quick scanning tools for the following purposes, to predict and assess early-age behavior of concrete mixtures containing different types and levels of cement and fly ash, to identify incompatible blends and to verify performance.
Lightweight Concrete: Development of Mild Steel in Tension
Concrete with a unit weight between that of traditional lightweight concrete (LWC) and normal weight concrete (NWC) is not covered in the American Association of State Highway Transportation Officials (AASHTO) LRFD Bridge Design Specifications. This research program includes a significant number of bond strength tests on this type of concrete. The results from this research project are included in a database that covers a broader range of unit weights in order to determine trends for LWC as a function of unit weight. New design expressions for the development length of mild steel in tension are proposed for LWC that include a modification factor for LWC based on unit weight.
Lightweight Concrete: Mechanical Properties
There is a limited amount of test data on the mechanical properties of high-strength lightweight concrete (LWC) with a concrete unit weight (wc) between that of traditional LWC and normal weight concrete (NWC). Concrete with a wc in this range is also not covered in the American Association of State Highway and Traffic Officials (AASHTO) Load-and-Resistance Factor Design (LRFD) Bridge Design Specifications.(2) This research program includes a significant number of mechanical property tests on this type of concrete. The results from this research project are included into a LWC database that covers a range of wc to determine trends for LWC as a function of wc. New design expressions for mechanical properties are proposed for LWC as a function of wc as opposed to the more common method of using concrete constituent materials. The design expressions represent potential revisions to the AASHTO LRFD Bridge Design Specifications relating to the mechanical properties of LWC.(2). FHWA.
Rationale For PP65 Prescriptive Approach
In 2011, American Association of State Highway and Transportation Officials published PP65-11 “Standard Practice for Determining the Reactivity of Concrete Aggregates and Selecting Appropriate Measures for Preventing Deleterious Expansion in New Concrete Construction.” PP65-11 provides two approaches for selecting preventive measures: 1) a performance approach based on laboratory testing, and 2) a prescriptive approach based on a consideration of the reactivity of the aggregate, type and size of structure, exposure conditions, and the composition of cementitious materials being used. The options for preventive measures included in the prescriptive approach of PP65-11 are to 1) control the alkali content of the concrete to a maximum allowable level; 2) use a minimum level of supplementary cementitious material or combination of SCMs; or 3) use a combination of these two options.
This report shows the study that investigates the correlation of the SR tst with the widely used RCPT in evaluation concretes' ability to resist chloride penetration, including HVFA mixtures.
Ultra-High Performance Concrete: A State-of-the-Art Report for the Bridge Community
This report presents the state of the art in ultra high performance concrete (UHPC) with regard to uses in the highway transportation infrastructure. Compiled from hundreds of references representing research, development, and deployment efforts around the world, this report provides a framework for gaining a deeper understanding of UHPC as well as a platform from which to increase the use of this class of advanced cementitious composite materials.