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PMSS Project Details

 

Project ID:FHWA-PROJ-11-0022
Project Name: Characterization of Fresh and Hardened Cementitious Mixtures for Sustainable Pavements
Status: Active
Contact:
Last Name:Ardani
First Name:Ahmad
Telephone:202-493-3422
E-mail:ahmad.ardani@dot.gov
Office: Office of Infrastructure Research and Development
Team:Pavement Materials Team
Roadmap/Focus area(s): Infrastructure Research and Technology Strategic Plan and Roadmap
Project Description:A series of paste and mortar mixtures containing different fly ashes and replacement levels ranging from 20% to 60% with high and low alkali cement and with high and low carbon content Class F ash were evaluated. Tests included compressive strength at different ages, flow, setting time, isothermal calorimetry, and evaluating rheological properties. In general, for the same water-binder ratio and replacement level, Class C fly ash mixtures presented higher strength but a delayed setting when compared with Class F fly ash mixtures. Class C fly ash mixtures presented lower viscosity and lower yield stress, as well as higher flow. Viscosity and yield stress increased with the increase of fly ash content for both fly ashes. To address the excessive delays in setting times that are normally associated with high volume fly ash (HVFA) mixes, the authors are planning on using 5 to 10 percent replacement of fly ash with nano size to very fine limestone. The primary objective of this study is to develop performance- based specifications for incorporation of fly ash in concrete mixes and using dynamic shear rheometer (DSR) and calorimeter to characterize their behaviors. The ultimate goal is to take the guesswork out of using fly ash and encourage State departments of transportation (DOTs) to use them with more confidence in a variety of applications.
Laboratories: Concrete Laboratory
Chemistry Laboratory
Aggregate and Petrographic Laboratory
Start Date: February 1, 2011
End Date: December 31, 2017
Goals:
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:
  • Predict and assess early-age behavior of concrete mixtures containing different types and levels of cement and fly ash.
  • Identify incompatible blends.
  • Verify performance.
Background Information: As the concept of sustainability gains momentum, many transportation agencies, including State DOTs, the concrete industry, and academia, are exploring ways to make concrete more sustainable and environmentally friendly. Supplementary cementitious materials (SCMs) such as fly ash, slag cement, and natural pozzolans have been used by many State DOTs/transportation agencies in achieving sustainability through:Improved concrete performance and durability.Improved rheological properties (workability, finishability, reduced water demand).Increased use of by products.Reduced carbon dioxide footprint associated with the production of cement.Reduced overall cost of concrete.Although the use of fly ash has been steadily on the rise over the last couple of decades because of the benefits they afford, their use in highway applications still poses many unanswered questions due to the fact that there is no sound, systematic protocol that can be used to routinely evaluate and proportion fly ash into concrete mixtures while ensuring that performance and durability are not compromised.
Test Methodology: Characterization of cementitious materials using Dynamic Shear Rheometer (DSR), Isothermal Calorimeter, x-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopes (SEM), thermogravimetric analysis (TGA), and petrographic analysis.
Expected Benefits:The expected benefit is the development of environmentally friendly rigid pavement that is sustainable and cost effective.
Deliverables:Name: Guidelines and Protocol.
Product Type(s): Research report, Article, Promotional materials, Techbrief, Technical report
Description: The final product of this study is to develop a quality assurance protocol that can be used for characterizing/assessing the suitability of supplementary cementitious materials (SCMs), in particular fly ash, for use in paving concrete.
Keywords: Durability
Infrastructure
Cement
Research
Construction
Rehabilitation
Maintenance
Pavements
Subject Areas: Materials
Pavements
Research