Optimized Aggregate Gradation Concrete Mixtures with Cementitious Material Reduction

Search for this publication on Google Scholar
Theilgard, P. (2022). Optimized Aggregate Gradation Concrete Mixtures with Cementitious Material Reduction. Unc Charlotte Electronic Theses And Dissertations.
Download PDF

Analytics

20 views ◎
7 downloads ⇓


Abstract

Optimized aggregate gradation concrete mixtures with reduced cementitious materials are emerging in concrete mixture design in an effort to reduce costs and CO2 emissions while improving the concrete’s durability characteristics. Optimizing the aggregates enables lowered cementitious content and results in reduced permeability and shrinkage while also reducing costs. The Tarantula Curve, named by Oklahoma State University, describes a distribution of particle sizes that maximizes the packing of the aggregates while maintaining workability. The goal of this research was to evaluate the Tarantula Curve’s optimized aggregate gradation in concrete mixtures with a ten percent reduction in cementitious materials, using materials typical for use in concrete bridge and pavement construction specified by the North Carolina Department of Transportation (NCDOT). Twenty-one different optimized aggregate gradation concrete mixtures representative of structural and pavement type mixtures used by the NCDOT were produced and compared to twenty-one similar companion mixtures with non-optimized aggregate gradations. Using materials sourced from the same quarries and suppliers, the gradations were optimized using the Tarantula Curve. The fresh properties and hardened mechanical and durability properties were evaluated by the research team. The test set included variations in the water-cement ratio, cementitious material content, and fly ash replacement percentage. The mixtures were proportioned to encompass a range of designs typical of concretes used in structural and pavement construction. Both non-optimized and optimized aggregate gradation mixtures demonstrated consistent trends with increased mechanical performance as the w/cm ratio decreased. Optimized aggregate gradation mixtures did not show a significant decrease in mechanical when compared to the non-optimized aggregate gradation companion mixtures. Preliminary measurements of surface resistivity of the optimized aggregate gradation mixtures indicated a potential decrease in expected durability. However, additional experimentation is required to determine if the results of the electrical resistivity tests can be interpreted the same for optimized and non-optimized aggregate gradation mixtures and whether lower resistance of optimized mixtures is linked to lesser durability.

Details
Author

Theilgard, Peter

Title

Optimized Aggregate Gradation Concrete Mixtures with Cementitious Material Reduction

Physical Description

1 online resource (178 pages) : PDF

Date

2022

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

Optimized aggregate gradation concrete mixtures with reduced cementitious materials are emerging in concrete mixture design in an effort to reduce costs and CO2 emissions while improving the concrete’s durability characteristics. Optimizing the aggregates enables lowered cementitious content and results in reduced permeability and shrinkage while also reducing costs. The Tarantula Curve, named by Oklahoma State University, describes a distribution of particle sizes that maximizes the packing of the aggregates while maintaining workability. The goal of this research was to evaluate the Tarantula Curve’s optimized aggregate gradation in concrete mixtures with a ten percent reduction in cementitious materials, using materials typical for use in concrete bridge and pavement construction specified by the North Carolina Department of Transportation (NCDOT). Twenty-one different optimized aggregate gradation concrete mixtures representative of structural and pavement type mixtures used by the NCDOT were produced and compared to twenty-one similar companion mixtures with non-optimized aggregate gradations. Using materials sourced from the same quarries and suppliers, the gradations were optimized using the Tarantula Curve. The fresh properties and hardened mechanical and durability properties were evaluated by the research team. The test set included variations in the water-cement ratio, cementitious material content, and fly ash replacement percentage. The mixtures were proportioned to encompass a range of designs typical of concretes used in structural and pavement construction. Both non-optimized and optimized aggregate gradation mixtures demonstrated consistent trends with increased mechanical performance as the w/cm ratio decreased. Optimized aggregate gradation mixtures did not show a significant decrease in mechanical when compared to the non-optimized aggregate gradation companion mixtures. Preliminary measurements of surface resistivity of the optimized aggregate gradation mixtures indicated a potential decrease in expected durability. However, additional experimentation is required to determine if the results of the electrical resistivity tests can be interpreted the same for optimized and non-optimized aggregate gradation mixtures and whether lower resistance of optimized mixtures is linked to lesser durability.

Genre

masters theses

Subjects--Topics

Civil engineering
Materials science

Degree

M.S.

Subject Area

Civil Engineering

Advisor(s)

Tempest, Brett

Committee Members

Cavalline, Tara
Whelan, Matthew

Degree Note

Thesis (M.S.)--University of North Carolina at Charlotte, 2022.

Rights Statement

This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). For additional information, see http://rightsstatements.org/page/InC/1.0/.

Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

Theilgard_uncc_0694N_13155

Permalink

http://hdl.handle.net/20.500.13093/etd:3009