Effect of Larger Sized Coarse Aggregates on Mechanical Properties of Portland Cement Concrete Pavements and Structures

Effect of Larger Sized Coarse Aggregates on Mechanical Properties of Portland Cement Concrete Pavements and Structures
Author:
Publisher:
Total Pages: 172
Release: 2006
Genre: Pavements, Concrete
ISBN:

ODOT is continually searching for ways to improve the cost efficiency of Portland cement concrete without sacrificing concrete strength and stiffness. Because Portland cement is easily the most costly material used in normal concrete, limiting the amount of cement used is the quickest way to achieve cost effectiveness. In addition, limiting the cement content will also help to prevent dimensional instabilities in concrete such as shrinkage and creep. The use of larger sized coarse aggregates may be useful in limiting cement content, yet larger sized coarse aggregates may also decrease concrete strength by weakening the aggregate-cement paste bond. In many transportation structures, such as pavements, concrete strength is not critical, as dimensional stability, porosity, and durability play a more important role. It is possible, therefore, that larger sized coarse aggregates can reduce the cement content and improve these properties. Laboratory research is needed to determine if larger sized coarse aggregates can improve cement efficiency without reducing concrete strength.

Aggregates in Concrete

Aggregates in Concrete
Author: Mark Alexander
Publisher: CRC Press
Total Pages: 448
Release: 2010-02-25
Genre: Technology & Engineering
ISBN: 0203963695

Bringing together in one volume the latest research and information, this book provides a detailed guide to the selection and use of aggregates in concrete. After an introduction defining the purpose and role of aggregates in concrete, the authors present an overview of aggregate sources and production techniques, followed by a detailed study of their physical, mechanical and chemical properties. This knowledge is then applied to the use of aggregates in both plastic and hardened concretes, and in the overall mix design. Special aggregates and their applications are discussed in detail, as are the current main specifications, standards and tests.

Effect of Mineral Admixtures and Coarse Aggregate Size on Compressive Strength and Freeze-thaw Resistance of Portland Cement Concrete

Effect of Mineral Admixtures and Coarse Aggregate Size on Compressive Strength and Freeze-thaw Resistance of Portland Cement Concrete
Author: Thomas Francis McDonnell
Publisher:
Total Pages: 95
Release: 2007
Genre: Civil engineering
ISBN:

The Ohio Department of Transportation (ODOT) has developed a series of portland cement concrete mix designs for use on all infrastructure projects throughout the state. The standard forms of these mix designs differ in terms of the compressive strength they are expected to achieve after a curing period of 28 days. Because of the state's climate, one requirement common to every mix design used by ODOT, however, is high resistance to damage from cycles of freezing and thawing. Options currently permitted by ODOT for varying these mix designs include the use of different coarse aggregate sizes and substitution of a portion of the portland cement with additional fine aggregate or one of three mineral admixtures. These admixtures include fly ash, ground granulated blast furnace slag (GGBFS) and micro silica. All of these admixtures are produced from materials that are recycled from processes unrelated to concrete production. These processes include coal fired steam generation, pig iron production and silicon manufacturing.The objective of the research presented in this thesis was to evaluate the effect that mineral admixtures and coarse aggregate on ODOT Class C (4,000 psi) concrete in terms of compressive strength and freeze-thaw resistance. These evaluations were performed through laboratory testing of specimens cast from individual mixes. Information is provided on the materials used to create a concrete mix, as well as a brief summary of the development of mix design methodologies. Detailed descriptions of the freeze-thaw resistance and compressive strength testing are also included, with a discussion of the associated mechanisms of failure. Conclusions are offered based on trends observed from analysis of the test data. In general, the results of the testing indicate that freeze-thaw resistance is not detrimentally influenced by the addition of mineral admixtures or the size of the coarse aggregate used. Each of the mineral admixtures does affect the resulting concrete mix in slightly different ways, and one may be more desirable than another based on required performance. In addition, all of the mix designs studied attained average compressive strengths in excess of the target value of 4,000 psi.