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.

Effects of Aggregate Gradation on Properties of Masonry Cement and Portland Cement-Lime Masonry Mortars

Effects of Aggregate Gradation on Properties of Masonry Cement and Portland Cement-Lime Masonry Mortars
Author: CE. Buchanan
Publisher:
Total Pages: 18
Release: 1990
Genre: Aggregate
ISBN:

Eight laboratories participated in a round robin to evaluate variations in aggregate gradation when tested using Masonry cement and Portland cement-lime masonry mortars. A control gradation was used which,was near the center of C144 gradation limits and five other gradations were used which tested the limits of C144. It appears from the data that the limits on C144 can be broadened without appreciably altering the safety built in for user protection. Although not part of the original test program, a study was made of the yield of the various mortars produced, and it was determined that the masonry cements had on average a 5.3% increase in volume over the Portland cement-lime mixes.

Computer Software Program for On-line Process Control of Production of Portland-cement Concrete

Computer Software Program for On-line Process Control of Production of Portland-cement Concrete
Author: Steven A. Ragan
Publisher:
Total Pages: 190
Release: 1997
Genre: Cement plants
ISBN:

This report presents the results of a research program to develop a computer software program, SmartPlant, which could reduce the cost of concrete mixtures and increase construction productivity by minimizing the adverse effects of materials and mixture variations upon construction operations. SmartPlant is comprised of five component programs. Most attention was given to seeMIX, the mixture proportioning program. A laboratory evaluation of this program was conducted in which simulated paving, structural, and mass concrete mixtures were proportioned using current American Concrete Institute (ACI) proportioning practices and seeMIX technology. Two field evaluations of seeMIX were also conducted. SeeMAT-A, the aggregate database program, was also evaluated under field conditions on two occasions. SeeMAT-C, the cement database program, and seeMAT-P, the pozzolan database program, were evaluated in the laboratory. SeeSTAT, the statistical database program was not evaluated. The results indicated that seeMIX mixture proportioning technology can proportion concrete mixtures having fresh and hardened properties equal to, and in some instances superior to, current ACI proportioning practices when richer mixtures, such as those used in paving or structural applications, are being proportioned. SeeMIX was less effective in proportioning lean mass concrete mixtures. SeeMAT-A, seeMAT-C, and seeMAT-P performed well and were judged to be useful tools, both as components of SmartPlant and as stand-alone tools. While the individual components of SmartPlant were evaluated, numerous logistical and technical problems prevented the evaluation of a fully automated SmartPlant system either in the laboratory or the field.