Download or read book Effect of Larger Sized Coarse Aggregates and Microsilica on Environmental Properties of Portland Cement Concrete Pavements and Structures written by Kristina M. Cannady and published by . This book was released on 2009 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project examines whether the addition of microsilica or the use of aggregates with maximum size above 1.5 in., in concrete mixes prepared by the Ohio Department of Transportation (ODOT) for bridge decks and highway pavements, can have adverse effects on the durability properties of such structures. The behavior of several series of concrete specimens has been monitored over a period exceeding a year, and measurements of shrinkage, creep, abrasion, rapid chloride permeability, and freeze/thaw resistance have been recorded. Such data are evaluated to determine if altering the standard ODOT concrete mix design on either end of the gradation spectrum can indeed lower the cement content and increase its cost effectiveness and efficiency. It was found that different coarse aggregate gradations did not impact significantly the environmental properties of concrete examined. Variability issues related to the testing protocols themselves confounded the differences observed. These results indicate that larger sized coarse aggregates can be used for pavements and highway structures without significantly compromising the environmental properties of the concrete, and afford concrete producers more flexibility in creating cost-effective and cement-efficient mixes. It was found earlier in State Job No. 14800(0) that the compressive and flexural strengths of abused microsilica did not differ much from that of densified microsilica. This conclusion is brought into question, at least in the case of abused microsilica, by the rapid chloride permeability results obtained. Nonetheless, all values obtained are within the limits termed as low or moderate by the prevailing specifications.