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

Download or read book Effect of Larger Sized Coarse Aggregates on Mechanical Properties of Portland Cement Concrete Pavements and Structures written by and published by . This book was released on 2006 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Book Effect of Larger Sized Coarse Aggregates and Microsilica on Environmental Properties of Portland Cement Concrete Pavements and Structures

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.

Book Challenges Opportunities and Solutions in Structural Engineering and Construction

Download or read book Challenges Opportunities and Solutions in Structural Engineering and Construction written by Nader Ghafoori and published by CRC Press. This book was released on 2009-10-29 with total page 1032 pages. Available in PDF, EPUB and Kindle. Book excerpt: Challenges, Opportunities and Solutions in Structural Engineering and Construction addresses the latest developments in innovative and integrative technologies and solutions in structural engineering and construction, including: Concrete, masonry, steel and composite structures; Dynamic impact and earthquake engineering; Bridges and

Book The Effects of Mix Design on the Design of the Pavement Structure when Utilizing Recycled Portland Cement Concrete as Aggregate

Download or read book The Effects of Mix Design on the Design of the Pavement Structure when Utilizing Recycled Portland Cement Concrete as Aggregate written by James Stanley Fergus and published by . This book was released on 1980 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Preliminary Research Findings on the Effect of Coarse Aggregate on the Performance of Portland Cement Concrete Paving

Download or read book Preliminary Research Findings on the Effect of Coarse Aggregate on the Performance of Portland Cement Concrete Paving written by B. Frank McCullough and published by . This book was released on 1993 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report focuses on aggregates used in the construction of continuously reinforced concrete pavements (CRCP). Specific chapters address (1) past research regarding aggregates used in CRCP, (2) field and laboratory investigations of CRCP, and (3) CRCP behavior and distress. The report reviews such topics as spalling and punchout distresses in continuously reinforced and jointed pavements, aggregate shape characterization using fractals, and the determination of sawcut depth using fractal analysis. Some of these activities relate directly to improving pavement performance, regardless of aggregate type used for construction.

Book Optimum Size Coarse Aggregate for Portland Cement Concrete Paving

Download or read book Optimum Size Coarse Aggregate for Portland Cement Concrete Paving written by American Concrete Paving Association. Materials and Mix Design Technical Subcommittee and published by . This book was released on 1972 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Evaluation of High Absorptive Materials to Improve Internal Curing of Low Permeability Concrete

Download or read book Evaluation of High Absorptive Materials to Improve Internal Curing of Low Permeability Concrete written by Norbert J. Delatte and published by . This book was released on 2007 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Early age cracking of bridge decks is a national problem, and may substantially reduce service lives and increase maintenance costs. Cracking occurs when the tensile stress exceeds the tensile strength of the concrete. This is a time-dependent phenomenon, since both the stress and strength change at early ages. Moisture loss increases stress (with increasing shrinkage) and impairs strength gain. Internal curing is one method that has been suggested to reduce early age bridge deck cracking, particularly of concretes with low water to cementitious materials (w/cm) ratios. Many state highway agencies have implemented high performance concrete (HPC) for bridge decks. The low permeability of HPC is used to protect reinforcing steel and prevent corrosion. However, if the concrete cracks, then the protection may be greatly diminished. Transverse cracks due to concrete shrinkage allow water and corrosive chemicals to quickly reach the reinforcing steel causing corrosion and shortening the lifespan of the bridge deck. Reducing shrinkage cracking has been the focus of recent research into mitigation strategies. One unintended consequence of the use of high performance concrete may be early-age cracking. Field studies have shown that, in some cases, high performance concrete bridge decks have cracked less than a year after placement. The use of internal curing to reduce autogenous shrinkage was investigated in this study. One method of internal curing was through the use of coarse aggregates with high absorption capacities. Another method discussed is the use of a partial replacement of the fine aggregate with a structural lightweight aggregate with a very high absorption capacity. Bridge deck cracking is also affected by the nominal maximum size coarse aggregate. The effect on shrinkage with increasing size is discussed. ODOT's District 12, located in Northeastern Ohio, found in an investigation of 116 HPC bridge decks placed between 1994 and 2001 that bridges with little or no cracking used coarse aggregate with an absorption> 1 %, while 75 % of bridges with unacceptable cracking used coarse aggregate with absorption 1 %. This report discusses the laboratory investigation of the field results to determine the better ways to prevent bridge deck cracking-- internal curing or paste reduction by using an aggregate blend. The laboratory investigation found that the strongest effect on cracking was due to the replacement of a small maximum size coarse aggregate with an optimized coarse aggregate gradation. Increasing the coarse aggregate absorption level from

Book The Effect of Large Size Aggregate on the Strength and Wearing Qualities of Concrete

Download or read book The Effect of Large Size Aggregate on the Strength and Wearing Qualities of Concrete written by Walter James Connell and published by . This book was released on 1922 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: