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Author : Eric Charles Mack
Release : 2006
Genre : Concrete
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Using Internal Curing to Prevent Concrete Bridge Deck Cracking by : Eric Charles Mack
Download or read book Using Internal Curing to Prevent Concrete Bridge Deck Cracking written by Eric Charles Mack. This book was released on 2006. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Xuhao Wang
Release : 2019
Genre : Bridges
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Extended Life Concrete Bridge Decks Utilizing Internal Curing to Reduce Cracking by : Xuhao Wang
Download or read book Extended Life Concrete Bridge Decks Utilizing Internal Curing to Reduce Cracking written by Xuhao Wang. This book was released on 2019. Available in PDF, EPUB and Kindle. Book excerpt: With the ongoing concern about premature cracking of concrete bridge decks that reduces the service life of bridges and results in increased maintenance and replacement costs, this work aimed at assessing the benefits of using lightweight fine aggregate (LWFA) in concrete mixtures to assist the Ohio Department of Transportation (ODOT) in preparing a specification to increase the probability of achieving crack-free, long-lasting bridge decks. A laboratory testing program led to a recommended mix design for implementation on a bridge construction project in Ohio. The design included the use of 50% slag cement and LWFA for internal curing. Construction of two bridge decks involved a control using a conventional mix design and the other containing the recommended mixture. The decks were instrumented and load tested shortly after construction and inspected one year after placement. No differences in structural performance were noted, but there were far fewer cracks in the test deck compared to the control. A life-cycle cost analysis was also conducted and shown that the premium for the recommended mixture would be recovered in reduced maintenance over the life of the bridge.
Author : Norbert J. Delatte
Release : 2007
Genre : Bridges
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Evaluation of High Absorptive Materials to Improve Internal Curing of Low Permeability Concrete by : Norbert J. Delatte
Download or read book Evaluation of High Absorptive Materials to Improve Internal Curing of Low Permeability Concrete written by Norbert J. Delatte. This book was released on 2007. 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
Author : Daniel Robert Goad
Release : 2013
Genre : Concrete
Kind : eBook
Book Rating : 659/5 ( reviews)
Book Synopsis Mitigating Shrinkage Cracking of Concrete in Bridge Decks Through Internal Curing by : Daniel Robert Goad
Download or read book Mitigating Shrinkage Cracking of Concrete in Bridge Decks Through Internal Curing written by Daniel Robert Goad. This book was released on 2013. Available in PDF, EPUB and Kindle. Book excerpt: As the need for durable, long lasting infrastructure increases, new methods and techniques are being explored to prolong the service life of roads and bridges. One method to reduce shrinkage and early age cracking in concrete is internal curing. Internal curing supplies water to concrete, using pre-wetted lightweight aggregate (LWA), as needed throughout the process of hydration to reduce self desiccation, which leads to cracking. This research project analyzed two types of coarse LWA, expanded clay and expanded shale. The mixtures were developed specifically for use in bridge decks and adhered to specifications of the Arkansas State Highway and Transportation Department (AHTD). The concrete mixtures contained LWA at rates of 0, 100, 200, and 300 lb/yd3. The research was divided into two phases. The first phase measured autogenous and drying shrinkage in both plastic and elastic states using embedded vibrating wire strain gages (VWSG) cast in concrete prisms. The expanded clay LWA mixtures, with the 300 lb. replacement rate yielding the best results, were most effective in reducing shrinkage. Compressive strength decreased as the amount of LWA included in the mixture increased. However, all mixtures surpassed the 28 day compressive strength specified by AHTD. The second phase of the research project measured plastic shrinkage cracking in thin concrete test slabs. Methods and materials were investigated to produce consistent plastic shrinkage surface cracks of the concrete slabs. The extent of plastic shrinkage that occurred was quantified by measuring the total crack area of the test slabs. Implementation of 300 lb. of expanded clay LWA did not reduce the crack lengths, but did reduce the average crack widths experienced by the test slabs due to plastic shrinkage.
Author : Waleed Khalid Hamid
Release : 2020
Genre : Bridges
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis Behavior of Bridge with Internally Cured Concrete Deck Under Environmental and Truck Loading by : Waleed Khalid Hamid
Download or read book Behavior of Bridge with Internally Cured Concrete Deck Under Environmental and Truck Loading written by Waleed Khalid Hamid. This book was released on 2020. Available in PDF, EPUB and Kindle. Book excerpt: The long-term performance of a bridge deck depends on its resistance to bridge cracking. Most of these cracks are initiated at the early age. Early age cracking of bridge decks is a typical issue in the U.S. that reduces bridge service life. Therefore, internally cured concrete (ICC) has been used in some states to reduce or eliminate the development of cracks in reinforced concrete decks. In this study, the early age behavior of ICC deck and the effect of the internal curing on the long-term behavior of the bridge was measured and evaluated in the laboratory and field for newly adjacent constructed bridge, which were located on Route 271 in Mayfield, Ohio. Two different types of concrete mixtures were utilized for the decks: conventional concrete (CC) and internally cured concrete (ICC). Firstly, the ICC and CC mixtures were examined in the laboratory in terms of a mechanical properties test, a plastic shrinkage test, a free shrinkage test, and a restrained shrinkage test. Second, the field behavior of an ICC deck and an adjacent CC deck during their early age and long-term performance were evaluated. Also, the shrinkage development for both decks was examined during the very early age. Instrumentation was used to measure the concrete and reinforcement strains and the temperature in both bridges. The instrumentation and results for both bridges are discussed. Laboratory results indicated that using pre-wetted lightweight concrete in the concrete mixture led to decreased density, coefficient of thermal expansion, and free shrinkage strain, and increased tensile strength and cracking time of concrete compared to conventional concrete. In the field, from the early age test, it was observed that the time to develop concrete shrinkage was approximately 5-6 hours after casting the deck of the ICC and the CC.
