Download or read book Reducing Cracks in Concrete Bridge Decks Using Shrinkage Reducing Admixture written by Harikrishnan Nair and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Restrained shrinkage cracking of concrete bridge decks creates a significant durability problem. Major admixture suppliers in the United States have introduced a new category of chemical admixtures called shrinkage reducing admixtures (SRAs). SRAs work by reducing the surface tension of pore water and thereby decreasing the capillary stress and shrinkage induced by drying. Several studies have reported that using SRAs in concrete mixtures is one of the most effective ways of reducing shrinkage cracking. The purpose of this study was to investigate the effectiveness of SRAs in reducing drying shrinkage in Virginia Department of Transportation (VDOT) concrete mixtures and thus reducing cracks in bridge decks. Nine bridges located in VDOT's Northern Virginia, Staunton, and Fredericksburg districts were selected for study. Three different SRA products were used. With the exception of one mixture, the maximum cementitious content was limited to 600 lb/yd3. Fresh and hardened concrete properties were determined for each mixture, and field placement details were documented. The results showed that low cementitious concrete with SRA was effective in minimizing bridge deck cracking. The study showed that bridges with fewer and narrower cracks or no cracks can be constructed and that proper construction practices are needed to reduce bridge deck cracking. The study recommends the use of SRA with a lower cementitious content in VDOT bridge deck concrete mixtures. A VDOT special provision was developed for the future use of SRA in concrete mixtures.
Download or read book Reducing Cracks in Concrete Bridge Decks Using Shrinkage Reducing written by Harikrishnan Nair and published by . This book was released on 2016 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Restrained shrinkage cracking of concrete bridge decks creates a significant durability problem. Major admixture suppliers in the United States have introduced a new category of chemical admixtures called shrinkage reducing admixtures (SRAs). SRAs work by reducing the surface tension of pore water and thereby decreasing the capillary stress and shrinkage induced by drying. Several studies have reported that using SRAs in concrete mixtures is one of the most effective ways of reducing shrinkage cracking. The purpose of this study was to investigate the effectiveness of SRAs in reducing drying shrinkage in Virginia Department of Transportation (VDOT) concrete mixtures and thus reducing cracks in bridge decks. Nine bridges located in VDOT Northern Virginia, Staunton, and Fredericksburg districts were selected for study. Three different SRA products were used. With the exception of one mixture, the maximum cementitious content was limited to 600 lb/yd3. Fresh and hardened concrete properties were determined for each mixture, and field placement details were documented. The results showed that low cementitious concrete with SRA was effective in minimizing bridge deck cracking. The study showed that bridges with fewer and narrower cracks or no cracks can be constructed and that proper construction practices are needed to reduce bridge deck cracking. The study recommends the use of SRA with a lower cementitious content in VDOT bridge deck concrete mixtures. A VDOT special provision was developed for the future use of SRA in concrete mixtures.
Download or read book Low Shrinkage Mix Designs to Reduce Early Cracking of Concrete Bridge Decks written by Eric Simonton and published by . This book was released on 2020 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract Shrinkage cracking is reducing the service life of concrete bridge decks in South Dakota due to premature deterioration. In this study, the effects of varying concrete mix design parameters on autogenous and drying shrinkage was observed. Tested mix design changes include aggregate type (limestone and quartzite) and gradations (ASTM C33, Tarantula Curve, and 0.45 Power Curve), supplementary cementitious materials (fly ash), cementitious content, water-to-cementitious ratio, internal curing using saturated lightweight aggregates (expanded shale), and shrinkage reducing admixtures. These changes were evaluated for their effect on the shrinkage of paste, mortar, and concrete as measured by ASTM C1698 (autogenous shrinkage) and ASTM C157 (drying shrinkage). Fresh property tests, compressive strength, and electrical resistivity measurements were performed on each mix as well. A survey of state Department of Transportations revealed the current state-of-the-art practices on shrinkage reduction in bridge decks, including the use of admixtures, internal curing agents, and external curing methods.
Download or read book Mitigation Strategies for Early age Shrinkage Cracking in Bridge Decks written by Pizhong Qiao (Civil engineer) and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Early-age shrinkage cracking has been observed in many concrete bridge decks in Washington State and elsewhere around the U.S. The cracking increases the effects of freeze-thaw damage, spalling, and corrosion of steel reinforcement, thus resulting in premature deterioration and structural deficiency of the bridges. In this study, the main causes of the early-age cracking in the decks are identified, and concrete mix designs as a strategy to prevent or minimize the shrinkage cracking are evaluated. Different sources (eastern and western Washington) and sizes of aggregates are considered, and the effects of paste content, cementitious materials (cement, fly ash, silica fume, slag), and shrinkage reducing admixture (SRA) are evaluated. A series of fresh, mechanical and shrinkage property tests were performed for each concrete mix. The outcomes of this study identify optimum concrete mix designs as appropriate mitigation strategies to reduce or eliminate early-age shrinkage cracking and thus help minimize shrinkage cracking in the concrete bridge decks, potentially leading to longer service life.
Download or read book Mitigation Strategies for Early age Shrinkage Cracking in Bridge Decks written by Pizhong Qiao and published by . This book was released on 2010 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: Early-age shrinkage cracking has been observed in many concrete bridge decks in Washington State and elsewhere around the U.S. The cracking increases the effects of freeze-thaw damage, spalling, and corrosion of steel reinforcement, thus resulting in premature deterioration and structural deficiency of the bridges. In this study, the main causes of the early-age cracking in the decks are identified, and concrete mix designs as a strategy to prevent or minimize the shrinkage cracking are evaluated. Different sources (eastern and western Washington) and sizes of aggregates are considered, and the effects of paste content, cementitious materials (cement, fly ash, silica fume, slag), and shrinkage reducing admixture (SRA) are evaluated. A series of fresh, mechanical and shrinkage property tests were performed for each concrete mix. The outcomes of this study identify optimum concrete mix designs as appropriate mitigation strategies to reduce or eliminate early-age shrinkage cracking and thus help minimize shrinkage cracking in the concrete bridge decks, potentially leading to longer service life.
Download or read book Evaluation of Concrete Mix Designs to Mitigate Early age Shrinkage Cracking in Bridge Decks written by Jianmin Zhuang and published by . This book was released on 2009 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Eclipse Shrinkage Reducing Admixture Product Evaluation written by Irene K. Battaglia and published by . This book was released on 2008 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Controlling Early age Transverse Cracking in High Performance Concrete Bridge Decks written by Eric Ying Xian Liu and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reducing Shrinkage Cracking of Structural Concrete Through the Use of Admixtures written by Tarun R. Naik and published by . This book was released on 2006 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bridge Decks Mitigation of Cracking and Increased Durability written by Piyush Chaunsaki and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Use of Lightweight Concrete for Reducing Cracks in Bridge Decks written by and published by . This book was released on 2016 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cracks in bridge decks can be due to many factors related to environmental effects, chemical reactions, and structural loads. Careful selection of materials and mixture proportions can minimize cracking to some degree. To reduce cracking, shrinkage must be reduced; however, cracking also depends on other factors such as modulus of elasticity, creep, tensile strength, and restraint. A low modulus of elasticity and high creep help to minimize cracking. Lightweight concrete (LWC) has a lower modulus of elasticity, higher inelastic strains, a lower coefficient of thermal expansion, a more continuous contact zone between the aggregate and the paste, and more water in the pores of aggregates for continued internal curing when compared to normal weight concrete. These properties tend to reduce cracking in the concrete and are highly desirable in bridge decks. The Virginia Department of Transportation (VDOT) has been successfully using LWC in bridge structures. In most of these bridges, the coarse aggregate has been lightweight and the fine aggregate normal weight natural sand. The purpose of this study was to investigate the effectiveness of LWC in reducing cracks in bridge decks. Seven bridges from six VDOT districts were included in the study. Three bridge decks each were constructed in 2012 and 2013, and one was constructed in 2014. The results showed that bridge decks with fewer cracks than were typical of decks constructed with normal weight aggregate over the past 20 years or no cracks can be constructed with LWC mixtures. The study recommends that LWC with a maximum cementitious content of 650 lb/yd3 be used in VDOT bridge deck concrete mixtures.
Download or read book Bridge Decks written by Ardavan Ardeshirilajimi and published by . This book was released on 2016 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study on Reduction of Shrinkage Cracks in Bridge Deck Concrete written by Rajesh Anumakonda and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Shrinkage is an unavoidable property of concrete that can lead to cracking, thereby limiting the serviceability of concrete structures. Shrinkage cannot be eliminated but can be minimized. Shrinkage cracking can be a critical problem in concrete construction, especially for flat slab structures such as highway pavements, industrial slab-on-grade, for parking garages, and bridge decks. The primary objective of the research is to evaluate three practical methods to reduce shrinkage cracks in concrete for bridge deck applications. The three methods evaluated are: 1) use of optimized aggregate gradation concrete, 2) use of a new high performance concrete known as low-cracking high performance concrete (LC-HPC) and 3) the use of Fibra Shield Fibers to reduce plastic shrinkage cracking in concrete.
Download or read book Evaluation of Shrinkage Cracking Potential of Concrete Used in Bridge Decks in Florida written by Rajarajan Subramanian and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: From the test data and the analysis results obtained from the 15 concrete mixes tested in this set of experiments, the developed Constrained Long Specimen method demonstrated that it provided reasonable assessment of expected shrinkage-induced stresses in the concrete. Due to the creep of concrete at early age, the shrinkage-induced stress in the concrete is much lower than that estimated by multiplying the shrinkage strain by the elastic modulus of the concrete. Using the CLS test method enables the creep component to be properly considered, and a realistic determination to be made of the expected induced shrinkage stresses in concrete in service. The results of the CLS tests on the 15 concrete mixes showed the possible benefits of using a shrinkage-reducing admixture in reducing the potential shrinkage cracking of concrete in service.
Download or read book Field Evaluation of Shrinkage Reducing Admixture written by David Fujiwara and published by . This book was released on 2003 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mitigating Shrinkage Cracking of Concrete in Bridge Decks Through Internal Curing written by Daniel Robert Goad and published by . This book was released on 2013 with total page 160 pages. 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.
Download or read book Transverse Cracking in Newly Constructed Bridge Decks written by Paul D. Krauss and published by . This book was released on 1996 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
