Investigation Into Shrinkage Of High Performance Concrete Used For Iowa Bridge Decks And Overlays PDF Download
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| Author | : Kejin Wang |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2013 |
| Genre | : |
| ISBN | : |
Download Investigation Into Shrinkage of High-Performance Concrete Used for Iowa Bridge Decks and Overlays Book in PDF, ePub and Kindle
High-performance concrete (HPC) overlays have been used increasingly as an effective and economical method for bridge decks in Iowa and other states. However, due to its high cementitious material content, HPC often displays high shrinkage cracking potential. This study investigated the shrinkage behavior and cracking potential of the HPC overlay mixes commonly used in Iowa. In the study, 11 HPC overlay mixes were studied. These mixes consisted of three types of cements (Type I, I/II, and IP) and various supplementary cementitious materials (Class C fly ash, slag and metakaolin). Limestone with two different gradations was used as coarse aggregates in 10 mixes and quartzite was used in one mix. Chemical shrinkage of pastes, free drying shrinkage, autogenous shrinkage of mortar and concrete, and restrained ring shrinkage of concrete were monitored over time. Mechanical properties (such as elastic modulus and compressive and splitting tensile strength) of these concrete mixes were measured at different ages. Creep coefficients of these concrete mixes were estimated using the RILEM B3 and NCHRP Report 496 models. Cracking potential of the concrete mixes was assessed based on both ASTM C 1581 and simple stress-to-strength ratio methods. The results indicate that among the 11 mixes studied, three mixes (4, 5, and 6) cracked at the age of 15, 11, and 17 days, respectively. Autogenous shrinkage of the HPC mixes ranges from 150 to 250 microstrain and free dying shrinkage of the concrete ranges from 700 to 1,200 microstrain at 56 days. Different concrete materials (cementitious type and admixtures) and mix proportions (cementitious material content) affect concrete shrinkage in different ways. Not all mixes having a high shrinkage value cracked first. The stresses in the concrete are associated primarily with the concrete shrinkage, elastic modulus, tensile strength, and creep. However, a good relationship is found between cementitious material content and total (autogenous and free drying) shrinkage of concrete.
| Author | : Mohammad Hadi Kazemi Kamyab |
| Publisher | : |
| Total Pages | : 204 |
| Release | : 2008 |
| Genre | : |
| ISBN | : |
Download Investigation of Cracking in High Performance Concrete Used in New York State Bridge Decks Book in PDF, ePub and Kindle
| Author | : Timothy Walkowich |
| Publisher | : |
| Total Pages | : 107 |
| Release | : 2011 |
| Genre | : Bridges |
| ISBN | : |
Download Field Monitoring of Shrinkage Cracking Potential in a High-performance Bridge Deck Book in PDF, ePub and Kindle
Over the past decade many state engineers throughout New Jersey have reported cracking on High Performance Concrete (HPC) bridge decks at early ages. The presence of cracking early in the life of a high performance deck offsets the benefits gained in using the material as the potential for corrosion begins at the onset of cracking. While many factors apply to bridge deck cracking, the shrinkage of the concrete's mass is a primary concern. Because of shear studs and boundary conditions, among other causes that act in restraining the deck itself, it is important to understand the mechanics of concrete under restraint. The AASHTO Passive Ring Test (PP 34-06) is seeing an increase in use in studies analyzing restrained shrinkage. The test simulates a concrete member of infinite length and allows researchers to study the effects of various parameters on restrained shrinkage. This thesis presents the results of a study that analyzed the ring test's ability to simulate restrained shrinkage on HPC bridge decks. The investigation incorporated an instrumented, simply supported composite bridge deck with laboratory samples taken on the day of the pour as well as a finite element analysis. The results suggest the AASHTO Passive Ring Test simulates the restrained shrinkage of simply supported HPC decks reasonably well. Fewer than 1% of all cracking present on the ring specimens saw complete penetration through the sample with 80-90% of all cracking considered to be micro cracking. While the presence of several cracks along the bridge deck itself showed no correlation with the shrinkage ring specimens, finite element analysis suggests these cracks are a result of adjacent live load. Also, the findings of this study highlight the importance of following design in the field as well as the effect of live load on staged construction of HPC bridge decks.
| Author | : Tengfei Fu |
| Publisher | : |
| Total Pages | : 109 |
| Release | : 2013 |
| Genre | : High strength concrete |
| ISBN | : |
Download Shrinkage Study of High Performance Concrete for Bridge Decks Book in PDF, ePub and Kindle
In the field of civil infrastructure, bridge desks are typically constructed using high performance concrete (HPC). Concrete bridge decks demand qualities such as low permeability, high abrasion resistance, superior durability, and long design life. Over decades of field and laboratory experience, many HPC bridge decks have been found to be susceptible to shrinkage and subsequent cracking, which is regarded as a significant cause for premature deterioration, increased maintenance costs and even structural deficiency. Appropriate shrinkage limits and standard laboratory/field tests that allow proper criteria to ensure crack resistant HPC are not clearly established either in the technical literature or in specifications. A comprehensive study is presented in this dissertation on shrinkage and shrinkage induced cracking in HPC, with four main objectives: 1) mitigate the shrinkage and cracking issues in HPC using internal curing by fine lightweight aggregate (FLWA) and/or incorporation of shrinkage reducing admixture (SRA); 2) improve the standard ASTM chemical shrinkage test method for HPC systems containing supplementary cementitious materials (SCMs) and/or SRA; 3) modify existing drying shrinkage models mainly the ACI 209 model to predict long-term drying shrinkage for modern HPC concrete by using short-term experimental measurements; 4) complete a state-of-the-art literature review on shrinkage and cracking issues in HPC bridge decks. One of the most significant research findings is a proposed "cracking potential indicator" (CPI) that uses only the free shrinkage and mechanical properties of HPC. This was correlated to standard restrained ring tests.
| Author | : Brian Keierleber |
| Publisher | : |
| Total Pages | : 42 |
| Release | : 2005 |
| Genre | : Bridges |
| ISBN | : |
Download Evaluation of High-slump Concrete for Bridge Deck Overlays Book in PDF, ePub and Kindle
The Iowa Method for bridge deck overlays has been very successful in Iowa since its adoption in the 1970's. This method involves removal of deteriorated portions of a bridge deck followed by placement of a layer of dense (Type O) Portland Cement Concrete (PCC). The challenge encountered with this type of bridge deck overlay is that the PCC must be mixed on-site, brought to the placement area and placed with specialized equipment. This adds considerably to the cost and limits contractor selection, because not all contractors have the capacity or equipment required. If it is possible for a ready-mix supplier to manufacture and deliver a dense PCC to the grade, then any competent bridge deck contractor would be able to complete the job. However, Type O concrete mixes are very stiff and generally cannot be transported and placed with ready-mix type trucks. This is where a "super-plasticizer" comes in to use. Addition of this admixture provides a substantial increase in the workability of the concrete - to the extent that it can be delivered to the site and placed on the deck directly out of a ready-mix truck. The objective of this research was to determine the feasibility of placing a deck overlay of this type on county bridges within the limits of county budgets and workforce/contractor availability.
| Author | : |
| Publisher | : |
| Total Pages | : 112 |
| Release | : 2006 |
| Genre | : Concrete |
| ISBN | : |
Download Transverse Cracking of High Performance Concrete Bridge Decks After One Season Or Six to Eight Months Book in PDF, ePub and Kindle
Cracking is a major problem with newly placed concrete decks. These decks tend to develop full depth, transverse cracks and partial depth longitudinal cracks within a few months of the concrete being placed. A literature review showed that several other states had experienced similar problems. A review of data from Ohio bridge decks showed weak correlations between deck cracking and slump, time of year when the deck was placed, shrinkage, chloride permeability and compressive strength, but there was no clear relationship between cracking and any of these properties. Data also suggested that using a coarse aggregate with an absorption> 1% may help mitigate deck cracking but will not always stop it. As part of this study, 3 bridge decks were instrumented. One was a standard class "S" concrete deck and the other two were high performance concrete. The class "S" deck showed only hairline cracking after 1 year, but transverse cracking occurred in the HPC decks. Instruments were placed in the decks to monitor strains. From the data, it appears that cracking is caused by several factors. High heat of hydration caused the plastic concrete to expand. When the concrete sets and cools, tensile stressed develop. Further tensile stresses develop through drying shrinkage. Restraining the deck against normal thermal movement contributes to additional tensile stress. Autogeneous shrinkage, where high heats of hydration cause water evaporation during hydration, and plastic shrinkage may cause more tensile stress. Recommendations for mitigating cracking include using lower cement contents, adding pozzolans and retarders, using slightly higher water/cement ratios, using larger aggregates, taking steps to limit shrinkage and eliminating restraints.
| Author | : |
| Publisher | : |
| Total Pages | : 146 |
| Release | : 2007 |
| Genre | : Concrete |
| ISBN | : |
Download Assessment of Cracking Potential of High-performance Concrete Due to Restrained Shrinkage Book in PDF, ePub and Kindle
Many State Engineers have observed that a number of high-performance concrete (HPC) bridge decks exhibited cracking and sometimes soon after being poured. Although deck cracking can be attributed to various causes, in many cases, concrete shrinkage is considered the main contributor. Additionally, concrete in bridge decks is considered restrained and there is a need to examine the behavior of HPC mixes under those conditions. The AASHTO test (PP 34-06, The Passive or Restrained Ring Test) is employed to measure the cracking potential and restrained shrinkage behavior of various HPC mixes used in bridge deck projects contracted by the New Jersey Department of Transportation (NJDOT). This thesis presents the results of a study which utilized a method for directly measuring the strain development in the concrete ring using Vibrating Wire Strain Gages (VWSG). For each mix, additional tests were performed to determine the corresponding mechanical properties (e.g., elastic modulus, tensile splitting strength, compressive strength, etc.). The effect of total amount of cementitious materials and the potential of cracking for various mixes are also reported. The results of the study are used to correlate strains from restrained shrinkage tests with those from free shrinkage tests. Results show that the coarse aggregate (CA) content, the coarse/fine aggregate ratio, and cementitious content have the greatest effect on both free and restrained shrinkage. Mixes with higher cementitious content were observed to crack earlier. In general, to minimize HPC cracking potential, it is suggested that a limit on free shrinkage (450 micro strain at 56 days) be specified in bridge decks to indirectly reflect restrained shrinkage conditions. Additional limits for the total amount of coarse aggregate (1800 lb/cu yd.) and Coarse/Fine aggregate ratio (1.48) should also be considered.
| Author | : Nicole Duffala |
| Publisher | : |
| Total Pages | : 85 |
| Release | : 2016 |
| Genre | : Concrete bridges |
| ISBN | : |
Download Phase I: Minimization of Cracking in New Concrete Bridge Decks Book in PDF, ePub and Kindle
Cracking of newly constructed high-performance concrete (HPC) bridges is a problem recognized nationwide and the Nevada Department of Transportation has been plagued with this distress in their HPC concrete bridge decks. This research effort is a strategic attempt to reduce or eliminate random cracking that is caused by restrained shrinkage in new concrete bridge decks constructed in Nevada. The overall objective will be achieved through a three phase research program of which the results of Phase I are being reported in this document. Phase I research findings provide a synthesis of state, regional, and national practices and knowledge on factors contributing to HPC bridge deck cracking. With respect to materials and mixture proportioning, the overwhelming conclusion is that the shrinkage of the concrete mixture, especially at early-ages, must be reduced and the concrete’s resistance to cracking must be Improved. A rigorous, Phase II laboratory experiment was designed and is presented herein. This Phase II laboratory experiment focuses on local materials and will assess the properties of concrete mixtures that are related to early-age drying shrinkage restraint cracking. Ultimately, these research findings could be used to revise standard specifications and special provisions for Nevada DOT bridge decks and eventually reduce the overall incidence of restraint cracking due to concrete drying shrinkage.
| Author | : Zhigang Zhang |
| Publisher | : Frontiers Media SA |
| Total Pages | : 303 |
| Release | : 2022-09-23 |
| Genre | : Technology & Engineering |
| ISBN | : 2832500579 |
Download Advanced Concretes and Their Structural Applications Book in PDF, ePub and Kindle
| Author | : Norbert J. Delatte |
| Publisher | : |
| Total Pages | : 148 |
| Release | : 2007 |
| Genre | : Bridges |
| ISBN | : |
Download Evaluation of High Absorptive Materials to Improve Internal Curing of Low Permeability Concrete Book in PDF, ePub and Kindle
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
