Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 240 for “"early-age"”.
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Micromechanical modeling of concrete at early age
… characterization of Portland cement concrete at early age (less than 28 days). Concrete’s viscoelastic properties change significantly at early age due to solidification of its matrix component. Bažant’s solidification theory models concrete as a material solidifying in time. This approach is …
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Early Age Assessment of Cement Treated Materials
In order to avoid the occurrence of early-age damage, cement-treated base (CTB) materials must be allowed to cure for a period of time before the pavement can be opened to traffic. The purpose of this research was to evaluate the utility of the soil stiffness gauge (SSG), heavy Clegg impact soil …
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Monitoring Early Age Cementitious Materials Using Ultrasonic Guided Waves
… the setting times and compressive strength of early age cementitious materials can be monitored using ultrasonic guided waves.
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Early age creep and shrinkage of emerging concrete materials
… are especially vulnerable to cracking at early age. The volumetric instability of concrete at early age is a frequent cause of cracking. The primary components of volume change are external drying shrinkage, autogenous shrinkage, and thermal dilation. When concrete is restrained, tensile …
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Early Age Stresses and Creep-Shrinkage Interaction of Restrained Concrete
The analysis revealed stress-induced shrinkage as a major mechanism of drying creep for plain and fiber reinforced concrete (FRC). Microcracking forms a significant portion of drying creep of plain concrete, but it is less significant in FRC. Therefore, creep of FRC is dominated by real mechanisms, …
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Mitigation of early age cracking of concrete for bridge decks
… due to deterioration mechanisms that exist at early ages of the concrete. Early age deterioration mechanisms such as early age cracking cause the reinforcing steel rebar to be exposed prematurely to the elements of the environment, which causes for lower service life of the bridge deck through …
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Numerically Modeling Steel Continuous Bridges for Early Age Concrete Deck Cracking
<p>Early age bridge deck cracking is a common problem throughout the United States. Early age cracking develops shortly after the deck is poured. It reduces the serviceability and lifespan of bridges. Early age cracking can be typically attributed to either of two factors, 1) construction …
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Noncontact sensing systems and autonomous decision-making for early-age concrete
Early-age cracking and spalling in concrete pavements reduces slab capacity, joint load transfer, ride quality, and its long-term performance. These premature distresses lead to increased maintenance costs for sealing, patching, and grinding. Proper timing of sawcutting and curing are two …
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Field observations of the early-age behavior of jointed plain concrete pavements
… The large joints were believed to develop at early-ages of the slabs curing (within the first 48 hours). The early-age stress developments were found controlled by slab temperature history, material property development and frictional resistance. Minimal recommendations for corrects to the …
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Early-age behavior of CRCP and its implications for long-term performance
… used rigid pavement type in Texas. The advantages of CRCP over other rigid pavement types include the absence of transverse contraction joints. With the increased use of CRCP, a vast amount of information has been collected on design variables and their effects on CRCP performance. Most …
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Early-age hydration and volume change of calcium sulfoaluminate cement-based binders
Shrinkage cracking is a predominant deterioration mechanism in structures with high surface-to-volume ratio. One way to allay shrinkage-induced stresses is to use calcium sulfoaluminate (CSA) cement whose early-age expansion in restrained condition induces compressive stress that can be utilized to …
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Early Age Behavior of Bonded Concrete Overlays Due to Shrinkage and Thermal Changes
… cracking tendency in bonded concrete overlay at early age. The design guide, implemented as an EXCEL spreadsheet, is a practical tool for pavement engineers. The design guide calculates surface stresses and interfacial debonding stress due to shrinkage and thermal changes at early age. An …
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Development, application and early-age monitoring of fiber-reinforced ‘crack-free’ cement-based overlays
… cited for lack of durability in repairs, early-age shrinkage cracking in overlay materials is of utmost importance. Fiber-reinforcement can be used to alleviate some of the issues related to plastic shrinkage. However, quantifying the performance of cement-based composites under restrained …
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The relationship between early age of first sexual intercourse and vulnerability to depression among adolescents
… variables that may predict both depression and early sexual intercourse. Using the Add Health restricted dataset, I analyzed the depressive symptomatology of adolescents over a seven-year time period. The final sample (n=6,51O) was comprised of 49.35% male (n=3,213) and 50.65% female (n=3,297) …
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Prediction of early-age cracking of UHPC materials and structures : a thremo-chemo-mechanics approach
… ductility, economical benefit, etc., but early-age cracking of UHPC can become an issue during the manufacturing process due to the high cement content and the highly exothermic hydration reaction. Because of the risk of early-age UHPC cracking, there is a need to develop a material model …
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The Effects of Early-Age Stress on the Elastic and Viscoelastic Behavior of Cement Paste
The viscoelastic behavior of concrete, nearly completely attributable to changes in properties in the cement paste, is an ongoing area of research with the objective of avoiding unpredictable response and potentially failure of concrete structures. This research explores the elastic and …
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Expansion and shrinkage of early age cementitious materials under saturated conditions : the role of colloidal eigenstresses
… first a volume expansion followed at later stages of hydration by volume shrinkage that cannot be explained by classical theories. By analyzing both expansion and shrinkage within the framework of incremental micro-poro-mechanics, we suggest that the expansion is caused by the relative volume …
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Predictions of reinforced concrete durability in the marine environment
… was to identify reliable means of characterizing early-age properties of concrete which affect durability and relate these to the durability performance of the material under marine conditions. Establishing a relationship between early-age testing and long-term performance of concrete is a …
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Study of Internal Strains Developed in Concrete Decks at Early Ages in Steel Continuous Bridges
… restrict the concrete slab from movement during early age shrinkage, causing tensile stresses to develop. The final stresses at the end of construction must be lower than the concrete tensile strength, if not cracking issues will develop. Eventually, these cracks may enlarge due to service load …
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