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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Reinforcing Bar Splice Performance in Masonry with Self-Consolidating Grout

Roper, Aaron Brent 01 April 2018 (has links)
The use of self-consolidating grout in reinforced masonry construction provides various advantages such as reduced labor, faster construction, decreased noise pollution and better structural response. This is a relatively new building material however, and little research on self-consolidating grout's structural properties has been conducted. The purpose of this study was to analyze the performance or bond capacity of steel reinforcing bar splices in masonry with self-consolidating grout. Twelve masonry panels approximately 40 in. wide and 32 in. tall consisting of Type S mortar and concrete masonry units grouted with self-consolidating grout and No. 5 steel reinforcing bars were constructed with splice lengths as prescribed by the current design equation and splices that were slightly shorter. Test Group 1 consisted of six reinforced masonry panels with the code required lap length while Test Groups 2 and 3 had splices two and four inches shorter, respectively. The lap-splices were tested in pure tension to determine if they would fully develop the code mandated stress of 125% of the specified yield strength of the reinforcing bars. More samples were tested with the code required development length to verify if the current provision is adequate for design and the other two groups were used to explore if the required capacity could be achieved with shorter splices. All lap-splices developed the minimum required stress, even those with splices shorter than required by the design equation. For masonry with self-consolidating grout containing No. 5 bars in the specific configurations tested, the current design equation was shown to be adequate for calculating development length. Testing indicates that a reduction in required splice length for masonry with self-consolidating grout is possible.
2

Performance of No Vibration/No Admixture Masonry Grout Containing High Replacement of Portland Cement with Fly Ash and Ground Granulated Blast Furnace Slag

Bateman, Eric 01 February 2014 (has links)
When hollow concrete masonry is used for construction in high seismic regions, structural designs typically require fully grouted walls. The grouting process is labor-intensive, time-consuming and has a high energy demand due to requirements of consolidation in each and subsequent grout lifts. Self-consolidating grout with admixtures has been successfully used without segregation in walls of up to 12.67 ft. in height. Investigation of self-consolidating grout mixes without admixtures has potential for sustainability improvement. This thesis reports on the compression strength and consolidation observations of self-consolidating characteristics of no vibration/no admixture grout made by substituting various proportions of Portland cement with Type F fly ash and/or ground granulated blast furnace slag (GGBFS). The percentages of Portland cement replacement evaluated were 0%, 50%, 60%, and 70% for Type F fly ash. The percentages of Portland cement replacement evaluated were 0%, 60%, 70% and 80% for Type F fly ash and GGBFS. Grout compressive strengths were evaluated from individually filled grout specimens constructed in concrete masonry hollow core units, dry cured, and tested after 7, 14, 28, 42, 56, and 130 days. Also, hollow concrete masonry walls were built 12.67 ft. tall and grouted. The relative performance was assessed by comparing to conventional grouted masonry and evaluating consolidation characteristics around mortar fins and reinforcement; compressive strength tests after 130 days of curing, and rebar pull-out tests were taken from various wall heights. All experimental grouts had acceptable consolidation characteristics but fly ash replacement grouts did not meet the compressive strength requirements.
3

Splice Performance of #6 Reinforcing Bars in Masonry with Self-Consolidating Grout

Nielson, Annie Ruth 01 December 2019 (has links)
Reinforced masonry grouted using self-consolidating grout (SCG) is a relatively new and economically competitive option for construction, providing advantages such as reduced construction time, decreased noise and vibration, and reliable consolidation. However, SCG has different properties than conventional grout and its performance should be verified using current governing code requirements. The purpose of this research program was to determine the development length of spliced reinforcing bars in masonry grouted with SCG.Twelve masonry panels, four courses high and two and a half blocks wide, were constructed using 8-inch concrete masonry units, each with two pairs of vertically spliced #6 reinforcing bars. Six of the panels had splice lengths that met current code provisions to verify that the code requirements are adequate for use with SCG. The remaining panels had shorter splice lengths than required to investigate the possibility of shorter splices in SCG. The ultimate bond strengths were compared to the design requirement for a splice to develop 125% of the yield strength of the rein-forcing bars.All lap splices developed the required stress, including those with shorter lengths. This indicates that the current code provisions are adequate to determine the development length of reinforcement splices in masonry grouted with SCG and reinforced with #6 bars in the specific configurations tested. According to this study, a development length reduction factor may be viable when SCG is used in masonry.

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