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theses

The deteriorated state of the current infrastructure is problematic and economic factors limit the complete replacement of structures, stressing the importance on rehabilitation to extend the service life of existing structures. The use of self-consolidating concrete (SCC) in recent years has greatly reduced the cost of labor due to the fresh material properties such as superior flowability and workability compared to other types of concrete, allowing it to flow under its own weight and fill formwork and without the use of mechanical consolidation. It’s application in rehabilitation of reinforced concrete beams can significantly shorten construction time while simultaneously enhancing flexural behavior. This study addresses the effect of steel and synthetic fibers to the fresh and hardened properties of SCC when applied as a strengthening laminate for reinforced concrete beams. Eight fiber-reinforced self-consolidating concrete (FR-SCC) mixes were developed by introducing crimped steel fibers (1.5”), macro-synthetic fibers (0.75”, 1.5” and 2.0”), and micro-synthetic fibers (0.75”) at variable dosages, with respect to a control SCC mix. Four FR-SCC mixes and the control were utilized for retrofitting reinforced concrete beams. Results show that certain FR-SCC mixes enhance hardened properties relative to the control SCC, while still maintaining highly workable fresh properties. To simulate deterioration and loss of concrete cover, reinforced concrete beams were casted with exposed stirrups. Beams were then retrofitted varying the amount and type of steel reinforcement (#2 rebar, galvanized welded wire mesh, and galvanized low-density tape), type and size of the shear studs, fiber type and length, and fiber content of the laminate. Results show that the addition of welded wire mesh reinforcement increases service loads by an average of 8% per layer and ultimate deflection by an average of 9%, but also increases crack width in bending. The addition of #2 rebar in the laminate increases ultimate loads by 34% and ultimate deflection by 30% on average while also reducing crack width. Cracking loads and ultimate loads were enhanced by up to 34% and 18%, respectively as stud size increased. The use of FR-SCC for laminates reduced crack width relative to plain SCC laminates up to 16%, while also enhancing deflection up to 35% and increasing cracking loads.

ETD_8930

M.S.

Includes bibliographical references

by Christopher Sholy

doi:10.7282/T3VX0M0M

ETD graduate

The author owns the copyright to this work.