Text

theses

High performance concrete (HPC) is generically categorized as the type of concrete having both high strength and durability compared to conventional concrete. This is often achieved with the addition of cementitious materials such as fly ash, silica fume, and blast furnace slag as well as admixtures. This type of concrete is often also accompanied with a lower water:cement ratio. HPC mixes can be optimized in terms of strength, durability, workability, shrinkage, and commonly used around the world, but it is not without its flaws. A common problem seen in using this concrete in bridge decks specifically is its high cracking potential. This research is aimed to investigate an effective tool that reduces and mitigates the cracking potential in bridge decks. Steel and synthetic fibers are implemented to address this issue. Fibers will be dosed into HPC mixes and the effects on fresh properties as well the strength development and shrinkage over time. The experimental work will occur in two phases. The first section will be lab-based and compare the contributions of fiber additions and blending. Blending is implemented to promote pumpability and fibers are added to reduce cracking potential. Three fiber types will be analyzed in the lab. Two synthetic macro fibers and one steel hooked fiber, all with equivalent lengths of 2”. Class A will also be compared for the data set. The second phase will involve the implementation of fiber reinforced HPC to a bridge in New Jersey. Blended HPC and blended FR-HPC will be cast in an alternating pattern for eight three span continuous bridge decks. The same tests will be run on the concrete sampled from these mixes and the bridge decks are also crack mapped and analyzed. Fiber implementation proved effective in the reduction of cracking potential for HPC. The addition of steel hooked fibers and Euclid macro PPE fibers into this concrete reduced the cracking area of an AASHTO restrained ring by 26.3% and 23.2% respectively. The results were further reinforced in the field, both through the rings and through the crack surveys of the deck. The addition of fiber to blended HPC in the field resulted in a 42.5% reduction in cracking area when poured and a 79.5% reduction when pumped. These results translate to the actual bridge decks as well, where a 33.4% reduction in cracking area and 16.7% decrease in average crack width was observed when PPE Macro fibers were introduced to the mix.

ETD_8928

M.S.

Includes bibliographical references

by Gregory Brewer

doi:10.7282/T3QF8X9B

ETD graduate

The author owns the copyright to this work.