Semester

Fall

Date of Graduation

2011

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Indrajit Ray

Committee Co-Chair

An Chen

Committee Member

Julio F Davalos

Abstract

Concrete is the most widely used man-made material in the world and is second only to water in terms of its utilization. Annually, 6 billion tons of concrete is produced in the world and the US consumption of concrete is over 2.5 tons a year per person (SDC Vision 2030 -- US Concrete Industry). It drives a US{dollar}100 billion industry in the United States alone employing over 2 million people. It enjoys huge acceptability over other construction materials across the globe. Though concrete is strong and durable, it does not last forever, especially when exposed to aggressive conditions. Deicing salts, freeze-thaw cycles, high heat, high mechanical loading, seismic events, etc. lead to potential deterioration of the concrete structure. As a consequence, the service life of the structure is reduced. In US, 1 in every 4 bridges is either structurally deficient or functionally obsolete. The nation's crumbling infrastructures and buildings need urgent replacement. The replacement cost of these structures being enormous, there is a pressing need for repairing and rehabilitating these deficient structures.;Keeping the above points in mind, the present study focused on developing a high performance fiber reinforced concrete (HPFRC) material with very high strength and improved ductility, which can rehabilitate the structure by repairing it at a fraction of replacement cost required for new construction.;All the materials used in this study are commercially available in the United States. Initially two HPFRC mixtures were developed using portland cement, two types of fine sand with optimized grading, ultrafine quartz powder, discontinuous steel fibers, and a next generation polycarboxylate-based full range water reducing admixture. The water to cementitious materials ratio and the fiber volume fraction were kept at 0.2 and 2%, respectively. To study the effect of curing temperature on the hardened properties of the mixtures, four different curing conditions were selected. Compressive strength, flexural strength, and flexural toughness were determined for those eight combinations. Compared to high performance fiber reinforced cement composites (HPFRCC) the increase in compressive strength was in the range of 25-105%. Flexural strength was found to be similar to that of HPFRCC. Based on these strength results, the better performing mixture and the two best performing curing conditions were further selected to study the bond behavior of HPFRC to NC.;The bond strength was determined by conducting three tests, such as, direct shear, slant shear, and pull-off. The results showed comparable bond strength in case of direct shear and 20% increase in bond strength by slant shear, when compared with other similar studies. The pull-off strength exceeded the minimum acceptance criterion for bond strength of repairing materials per International Concrete Repair Institute -- Technical Guidelines.

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