Date of Graduation

8-2013

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Hale, W. Micah

Committee Member

Grimmelsman, Kirk A.

Second Committee Member

Heymsfield, Ernest

Keywords

Applied sciences; Internal curing; Lightweight aggregate

Abstract

Putting an end to the rapid deterioration of concrete structures in the United States will only occur through the introduction of better materials and construction methods. The American Society of Civil Engineers (ASCE) reports the overall condition of concrete bridges in the United States to be a "C+". Though better than other areas of the infrastructure, there is still room for improvement in concrete bridges. One major area that may be improved is that of the concrete bridge deck. The bridge deck is comprised of the actual driving surface. It is subject to many deterioration mechanisms including freeze/thaw cycles, de-icing salts, and cyclic loading. The bridge deck must be highly durable to combat the negative effects it is subjected to. A recent advancement to increase durability is the placement of a pre-saturated lightweight aggregate (LWA) inside concrete. This LWA will offset cracking associated with drying shrinkage and self-desiccation. The pre-saturated LWA is an expanded clay or expanded shale material is able to absorb water into the pores of its structure and release that water to hydrating cement. The current research is focused on determining the effects of this LWA soaking durations of 1, 3, and 7 days. A constant replacement rate of 300 lbs/yd3 was used for the current study. A control mixture was cast for comparison purposes which contained no LWA. The research program concrete mix designs were developed in accordance with the Arkansas State Highway and Transportation Department bridge deck specification. Reported results included shrinkage/strain, compressive strength, modulus of rupture, and modulus of elasticity. Findings indicated that a 1 day soaked LWA preformed equivalent or better than extended soaking durations at mitigating concrete shrinkage.

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