Date of Graduation

12-2019

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Murray, Cameron D.

Committee Member

Hale, W. Micah

Second Committee Member

Fernstrom, Eric

Keywords

Capillary pressure; Concrete; Curing Regimens; Plastic shrinkage cracking; slab testing

Abstract

Early-age plastic shrinkage cracking is a common problem with the construction of concrete bridge decks due to the high surface area-to-volume ratio and exposure to potentially detrimental environmental effects. Curing regimens are utilized to mitigate cracking risk during the plastic stage of the concrete; the curing regimens evaluated for this study were wet burlap-polyethylene sheeting, two acrylic curing compounds, and one lithium compound. Capillary pressure in the water filled pores has been shown to correlate to the plastic shrinkage cracking risk of concrete. A new portable system has been developed to measure the capillary pressure that could potentially be used in the field on fresh bridge deck concrete. Individual test slabs were performed to test the curing regimens using the capillary pressure sensor system (CPSS). The system contains multiple sensors that contain pressure transducers that measure the capillary pressure changes during the plastic stage. Overall, wet burlap-polyethylene sheeting was shown to be the most effective curing regimen, with the lithium curing compound performing similarly to the control slab with no curing regimen applied. Both acrylic compounds were shown to perform comparatively well, completely mitigating early-age plastic shrinkage cracking in some instances, and allowing small shrinkage cracks to form in others. While the CPSS exhibited the ability to show when cracking occurred in most cases, the magnitude of the capillary pressure at which plastic shrinkage cracks formed varied significantly across tests.

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