Nondestructive characterization methods for quality control of steel fiber reinforced concrete

Pacadar is a precast concrete company, headquartered in Madrid, Spain, that had proposed a research project to the University of Illinois based on their need to nondestructively characterize steel fiber dispersion and orientation within concrete wind-tower elements in order to ensure adequate structural capacity. This thesis documents the nondestructive testing research effort. A literature review was performed and preliminary laboratory tests were carried out, all of which indicated that electrical and magnetic methods exhibited much promise with regard to steel fiber characterization. Specific focus was given to electrical surface resistivity, and specimens were designed to be representative of the final production elements, both in terms of fiber content and reinforcing steel dimensions. Moisture content and maturity were found to be major factors that affected the measured surface resistivity, as both factors related to the conduction of electricity through the internal pore network of concrete. When reinforcing steel (i.e. internal rebar) was considered, a decrease in resistivity was observed and the effective reduction in average resistivity was similar in both specimens, with and without steel fibers. Also, when varying the angle of the resistivity probe relative to a reinforcing bar, the presence of steel fibers had more of an effect compared to the plain sample as the resistivity reading was more influenced by the individual steel fibers rather than the single steel bar. From the field testing, it was found that the predictions based on the resistivity testing matched the expected fiber dispersion and orientation in large prestressed panels and validation through destructive means (i.e. coring) is underway. There is more work that could be done in the area of nondestructive testing for SFRC (e.g. radar testing), but the results presented here are both promising to Pacadar and useful as a guide for furthering the area of research.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2019

Author dc:creator

• Garrett, Stephen

Contributors dc:contributor

• Popovics, John S.

• resistivity
• nondestructive testing
• steel fiber reinforced concrete
• concrete

Statement dc:rights

• Copyright 2014 Stephen Michael Garrett

Handle dc:identifier

http://hdl.handle.net/2142/105278

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/105278