Evaluation of Surface Resistivity Measurements as an Alternative to the

Rapid Chloride Permeability Test for Quality Assurance

PI: Tyson D. Rupnow, Ph.D., P.E.

Co PI: Patrick Icenogle, E.I.

Mark Morvant P.E.RAC Meeting

July 2011

Background

Permeability specifications required by LADOTD for LRFD designed bridges

ASTM C 1202 most widely accepted test Surface resistivity test

Florida DOTD study AASHTO round robin study (on-going)

LTRC study Wider range of w/c ratios

Background

ASTM C 1202 Sample

preparation 2 days of ‘testing’ Equipment cost

Background

Wenner Probe Much quicker Lower equipment cost Shorted curing time Portable!

Research Objectives

Characterize surface resistivity of concrete produced at LTRC and in field conditions

Characterize the rapid chloride permeability of the same specimens

Comparative testing Caminada Bay Bridge Project I-10 Twin Spans Bridge Project LA 1 Bridge Project

Work Plan

Measure surface resistivity and RCP on varying ages of samples Ages of 14, 28, and 56 days Sample size = 4 in. x 8 in. cylinders Over 220 test results

Mixture IDw/c

0.35 0.50 0.65100TI X X X80TI-20C X X X50TI-50G120S

X X X

90TI-10SF X X X95TI-5SF X X X

Results – Overall Relationship

Conclusions

SR measurements correlate well with RCP across a wide range of values and ages

Deviations are low Able to identify great differences in w/cm User friendly Save $$$

Recommendations

Test at 28-days of age

Purchase 11 SR meters

Training program Develop TR

procedure

Permeability Class

28-Day Surface Resistivity

(kΩ-cm)

High < 12

Moderate 12 - 21

Low 21 - 37

Very Low 37 - 254

Negligible > 254

Cost:Benefit

Cost:Benefit

Total cost of the research & Implementation Research: $102,878 Equipment Purchase: $30,000 (11 meters)

Estimated 1 year savings DOTD - $96,000 Contractors: $1.5 million

Implementation Strategy

Training Step-by-step of TR procedure and template Training video Hands on with equipment Automated template LTRC certification

Demonstration Projects Equipment purchased for each district Cost/Benefit Validation Implementation Report