United States Department of Transportation
i
Evaluation of resistivity meters for concrete quality assurance.
-
2015-06-01
[PDF-6.92 MB]
Details:
-
Creators:
-
Corporate Creators:
-
Corporate Contributors:
-
Subject/TRT Terms:
-
Publication/ Report Number:
-
Resource Type:
-
Geographical Coverage:
-
Corporate Publisher:
-
Abstract:This research evaluated a series of MoDOT concrete mixtures to verify existing relationships between surface resistivity (SR), rapid
chloride permeability (RCP), chloride ion diffusion, and the AASHTO penetrability classes. The research also performed a precision
and bias evaluation to provide acceptable limits should SR be implemented for quality assurance and to refine language in the AASHTO
test standard. In the precision and bias determination concrete was produced from three field sites and tested at both UMKC and
MoDOT labs. Field mixtures included a paving mixture, a bridge deck mixture, and a structural mixture. Eleven other mix designs were
produced in the lab and evaluated for RCP correlation and included paving, bridge deck, structural, and repair mixtures per Missouri
Department of Transportation requirements. Additional testing included surface resistivity testing on sealed samples and an existing
bridge deck. Results showed excellent correlation between SR and RCP which matched existing relationships provided by AASHTO
and other state DOTs. The structural mixture containing 50% Class F fly ash had the best performance with “very low” chloride ion
penetrability at 90 days. A ternary paving mixture with 20% Class C fly ash and 30% slag replacement for cement also demonstrated
low permeability as well as high compressive strength with an average value of over 9,000 psi at 90 days. The two repair mixtures
showed moderate to low penetrability readings and high early strength consistent with their desired purpose. Tests were also performed
on a series of slab samples to evaluate SR as a tool for evaluating sealer application. The presence of silane and lithium silicate were
able to be detected by the SR test. As value added to the laboratory research, field testing was attempted on a bridge deck with the goal
of providing non-destructive insight to the steel condition in the field. Due to the condition of the bridge conclusions could not be drawn
other than making recommendations for future bridge deck evaluations. The extensive amount of surface resistivity testing (>4500 tests)
on 14 concrete mixtures at ages from 3 hours to 90 days using multiple labs, equipment, operators, and curing conditions has verified
RCP relationships and allowed refinement of a testing procedure for a MoDOT standard in the Engineering Policy Guide. Surface
resistivity presents an opportunity to improve MoDOT concrete mixtures and specifications to increase durability without adding
significant additional testing costs.
-
Format:
-
Collection(s):
-
Main Document Checksum:
-
Download URL:
-
File Type:
