Details:

Creators:
Sharp, Stephen R. ; Mokarem, David W.
Sharp, Stephen R. ; Mokarem, David W. Less -
Corporate Creators:
Virginia Center for Transportation Innovation and Research
Corporate Contributors:
Virginia. Dept. of Transportation ; United States. Federal Highway Administration
Virginia. Dept. of Transportation ; United States. Federal Highway Administration Less -
Subject/TRT Terms:
[+]
Air Voids Alkalinity Corrosion Reinforced Concrete Pavements Water Cement Ratio
Publication/ Report Number:
FHWA/VCTIR 14-R11
Resource Type:
Tech Report
Geographical Coverage:
Virginia
Corporate Publisher:
Virginia. Dept. of Transportation
Abstract:
"Research on steel corrosion has demonstrated that the concentrations of chloride and hydroxide ion at the concrete/steel

interface influence the susceptibility of the steel to corrosive attack. This study used electrochemical means and changes in mix

design to increase the alkalinity and improve consolidation of the concrete against the steel to determine if this would increase the

corrosion resistance of the reinforcing steel without compromising the properties of the concrete. To understand these effects

better, the following concrete properties were evaluated: compressive strength, splitting tensile strength, modulus of elasticity,

and length change (shrinkage).

The evaluation involved the casting of different types of concrete samples, all of which contained artificial voids, for

corrosion testing. These samples were composed of one of two concrete mixtures: (1) the Virginia Department of

Transportation’s (VDOT) Class A4 General Bridge Deck Concrete with Straight Portland Cement (A4), or (2) a selfconsolidating

concrete (SCC). Selected A4 and SCC mixtures were electrochemically treated 135 days after samples were cast.

Some samples were left untreated and functioned as control samples.

There were no significant differences in the concrete properties between the short-term treatment (less than 7 hr) and

control samples tested in this study. It was determined that alkalinity, water-to-cement ratio, and steel type all influence the

corrosion potential of reinforcing steel when reinforced concrete is subjected to saltwater. In addition, introducing small voids

adjacent to the steel created a greater spread between the 25th and 75th percentile of the half-cell potential measurements when

compared to locations without voids; however, these same voids have little influence on the average value measured. A study is

underway to perform cyclical saltwater ponding on selected samples to allow for future evaluation of corrosion resistance.

This study showed that alkalinity, water-to-cement ratio, concrete fluidity during placement, and steel type all influence

the corrosion potential of the reinforcing steel when reinforced concrete is subjected to saltwater. The study recommended that

the Virginia Center for Transportation Innovation and Research (VCTIR) continue performing saltwater exposure on these

specimens until corrosion becomes evident and then autopsy them and characterize the corrosion of the steel reinforcement. In

addition, VCTIR should work with VDOT’s Materials Division to compare various concrete mix designs that would be

considered acceptable to VDOT and assess how each influences the corrosion potential on embedded steel. Further, more

emphasis should be placed on mix designs, such as SCC mixtures, that could provide VDOT with greater corrosion resistance

and reduced labor during placement."


Format:
PDF
Funding:
99205
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:ac74169d52b52e371ce7de206fea59020e5fd69b03f91ec92132c6e6fc064451
Download URL:
https://rosap.ntl.bts.gov/view/dot/27446/dot_27446_DS1.pdf
File Type:

Supporting Files

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