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Equation 1:

The change in potential energy divided by the change in applied current is equal to the Tafel slope A times the Tafel slope C over 2.3 times the corrosion rate times the sum of the Tafel slopes A and C.

Figure 1: Schematic drawing of polarization resistance test setup.

The figure shows the electronics in a rectangular box. Within the electronics box are the rebar connection, applied current, and half-cell response. Beneath the electronics box is a cross-section of the concrete test section. Rebar is shown running through the center of the test section. The rebar connection is shown connected to the rebar through the concrete. The Applied current box is shown connected to electrode and the half-cell response is shown connected to the half-cell, which is connected to the electrode. The electrode is shown on the surface of the pavement with arrows emanating from the electrode through the pavement towards the rebar. Directly below the area covered by the electrode and beneath the rebar is the area that may be measured.

Figure 2.

Photograph showing the test section on Interstate 270 northbound in 1995, which consists of a concrete bridge section.

Figure 3.

Photograph showing the test section on Interstate 270 southbound in 1995, which consists of a concrete bridge section.

Figure 4. Histogram of half-cell potentials for Interstate 270 northbound S F C test section for 1994 and 1997.

The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges from 0 to negative 149, negative 150 to negative 199, negative 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 499, and negative 500 to negative 549, there were 0, 3, 14, 21, 35, 25, 16, 6 and 0 observations, respectively in 1994 and 3, 7, 16, 23, 28, 15, 11, 3 and 2 observations in 1997.

Figure 5.

Equipotential map of half-cell potentials for I-270 northbound silica fume-modified concrete. Traffic direction is shown moving from left to right. Readings along the guard rail are shown on horizontal and vertical axes.

Figure 6.

Histogram of half-cell potential readings for I-270 southbound L M C roman numeral 3 test section for 1994 and 1997. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges from 0 to negative 149, negative 150 to negative 199, negative 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 499, and negative 500 to negative 549, there were 0, 1, 1, 7, 30, 48, 30, 10 and 2 observations, respectively in 1994 and 0, 2, 15, 35, 40, 28, 10, 0, and 0 observations in 1997.

Figure 7.

Equipotential map of half-cell potentials for I-270 southbound latex-modified concrete. Traffic direction is shown moving from left to right. Readings along the guard rail are shown on horizontal and vertical axes.

Figure 8.

Cumulative frequency diagram for I-270 northbound and southbound for years 1994 and 1997. The figure consists of a line graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For the northbound lanes in 1994, the potential range at 20, 40, 60, 80, and 100 observations was negative 250 to negative 299, negative 200 to negative 249, negative 300 to negative 349, negative 350 to negative 399, and negative 450 to negative 499, respectively, and negative 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, and negative 500 to negative 549 in 1997. For the southbound lanes, in 1994, the potential range at 20, 40, 60, 80, and 100 observations was negative 300 to negative 249, negative 300 to negative 349, negative 350 to negative 399, negative 400 to negative 449, and negative 500 to negative 549, respectively, and negative 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 300 to negative 349, and negative 400 to negative 449 in 1997.

Figure 9.

Photograph showing the eastbound deck of U S 52 over Raymond Run in Columbus, Ohio. The overlay is latex-modified.

Figure 10.

Photograph showing the westbound travel of lane of U S 52 over Raymond Run in Columbus, Ohio. The overlay is latex-modified.

Figure 11.

Photograph showing the westbound passing lane of U S 52 over Raymond Run in Columbus, Ohio. The overlay is silica fume-modified concrete.

Figure 12.

Histogram of half-cell potential readings for U S 52 eastbound travel lane L M C in 1994 and 1997. The lane is latex-modified concrete. The graph is a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. In 1994, for potential ranges of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, and negative 400 to negative 449, there were 5, 100, 380, 125, 50, 6, less than 5, less than 5, and less than 5 observations, respectively, and in 1997 there were 0, 5, 260, 300, 75, 10, less than 5, less than 5, and less than 5, respectively.

Figure 13.

Histogram of half-cell potentials for U S 52 westbound travel lane L M C in 1994. The lane is latex-modified concrete. The graph is a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, and negative 300 to negative 349, there were 20, 455, 245, 45, 15, 5, and less than 5 observations, respectively.

Figure 14.

Histogram of half-cell potentials for U S 52 westbound passing lane S F C in 1997. The lane is silica fume-modified concrete. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For a potential range of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, and negative 300 to negative 349, there were 20, 455, 245, 40, 10, 5, and less than 5 observations, respectively.

Figure 15.

Equipotential map of half-cell potentials for eastbound travel lane U S 52 in 1997 latex-modified concrete. Traffic direction is shown moving from left to right. Readings along the guard rail are shown on horizontal and vertical axes.

Figure 16.

Equipotential map of half-cell potentials for westbound travel lane U S 52 in 1997 silica fume-modified concrete. Traffic direction is shown moving from left to right. Readings along the guard rail are shown on horizontal and vertical axes.

Figure 17.

Photograph of I-265 northbound lanes with latex-modified overlay.

Figure 18.

Photograph showing I-265 southbound lanes with silica fume-modified concrete overlay.

Figure 19.

Histogram of half-cell potential readings for I-265 southbound S F C test section. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and the number of observations on the vertical axis. In 1994, for potential ranges of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, negative 400 to negative 449, and negative 450 to negative 499, there were 50, 260, 310, 275, 245, 125, 50, 10, less than 5, and 0 observations, respectively, and for 1997 there were 50, 215, 353, 325, 210, 110, 50, 20, less than 5, and less than 5.

Figure 20.

Histogram of half-cell potential readings for the I-265 northbound L M C test section. The figure consists of a graph with potential range in millivolts on the horizontal axis and number of observations of the vertical axis. In 1994, for potential ranges of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, and negative 350 to negative 399, there were 500, 320, 140, 80, 20, 10, less than 5, and 0 observations, respectively, and for 1997, there were 620, 220, 100, 50, 10, less than 5, and 0 observations.

Figure 21.

Equipotential maps of half-cell potentials of the three southbound spans S F C of the I-265 test section in 1997. Traffic direction is shown moving from left to right. Readings along the guard rail are shown on horizontal and vertical axes.

Figure 22.

Equipotential maps of half-cell potentials of the three northbound spans L M C of the I-265 test section in 1997. Traffic direction is shown moving from left to right. Readings along the guard rail are shown on horizontal and vertical axes.

Figure 23.

Photograph of northbound test section of U S 41 latex-modified concrete overlay.

Figure 24.

Photograph of southbound test section of U S 41 silica fume concrete overlay.

Figure 25.

Photograph showing typical cracking found in the northbound deck of the U S 41 test section L M C. The section is latex-modified concrete.

Figure 26.

Photograph showing typical cracking associated with the southbound test section of U S 41 S F C. The section is silica fume-modified concrete. Significant cracking is shown throughout the area pictured.

Figure 27.

Histogram of half-cell potential reading for U S 41 southbound in 1994 S F C. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges from 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, and negative 350 to negative 399, there were 0, 9, 32, 67, 35, 27, 15, and 4 observations, respectively for U S 41 southbound span 1; 140, 39, 4, 3, 2, 0, and 0, respectively for U S 41 southbound span 2; and 52, 80, 35, 13, 3, 2, and 0, respectively for U S 41 southbound span 3.

Figure 28.

Histogram of half-cell potential readings for U S 41 southbound in 1997 S F C. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges from 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, and negative 400 to negative 449, there were 0, 0, 3, 45, 43, 47, 25, 18, and 7 observations, respectively for U S 41 southbound span 1; 8, 100, 52, 15, 5, 5, 1, 0, and 0, respectively for U S 41 southbound span 2; and 3, 40, 82, 41, 8, 5, 5, 4, and 0, respectively for U S 41 southbound span 3.

Figure 29.

Histogram of half-cell potential readings for U S 41 southbound S F C in 1994 and 1997. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges from 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, and negative 400 to negative 449, there were 192, 130, 72, 82, 40, 80, 15, 4, and 0 observations, respectively for U S 41 southbound in 1994; and 1-0, 140, 140, 100, 58, 60, 30, 22, and 8, respectively for U S 41 southbound in 1997.

Figure 30.

Histogram of half-cell potential readings for U S 41 northbound L M C in 1994. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges from 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, negative 400 to negative 449, and negative 450 to negative 499, there were there 0, 0, 7, 54, 62, 37, 17, 11, 1, and 0 observations, respectively for U S 41 northbound span 1; 0, 6, 55, 78, 43, 4, 2, 0, 0, and 0, respectively for U S 41 northbound span 2; and 0, 0, 0, 12, 63, 57, 21, 19, 11, and 6, respectively for U S 41 northbound span 3.

Figure 31.

Histogram of half-cell potential readings for U S 41 northbound L M C in 1997. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges from 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, negative 400 to negative 449, negative 450 to negative 499, negative 500 to negative 549, negative 550 to negative 599, negative 600 to negative 649, and negative 650 to negative 699, there were there 0, 0, 18, 44, 49, 33, 14, 20, 5, 5, 0, 0, 0, and 0 observations, respectively for U S 41 northbound span 1; 0, 5, 33, 71, 64, 9, 3, 1, 1, 1, 0, 0, 0, and 0, respectively for U S 41 northbound span 2; and 0, 0, 0, 18, 48, 47, 38, 10, 14, 8, 5, 1, 0, and 1, respectively for U S 41 northbound span 3.

Figure 32.

Histogram of half-cell potential readings for U S 41 northbound spans in 1994 and 1997. The figure consists of a bar graph with potential range in millivolts on the horizontal axis and number of observations on the vertical axis. For potential ranges from 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, negative 400 to negative 449, negative 450 to negative 499, negative 500 to negative 549, negative 550 to negative 599, negative 600 to negative 649, and negative 650 to negative 699, there were there 0, 5, 62, 144, 168, 100, 40, 30, 12, 6, 0, 0, 0, and 0 observations, respectively for U S 41 northbound in 1994; and 0, 4, 30, 134, 160, 88, 56, 32, 20, 15, 5, 1, 0, and 1, respectively for U S 41 northbound in 1997.

Figure 33.

Cumulative frequency diagram for U S 41northbound and southbound for years 1994 and 1997. The figure consists of a line graph with potential range in millivolts on the horizontal axis and cumulative percent observations on the vertical axis. For the southbound lanes in 1994, there were 36, 58, 62, 84, 90, and 100 percent observations for potential ranges of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, and negative 250 to negative 699, respectively. For the southbound lanes in 1997, there were 0, 28, 54, 70, 80, 90, 97, and 100 percent observations for potential ranges of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, and negative 250 to negative 299, negative 300 to negative 349, and negative 350 to 699, respectively. For the northbound lanes in 1994, there were 0, 0, 10, 38, 68, 86, 90, 98,and 100 percent observations for potential ranges of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, and negative 400 to negative 699, respectively. For the northbound lanes in 1997, there were 0, 0, 10, 35, 60, 78, 88, 93, 96, 99, and 100 percent observations for potential ranges of 0 to negative 49, negative 50 to negative 99, negative 100 to negative 149, negative 150 to negative 199, 200 to negative 249, negative 250 to negative 299, negative 300 to negative 349, negative 350 to negative 399, and negative 400 to negative 449, negative 450 to negative 499, and negative 500 to negative 699, respectively.

Figure 34.

Equipotential map of half-cell potentials for the three spans of the southbound test section of U S 41 in 1997 S F C. Traffic direction is shown moving from left to right. Readings along the guard rail are shown on horizontal and vertical axes.

Figure 35.

Equipotential map of half-cell potentials for the three spans of the northbound test section of U S 41 in 1997 L M C. Traffic direction is shown moving from left to right. Readings along the guard rail are shown on horizontal and vertical axes.