TECHBRIEF

Research, Development, and 

Technology

Turner-Fairbank Highway 

Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

www.fhwa.dot.gov/research/

Surface Resistivity Test 

Evaluation as an Indicator 

of the Chloride Permeability

of Concrete

FHWA Publication No.: FHWA-HRT-13-024

FHWA Contact: Ahmad Ardani, HRDI-10, (202) 493-3422, 

ahmad.ardani@dot.gov

Introduction

Many agencies have adopted the standard tests for electrical 

indication of concrete’s ability to resist chloride ion penetration 

(AASHTO T 277 and ASTM C1202), commonly known as the rapid 

chloride permeability test (RCPT), in their specifications for qualification and acceptance and as a means of indirectly assessing 

the permeability of concrete mixtures. (See references 1–5.) 

Nevertheless, the RCPT is labor-intensive and costly and presents 

high variability.(3,6,7)

Research studies have shown that the surface resistivity (SR) 

test (AASHTO TP 95) is a promising alternative to the RCPT. 

(See references 3, 6, 8, and 9.) Recently, some agencies have 

shown interest in replacing the RCPT with the SR test and have 

started implementation efforts.(3,8) However, none of the studies 

have included high-volume fly ash (HVFA) mixtures or mixtures 

containing fly ash and fine limestone powder.

Objective

The purpose of this study was to investigate the correlation of the 

SR test with the widely used RCPT in evaluating concretes' ability to 

resist chloride penetration, including HVFA mixtures. 

Experimental Program

In this study, a total of 25 concrete mixtures were prepared. They 

covered a variety of mix designs, including plain portland cement 

mixtures (Type I/II cement), fly ash mixtures (Class F and Class C fly 

ashes), and ternary mixtures containing HVFA and fine limestone 

powder (0.3 mil). The water-to-binder ratio varied from 0.37 to 0.50, 

and the cementitious content varied from 423 to 643 lb/yd3

. Natural 

sand with specific gravity of 2.61, absorption of 1.1  percent, and 

fineness modulus of 2.76 was used. Different coarse aggregates 

were used, including gravel, limestone, granite, and diabase, with 

maximum size varying from 3⁄4 to 11⁄2 inches. 
2

Table 1 shows the proportions of plain portland 

cement mixtures with different cement content, 

water-to-cement ratios, and aggregate types and 

gradation. In the mixture ID, the first number represents the AASHTO M 43 aggregate size designation 

(size numbers 57, 67, and 467), the following letter 

represents the type of aggregate (L for limestone, DB 

for diabase, and GV for gravel), and the last number 

represents the water-to-cement ratio.(10) For example, 

mixture 57DB47 is a mixture with a No. 57 diabase 

and a 0.47 water-to-cement ratio.

Table 2 shows the mixture proportions of the binary 

and ternary mixtures. In the mixture ID, PC stands 

for Type I/II portland cement, F for Class F fly ash, 

Table 1. Mixture proportions of plain portland cement mixtures.

ID

Cement 

(lb/yd3)

Coarse 

Aggregate 

(lb/yd3)

Type of 

Coarse 

Aggregate

AASHTO 

M 43 

Gradation

Maximum 

Size 

(inches)

Coarse 

Aggregate 

Specific 

Gravity

Coarse 

Aggregate 

Absorption 

(percent)

Fine 

Aggregate

(lb/yd3

) W/C

WR 

(oz/

cwt)

AEA 

(oz/

cwt)

57LS42 643 1,790 Limestone 57 1 2.86 0.3 1,262 0.42 2.0 0.18

57GV47 643 1,699 Gravel 57 1 2.58 1.9 1,089 0.47 — 0.30

57DB37 643 1,699 Diabase 57 1 2.97 0.6 1,481 0.37 6.0 0.15

57GV40 564 1,750 Gravel 57 1 2.58 1.9 1,444 0.40 7.7 —

57DB42 643 1,699 Diabase 57 1 2.97 0.6 1,397 0.42 5.8 0.58

57DB47 643 1,699 Diabase 57 1 2.97 0.6 1,315 0.47 — 0.30

467LS37 521 1,790 Limestone 467 1.5 2.71 0.5 1,464 0.37 12.0 0.05

467LS42 521 1,790 Limestone 467 1.5 2.71 0.5 1,398 0.42 3.2 0.20

467LS47 521 1,790 Limestone 467 1.5 2.71 0.5 1,331 0.47 1.7 0.28

67GV42 564 1,750 Gravel 67 0.75 2.57 1.6 1,265 0.42 3.2 0.05

67GV45 564 1,750 Gravel 67 0.75 2.57 1.8 1,223 0.45 — 0.20

67LS37 564 1,750 Limestone 67 0.75 2.83 0.6 1,506 0.37 10.0 0.05

67LS42 564 1,750 Limestone 67 0.75 2.83 0.6 1,434 0.42 1.5 0.23

67DB37 564 1,750 Diabase 67 0.75 2.97 0.6 1,581 0.37 11.0 1.00

67DB42 564 1,750 Diabase 67 0.75 2.97 0.6 1,509 0.42 1.8 0.20

67DB45 564 1,750 Diabase 67 0.75 2.97 0.6 1,465 0.45 0.8 0.22

— Admixture was not used.

W/C = Water-to-cement ratio.

WR = Water-reducing admixture.

AEA = Air-entraining agent.

Table 2. Mixture proportions of binary and ternary mixtures.

ID

Cementitious 

Material

(lb/yd3)

Fly Ash 

Content

(percent)

Limestone

Powder

Content 

(percent)

Type of 

Coarse 

Aggregate

AASHTO 

M 43 

Gradation

Coarse 

Aggregate 

Specific 

Gravity

Coarse 

Aggregate 

Absorption 

(percent)

Coarse 

Aggregate

(lb/yd3

)

Fine 

Aggregate

(lb/yd3) W/CM

WR 

(Type A)

(oz/

cwt)

AEA 

(oz/

cwt)

69PC31F 491 31 0 Gravel 57 2.56 1.9 1750 1444 0.46 3.90 —

68PC23F9L 499 23 9 Gravel 57 2.56 1.9 1750 1444 0.45 3.90 —

65PC35C 522 35 0 Gravel 57 2.56 1.9 1750 1444 0.43 3.00 —

65PC26C9L 522 26 9 Gravel 57 2.56 1.9 1750 1444 0.43 3.00 —

50PC50F 454 50 0 Gravel 57 2.56 1.9 1750 1444 0.50 3.90 —

48PC37F15L 467 37 15 Gravel 57 2.56 1.9 1750 1444 0.48 3.90 —

45PC55C 501 55 0 Gravel 57 2.56 1.9 1750 1444 0.45 3.00 —

45PC41C14L 502 41 14 Gravel 57 2.56 1.9 1750 1444 0.45 3.00 —

75PC25F 564 25 0 Granite 57 2.80 0.5 1823 1264 0.45 1.75 0.77

— Admixture was not used.

W/CM = Water-to-cementitious materials ratio.

WR = Water-reducing admixture.

AEA = Air-entraining agent.

Note: The nominal maximum size of all coarse aggregate was 0.75 inches.
3

C for Class C fly ash, and L for fine limestone powder 

(0.3  mil), which was used as a portland cement 

replacement. The number preceding the letters represents the percentage of that material in relation 

to the total mass of cementitious material. For 

example, mixture 68PC23F9L is a mixture that contains 68 percent portland cement, 23 percent Class F 

fly ash, and 9 percent fine limestone on a mass basis.

Mixtures were prepared and cast following ASTM 

C192.(11) A minimum of six cylinders were cast, three 

for 28-day compressive strength tests and three for 

SR tests as well as RCPT. In some cases, three extra 

specimens were cast for testing at different ages. 

Specimens were protected from moisture loss for 

the first 24 h, then demolded, placed in a standard 

lime water tank, and cured at 73 ±3 °F until tested.

Slump tests (ASTM C143/143M), air content tests 

(ASTM C231/C231M), unit weight tests (ASTM C138), 

28-day compressive strength tests (ASTM C39/

C39M), SR tests (AASHTO TP 95), and RCPT (ASTM 

C1202) were carried out. (See references 2, 9, and 

12–15.) SR tests and RCPT were carried out by a 

single operator.

A four-point Wenner probe with 1.5-inch probe 

spacing was used for the SR tests (see figure 1). A 

total of eight readings per specimen were taken. The 

readings were averaged and a correction factor of 

1.1 was applied to take into account the lime water 

curing condition. 

Immediately after the SR test, the specimens were 

cut, prepared, and tested according to ASTM C1202, 

so the same specimen was used for both the SR test 

and the RCPT. The SR test was carried out at 28 days 

on plain mixtures and at 56 days on binary and 

ternary mixtures. In a few cases, binary and ternary 

mixtures were also tested at 28 days. 

Results

Table 3 shows the fresh property test results and 

28-day compressive strength of all the mixtures. The 

mixtures presented a wide range of results; slump 

varied from 0.25 to 7.5 inches, air content varied from 

2.6 to 7.9 percent, and compressive strength varied 

from 1,730 to 7,860 lbf/in2

.

Figure 2 shows the relationship between the SR 

test and the RCPT, where each point represents the 

average of three tests. According to Broomfield and 

Millard and Gowers and Millard, the maximum size 

of the aggregate should not exceed 1 inch for the 

Figure 1. SR test using a four-point Wenner probe.

Table 3. Fresh properties and compressive strength 

results.

ID

Slump 

(inches)

Unit 

Weight

(lb/ft3)

Air 

Content 

(percent)

28-day 

Compressive 

Strength

(lbf/in2

)

57LS42 3.00 145.3 6.0 6,150

57LS47 3.00 144.2 5.5 5,220

57GV37 2.50 139.9 7.0 5,490

57GV40 1.50 144.3 4.0 6,750

57DB42 2.25 148.4 6.9 5,350

57DB47 7.50 145.3 7.0 5,130

467LS37 0.25 144.8 6.0 7,860

467LS42 0.75 142.9 7.0 5,420

467LS47 3.50 142.2 7.9 4,590

67GV42 4.50 141.4 6.6 5,170

67GV45 3.00 142.0 5.5 4,450

67LS37 0.25 147.0 4.5 7,710

67LS42 1.25 146.9 5.0 5,610

67DB37 0.25 155.5 4.7 7,540

67DB42 2.00 149.7 6.8 5,570

67DB45 1.00 152.6 5.0 5,730

57GT45 3.00 149.8 5.1 5,040

69PC31F 0.75 145.0 2.6 3,730

68PC23F9L 1.00 143.9 3.0 4,580

65PC35C 2.00 144.7 3.0 4,031

65PC26C9L 1.25 144.6 3.3 5,470

50PC50F 1.00 143.4 3.1 1,730

48PC37F15L 0.75 143.4 3.0 2,460

45PC55C 5.00 143.3 4.4 1,870

45PC41C14L 2.50 143.1 3.8 3,640
4

probe spacing used in this study (1.5 inches), but 

there were three mixtures with a 1.5-inch maximum 

size.(16,17) Nonetheless, these mixtures followed the 

trend of the other mixtures, and the overall correlation between the two tests resulted in a best-fit line 

with an R2

 of 0.92. If supplementary cementitious 

materials other than fly ash or admixtures that 

could affect the electrical conductance are used, 

this regression line should not be used without 

validation. 

The SR tests were easier and faster to run and presented lower variability than the RCPT. The coefficient 

of variation (COV) of the SR tests ranged from 0.9 

to 14.9 percent with an average of 5.3 percent, and 

the COV of the RCPT varied from 2.9 to 19.3 percent 

with an average of 10.0 percent. The SR test results 

ranged from about 6 to about 29 kohm-cm, and the 

RCPT results ranged from about 1,160 to 12,000 C, 

which represent mixtures with low to high chloride 

ion penetrability.

Table 4 shows how AASHTO TP 95 and ASTM C1202 

classify mixtures by chloride penetrability, depending on resistivity or charge passed, respectively.(2,9)

According to the ASTM C1202 criterion, 7 of the 

33 sets of tests were classified as low penetrability 

(< 2,000 C), 20 sets as moderate penetrability (2,000–

4,000 C), and 6 sets as high penetrability (> 4,000 C). 

According to the AASHTO TP 95 criterion, 5 sets were 

classified as low penetrability (21–37  kohm-cm), 

20 sets as moderate penetrability (12–21 kohm-cm), 

and 8 sets as high penetrability (< 12 kohm-cm).

The shaded areas in figure 2 represent the combination of these classifications. Points within the 

shaded areas receive the same classification by both 

standards. There were only four points outside of 

the shaded areas, and they were classified with a 

higher penetrability by the AASHTO TP 95 criterion 

than by the ASTM C1202 criterion, indicating that the 

AASHTO TP 95 classification is more conservative.

Figure 3 shows the data and best-fit curve obtained in 

this study compared to two other studies. Chini et al. 

evaluated 508 sets of samples representing a total 

of 134 mixtures, including plain, binary, and ternary 

mixtures.(6) Rupnow and Icenogle only evaluated 

plain and binary mixtures.(3)

As shown, the curve obtained in this study is in 

agreement with the curve obtained by Chini et al.(6)

However, the Rupnow and Icenogle curve yields up 

to 40 percent lower Coulomb values for resistivities 

less than 15  kohm-cm.(3) For resistivities of about 

15 kohm-cm and higher, the difference between this 

study’s curve and the Rupnow and Icenogle curve is 

negligible.

y = 98,441.22x-1.35

R2 = 0.92

8000

10000

12000

14000

PT (Coulombs)

High

0

2000

4000

6000

0 5 10 15 20 25 30 35

Average RCP

Moderate

Low

0

0 5 10 15 20 25 30 35

Average surface resistivity (kohm.cm)

Figure 2. Relationship between SR test and RCPT.

Table 4. Chloride penetrability classification.

Chloride Ion 

Penetrability

AASHTO TP 95 

(kohm-cm)

ASTM C1202

(Coulombs)

High < 12 > 4,000

Moderate 12–21 2,000–4,000

Low 21–37 1,000–2,000

Very Low 37–254 100–1,000

Negligible > 254 < 100
5

Conclusions

Twenty-five plain, binary, and ternary mixtures containing up to 55 percent class F or class C fly ashes 

and, in some cases, fine limestone powder and with 

different aggregate types and maximum sizes were 

used to evaluate the correlation between the RCPT and 

the SR test. The results show that the SR test results 

are highly correlated with the RCPT even for HVFA 

mixtures and ternary mixtures with finely ground 

limestone, and a correlation curve was proposed. 

The SR test was easier and faster to run compared to 

the RCPT and did not require any specimen preparation. It also presented lower variability than the RCPT. 

References

1. AASHTO T 277 (2007). Standard Method of Test for 

Electrical Indication of Concrete’s Ability to Resist 

Chloride Ion Penetration, American Association 

of State Highway and Transportation Officials, 

Washington, DC.

2. ASTM C1202 (2010). Standard Test Method for 

Electrical Indication of Concrete’s Ability to Resist 

Chloride Ion Penetration, ASTM International, West 

Conshohocken, PA.

3. Rupnow, T. and Icenogle, P. (2012). “Evaluation 

of Surface Resistivity Measurements as an 

Alternative to the Rapid Chloride Permeability Test 

for Quality Assurance and Acceptance.” TRB 91st 

Annual Meeting, Transportation Research Board, 

Washington, DC. 

4. Hoppe, E., Lundy, L., and Schinkel, T. (2007). 

Implementation of an Automated Test Setup for 

Measuring Electrical Conductance of Concrete, 

Report No. FHWA/VTRC 07-R21, Virginia Transportation Research Council, Charlottesville, VA. 

5. Ontario Ministry of Transportation (2008). 

“Material Specification for Concrete—Materials 

and Production.” Ontario Provincial Standard 

Specification, OPSS.MUNI 1350, Toronto, ON. 

6. Chini, A., Muszynski, L., and Hicks, J. (2003). 

Determination of Acceptance Permeability Characteristics for Performance-Related Specifications 

for Portland Cement Concrete, Report No. 

BC  354-41, Florida Department of Transportation, 

Tallahassee, FL. 

7. Obla, K. and Lobo, C. (2007). “Acceptance Criteria for 

Durability Tests: Minimizing the Risks of Accepting 

Defective Concrete or Rejecting Acceptable 

Concrete.” Concrete International, Vol. 29, Issue 5, 

American Concrete Institute, Farmington Hills, MI. 

8. Kessler, R., Powers, R., Vivas, E., Paredes, M., 

and Virmani, Y. (2008). “Surface Resistivity as 

an Indicator of Concrete Chloride Penetration 

Resistance.” Presented at the 2008 Concrete Bridge 

Conference, St. Louis, MO. 

9. AASHTO TP 95 (2011). Standard Method of Test for 

Surface Resistivity of Concrete’s Ability to Resist 

Chloride Ion Penetration, American Association 

of State Highway and Transportation Officials, 

Washington, DC.

4,000

6,000

8,000

10,000

12,000

14,000

erage RCPT (Coulombs)

TFHRC data

Chini et al. 

correlation curve

R Il

0

2,000

0 10 20 30

Ave

Average surface resistivity (kohm.cm)

Rupnow; Icenogle 

correlation curve

Figure 3. Correlation between SR test and RCPT obtained in different studies.
6

10. AASHTO M 43 (2005). Standard Specification 

for Sizes of Aggregate for Road and Bridge 

Construction, American Association of State Highway and Transportation Officials, Washington, DC.

11. ASTM C192 (2007). Standard Practice for 

Making and Curing Concrete Test Specimens 

in the Laboratory, ASTM International, West 

Conshohocken, PA.

12.ASTM C143/143M (2010). Standard Test Method 

for Slump of Hydraulic-Cement Concrete, ASTM 

International, West Conshohocken, PA.

13.ASTM C231/C231M (2010). Standard Test Method 

for Air Content of Freshly Mixed Concrete by 

the Pressure Method, ASTM International, West 

Conshohocken, PA.

14. ASTM C138 (2009). Standard Test Method for 

Density (Unit Weight), Yield, and Air Content 

(Gravimetric) of Concrete, ASTM International, 

West Conshohocken, PA.

15.ASTM C39/39M (2009). Standard Test Method 

for Compressive Strength of Cylindrical 

Concrete Specimens, ASTM International, West 

Conshohocken, PA.

16.Broomfield, J. and Millard, S. (2002). “Measuring 

Concrete Resistivity to Assess Corrosion Rates.” 

Current Practice Sheet 128, The Concrete Society, 

Surrey, UK. 

17. Gowers, K. and Millard, S. (1999). “Measurement of 

Concrete Resistivity for Assessment of Corrosion 

Severity of Steel Using Wenner Technique.” ACI 

Materials Journal, Vol. 96, Issue 5, American 

Concrete Institute, Farmington Hills, MI.

Researchers—Jussara Tanesi, Ph.D. and Ahmad Ardani, P.E. at the Federal Highway Administration (FHWA) 

Turner-Fairbank Highway Research Center. For additional information, contact Mr. Ardani at (202) 493-3422 

or through the FHWA Office of Infrastructure Research and Development located at 6300 Georgetown Pike, 

McLean, VA, 22101-2296.

Distribution—This TechBrief is being distributed according to a standard distribution. Direct distribution 

is being made to the Divisions and Resource Center.

Availability—This TechBrief may be obtained from the FHWA Product Distribution Center by email to 

report.center@dot.gov, fax to (814) 239-2156, phone to (814) 239-1160, or online at http://www.fhwa.

dot.gov/research. 

Key Words—Surface resistivity (SR test), Chloride penetration/permeability test (RCPT).

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December 2012 FHWA-HRT-13-024

HRDI-10/12-12(500)E