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Practicalevaluationofrelationshipbetweenconcreteresistivity,waterpenetration,rapidchloridepenetrationandcompressivestrengthARTICLEinCONSTRUCTIONANDBUILDINGMATERIALSMAY2011ImpactFactor:2.3DOI:10.1016/j.conbuildmat.2010.11.069

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2010 Elsevier Ltd. All rights reserved.

tion ofost signy is colly occel, duesence

Nevertheless, the primary driving force in the diffusion of chlo-ride ions in concrete is the difference in the concentration of chlo-ride ions which are present in different sections of concrete [3].There are several methods to evaluate the penetration of chlorideinto concrete. The methods which are solely based upon the diffu-sion mechanism suffer from a major limitation in that the diffusionprocess. The limitation is that diffusion process needs a long timeto completely attain steady-state condition, and therefore it is

across the specimen for a period of 6 h [8]. The measured currentvs. time data is integrated to obtain the total charge passed in cou-lombs. Five levels are identied to classify the charge passed ascorresponding to chloride ion penetrabilities of high, moderate,low, very low, or negligible.

The Rapid Chloride Penetration Test (RCPT) is very commonlyused because of its simplicity. However, several researchers[9,10] have raised concerns over this test. The RCPT is an index testin which no steady-state conditions exist.

Other problems associated with the RCPT include the heatevolved in the test [10] and alteration in the pore uid characteristics

Corresponding author. Tel.: +98 21 6454 3074; fax: +98 21 6641 4213.

Construction and Building Materials 25 (2011) 24722479

Contents lists availab

B

evE-mail addresses: amir63p@aut.ac.ir, amir63p@yahoo.com (A. Pilvar).Soluble chlorides in deicing salts or those occurring naturally insoils, seawater and groundwater can penetrate into concrete coverby absorption through its surface, diffusion in interconnected capil-lary pores or direct access through cracks in the concrete. Althoughthe primary mechanism of chloride transport for the near-surfaceunsaturated concrete is absorption, the accumulation of chloridesin this layer leads to further penetration of chlorides into concreteby diffusion [2]. As a consequence, diffusion becomes themost dom-inant mechanism of chloride transport at higher depths.

for the Federal Highway Administration (FHWA) in the late 1970s.It is typically referred to the Rapid Chloride Penetration Test (RCPT)[6,7], even though it is really a measure of electric conductivity.This test was adopted by AASHTO in 1983 as T277 and by ASTMin 1991 as ASTM C1202 [8].

The ASTM C1202 standard test method for electrical indicationof concretes ability to resist chloride ion penetration monitors theamount of electrical current that passes through a cylindrical con-crete specimen when a 60 V dc potential difference is applied1. Introduction

It is widely known that deteriorasion of reinforcement is one of the mlems that the construction industrcorrosion of steel in concrete normathe reduction in alkalinity at the stecrete or leaching of alkalis, or the preof chloride ions in the concrete.0950-0618/$ - see front matter 2010 Elsevier Ltd. Adoi:10.1016/j.conbuildmat.2010.11.069concrete due to corro-icant durability prob-ncerned with [1]. Theurs as a result of eitherto carbonation of con-of a signicant quantity

not practical method to assess the resistance of concrete to chlo-ride ions [4]. However, the diffusion process can be acceleratednot only by decreasing the specimen thickness but also by increas-ing the upstream chloride concentration as quoted by Streicherand Alexander [5].

Since the 1970s different organizations and professionals havetried to develop and implement rapid, inexpensive and reliabletests to measure the ability of concrete to resist the penetrationof chloride ions. For instance Whiting developed one of these testsRCPTPermeability

on the correlation of concrete resistivity with water penetration and Rapid Chloride Penetration Test(RCPT) results, two new models for relating these parameters are presented.Practical evaluation of relationship betwepenetration, rapid chloride penetration a

Ali Akbar Ramezanianpour, Amirreza Pilvar , MahdConcrete Technology and Durability Research Center (CTDRc), Amirkabir University of T

a r t i c l e i n f o

Article history:Received 15 June 2010Received in revised form 17 October 2010Accepted 13 November 2010Available online 28 December 2010

Keywords:Water penetrationElectrical resistivity

a b s t r a c t

There are several factors andeal of attention has been pduction of sustainable concwhich are most commonlymethods specied by BS E(SR) test is also a suitabledestructive, simple, rapid aThe present study is an e

Construction and

journal homepage: www.elsll rights reserved.n concrete resistivity, watercompressive strength

ahdikhani, Faramarz Moodiology, Tehran, Iran

st methods for evaluating the durability of concrete. In recent years a greatto research and development of relationships of these parameters for pro-es: water penetration and Rapid Chloride Penetration Test (RCPT) methodsed to evaluate the permeability of concrete are two of the most famous2390-8:2000 and ASTM C1202 respectively. Concrete surface resistivityicator for concrete penetration and chloride ion permeability. It is a non-economical method that can also be used on site.oratory research concerned with the relationship of these methods. Based

le at ScienceDirect

uilding Materials

ier .com/locate /conbui ldmat

when pozzolanic materials are used. In addition, the ux in theRCPT may not be in steady-state condition due to the high poten-tial difference of 60 V [11]. Consequently the results obtained maynot represent true chloride diffusion in concrete. However, it iswidely used because of its convenience and short-term duration.On the other hand, concrete resistivity is also a geometry indepen-dent material property that depends on the moisture content andthe concrete composition [12].

Theoretical and experimental studies indicate a correlation be-tween concrete resistivity and chloride ingress [1315]. In general,the chloride diffusion coefcient is inversely proportional to theconcrete resistivity. Within a particular structure, more permeable

four equally spaced surface contacts, where a 25 V peak to peak

For all mix designs, coarse aggregates were crushed calcareous stone with amaximum size of 19 mm and ne aggregates were natural sand. The coarse aggre-gates have a specic gravity and a water absorption of 2510 kg/m3 and 1.90%,respectively, and the ne aggregate has a water absorption of 2.75% and a specicgravity of 2570 kg/m3. A superplasticizer was employed to achieve the desiredworkability. Potable water was used for casting and curing all concrete specimens.The concrete production was carried out in a 60 l capacity mixer. All replacementswere made by mass. The mixture proportions for concrete specimens are summa-rized in Table 2.

2.2. Testing procedure and specimen preparation

Concrete test specimens were vibrated over a vibrating table to remove en-trapped air. After casting, the concrete specimens were covered with a wet towel

ability. The test result is a function of the electrical resistance of the specimen. Aschematic gure of electrical resistivity meter is shown in Fig. 1. Saturated cylinders

Pumice Silica fume Metakaolin

A.A. Ramezanianpour et al. / Construction and Building Materials 25 (2011) 24722479 2473and 13 Hz alternating trapezoidal voltage is passed through a con-crete sample between the outer pair of contacts [16].

Another main factor of concrete durability is permeability. Con-crete with lower permeability shows better resistance againstchemical attacks. When water penetrates into the concrete, somesoluble salts including chloride ions go through concrete causingcorrosion. Generally, it seems that lower permeability causes high-er durability in concretes. Various tests such as water penetrationtest are used to evaluate the permeability of concretes and severalstudies have been carried out on this issue and validity of thesetests has been approved [17] and several researchers used thesemethods for evaluation of performance of concrete [1820].

The aim of this study is to investigate the possibility of replac-ing the Rapid Chloride Penetration Test and water penetration testby the simple non-destructive surface resistivity test.

2. Experimental programs

2.1. Material and mixture proportion

A total of 57 concrete mixtures were used throughout this investigation. Theseconcrete mixtures were made in the Concrete Technology and Durability ResearchCenter (CTDRc) at Amirkabir University. ASTM C 150 type I Portland cement wasused for all of the concrete mixtures. The two natural pozzolans which were usedin this work included Tuff and Pumice. In addition, rice husk ash and metakaolinproduced by a special designed furnace at 650 C for 60 min burning time whereadded to the mixture. Silica fume was used as cement replacement material. Chem-ical characteristics of the above mentioned materials are shown in Table 1.

Table 1Chemical characteristics of supplementary materials and cement.

Chemical components Cement type I RHA Tuff

SiO2 21.5 89.61 65.74Al2O3 3.68 0.04 12.24Fe2O3 2.76 0.22 2.05CaO 61.5 0.91 2.87SO3 2.5 0.15 0MgO 4.8 0.42 0.96Na2O 0.12 0.07 1.92K2O 0.95 1.58 2.02P O 0.23 0.41 0.03zones will have a comparatively lower resistivity and higher chlo-ride penetration.

It well understood that the resistivity of concrete and the corro-sion rate of reinforcement after depassivation are related. Iontransport between anodes and cathodes on the steel surface isone of the factors controlling the rate of corrosion [12].

One of the best methods to measure concrete resistivity is usingfour-point Wenner array probe resistivity meter. The non-destruc-tive nature, speed, and ease of use, make the Wenner array proberesistivity technique a promising alternative test to characterisethe chloride penetration resistance concrete. The set up utilizes2 5

TiO2 0.04 0.02 0.29LOI 1.35 5.91 8.5A B C

67.7 94.66 72.5 76.73 68.9915.8 0.31 22.21 17.41 20.463.39 0.60 0.81 0.59 0.993.9 0.36 2.22 3.58 2.750.33 0.23 0.99 0.78 0.13 0.19 0.502.95 0.22 0.05 0.05 2.802 0.22 0.55 0.31 2.240.12 0.05 0.04 0.05(100 200 mm) were used at each test age. The electrical resistivity test for con-cretes was carried out by the four-point Wenner array probe technique. The probearray spacing used was 40 mm. The resistivity measurements were taken at fourquaternary longitudinal locations of the specimen [21].

The Rapid Chloride Penetration Test was conducted in accordance with ASTMC1202 for each mixture. Two specimens of 100 mm in diameter and 50 mm inthickness which had been conditioned according to the standard were subjectedto a 60 V potential for 6 h. The total charge passed through the concrete specimenswas determined and used to evaluate the chloride permeability of each concretemixture. The ages of specimens for the tests are shown in Table 3.

3. Results and discussions

Electrical resistance and conductivity are both intrinsic proper-ties of materials that can be evaluated for the durability of con-cretes. Several research studies concerning with the electricalresistance, permeability of concretes and resistance of concretesagainst chloride ions ingress have been carried out [14,15]. The re-sults show that there is a strong relationship between electricalresistivity and permeability of concretes.

Electrical resistivity of concrete represents moving ions (such aschloride ions) in pore solution. Therefore, the relationship betweenelectrical resistivity and chloride ion penetration in concrete isreasonable.for 24 h and cured under laboratory conditions. Then they were demolded andcured in lime-saturated water at 23 2 C to prevent possible leaching of Ca(OH)2from these specimens.

Concrete cubes of 100 100 100 mm dimension were cast for compressivestrength. They were tested after 7 and 28 days of water curing.

The water penetration test, which is most commonly used to evaluate the per-meability of concrete, is the one specied by BS EN-12390-8:2000. In this test,water was applied on one face of the 150 mm concrete cubes specimen under apressure of 0.5 MPa. This pressure was maintained constant for a period of 72 h.After the completion of the test, the specimens were taken out and split open intotwo halves. The water penetration prole on the concrete surface was then markedand the maximum depth of water penetration in specimens was recorded and con-sidered as an indicator of the water penetration.

The electrical resistivity meter was used to measure the surface resistivity (SR)of the specimens. This non-destructive laboratory test method measures the electri-cal resistivity of water-saturated concrete and provides an indication of its perme-0.33 0.06 0.06 0.092.3 1.77 0.76 0.82 0.89

Table 2Mixture proportions of concrete.

No. Mixtures Cement content w/c Supplementary materi

Type

1 C35.50P0 350 0.5 Pumice2 C35.50P10 350 0.5 Pumice3 C35.50P15 350 0.5 Pumice4 C35.50P20 350 0.5 Pumice5 C35.50T15 350 0.5 Tuff6 C35.50T20 350 0.5 Tuff7 C35.50T25 350 0.5 Tuff8 C42.45R0 420 0.45 RHA9 C42.45R7 420 0.45 RHA

10 C42.45R10 420 0.45 RHA11 C42.45R15 420 0.45 RHA12 C40.45MS0 400 0.45 NS13 C40.45NS4.5 400 0.45 NS14 C40.45NS7.5 400 0.45 NS15 C40.45MS4.5 400 0.45 SF16 C40.45MS7.5 400 0.45 SF17 C40.45M0 400 0.45 Metakaoline18 C40.45Ma5 400 0.45 Metakaoline-A19 C40.45Ma10 400 0.45 Metakaoline-A20 C40.45Ma15 400 0.45 Metakaoline-A21 C40.45Ma20 400 0.45 Metakaoline-A22 C40.45Mb5 400 0.45 Metakaoline-B23 C40.45Mb10 400 0.45 Metakaoline-B24 C40.45Mb15 400 0.45 Metakaoline-B25 C40.45Mb20 400 0.45 Metakaoline-B26 C40.45Mc5 400 0.45 Metakaoline-C27 C40.45Mc10 400 0.45 Metakaoline-C28 C40.45Mc15 400 0.45 Metakaoline-C29 C40.45Mc20 400 0.45 Metakaoline-C30 C45.40MS0 450 0.4 SF31 SCC45.40MS0 450 0.4 SF32 SCC45.40MS7.5 450 0.4 SF33 SCC45.40MS7.5 480 0.4 SF34 SCC45.40P15 450 0.4 Pumice35 SCC45.40P15 515 0.4 Pumice36 SCC45.40R10 450 0.4 RHA37 SCC45.40R10 495 0.4 RHA38 C25.45 250 0.45 39 C25.55 250 0.55 40 C25.60 250 0.6 41 C30.45 300 0.45 42 C30.55 300 0.55 43 C30.60 300 0.6 44 C35.45 350 0.45 45 C35.55 350 0.55 46 C35.60 350 0.6 47 C42.45 425 0.45 48 C42.55 425 0.55 49 C42.60 425 0.6 50 C32.50MS0 325 0.5 SF51 C32.50MS7.5 325 0.5 SF52 C40.50MS0 400 0.5 SF53 C40.50MS7.5 400 0.5 SF54 C32.40MS0 325 0.4 SF55 C32.40MS7.5 325 0.4 SF56 C40.40MS0 400 0.4 SF57 C40.40MS7.5 400 0.4 SF

Fig. 1. Schematic gure of electrical resistivity meter [21].

2474 A.A. Ramezanianpour et al. / Construction andal Aggregate (kg/m3, SSD) Compressive strength (MPa, 28 days)

(%) Coarse Fine

0 802 980 43.310 802 980 37.815 802 980 39.020 802 980 39.315 802 980 49.8

Building Materials 25 (2011) 24722479If the electrical resistivity is high, then the movement of chlo-ride ions in concrete will be slow and consequently the corrosionrate of reinforcements in concrete will decrease. Therefore, con-crete elements will be more durable and have a longer life cycle.The results of Polders investigation [22] show that there is a linearrelationship between electrical resistivity and probability of corro-sion in concrete.

On the other hand, there are some differences between concreteresistivity and its permeability. Concrete resistivity (rspecimen) de-pends both on the microstructure properties of the concrete (F)and the conductivity of the pore solution (rporesoln). Parameter F

20 802 980 45.525 802 980 50.20 760 929 40.37 760 929 42.810 760 929 44.815 760 929 46.90 778 951 52.34.5 778 951 57.87.5 778 951 62.04.5 778 951 55.27.5 778 951 61.00 778 951 46.35 778 951 49.710 778 951 52.015 778 951 51.820 778 951 47.35 778 951 52.210 778 951 50.015 778 951 46.720 778 951 43.75 778 951 50.010 778 951 48.315 778 951 42.020 778 951 39.00 760 929 52.80 740 949 56.77.5 740 949 65.97.5 715 918 69.515 740 949 46.515 686 883 58.210 740 949 55.910 703 903 61.3 910 1112 65.3 881 1077 52.5 867 1060 42.3 866 1059 61.9 832 1016 46.7 814 995 35.3 822 1005 54.0 782 956 42.6 762 931 33.8 756 924 46.5 707 864 36.8 683 835 28.30 825 1009 28.47.5 825 1009 34.70 755 923 23.17.5 755 923 32.60 863 1054 48.37.5 863 1054 43.10 801 979 33.67.5 801 979 41.0

andTable 3Ages of tests.

No. Mixtures Test ages

SR RCPT W.P.

1 C35.50P0 72,890,180 90,180 90,1802 C35.50P10 72,890,180 90,180 90,1803 C35.50P15 72,890,180 90,180 90,1804 C35.50P20 72,890,180 90,180 90,1805 C35.50T15 72,890,180 90,180 90,1806 C35.50T20 72,890,180 90,180 90,1807 C35.50T25 72,890,180 90,180 90,180

A.A. Ramezanianpour et al. / Constructionis an experimentally constant factor and represents the effects ofmicrostructure on permeability of concrete and it depends onmany factors.

rspecimen rporesoln=F 1Thus, a concrete containing a low-alkali cement should exhibit a

lower resistivity even when it has the same microstructure as oneproduced by using a high-alkali cement. This is one of the com-monly cited limitations in utilizing conductivity methods to assessdiffusive transport in cement based materials [6,23]. As can be seenin RCPT and SR test results, the passing charge and electrical resis-tivity of concrete samples containing pozzolanic materials are im-proved 45 times compared to control samples.

8 C42.45R0 72,890,180 72,890,1809 C42.45R7 72,890,180 72,890,180

10 C42.45R10 72,890,180 72,890,18011 C42.45R15 72,890,180 72,890,18012 C40.45MS0 72,890,180 2,890,180 2813 C40.45NS4.5 72,890,180 2,890,180 2814 C40.45NS7.5 72,890,180 2,890,180 2815 C40.45MS4.5 72,890,180 2,890,180 2816 C40.45MS7.5 72,890,180 2,890,180 2817 C40.45M0 72,890,180 72,890,180 72,890,18018 C40.45Ma5 72,890,180 72,890,180 72,890,18019 C40.45Ma10 72,890,180 72,890,180 72,890,18020 C40.45Ma15 72,890,180 72,890,180 72,890,18021 C40.45Ma20 72,890,180 72,890,180 72,890,18022 C40.45Mb5 72,890,180 23 C40.45Mb10 72,890,180 24 C40.45Mb15 72,890,180 25 C40.45Mb20 72,890,180 26 C40.45Mc5 72,890,180 72,890,180 72,890,18027 C40.45Mc10 72,890,180 72,890,180 72,890,18028 C40.45Mc15 72,890,180 72,890,180 72,890,18029 C40.45Mc20 72,890,180 72,890,180 72,890,18030 C45.40MS0 7,284,290 7,284,290 72,89031 SCC45.40MS0 7,284,290 7,284,290 72,89032 SCC45.40MS7.5 7,284,290 7,284,290 72,89033 SCC45.40MS7.5 7,284,290 7,284,290 72,89034 SCC45.40P15 7,284,290 7,284,290 72,89035 SCC45.40P15 7,284,290 7,284,290 72,89036 SCC45.40R10 7,284,290 7,284,290 72,89037 SCC45.40R10 7,284,290 7,284,290 72,89038 C25.45 728 728 72839 C25.55 728 728 72840 C25.60 728 728 72841 C30.45 728 728 72842 C30.55 728 728 72843 C30.60 728 728 72844 C35.45 728 728 72845 C35.55 728 728 72846 C35.60 728 728 72847 C42.45 728 728 72848 C42.55 728 728 72849 C42.60 728 728 72850 C32.50MS0 28 28 2851 C32.50MS7.5 28 28 2852 C40.50MS0 28 28 2853 C40.50MS7.5 28 28 2854 C32.40MS0 28 28 2855 C32.40MS7.5 28 28 2856 C40.40MS0 28 28 2857 C40.40MS7.5 28 28 28The conductivity property of the concrete is predominantly gov-erned by the chemical compositions of the pore solutions, althoughalso affected by the pore structure of the concrete [24]. OH-ions,for example, have a greater ionic conductance than chloride ions(Table 4). Consequently in pore solution with a high concentrationof OH-ions, these would be much more contribute to the cell cur-rent that chloride ions, and thereby by misleading any unsuspect-ing observer to believe, that the tested concrete shows anunacceptably high level of chloride permeability. In addition, Shiet al. [25] showed that the presence of silica fume can alter thecomposition of the concrete pore solution to the extent that theelectrical conductivity of the concrete may be reduced by 90%against conventional mixtures with Portland cement alone.

During the RCPT test because of the high voltage of 60 V, andrelatively long duration of the test (6 h), temperature of specimensincreases, causing to enhance the total passing charges. Tempera-ture may also increase the microstructure damages and can changethe chemical composition of pore solutions, and thereby the pri-mary condition of concrete will be changed especially in a highwater/cement ratio concrete. Therefore, due to the widespreaduse of RCPT, the idea of utilizing SR test instead of RCPT test isfavorable. It means change in the type of measured data (conduc-tivity instead of total charge) is an option that provides animprovement to the RCPT test. It is noticeable that the correlationbetween total charge and conductivity should be conrmed if it isexpected to use SR test instead of RCPT test.

Assuming constant conductivity of concrete samples during thetest process, and based on physical principles of RCPT and SR tests,it can be concluded that the relationship between the two testsshould be linear. However, the results of this study, show thatthere is a strong power relation (y = axb) between themwith a levelof agreement (R2) of 0.898 for a wide range of concrete specimens(see Fig. 2). Because temperature increases during the RCPT test,electrical resistance of samples decreases and the current throughthe sample increases. As a result, this correlation would not be lin-ear and therefore with greater conductivity and higher permeabil-ity of concrete specimens, the power of relation (b) will be lower.Based on Julio-Betancourt and Hooton [26] investigation, if thesample temperature during the RCPT test remains constant, thena linear relationship between conductivity and total charge fromRCPT test will be achieved with R2 = 0.988. They also recommendthe 1 min conductivity test using the RCPT test equipment as apractical way of improving the current ASTM C1202 standard.

One of the main factors of concrete durability is permeability. Inthis study, water penetration test in accordance with BS EN-12390-8 has been used to evaluate the permeability of concrete. As can beseen in Fig. 3, there is a relation with R2 = 0.827 between electricalresistivity and water Penetration of concrete in various mixtures.

As can be seen in Figs. 4 and 5 a good relationship is obtained2

Table 4Comparison of ionic conductance [24].

Ions Conductance (X1 m2)

Cl 0.007523OH 0.019800

Building Materials 25 (2011) 24722479 2475with the same type of cementitious materials (R = 0.875 and0.866). However when samples with different cementitious mate-rials are used, the correlation coefcient is reduced. This phenom-enon can be described in that the result of SR test depends on bothmicrostructure and pore solution of concretes while water pene-tration test depends only on microstructure.

In the concrete samples with different cementitious materialsthe chemical compounds of pore solution is changed and variouslevel of conductivities for pore solution are achieved. Therefore,the resistivity of concrete samples changes and the correlation

Fig. 2. Relationship between RCPT and SR for all mixtures.

Fig. 3. Relationship between water penetration and SR for all mixtures.

Fig. 4. Relationship between water penetration and SR for mixtures containing metakaolin.

2476 A.A. Ramezanianpour et al. / Construction and Building Materials 25 (2011) 24722479

Fig. 5. Relationship between water penetration and SR for plain mixtures.

Fig. 6. Relationship between compressive strength and SR for all mixtures.

Fig. 7. Relationship between compressive strength and SR for mixtures containing metakaolin.

A.A. Ramezanianpour et al. / Construction and Building Materials 25 (2011) 24722479 2477

ssive

Parameters

andbetween the results of SR and water penetration is reduced. How-ever in samples made with the same cementitious materials and asa result of the similar chemical compounds of pore solution, the re-sults of both tests are more sensitive to microstructure of concretesand a good correlation between the results can be achieved.

Compressive strength is one of the most important mechanicalproperties of concrete and a simple test is used to measure it. Inthis paper several trial and error relationships between compres-

Fig. 8. Relationship between compre

Table 5Obtained models.

Model no. Obtained models R2

1 SR = 67,998 RCP1.028 R2 = 0.902 SR = 107.88 Depth0.777 R2 = 0.83

2478 A.A. Ramezanianpour et al. / Constructionsive strength and surface resistivity have also been studied. Gener-ally, one of the main factors in compressive strength is the strengthof Interlayer Transition Zone (ITZ) that has no signicant effect onconcrete resistivity. On the other hand, chemical compound of poresolution has a great inuence on concrete resistivity while notaffecting the compressive strength of concrete. Therefore, as seenin Fig. 6, there is no sensible correlation between compressivestrength and concrete resistivity (R2 = 0.413) when concrete mix-tures are made with various cementitious materials. However inthe case of similar cementitious materials and due to the relation-ship between compressive strength and permeability, better corre-lations (R2 = 0.767 and 0.872) can be observed betweencompressive strength and concrete resistivity (see Figs. 7 and 8).

Finally, considering to obtained correlations, two new modelsfor correlating SR with RCPT and water penetration are presentedin Table 5.

4. Conclusions

Based on the correlation of concrete resistivity with water pen-etration and Rapid Chloride Penetration Test (RCPT) data, a rela-tionship that can be used to estimate permeability of concretefrom the measured resistivity values was discovered.

For a wide range of concrete compositions in terms of cementtype and w/c ratio, it appears that surface resistivity (SR) can beused as an electrical indicator of concrete chloride penetrationresistance. It can specially be used on concretes when a large por-tion of their cementitious chemical reactions have been completedsuch as those concretes made with silica fume or metakaolin. Thetest should be used as a quality control predictor of the chloridepenetration resistance of the concrete, but not as a predictor of dif-fusion behavior for all kinds of concretes or as replacement of thelong term diffusion tests. The long term diffusion tests should stillbe used when new concrete formulations are used in order toestablish if the relationship between electrical properties and dif-fusion properties still holds.

Results show that although in concretes with similar cementi-tious materials different relationships can be found, but generally

SR: surface resistivity (KX C m), RCP: charge pass through the specimen (C)SR: surface resistivity (KX C m), Depth: depth of water penetration (mm)strength and SR for plain mixtures.

Building Materials 25 (2011) 24722479because of different mechanisms of compressive strength and elec-trical resistivity, there is no appropriate relationship betweenthem. Consequently it is not recommended to use electrical resis-tivity as an indicator for evaluation of compressive strength.

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