durability performance of bridge concretes, part i:...

Journal of ASTM International, July/August 2005, Vol. 2, No. 8 Paper ID JAI13066

Available online at www.astm.org

Mahmut Ekenel1 and John J. Myers2

Durability Performance of Bridge Concretes, Part I: High Performance Concrete (HPC)

ABSTRACT: A study was undertaken on the durability of high performance concrete (HPC) mixtures produced using locally available materials in the State of Missouri. Eighteen (18) mixtures were categorized as HPC. 30 % fly ash replacement by cement weight was utilized in the HPC mixtures, and ground granulated blast-furnace slag (GGBFS) was also substituted by 5 % of the cement for some mixtures. The mixtures included locally available limestone, trap rock, and river gravel as coarse aggregate. The mixtures of HPC without cement replacement displayed higher strength development at the end of 56 days. The compression strength development of the mixtures produced with locally available dolomitic limestone performed superior relative to other mixtures. All the mixtures performed poorly under 300 freezing and thawing cycles, except the control mixtures. The samples in which GGBFS was utilized performed poorly relative to the other samples. Similar poor performance was obtained from the same samples in chloride permeability tests.

KEYWORDS: high performance, mix proportions, limestone, trap rock, river gravel, durability

Introduction As the deterioration of concrete structures due to durability issues became more apparent

after the 1970s, construction companies in the United States gradually moved toward the use of higher strength concrete mixtures. However, a report published by the National Cooperative Highway Research Program (NCHRP) in 1995 by Rogella et al. suggested that high-strength concrete (HSC) decks were not the solution. It was noted in this report that more than 100 000 HSC bridge decks developed full depth transverse cracks before the concrete was one month old; consequently these decks became vulnerable to durability problems [1]. Since the replacement cost of these components is high, alternative methods are being sought to extend the service life of the structures.

Although HPC has been used widely in many Civil Engineering applications, bridge decks were the primary interest of this investigation, since it was reported that 31 % of the nation’s 581 862 bridges are sub-standard. 17 % are classified as “insufficient,” meaning they are either closed or require immediate rehabilitation to remain open [2]. Consequently, developing more durable concrete mixtures is of keen interest. One viable alternative to repair or replace existing deteriorated concrete bridges is the use of high performance concrete (HPC) in deck applications, where durability performance is a primary characteristic of interest [3]. HPC is not a revolutionary concrete; it is a development from conventional concretes used in the past. The difference is that HPC meets special performance and uniformity requirements that cannot always be obtained by using conventional ingredients and methods, such as enhancement of

Manuscript received 22 September 2004; accepted for publication 20 April 2005; published July 2005. 1Post-Doctoral Research Fellow - Civil, Environmental. & Architectural Engineering Department, University of Missouri-Rolla, Rolla, MO, 65409. 2Assistant Professor - Civil, Environmental. & Architectural Engineering Department, University of Missouri-Rolla, Rolla, MO, 65409.

Copyright © 2005 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.

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placement and compaction without segregation, early-age strength, curing, toughness, volume stability, or service life in a severe environment [4,5].

The increased durability of HPC is based on moderate strength concrete with low permeability. The basic concept of providing these two major properties is using moderate w/c ratio mix with moderate cement content, and in many cases one or more supplementary cementitious materials, such as fly ash, silica fume, or ground granulated blast-furnace slag. When these properties come together, it provides a discontinuous capillary pore system, which is essential for high durability and longer life concrete in severe environments. The primary advantages of high durable concrete are increased service life and reduced maintenance costs for concrete structures. Because of these reasons, an increasing demand for HPC has been observed in recent years. In production of HPC, it is necessary to obtain the maximum performance from all of the material constituents. The materials should be well identified, and their behavior when combined in a concrete mixture should be examined. Any material that presents incompatibilities will yield to detrimental effects to fresh properties, as well as hardened properties of concrete [6].

HPC normally contains portland cement, aggregate, and water, as well as chemical or mineral admixtures (in many cases both), and one or more supplementary mineral admixtures. A well-graded aggregate is also required for providing low volumes of pores. Moreover, the quality of aggregate is important when long-term strength and durability of concrete are required. Hence, high quality aggregates are necessary to ensure good bond between the coarse aggregate particles and the matrix [7]. HPC has recently been used in the state of Missouri. The first application for use in a bridge deck was in 2000 [8]. Consequently, further investigations using locally available materials to ensure adequate durability are of interest.

The research presented herein evaluates the durability of high performance concrete by using locally available materials in State of Missouri. The mineral admixtures used in this research were expected to reduce the concrete cost, improve concrete durability, reduce permeability and heat of hydration, and minimize CO2 production [9–11]. The investigation herein addresses: i) physical and chemical properties of mixture constituents, ii) fresh characteristics including workability and air content, iii) strength properties, and iv) long-term durability in terms of chloride permeability and resistance to freezing and thawing (F-T).

Research Objectives

The main objective of this research is to investigate the durability of HPC when using locally available materials in the state of Missouri. This investigation was focused on the examination of the long-term durability of HPC including freeze-thaw resistance and chloride permeability, as well as its mechanical properties, primarily compressive strength. Various mineral admixtures and three (3) different aggregates have been investigated to identify aggregate sources that are most appropriate for the production of HPC in Missouri.

Experimental Program

Materials

The raw material used in this research included a Type I portland cement, an ASTM Class F fly ash, Grade 100 ground granulated blast-furnace slag (GGBFS), natural fine aggregate, coarse aggregate, potable tap water, and chemical admixtures. All cementitious materials were commercially available in the state of Missouri. All materials were originated in the state of

EKENEL AND MYERS ON BRIDGE DURABILITY PART 1 3

Missouri except the Class F fly ash, which was transported from an adjacent state. Class C fly ash was unavailable in the State of Missouri when the research was in progress. ASTM Class F fly ash and low replacement levels of GGBFS were specifically used together in this mix design study because there were no studies available to the researchers on this combination. Another motivation was the cost of GGBFS. As reported by the manufacturer, the cost of GGBFS ($60 per ton) was very close to Type I portland cement ($70 per ton) as compared to Class F fly ash ($20 per ton). Hence, replacement of cement by fly ash reduced the price by almost 1/3 of the cementitious material cost. Moreover, the increase in workability by utilizing fly ash could also cause a slight decrease in labor cost. The contribution of fly ash to workability is generally attributed to the spherical shape and smooth surface of fly ash particles and adsorption-dispersion mechanism, which is similar to water-reducing agents. Very fine particles of fly ash get absorbed on the oppositely charged surface of cement particles and prevent them from flocculation [7,9,10].

The physical properties of cement and cementitious materials are listed in Table 1. These material properties were provided by the manufacturer. As illustrated in Table 1, the fineness (specific surface) of GGBFS was 1.5 times higher than the fineness of Type I portland cement according to the manufacturer’s Blaine fineness test. The specific surface of fly ash was not reported by the manufacturer and thereby not available to the researchers. The available Blaine test was not suitable because of the spherical nature of the fly ash particles. They are packed more closely than the irregular shaped particles of cement and more resistant to air flow; on the other hand, porous carbon particles allow air to flow easily, which might be misleading [7]. The chemical properties of cement and cementitious materials are listed in Table 2. The Bogue properties of Grade 100 GGBFS are not detailed because of their glassy nature. These properties were obtained by the same manufacturer using the same test methods. The chemical properties of Type I cement, fly ash, and Grade 100 GGBFS meet ASTM C 150, ASTM C 618, and ASTM C 989, respectively [12].

TABLE 1—Physical properties of Type I portland cement and class F fly ash, and Grade

100 ground granulated blast-furnace slag (GGBFS). Physical Tests Type I PC Fly Ash GGBFS Autoclave Expansion, % 0.13 N/A N/A Specific Surface Blain, m2/kg 373 N/A 565 Time of Setting: Vicat, Initial, min 86 … … Vicat, Final, min 183 … … Air Content, % 7 N/A 5 Specific Gravity 3.15 2.5 2.90 No. 325 Sieve Fineness, % N/A 16.40 1 Water Requirement, % N/A 95.9 … 7-Day Str. Activity Index N/A 77.0 84 28-Day Str. Activity Index N/A … 120 N/A – Not Applicable or Not Available.


TABLE 2—Chemical properties of Type I portland cement and class F fly ash. Chemical Composition Type I PC (%) Fly Ash (%) Silicon Dioxide (SiO2) 20.8 50.45 Aluminum Oxide (AL2O3) 4.9 19.26 Ferric Oxide (Fe2O3) 2.1 17.82 Calcium Oxide (CaO) 64.4 4.77 Magnesium Oxide (MgO) 3.5 0.94 Sulfur Oxide (SO3) 2.5 1.59 Loss on Ignition 1.4 1.14 Insoluble Residues 0.19 N/A Tricalcium Silicate (C3S) 61 N/A Dicalcium Silicate (C2S) 14 N/A Tricalcium Alimunate (C3A) 9 N/A Tetracalcium Alumino-Ferite (C4AF) 6 N/A Na2O Equivalent 0.49 N/A Available Alkalis as Na2O N/A 0.81 Free Moisture N/A 0.10 Total K2O N/A 2.38

N/A – Not Applicable or Not Available.

The natural fine aggregate and coarse aggregates were obtained from quarries in the State of Missouri and approved for use in bridge structures by the Missouri Department of Transportation (MoDOT). Limestone, trap rock, and river gravel were used as the coarse aggregates. Dolomitic limestone was mainly formed of dolomite, quartz, and calcite; river gravel was mainly formed of quartz and calcite; and trap rock was mainly formed of diopside, forsterite, and epidote. The locally available coarse aggregates had a maximum aggregate size of 19 mm. The locally available fine aggregate (sand) had a fineness modulus of 2.11. The moisture conditions and specific gravities of aggregates are presented in Table 3. The size distribution of the coarse and fine aggregates is shown in Table 4. Their particle sizes are within the aggregate grading recommended by ASTM 33 [12]. All these values were determined by laboratory tests. The chemical and physical properties of trap rock, as reported by the manufacturer, were obtained from Iron Mountain quarries and shown in Table 5. River gravel was obtained from the Gasconade River; however, properties were not reported by the manufacturer. The average chemical and physical properties for Jefferson City & Phelps County dolomitic limestone were obtained from a report published by the Missouri Department of Natural Resources (see Table 5) [13]. Potable water was used throughout the research, which conformed to ACI 301 [14]. A constant air-entrainment admixture (AEA) was utilized in HPC mixtures with the range of 85 g/cwt.


TABLE 3—The moisture conditions and specific gravities of aggregates. Limestone Trap Rock River Gravel Sand

SSD Specific Gravity 2.45 2.73 2.63 2.54 Absorption, % 3.80 1.91 0.41 2.58

TABLE 4—Size distribution of aggregates (% passing).

Sieve Size Coarse Aggregate Fine Aggregate Limestone Trap Rock River Gravel Sand

19.0 mm 100.00 100.00 100.00 100.00 9.50 mm 61.00 44.50 37.50 100.00 4.75 mm 10.60 3.20 6.45 99.10 2.36 mm 3.00 2.25 2.90 90.90 1.18 mm 1.65 2.10 2.05 84.40 600 µm 1.25 2.00 1.8 75.50 300 µm 0.7 1.9 1.5 27.70 150 µm 0.4 1.7 1.2 1.30

TABLE 5—Chemical and physical properties of coarse aggregates.

Chemical Properties (%) Limestone Trap Rock River Gravel

SiO2 7.44 77.01 Al2O3 1.39 11.67 Na2O 0.11 4.22 K2O 0.81 3.55

Fe2O3 0.41 2.18 N/A CaO 27.7 0.50 MgO 18.4 0.30 TiO2 N/A 0.14

Mn2O3 N/A 0.08 LOI 42.34 0.68

Physical Properties LA wear ( %) 31 17 N/A

Comp. strength (MPa) 62.7 325 N/A: Not available.

Mixture Proportions Eighteen (18) mixtures were utilized for HPC with a cement content of 363 kg/m3. 25 % and

30 % Class F fly ash replacement by cement weight were utilized in the HPC mixtures except control samples, which were produced by 100 % Type I portland cement. GGBFS also replaced 5 % of the cement by weight in the mixtures in which fly ash replaced 25 % of the cement weight. HPC mixtures were developed primarily for bridge deck applications at two (2) water-to-cementitious ratios (w/cm) of 0.40 and 0.45, in which better handling and workability characteristics are sought rather than higher levels in strength [3]. Three different coarse aggregate sources were used in the HPC mixtures including limestone, trap rock, and river gravel. The quarries from which the sources were obtained have been widely used in bridge construction in Missouri by MoDOT, which has been in service since the 1900s [15]. These materials were MoDOT approved, and it has also been observed that the dolomitic limestone, trap rock, and river gravel do not cause alkali-aggregate reaction to any significance that would


prohibit its use in concrete. The mixtures prepared for HPC utilizations are compared with those of conventional concrete (without replacement materials) in which cement is used as the binder. The mixture designs, slump, and air content measurements for the HPC series are presented in Table 6. The average unit weight measurements were 2240 kg/m3, 2263 kg/m3, and 2262 kg/m3 for control, fly ash replacement, and fly ash-GGBFS replacement samples, respectively.

TABLE 6—Mix design for HPC mixtures.

No w/c % Replacement Cement Coarse Aggr.

Coarse Aggr.

Fine Aggr.

Slump Air

ratio FA GGBFS (kg/m3) Type (kg/m3) (kg/m3) (mm.) % 1 0.45 0 0 363 River G. 1075 855 102 4.82 0.45 0 0 363 Trap Rock 1075 855 95 5.53 0.45 0 0 363 Limestone 1075 855 140 5.04 0.45 30 0 254 River G. 1075 855 108 5.75 0.45 30 0 254 Trap Rock 1075 855 165 2.86 0.45 30 0 254 Limestone 1075 855 152 4.57 0.45 25 5 254 River G. 1075 855 171 3.08 0.45 25 5 254 Trap Rock 1075 855 127 5.59 0.45 25 5 254 Limestone 1075 855 127 4.810 0.40 0 0 408 River G. 1075 855 127 4.711 0.40 0 0 408 Trap Rock 1075 855 127 4.512 0.40 0 0 408 Limestone 1075 855 76 4.313 0.40 30 0 286 River G. 1075 855 152 4.514 0.40 30 0 286 Trap Rock 1075 855 133 4.015 0.40 30 0 286 Limestone 1075 855 165 2.516 0.40 25 5 286 River G. 1075 855 127 4.817 0.40 25 5 286 Trap Rock 1075 855 152 3.018 0.40 25 5 286 Limestone 1075 855 89 3.5

Note: A constant air-entrainment admixture of 85 g/cwt was used in all mixtures.

Test Methods & Specimens

Concrete was batched under laboratory conditions using a 0.25 m3 rotary drum mixer. Test specimens were demolded at 24 ± 1 h after casting. The samples were placed in a moist cured room following the demolding. The temperature of moist cured room was 25 ± 2oC with 100 % relative humidity.

The unconfined-compression test followed the procedure of ASTM C 39 [12]. The test specimens were 102 × 204 mm cylinders. The rapid freezing and thawing test was conducted as per ASTM C 666, procedure A, and the specimens with the dimensions of 76 × 76 × 406 mm used [12]. The authors wanted to test the specimens under extreme freezing and thawing conditions, which was the reason for choosing procedure A over procedure B [10]. The resistance of concrete samples to external chloride attack was determined using AASHTO T 259-80I procedure with an increased calcium chloride solution of 7.5 % in order to study the behavior under a severe chloride concentration [16]. The dimensions of the test samples were 152.4 × 152.4 × 89 mm (see Figs. 1 and 2).


FIG. 1—Chloride permeability test samples. FIG. 2—Chloride content testing.

Test Results and Discussions

Unconfined Compressive Strength of HPC Mixtures

The strength development of each material at 56 days is illustrated in Fig. 3. The mixtures presented a compressive strength distribution ranging from 23.2 MPa up to 46.3 MPa. The strength development of limestone mixtures was superior to all other mixtures produced by river gravel and trap rock (see Table 7). For the mix designs with a 0.40 w/cm ratio, the average of the compressive strength of limestone samples were 21 % and 36 % higher than the river gravel samples and trap rock samples, respectively. The 0.45 w/cm ratio samples illustrated the same trend. The limestone mixtures presented 34 % and 45 % higher results in average compared to river gravel and trap rock mixtures, respectively. The increase in compressive strength when the w/cm ratio decreased from 0.45 to 0.40 were 13 %, 25 %, and 21 %, in average, for the mixtures with limestone, river gravel, and trap rock, respectively. These test results were also consistent with the results presented by Myers and Carrasquillo [17]. According to Myers and Carrasquillo, crushed river gravel exhibits lower compressive strengths due to the poor mechanical shape and texture; aggregates that are significantly harder than mortar, such as trap rock (325 MPa), causes stress concentrations at higher stress levels, introducing microcracking in the transition zone.

FIG. 3—Compressive strength of HPC mixtures at 56-day versus w/cm ratio.


TABLE 7—Compressive test results (56-day) of HPC samples. Compressive Strength at 56 days, (MPa)

Mix Description River Gravel Trap Rock Limestone 0.45 w/cm

Control Mix. 32.4 28.3 41.9 Cem. + FA 30.9 27.6 37.7

Cem. + FA + GGBFS 23.8 23.2 37.2 0.40 w/cm

Control Mix. 38.5 37.9 46.3 Cem. + FA 38.4 32.4 43.7

Cem. + FA + GGBFS 33.3 27.3 42.3 The average 56-day compressive strength of control mixtures was higher than fly ash-

GGBFS and fly ash replacement samples, respectively. This is attributed to decreased amount of cement content, the slow reaction capability of GGBFS, and the low CaO content of Class F fly ash (4.77 %), which yielded a lesser amount of CSH gel production with respect to control samples. Although the test date of 56-day for comparison was considered a more appropriate test age for the control and mineral material utilized mixtures, longer term may also be suggested to better understand the behavior of GGBFS utilized mixtures.

Freezing & Thawing Resistance of HPC Mixtures

Figures 4 and 5 illustrate the percent mass loss as a function of number of freezing and thawing cycles for the HPC mixtures with 0.40 w/cm and 0.45 w/cm, respectively. Only twelve (12) samples were tested due to limitation in machine capacity at the time of testing.

As Fig. 4 illustrates, control samples performed better than fly ash replacement samples. Similar test results can be observed in Fig. 5, in which fly ash replacement samples exhibited higher mass loss than the control mixtures; whereas there was less mass loss compared to the fly ash-GGBFS replacement sample, in which limestone coarse aggregate was utilized. No conclusion on performance evaluation of aggregate types can be drawn based on the scatter of results, which could also suggest that there is no difference among aggregate types in freeze and thaw performance. The associated mass loss for the mixes without replacement materials (control) would be expected to translate into a durability factor (DF) above 85, which is representative of highly freeze-thaw resistant concrete. The sample in which GGBFS was utilized exhibited considerably lower freezing and thawing resistance and therefore is not recommended for use where high F-T durability is required. Some researchers noted that the presence of class F fly ash and/or GGBFS in concrete improves the freeze-thawing resistance when compared with 100 % portland cement at equal strength and equal air contents [7,10]. However, it was also noted that the non air-entrained concrete incorporating fly ash and/or slag showed poor freezing and thawing resistance compared to that of portland cement concrete [18]. The lower strength development of cementitious material utilized mixtures compared to control samples could also be a reason for their poorer freezing and thawing resistance.


FIG. 4—Freeze and thawing cycles of HPC with 0.40 w/cm.

FIG. 5—Freeze and thawing cycles of HPC with 0.45 w/cm.

Chloride Permeability of HPC Mixtures

Chloride permeability of the HPC samples is presented in the Figs. 6–8. The percent chloride content readings for the depths of 12.7 mm and 38.1 mm are also presented in Table 8. The Building Research Establishment suggests that a total (acid-soluble) chloride content of less than


0.4 (% by weight) produces low risk of corrosion, between 0.4 % and 1.0 % produces a medium risk, and greater than 1.0 % produces a high risk [19,20]. The superior performance of 30 % fly ash replacement mixtures over the control and fly ash-GGBFS replacement mixtures is illustrated. River gravel utilized mixtures exhibited the highest chloride content, which was 15 % and 37 % higher than the samples produced (average) consisting of trap rock and limestone, respectively.

As for the mixtures produced with river gravel (Fig. 6), average chloride content of fly ash replacement samples with 0.40 and 0.45 w/cm ratio exhibited 41 % and 52 % less chloride content than the average of control samples and fly ash-GGBFS replacement samples at the depth of 12.7 mm, respectively. A similar trend can also be seen with the trap rock (Fig. 7) at the depth of 12.7 mm.

FIG. 6—Chloride content of HPC (river gravel) samples versus depth of concrete.

FIG. 7—Chloride content of HPC (trap rock) samples versus depth of concrete.


FIG. 8—Chloride content of HPC (limestone) samples versus depth of concrete.

TABLE 8—Percent chloride content measurements at depths of 12.7 mm and 38.1 mm.

% Chloride Content 0.40 w/c 0.45 w/c 12.7 mm 38.1 mm 12.7 mm 38.1 mm Cement 0.384 0.001 0.438 0.001

River Gravel Cem.+FA 0.234 0.016 0.248 0.025 Cem.+FA+GGBFS 0.514 0.01 0.487 0.028 Cement 0.391 0.002 0.508 0.005

Trap Rock Cem.+FA 0.276 0.006 0.181 0.001 Cem.+FA+GGBFS N/A N/A 0.487 0.033 Cement 0.570 0.009 0.637 0.02

Limestone Cem.+FA 0.179 0.015 0.216 0.001 Cem.+FA+GGBFS 0.300 0.008 0.590 0.001

N/A: Not Available.

For the specimens with limestone coarse aggregate (Fig. 8), the lowest values are presented by the fly ash replacement samples with 0.40 and 0.45 w/cm ratios as 0.18 % and 0.21 % by weight, respectively, at the depth of 12.7 mm. As for comparison, the HPC samples produced by Myers, Touma, and Carrasquillo with 100 % portland cement, 25 % fly ash replacement, and 35 % fly ash replacement were ponded with 3 % sodium chloride (half of the amount used in this research) for 90 days and tested according to AASHTO T 259. Test samples exhibited a chloride content (% by weight) ranging between 0.08 (0.35 fly ash replacement) and 0.32 (no fly ash) at a depth of 12.7 mm [21].

The superior performance of fly ash used in concrete mixtures was also reported by Massazza [22]. He noted that the diffusion coefficient of chloride is reduced as the Pozzolanic material content increased. For example, 30 % substitution of a portland cement for fly ash decreased the diffusion coefficient of chloride by one order of magnitude. Massazza noted that the volume of the precipitating mass of CSH gel produced by fly ash is unable to fill the larger


pores; however, it was sufficient in amount to obstruct the thin connections existing between the larger pores or at least to reduce the span thereof which enhanced the chloride resistance [22].

Conclusions

Based on the research study undertaken, the following conclusions were drawn for the mix designs investigated:

• The control mixtures (100 % portland cement) for the high performance concrete (HPC)

series displayed higher strength development at the end of 56 days compared to the mixtures in which a Class F fly ash and fly ash-GGBFS blend were utilized as cement replacement material. This is attributed to the reduced amount of cement content due to cementitious material replacement; slow reaction capability of ground granulated blast-furnace slag, which started contributing to the strength development around 56 days; and the low CaO content of Class F fly ash (4.77 %), which yielded to a lesser amount of CSH gel production with respect to control samples. Although the test date of 56 days for comparison was considered a more appropriate test age for the control and fly ash utilized mixtures, a longer term may also be suggested to understand the behavior of Grade 100 GGBFS utilized mixtures.

• For the HPC series, the compression strength development of the mixtures produced with locally available limestone at the end of 56 days of curing performed superior compared to the mixtures prepared with river gravel and trap rock. The poor performance of river gravel can be attributed to poor mechanical bond due to the shape and texture. The reason of poor performance of trap rock can be explained with the significantly harder aggregate particles (325 MPa) as compared to mortar, hence causing higher stress concentrations and introducing microcracking in the transition zones [17]. Substitution of 5 % GGBFS reduced the strength gain compared to other mixtures throughout the 56-day curing period. However, long-term testing is strongly suggested in order to better understand the behavior of GGBFS.

• The fly ash and fly ash-GGBFS blend mix resulted in lower freeze-thaw resistance compared to the control mixes without replacement materials. The associated mass loss for the mixes without replacement materials would be expected to translate into a durability factor (DF) above 85, which is representative of highly freeze-thaw resistant concrete. The samples in which 5 % GGBFS was utilized would be considerably lower and not recommended for use where high F-T durability is required.

• In terms of chloride permeability of HPC mixtures, the Class F fly ash replacement mixtures performed superior compared to control and fly ash-GGBFS replacement mixtures. The lower performance of fly ash-GGBFS replacement samples compared to the control mixes is explained by the relatively slower reaction speed of GGBFS and being a kind of hydraulic cement, not a pozzolan. All the HPC mixtures showed practically 0 % chloride concentration at the depth of 38.1 mm, which is often recommended as a minimum cover depth for reinforced concrete structures [23]. The w/cm ratio was clearly a dominant factor to reduce the level of chloride content close to the surface of the concrete.


Acknowledgments

The present research was funded by the University of Missouri Research Board and the University Transportation Center (UTC) at the University of Missouri-Rolla (UMR). The authors are thankful to several manufacturers in the State of Missouri, USA, who donated materials used in this research study. Their names are not mentioned herein to prevent any concern of commercialism. The authors would also like to acknowledge Mr. Brian Sides and Mr. Brian Sims for their effort on this project as undergraduate research assistants (URA).

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[6] Shah, S. P. and Ahmad, S. H., “High Performance Concrete: Properties and Applications,” McGraw-Hill, NY, 1994.

[7] Neville, A., “Properties of Concrete,” John Wiley & Sons, NY, 1996. [8] Yang, Y. and Myers, J. J., “Live Load Test Results of Missouri’s First High Performance

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[10] Mehta, P. K., “Concrete: Structure, Properties, and Materials,” Prentice-Hall, Englewood Cliffs, NJ, 1986.

[11] Myers, J. J. and Carrasquillo, R. L., “Influence of Hydration Temperature on the Durability and Mechanical Property Performance of HPC Prestressed/Precast Beams,” National Research Council, Transportation Research Record – Journal of the Transportation Research Board, Washington, DC, No. 1696, Vol. 1, Publication 5B0038, April 2000, pp. 131–142.

[12] Annual Book of ASTM Standards: Vol. 4.02, ASTM International, West Conshohocken, PA, 2002.

[13] Rueff, A. W., “Chemical and Physical Properties of Selected Stone Resources in South-Central Missouri,” Missouri Department of Natural Resources, Geological Survey and Resources Assessment Division, Open File Report Series, OFR-91-82-MR, 2nd ed., Rolla, MO, 1991.

[14] ACI Committee 301, “Specifications for Structural Concrete for Buildings,” Farmington Hills, MI, 1999.

http://www.ota.fhwa.dot.gov/


[15] Buckley, E. R. and Buehler, H. A., “The Quarrying Industry in Missouri,” Missouri Bureau of Geology and Mines, Vol. 2, 2nd Series, 1904.

[16] AASHTO T 259, “Resistance of Concrete to Chloride Ion Penetration,” 1980. [17] Myers, J. J. and Carrasquillo, R. L., “Mix Proportioning for High-Strength Bridge Beams,”

American Concrete Institute Special Publication 189, American Concrete Institute, Detroit, MI, 1999, p. 37-6.

[18] Virtanen, J., “Freeze-Thaw Resistance of Concrete Containing Blast-Furnace Slag, Fly Ash and Condensed Silica Fume,” Proceedings, First International Conference in the Use of Fly Ash, Silica Fume, Slag and Other Mineral By-Products in Concrete, Montebello, Quebec, Canada, Vol. 2, 1983, pp. 923–942.

[19] Arya, C., “Problem of Predicting Risk of Corrosion of Steel in Chloride Contaminated Concrete,” Proc. Instn Civ. Engrs, Part 1, 88, Oct., 889, 1990.

[20] Haque, M. N. and Kayyali, O. A., “Free and Water Soluble Chloride in Concrete,” Cement and Concrete Research, Vol. 25, No. 3, 1995, pp. 531–542.

[21] Myers, J. J., Touma, W., and Carrasquillo, R. L., “Permeability of High Performance Concrete: Rapid Chloride Ion Test vs. Chloride Ponding Test,” Proceedings for the PCI/FHWA International Symposium on High Performance Concrete, Advanced Concrete Solutions for Bridges and Transportation Structures, New Orleans, LA, October 1997, pp. 268–282.

[22] Massazza, F., “Pozzolanic Cements,” Cement & Concrete Composites, Vol. 15, 1993, pp. 185–214.

[23] ACI Committee 318-02, “Building Code Requirements for Structural Concrete and Commentary,” Farmington Hills, MI, 2002.

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