PROPERTIES OF CONCRETE PRODUCED WITH ADMIXTURES INTENDED TO INHIBIT CORROSION

Transcription

1 PROPERTIES OF CONCRETE PRODUCED WITH ADMIXTURES INTENDED TO INHIBIT CORROSION Phong A. Pham Craig M. Newtson Prepared in ooperation with the State of Hawaii Department of Transportation, Highways Division and U.S. Department of Transportation, Federal Highway Administration UNIVERSITY OF HAWAII COLLEGE OF ENGINEERING DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING Researh Report UHM/CE/01-01 February 2001

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3 PROPERTIES OF CONRETE PRODUCED WITH ADMIXTURES INTENDED TO INHIBIT CORROSION Phong A. Pham Craig M. Newtson Researh Report UHM/CE/01-01 February 2001

4 ABSTRACT A study was onduted to evaluate properties of fresh and hardened onrete produed with Hawaiian aggregates and admixtures that are added to onrete to protet reinforing steel from orrosion. DCI, Rheorete CNI, Rheorete 222+, FerroGard 901, Xypex Admix C-2000, a latex-modifier, silia fume, and fly ash were the admixtures intended to slow the orrosion proess. These admixtures were used in mixtures designed by varying the proportions of mixtures that were already onsidered to be orrosion resistant. Compressive strength, elasti modulus, and Poisson s ratio were determined for all mixtures. DCI, Rheorete CNI, and silia fume signifiantly inreased ompressive strength, while Xypex Admix C-2000 and the latex-modifier redued ompressive strength. Conrete permeability, the ability to redue hloride penetration, and ph were evaluated for seleted mixtures. Silia fume and the latex-modifier produed substantial redutions in permeability. ACI equations for elasti modulus overestimated the elasti modulus values for almost all of the mixtures. The average overestimation was 14% for two equations provided by ACI 318, and 8% for the equation reommended by ACI 363 for high strength onrete. ii

5 TABLE OF CONTENTS Abstrat... ii List of Tables... vi List of Figures... viii Chapter 1: Introdution Introdution Objetive Sope...2 Chapter 2: Bakground and literature review Introdution Admixtures Testing Summary...14 Chapter 3: Experimental Program Introdution Materials Mixtures Speimens Testing period Testing proedures Summary...38 iii

6 Chapter 4: Results and disussion for ompressive strength Introdution Control mixtures Calium nitrite mixtures FerroGard mixtures Rheorete 222+ mixtures Xypex mixtures Latex-modified mixtures Silia fume mixtures Fly ash mixtures Compressive strength omparison for all mixtures Summary...62 Chapter 5: Results and disussion for other tests Introdution Elasti modulus Permeability Chloride onentrations ph test Poisson s ratio Summary...88 Chapter 6: Summary and onlusions Summary Conlusions...93 iv

7 Appendix A: Compressive strengths for all ylinders...96 Appendix B: Predited and experimental elasti modulus results for all mixtures Referenes v

8 LIST OF TABLES Table Page 2.1. Limits for water-soluble hloride-ion ontent in onrete Partile size distribution for fine aggregates Fineness modulus of fine aggregates Speifi gravity and absorption for fine aggregates Partile size distribution for oarse aggregate Speifi gravity and absorption for oarse aggregate Summary of admixture usage with various mixtures Mixture proportions for ontrol mixtures Mixture proportions for DCI and CNI mixtures Mixture proportions for Rheorete mixtures Mixture proportions for FerroGard mixtures Mixture proportions for Xypex mixtures Mixture proportions for latex-modified mixtures Mixture proportions for silia fume mixtures Fly ash hemial omposition Mixture proportions for fly ash mixtures Slump, average ompressive strength, elasti modulus and Poisson s ratio of ontrol mixtures Slump, average ompressive strength, elasti modulus, and Poisson s ratio of DCI mixtures...42 vi

9 Table Page 4.3 Slump, average ompressive strength, elasti modulus, Poisson s ratio, and air ontent of CNI mixtures Slump, average ompressive strength, elasti modulus, Poisson s ratio, and air ontent of FerroGard mixtures Slump, average ompressive strength, elasti modulus, Poisson s ratio, and air ontent of Rheorete 222+ mixtures Slump, average ompressive strength, elasti modulus, Poisson s ratio, and air ontent of Xypex mixtures Slump, average ompressive strength, elasti modulus, and Poisson s ratio of latex-modified mixtures Slump, average ompressive strength, elasti modulus, and Poisson s ratio of silia fume mixtures Slump, average ompressive strength, elasti modulus, and Poisson s ratio of fly ash mixtures ACI reommended design ompressive strengths Values of permeability and onrete ratings Air permeability for ontrol, DCI, latex-modified, and silia fume mixtures Water permeability for ontrol, DCI, latex-modified and silia fume mixtures Chloride onentrations for ontrol and DCI mixtures (% by mass of ement) Chloride onentrations for latex-modified and silia fume mixtures ph test results for ontrol and DCI mixtures ph test results for latex-modified and silia fume mixtures...84 vii

10 LIST OF FIGURES Figure Page 3.1. Partile size distribution for fine aggregates Partile size distribution for oarse aggregate Details and dimensions of beam speimens Beam ross-setion desribing the test hole for a hloride onentration test Average ompressive strength vs. water-ement ratio for ontrol mixtures Average ompressive strength vs. water-ement ratio for DCI mixtures Average ompressive strength vs. DCI ontent Average ompressive strength vs. water-ement ratio for CNI mixtures Average ompressive strength vs. Rheorete CNI ontent Comparison of ompressive strengths for DCI and CNI mixtures Average ompressive strength vs. water-ement ratio for FerroGard mixtures Comparison of ompressive strengths for ontrol and FerroGard Mixtures Average ompressive strength vs. water-ement ratio for Rheorete 222+ mixtures Comparison of ompressive strengths for ontrol and RHE mixtures Average ompressive strength vs. water-ement ratio for Xypex mixtures Comparison of ompressive strengths for ontrol and Xypex mixtures Average ompressive strength vs. water-ement ratio for latex-modified mixtures Average ompressive strength vs. latex ontent Average ompressive strength vs. silia fume ontent...57 viii

11 Figure Page Average ompressive strength vs. fly ash ontent Comparison of ompressive strengths for silia fume and fly ash mixtures Elasti modulus omparison using design ompressive strengths Elasti modulus omparison using average ompressive strengths Mean values for air permeability tests Mean values for water permeability tests Chloride onentration vs. yles of ponding for ontrol mixtures Chloride onentration vs. yles of ponding for DCI mixtures Chloride onentration vs. yles of ponding for latex-modified mixtures Chloride onentration vs. yles of ponding for silia fume mixtures ph vs. yles of ponding for ontrol mixtures pH vs. yles of ponding for DCI mixtures pH vs. yles of ponding for latex-modifier mixtures ph vs. yles of ponding for silia fume mixtures Poisson s ratio vs. average ompressive strength...87 ix

12 CHAPTER 1 INTRODUCTION 1.1 Introdution Reinfored onrete is a widely used onstrution material beause it provides durability and strength. However, onrete strutures exposed to marine environments oasionally deteriorate in a relatively short period. A major fator ontributing to this deterioration is orrosion of the reinforing steel. Aording to the U.S. Seretary of Transportation s report (1981), there were nearly 213,000 deteriorating bridge strutures in the USA with a repair ost of $41.1 billion. In 1986, it was estimated that the ost to orret orrosion-indued distress in bridges was $20 billion, and was inreasing by approximately $0.5 billion annually (AASHTO 1986). These rehabilitation osts illustrate the need to improve orrosion protetion in reinfored onrete strutures. Corrosion protetion systems used in reinfored onrete strutures inlude the use of orrosion-inhibiting admixtures, epoxy-oated reinforing steel, water proofing membranes, penetrants and sealers, galvanized reinforing steel, eletrohemial removal of hlorides, and athodi protetion. Among these protetion systems, using orrosioninhibiting admixtures is probably the most ost-effetive solution (Gu et al. 1997). However, orrosion-inhibiting admixtures may influene onrete properties suh as ompressive strength, elasti modulus, onrete permeability, the ability to slow the ingress of hloride ions into onrete, and ph. These properties may also be influened by the aggregates in the onrete. This is partiularly important in Hawaii beause onrete made with Hawaiian aggregates has been shown to have different harateristis than onrete produed using mainland 1

13 aggregates. Aording to Durbin and Robertson (1998), Hawaiian aggregate onretes exhibit higher shrinkage and reep strains ompared with data of other studies. 1.2 Objetive The objetive of this researh was to investigate the effets of loally available admixtures that have been proposed to protet embedded steel in onrete from orrosion, on engineering properties of onrete made with Hawaiian aggregates. These properties inluded ompressive strength, elasti modulus, Poisson s ratio, air and water permeability, ph, and the ability to slow the ingress of hloride ions into onrete. The admixtures used in this study were DAREX Corrosion Inhibitor (DCI), Rheorete CNI, Rheorete 222+, FerroGard 901, Xypex Admix C-2000, a latex-modifier, silia fume, and fly ash. These admixtures were used in mixtures designed by varying the proportions of mixtures that were already onsidered to have good orrosion resistane. 1.3 Sope Chapter 2 provides information on eah onrete admixture and how eah one works to protet reinforing steel from orrosion. The tests used in this study are also desribed. Chapter 3 presents the proportions for all of the onrete mixtures and the experimental proedures used to evaluate the mixtures. Compressive strengths and a disussion of their relevane are provided in Chapter 4. Results of elasti modulus, air and water permeability, hloride onentration, and ph tests are inluded in Chapter 5. A summary of the study and onlusions drawn from the test results are presented in Chapter 6. 2

14 CHAPTER 2 BACKGROUND AND LITERATURE REVIEW 2.1 Introdution Several admixtures ommonly used to protet reinforing steel in onrete against orrosion and hemial attak are reviewed in this hapter. A brief desription of how eah admixture works and its effets on onrete properties are provided. The tests used in this study to determine air and water permeability, hloride onentration, and ph are also desribed. 2.2 Admixtures DCI, Rheorete CNI, Rheorete 222+, FerroGard 901, Xypex Admix C-2000, fly ash, silia fume, and a latex-modifier were added to onrete mixtures for the researh in this study. This setion presents a brief desription of eah admixture and its effets on onrete properties Calium nitrite-based orrosion-inhibitors When used in onrete as an admixture, alium nitrite performs two funtions. It ats as a non-hloride aelerator and as a orrosion inhibitor. Calium nitrite provides good aeleration in initial setting time and improves ompressive strength of onrete at early ages. The performane of alium nitrite as an aelerator also depends on the partiular ement and other admixtures in the onrete (Chin 1987). Calium nitrite is often used with retarders to balane the setting time of the onrete (Holland 1992). 3

15 As a orrosion inhibitor, alium nitrite reats with ferrous ions to reate a ferri oxide, Fe 2 O 3, layer around the anode (Nmai et al. 1992, Rosenberg and Gaidis 1979) with the following hemial reation: 2Fe OH NO 2-2NO + Fe 2 O 3 +H 2 O (2.1) The additional ferri oxide enhanes the passivation layer near the surfae of the steel reated by the highly alkaline (ph > 12) environment of the onrete. For this reason, alium nitrite-based orrosion-inhibiting admixtures are also alled anodi inhibitors. However, in order to reat with ferrous ions in onrete, nitrite ions have to ompete with hloride ions. If there are fewer nitrite ions than hloride ions in onrete around the steel, ferrous ions will reat with hloride ions to start the orrosion proess. Consequently, alium nitrite is most effetive as a orrosion inhibitor when the onentration of nitrite ions is high. The dosage of the alium nitrite-based produt should be determined based on the antiipated hloride onentration at the steel level over the lifetime of onrete (Nmai et al. 1992). Two alium nitrite based orrosion-inhibiting admixtures used in this study were DCI, a produt of W.R. Grae & Co.-Conn, and Rheorete CNI, a produt of Master Builders, In. Both are pakaged in a liquid form ontaining a minimum of 30% alium nitrite. 4

16 2.2.2 Rheorete 222+ Rheorete 222+ is an organi-based orrosion-inhibiting admixture (OCIA) produed by Master Builders, In. It is a ombination of amines and esters in a water medium. OCIA s protet reinforing steel by forming a protetive layer on the steel surfae and reduing hloride diffusion into onrete (Nmai et al. 1992). When in ontat with steel reinforing bars, organi orrosion inhibitors bond to the steel by physial adsorption, hemial adsorption, or both, to form a protetive layer. This protetive layer ats as a physial barrier that slows or prevents eletrohemial reations at both the anode and the athode (Nmai et al. 1992). OCIA s also redue hloride diffusion into onrete by lining the pores with hemial ompounds that impart hydrophobi properties to the onrete (Nmai 1995). Consequently, orrosion of reinforing steel is further redued. It is important to note that unlike nitrite based orrosion inhibitors, OCIA s do not have to ompete with hloride to maintain the naturally passive layer near the surfae of the steel. Therefore, the predition of the hloride onentration is not neessary to selet an admixture dosage (Holland 1992). Also aording to Nmai et al. (1992), OCIA s do not signifiantly influene the properties of plasti and hardened onrete. However, onrete ontaining organi orrosion inhibitors may require a higher dosage of air-entraining admixture to obtain a speified air ontent Ferro Grad 901 FerroGard 901, a produt of Sika Corp., is also a liquid onrete admixture formulated to protet embedded reinforing steel from orrosion. It ontains a 5

17 ombination of amino-alohols, and organi and inorgani inhibitors. FerroGard 901 protets reinforing steel by forming a physial protetive layer (Sika 1997). This protetive layer is similar to the one desribed for Rheorete Therefore, FerroGard 901 inhibits formation of both the anode and the athode. Moreover, the manufaturer laims: beause of its high affinity to steel, Sika FerroGard 901 is able to displae hloride ions from the metal surfae to protet onrete from hloride indued orrosion. When used for onrete repairs, FerroGard 901 has demonstrated the ability to penetrate into the existing onrete, proteting the steel in this region and in the repair zone (Shnerh 1999) Xypex Admix C-2000 Aording to the manufaturer, Xypex Admix C-2000 is a dry powder onsisting of portland ement, very fine treated silia sand, and various ative, proprietary hemials. When mixed with onrete these ompounds reat with moisture and produts of ement hydration to form a non-soluble rystalline formation throughout the pores and apillary trats of the onrete. As a result, the onrete is sealed against the penetration of water and other liquids Fly Ash Fly ash is the most widely used mineral admixture in onrete (Kosmatka and Panarese 1994). It is olleted from the ombustion of pulverized oal in eletri power generating plants. Most of the fly ash partiles are solid spheres with diameters 6

18 less than 0.8x10-3 in. (20 μm). When introdued into onrete, fly ash inreases the density of onrete by filling voids in onrete. It also reats hemially with alium hydroxide released by the hydration of portland ement to provide ementitious properties. Replaing a portion of ement with fly ash an redue the hloride permeability. As a result, the orrosion proess is slowed. The fly ash also inreases the ompressive strength of onrete. However, the reation between alium hydroxide and fly ash ement paste is slow. Consequently, the strength improvement is not lear at early ages, but at ages of 56 and 90 days, the differene is signifiant (Maslehuddin et al. 1989). There are two types of fly ash, Class F and Class C. Class F fly ash generally has a low alium ontent with a arbon ontent less than 5%. Class C fly ash has a higher alium ontent with a arbon ontent less than 2%. Class C fly ash is generally onsidered to be more ementitious. However, strength gains produed by the fly ash are more apparent at later ages (greater than 28 days) (Naik et al. 1998) Silia Fume Silia fume is a pozzolani material with many similarities to fly ash. It is the produt of the redution of high-purity quartz with oal in an eletri ar furnae in the manufature of silion or ferrosilion alloy. Unlike fly ash, silia fume is very fine material with partile sizes less than 0.04x10-3 in. (1 μm) in diameter and ontains almost pure silion dioxide (Kosmatka and Panarese 1994). When used in onrete as an admixture, silia fume reats with water and alium hydroxide Ca(OH) 2, a produt of the hydration reation, to produe alium 7

19 siliate hydrate (CSH). This additional ementitious material enhanes the bonding within the onrete matrix and helps redue permeability. Silia fume redues onrete permeability even further by filling the mirosopi voids between ement partiles. As a result, silia fume onrete has an extremely low hloride permeability and a high eletrial resistivity to orrosion urrents, two key fators that ombine to protet reinforing steel and onrete from deterioration and orrosion aused by hemials, deiing salts, sea water intrusion, road traffi, aid rain, and freeze and thaw yles (Wolsiefer 1991). The silia fume used in this study was Fore 10,000 D, a produt of W.R. Grae & Co.-Conn Latex-Modifier Latex is a olloidal suspension of polymer in water. It is added to onventional onrete to produe latex-modified onrete. It is believed that the polymer forms a ontinuous polymer film within the paste. The high flexibility of the polymer inreases the tensile strength of onrete and also redues raking. Consequently, the raks do not beome a point of weakness for further environmental attak (Mindess and Young 1981). Furthermore, the latex modifies the pore struture of the onrete and redues its permeability (Holland 1992), inreasing the orrosion-resisting apabilities of the onrete. 8

20 2.3 Testing Several tests were performed to evaluate the basi properties of onrete, suh as slump, ompressive strength, elasti modulus, Poisson s ratio, and onrete permeability. Chemial tests were also performed to assess the orrosion-resistane properties of onrete. Eah of these tests will be desribed in the following setions Slump, ompressive strength, elasti modulus, and Poisson s ratio tests For eah mixture, slump tests were performed in aordane with ASTM C 143, ompressive strength was measured aording to ASTM C 39, and the modulus of elastiity and Poisson s ratio of the onrete were measured in aordane with the method desribed in ASTM C Permeability test Near-surfae onrete permeability has a major influene on the long-term performane of onrete strutures sine the near-surfae onrete provides both the hemial and physial resistane against the ingress of deleterious elements from the environment. Air permeability and water permeability tests are ommonly used to assess onrete permeability Air permeability test: There are two types of methods used to measure air permeability of onrete, output methods and input methods (Dhir et al. 1995). In the output methods, one end 9

21 of a speimen with the irumferential surfae sealed is subjeted to a onstant pressure and the other end is left free at normal atmospheri pressure. The flow rate is measured when the flow has attained steady state, where the inlet flow rate is equal to the outlet flow rate. Dary s law and onsideration of air as a ompressible fluid are applied to alulate the intrinsi permeability with the following equation (Dhir et al. 1989): k = 2μLP Q A ( P P ) 1 2 (2.2) where: k is the air permeability, Q is the volumetri rate of flow, A is the ross-setional area perpendiular to the diretion of flow, L is the length of speimen, P 1 and P 2 are the inlet and outlet pressures, respetively, μ is the visosity. Output methods provide aurate results, but are time onsuming and annot be applied to in-situ onrete (Dhir et al. 1995). The first input method was proposed by Figg (1973). In this method, a below atmospheri pressure is applied to a drilled hole in onrete using a hand vauum and a hypodermi needle inserted through a plug at the surfae of the hole. The measure of the air permeability of the onrete is taken as the elapsed time for the pressure to inrease from psi to psi (-55 kpa to -50 kpa). Unlike output methods, input methods are rapid and apable of being applied to in-situ onrete. The input method was later developed and modified by a number of authors. However, input methods still have 10

22 some drawbaks as Dhir et al. (1995) pointed out. The influene of moisture ontent, whih is signifiant, on the measured values of permeability is not onsidered in some methods, and the tehniques are partially destrutive Figg (1973). To avoid these draw baks, Dhir et al. (1995) proposed a new input method in whih the onrete is preonditioned with the test apparatus before testing. Calulation of the permeability is based on a detailed theoretial model, and the test is non-destrutive Water permeability Water permeability is tested in a manner similar to that used for air permeability. The steady flow and depth of penetration methods are two ommon praties. The priniple of the steady flow method is the same as that for the output methods for air permeability testing. In the depth of penetration methods, one end of the speimen is subjeted to a pressure head, while the other end of the speimen is free in normal atmospheri onditions. If the flow of water is uniaxial, the following relationship holds (Li and Chau 2000): 2 d v k = 2 ht (2.3) where k is the oeffiient of permeability equivalent to that used in Dary s law (m/s), d is depth of penetration of onrete (m), v is the fration of the volume of onrete oupied by pores, h is hydrauli head (m), t is time under pressure (s). 11

23 The water penetration is onsidered as uniaxial only if the depth of penetration in the onrete is smaller than the diameter of the test area. It is suggested that the steady flow method be used for onrete with high permeability while the depth of penetration method is most suitable for onrete with low permeability (Li and Chau 2000) Eletrial tests This study was the initial work performed in a projet to investigate the orrosion inhibiting abilities of the admixtures. The tests performed for the orrosion testing inlude half-ell potential, polarization resistane, and resistivity measurement. However, results from these tests are not presented in this report Chemial tests Two hemial tests that were performed for this study were a ph test and a hloride onentration test. These properties were evaluated beause ph and hloride ontent diretly influene the orrosion proess of reinforing steel ph test Sine the natural alkalinity of onrete (ph > 12) inhibits orrosion of reinforing steel, it is important to assess the atual ph of onrete. The method used to obtain the ph of onrete is the same as the method used to determine the ph of an aqueous solution. Conrete powder at the area surrounding reinforing steel is olleted and mixed with distilled water (10 drops of distilled water per gram of onrete powder). A ph meter is dipped in the solution to measure the ph. 12

24 Chloride onentration test Chloride ions, along with water and oxygen, initiate orrosion of reinforing steel in onrete. However, most hloride ions in hardened onrete are in hemially ombined forms. Only a portion of the hloride ions are free to ontribute to the orrosion proess (Berman 1972). There are two types of hloride intrusion tests: measurement of the water-soluble hloride onentration and measurement of the total-hloride onentration. For the water-soluble test, a onrete powder sample olleted from onrete near the steel is boiled in water for 5 minutes and soaked in water for 24 hours. Then, the water is used to determine the dissolved hloride. For the total-hloride test, the ground sample is dissolved in an extration liquid suh as nitri aid. A meter is dipped into the solution to measure the hloride onentration (Gaynor 1987). Test results are ompared to reommended safe limits of hloride ontent from ACI These limits are presented in Table 2.1. Table 2.1 Limits for water-soluble hloride-ion ontent in onrete (ACI ). Type of member Maximum water-soluble hloride ion ontent, perent by mass of ement Prestressed onrete 0.06 Reinfored onrete exposed to hloride 0.15 Reinfored onrete that will be dry or proteted from moisture in servie 1.00 Other reinfored onrete onstrution

25 2.4 Summary This hapter presented a literature review of several admixtures that are added to onrete to protet reinforing steel from orrosion. These admixtures were DCI, Rheorete CNI, Rheorete 222+, FerroGard 901, Xypex Admix-C2000, silia fume, fly ash, and a latex-modifier. Desriptions of tests performed to evaluate onrete permeability, hloride onentration, and ph were also presented. 14

26 CHAPTER 3 EXPERIMENTAL PROCEDURES 3.1 Introdution This hapter desribes the materials used in all of the onrete mixtures and how eah mixture was designed. The proesses of preparing the materials, mixing the onrete, and uring the onrete speimens are also desribed. The experimental proedures for measuring ompressive strength, elasti modulus, Poisson s ratio, hloride onentration, onrete permeability, and ph are also presented. 3.2 Materials Fine aggregates Two fine aggregates were used in this study. The first was dune sand, an aeolian deposit of oral on the island of Maui. The seond was a rushed basalt from the Kapaa quarry on the island of Oahu. The grain size distribution and fineness modulus for both sands were determined aording to ASTM C 136. The results from the grain size distribution tests are presented in Table 3.1 along with values for the blended sand obtained by using 65.7% basalt sand and 34.3% Maui dune sand. Gradation requirements from ASTM C 33 are also presented in Table 3.1. Figure 3.1 presents these data and requirements graphially. It an be seen from the gradation that Maui dune sand alone does not meet the requirements of ASTM C 33 for fine aggregate. However, the blend of 34.3% Maui dune sand and 65.7% basalt sand does satisfy ASTM C

27 Table 3.1. Partile size distribution for fine aggregates. Sieve size Maui dune sand Perent passing by weight Basalt sand Blended sand ASTM C 33 requirement 3/8 in. (9.5 mm) No. 4 (4.75 mm) to 100 No. 8 (2.36 mm) to 100 No. 16 (1.18 mm) to 85 No. 30 (600 µm) to 60 No. 50 (300 µm) to 30 No. 100 (150 µm) to Perent passing by weight (%) Maui dune sand Basalt sand 30 Blended sand 20 Lower bound in ASTM requirement 10 Upper bound in ASTM requirement Sieve size (mm) Figure 3.1. Partile size distribution for fine aggregates. 16

28 Table 3.2. Fineness modulus of fine aggregates. Maui dune Sand Basalt sand Blended sand ASTM C 33 requirement Fineness modulus to 3.1 Table 3.3. Speifi gravity and absorption for fine aggregates. Bulk speifi gravity Absorption (%) Maui dune sand Crushed basalt sand Blended sand The values of fineness modulus for Maui dune sand, basalt sand, the blended sand, and the ASTM C 33 requirement are presented in Table 3.2. Aording to requirements of ASTM C 33, the fineness modulus of fine aggregates must not be less than 2.3 or more than 3.1. To satisfy this requirement with the fine aggregates available in Hawaii, it is neessary to blend fine aggregates from the two soures. The blend of 34.3 % Maui dune sand and 65.7 % basalt sand provides a fineness modulus of Bulk speifi gravity and absorption of the fine aggregates were determined aording to ASTM C 128 and are provided in Table 3.3. Sine mix design alulations require the bulk speifi gravity for the mixture of two fine aggregates, the value of bulk speifi gravity is obtained using Equation 3.1. G = P1 100G 1 1 P G 2 (3.1) 17

29 where: G is average speifi gravity of the blended sand, G 1, G 2 are appropriate speifi gravity values for eah size fration, P 1, P 2 are the perentages of eah size fration present in the original sample Coarse aggregate The oarse aggregate used in this study was rushed basalt from the Kapaa quarry on the island of Oahu. The results of a sieve analysis performed on the oarse aggregate are presented in Table 3.4 along with the ASTM C 33 gradation requirements for oarse aggregates. These data are also shown graphially in Figure 3.2. It is lear that the oarse aggregate satisfies the ASTM C 33 gradation requirements. The bulk speifi gravity and absorption of the oarse aggregate were obtained aording to ASTM C 127 and are presented in Table 3.5. Table 3.4. Partile size distribution for oarse aggregate. Sieve size Perent passing by weight (%) Crushed oarse basalt ASTM C 33 Requirement 1 (25 mm) ¾ (19 mm) to 100 ½ (12.5 mm) 66.3 NA 3/8 (9.5 mm) to 55 No. 4 (4.75 mm) to 10 18

30 Table 3.5. Speifi gravity and absorption for oarse aggregate. Bulk speifi gravity Absorption (%) Coarse aggregate Perent passing by weight (%) Coarse aggregate Lower bound in ASTM requirement Upper bound in ASTM requirement Sieve size (mm) Figure 3.2. Partile size distribution for oarse aggregate Cement Oahu. The ement used in this study was a Type I-II ement produed on the island of 3.3 Mixtures Mixtures were designed for eah admixture with various water-ement ratios, paste ontents, and admixture onentrations or pozzolan ontents. A summary of all the mixtures prepared for this study is presented in Table

31 3.3.1 Control mixtures Control mixtures were proportioned by modifying an atual onrete mixture designed by Ameron and used for improvements to Pier-39 (Phase 2) in Honolulu. This mixture was seleted for use in the Pier 39 improvements beause it was onsidered an effetive mixture for proteting the reinforing steel. There are six ontrol mixtures denoted as C1 to C6 with 3 levels of w/ ratios 0.35, 0.4, and C1, C2, and C3 have the same paste ontent as the atual onrete mixture (31.2%). C4, C5, and C6 are based on the design reommendations of the PCA (Portland Conrete Assoiation). As a result, they have a slightly higher paste ontent (32.5%) than the referene mixture. The proportions for the ontrol mixtures are provided in Table 3.7. Admixture Table 3.6. Summary of admixture usage with various mixtures. w/(+p) Paste Content Pozzolan Content Admixture Dosage Latex Content Control 3 levels 2 levels DCI 2 levels 2 levels levels - - CNI 2 levels 2 levels levels - - Rheorete levels 2 levels level - - FerroGard levels 2 levels level - - Xypex Admix C levels 2 levels level - - Latex Modifier 2 levels levels Fly Ash 2 levels 2 levels 3 levels Silia Fume 2 levels 2 levels 3 levels

32 Table 3.7. Mixture proportions for ontrol mixtures. Material or property C1 C2 C3 C4 C5 C6 W/ Paste volume (%) Design slump (in) (mm) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) Coarse aggregate (lb/yd 3 ) (kg/m 3 ) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) Dune sand (lb/yd 3 ) (kg/m 3 ) 431 (255.7) 431 (255.7) 431 (255.7) (244.1) (244.1) (244.1) Conrete sand (lb/yd 3 ) (kg/m 3 ) (489.8) (489.8) (489.8) (467.6) (467.6) (467.6) Cement (lb/yd 3 ) (kg/m 3 ) (466.4) (435) (405.6) (486.3) (452.4) (422.9) Water (lb/yd 3 ) (kg/m 3 ) (163.2) (173.3) (182.6) (170.2) (181) (190.3) Daratard (oz./sk) (ml/sk) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) Darex (oz./sk) (ml/sk) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) Design air ontent (%) DCI mixtures DCI mixtures were designed by replaing 2, 4, and 6 gallons of water with the DCI admixture for 1 yd 3 (9.9, 19.8, 29.7 l/m 3 ) of onrete. D4, D5, and D6 were modified from C2 while D1, D2, D3 were based on C4. The proportions for the DCI mixtures are shown in Table CNI mixtures Sine DCI and Rheorete CNI both are alium nitrite-based orrosion inhibitors and ontain 30% of alium nitrite, CNI mixtures were developed by replaing DCI with 21

33 Rheorete CNI. Six CNI mixtures were denoted as CNI1 to CNI6. The proportions for the CNI mixtures are provided in Table Rheorete mixtures Rheorete mixtures, RHE1 to RHE6, were designed by adding the same amount of Rheorete 222+ to six ontrol mixtures C1 to C6. The dosage used in this study was 1 gallon of Rheorete 222+ per ubi yard (4.95 l/m 3 ) of onrete. The proportions for RHE mixtures are presented in Table 3.9. Material or property Table 3.8. Mixture Proportions for DCI and CNI mixtures. D1 CNI1 D2 CNI2 22 D3 CNI3 D4 CNI4 D5 CNI5 D6 CNI6 w/ Paste volume (%) Design slump (in) (mm) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) Coarse aggregate (lb/yd 3 ) (kg/m 3 ) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) Dune sand (lb/yd 3 ) (kg/m 3 ) (244.1) (244.1) (244.1) (256) (256) (256) Conrete sand (lb/yd 3 ) (kg/m 3 ) (467.6) (467.6) (467.6) (490.4) (490.4) (490.4) Cement (lb/yd 3 ) (kg/m 3 ) (486.3) (486.3) (486.3) (435) (435) (435) Water (lb/yd 3 ) (kg/m 3 ) (160.3) (150.4) (140.5) (163.4) (153.5) (143.6) Liquid DCI or CNI (gal/yd 3 ) (l/m 3 ) 2 (9.9) 4 (19.8) 6 (29.7) 2 (9.9) 4 (19.8) 6 (29.7) Daratard (oz./sk) (ml/sk) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) Darex (oz./sk) (ml/sk) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) Design air ontent (%)

34 Table 3.9. Mixture Proportions for Rheorete mixtures. Material or property RHE1 RHE2 RHE3 RHE4 RHE5 RHE6 w/ Paste volume (%) Design slump (in) (mm) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) Coarse aggregate (lb/yd 3 ) (kg/m 3 ) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) Dune sand (lb/yd 3 ) (kg/m 3 ) 431 (255.7) 431 (255.7) 431 (255.7) (244.1) (244.1) (244.1) Conrete sand (lb/yd 3 ) (kg/m 3 ) (489.8) (489.8) (489.8) (467.6) (467.6) (467.6) Cement (lb/yd 3 ) (kg/m 3 ) (466.4) (435) (405.6) (486.3) (452.4) (422.9) Water (lb/yd 3 ) (kg/m 3 ) (163.2) (173.3) (182.6) (170.2) (181) (190.3) Rheorete 222+ (gal/ yd 3 ) (l/m 3 ) 1 (4.95) 1 (4.95) 1 (4.95) 1 (4.95) 1 (4.95) 1 (4.95) Daratard (oz./sk) (ml/sk) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) 3 (88.7) Darex (oz./sk) (ml/sk) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) Design air ontent (%) FerroGard mixtures The FerroGard 901 dosage used for FerroGard mixtures was three gallons per ubi yard (14.85 l/m 3 ) of onrete. Six FerroGard mixtures, FER1 to FER6, were developed by replaing a portion of water in six ontrol mixtures with the same amount of FerroGard 901. The proportions for FER mixtures are presented in Table

35 Table Mixture Proportions for FerroGard mixtures. Material or property FER1 FER2 FER3 FER4 FER5 FER6 w/ Paste volume (%) Design slump (in) (mm) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) Coarse aggregate (lb/yd 3 ) (kg/m 3 ) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) Dune sand (lb/yd 3 ) (kg/m 3 ) 431 (255.7) 431 (255.7) 431 (255.7) (244.1) (244.1) (244.1) Conrete sand (lb/yd 3 ) (kg/m 3 ) (489.8) (489.8) (489.8) (467.6) (467.6) (467.6) Cement (lb/yd 3 ) (/m 3 ) (466.4) (435) (405.6) (486.3) (452.4) (422.9) Water (lb/yd 3 ) (kg/m 3 ) (148.4) (158.5) (167.7) 262 (155.4) 280 (166.1) (175.5) FerroGard 901 (gal/ yd 3 ) (l/m 3 ) 3 (14.85) 3 (14.85) 3 (14.85) 3 (14.85) 3 (14.85) 3 (14.85) Darex (oz./sk) (ml/sk) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) Design air ontent (%) Xypex mixtures Xypex mixtures were proportioned by replaing 2% of ement by mass from six ontrol mixtures with Xypex Admix C The Xypex mixtures were denoted as XYP1 to XYP6, orresponding to C1 to C6. The proportions for Xypex mixtures are provided in Table

36 Table Mixture Proportions for Xypex mixtures. Material or property XYP1 XYP2 XYP3 XYP4 XYP5 XYP6 w/ Paste volume (%) Design slump (in) (mm) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) 4 (100) Coarse aggregate (lb/yd 3 ) (kg/m 3 ) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) Dune sand (lb/yd 3 ) (kg/m 3 ) 431 (255.7) 431 (255.7) 431 (255.7) (244.1) (244.1) (244.1) Conrete sand (lb/yd 3 ) (kg/m 3 ) (489.8) (489.8) (489.8) (467.6) (467.6) (467.6) Cement (lb/yd 3 ) (kg/m 3 ) (457.1) (426.3) 670 (397.5) (476.5) (443) (414.4) Water (lb/yd 3 ) (kg/m 3 ) (163.2) (173.3) (182.6) (170.2) (181) (190.3) Xypex (lb/yd 3 ) (kg/m 3 ) (9.33) 14.7 (8.72) 13.7 (8.13) 16.4 (9.73) 15.8 (9.37) 14.3 (8.48) Darex (oz./sk) (ml/sk) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) 2 (59.1) Design air ontent (%) Latex-modified mixtures Latex-modified mixtures were proportioned by adding latex amounts whih were equal to 2.5, 5, and 7.5% of the mass of the ement in the ontrol mixtures. There were 6 latex-modified mixtures denoted as L1 to L6. L4, L5, and L6 were based on ontrol mixture C2 with latex ontents of 2.5, 5, and 7.5%, respetively. L1, L2, and L3 were based on ontrol mixture C1, and had the same latex ontents as L4, L5, and L6. Proportions for the latex-modified mixtures are provided in Table

37 Table Mixture Proportions for latex-modified mixtures. Material or property L1 L2 L3 L4 L5 L6 w/ Paste volume (%) Coarse aggregate (lb/yd 3 ) (kg/m 3 ) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) 1576 (935) Dune sand (lb/yd 3 ) (kg/m 3 ) (245.7) (235.7) (225.8) (246.3) (237) (227.7) Conrete sand (lb/yd 3 ) (kg/m 3 ) (470.7) (451.6) (432.4) (471.8) (454) (436.1) Cement (lb/yd 3 ) (kg/m 3 ) (466.4) (466.4) (466.4) (435) (435) (435) Water (lb/yd 3 ) (kg/m 3 ) (128.3) (93.3) 98.3 (58.3) (140.7) (108) (75.4) Latex liquid (lb/yd 3 ) (kg/m 3 ) 78.6 (46.6) (93.3) (140) 73.3 (43.5) (87) 220 (130.5) Design air ontent (%) Silia fume mixtures The designs for the silia fume mixtures were based on the onrete mixture used in the Ford Island Bridge projet. As with the mixture used for the Pier 39 improvements, this mixture was already onsidered to be effetive at proteting the reinforing steel. There were eleven silia fume mixtures with 2 water ement ratios 0.36 and SF1 to SF6 were designed by modifying the atual Ford Island Bridge mixture. The rest of the silia fume mixtures, SF7 to SF11, are based on the mixture design reommendations of PCA. Three silia fume ontents were used, 5, 10, and 15 % by mass of ement. The proportions for the silia fume mixtures are presented in Table

38 Table Mixture Proportions for silia fume mixtures. 27 Material or property SF 1 SF2 SF3 SF4 SF5 SF6 SF7 SF8 SF9 SF10 SF11 w/(+sf) Paste volume (%) D. Slump (in) (mm) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) Coarse agg. (lb/yd ) (kg/m 3 (989.6) (989.6) (989.6) (989.6) (989.6) (989.6) (989.6) (989.6) (989.6) (989.6) (989.6) ) Dune sand (lb/yd ) (kg/m 3 (319) (315.2) (311.7) (308) (315.2) (315.2) (295.4) (292) (288.6) (295.4) (295.4) ) Conrete sand (lb/yd ) (kg/m 3 (422.8) (417.9) (413.2) (408.3) (417.9) (417.9) (391.6) (387.1) (382.6) (391.6) (391.6) ) Cement (lb/yd 3 ) (kg/m 3 ) (481.2) (457.4) (433) (409) (428.7) (401) (425.9) (403.4) (381) (400) (374.4) Water (lb/yd 3 ) (kg/m 3 ) 292 (173.2) 292 (173.2) 292 (173.2) 292 (173.2) (171.5) (169.8) (201.7) (201.7) (201.7) (200) (198.2) Silia fume (lb/yd ) (kg/m 3 (0) (23.73) (48.12) (72.17) (47.64) (70.75) (22.42) (44.83) (67.24) (44.43) (66.07) ) Air ontent (%)

39 3.3.9 Fly ash mixtures Fly ash mixtures were designed similar to the silia fume mixtures sine fly ash and silia fume are both pozzolans. The silia fume was replaed by an equal mass of fly ash for eah mixture. The only differene between a fly ash mixture and a orresponding silia fume mixture was the sand ontent. This differene was due to the differene in speifi gravity between silia fume and fly ash. There were ten fly ash mixtures denoted as FA2 to FA11. There was no mixture FA1 beause it was exatly the same as SF1, whih had zero pozzolan ontent. The proportions for the fly ash mixtures are provided in Table The fly ash used in this study is olleted from a oal power plant on Oahu. It does not satisfy the ASTM requirements for either Class C or Class F fly ash. Its hemial omposition is provided in Table In this study, fly ash was used to replae 5, 10, and 15% of the ement. Table Fly ash hemial omposition. Chemial omposition (%) ASTM C Speifiations Hawaiian fly ash Class F Class C Total silia, aluminum, iron Min 50.0 Min Sulfur trioxide Max 5.0 Max Calium oxide Moisture ontent Max 3.0 Max Loss on ignition Max 6.0 Max Available alkalies (as Na 2 O) Max 1.5 Max 28

40 29 Table Mixture Proportions for fly ash mixtures. Material or property FA2 FA3 FA4 FA5 FA6 FA7 FA8 FA9 FA10 FA11 w/(+sf) Paste volume (%) Design slump (in) (mm) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) Coarse aggregate (lb/yd 3 ) (kg/m 3 ) 1668 (989.6) 1668 (989.6) 1668 (989.6) 1668 (989.6) 1668 (989.6) 1668 (989.6) 1668 (989.6) 1668 (989.6) 1668 (989.6) 1668 (989.6) Dune sand (lb/yd 3 ) (kg/m 3 ) (316.8) (314.6) (312.3) (316.8) (316.8) (296.9) (294.8) (292.8) (296.9) (296.9) Conrete sand (lb/yd 3 ) (kg/m 3 ) (419.9) (417) (414) (419.9) (419.9) (393.5) (390.8) (388.1) (393.5) (393.5) Cement (lb/yd 3 ) (kg/m 3 ) 771 (457.4) (433) (409) (430.4) (404.1) (425.9) 680 (403.4) (381) (401.3) (377) Water (lb/yd 3 ) (kg/m 3 ) 292 (173.2) 292 (173.2) 292 (173.2) (172.2) (171.2) 340 (201.7) 340 (201.7) 340 (201.7) (200.6) (199.6) Fly ash (lb/yd 3 ) (kg/m 3 ) 40 (23.73) 81.1 (48.12) (72.17) (47.82) (71.31) (22.42) (44.83) (67.24) (44.59) (66.53) Design air ontent (%)

41 Other admixtures Along with the orrosion inhibiting admixtures, some other admixtures that were added to the onrete mixtures were Daraem 19, Darex II AEA, and Daratard HC. These three admixtures are all produts of W.R. Grae & Co.-Conn. Daraem 19 is a high range water reduer, ommonly referred to as a superplastiizer. Adding Daraem 19 to the onrete inreases the workability of onrete, espeially for onrete mixtures that have low water-ement ratios. The manufaturer s reommended dosage is between 6 and 20 fl. oz. per 100 lbs (390 and 1300 ml per 100 kg) of ement. In this study, Daraem 19 was added to onrete until a desired slump was ahieved. Darex II AEA is an air-entraining admixture. It generates a stable air void system for protetion against damage from freezing and thawing. The Darex dosage was 3 oz./sk (88.7 ml/sk) Daratard HC is a set-retarding admixture. Adding Daratard HC to fresh onrete allows the setting time to be delayed and ontrolled. As a result, more time an be allowed for plaing, vibrating, and finishing the onrete. For the mixtures that inluded Daratard, the dosage was 2 oz./sk (59.1 ml/sk). It should be noted that these admixtures were not used for all mixtures. Aording to the manufaturers, ertain admixtures ould not be used together due to potential hemial reations that ould have adverse effets on the properties of the onrete. Certain admixtures were also omitted from some mixtures to ontrol workability of the mixture. 30

42 3.3 Speimens Three 6 by 12 in. (152 by 304 mm) ylindrial speimens were prepared for testing ompressive strength aording to ASTM C 39. One of the ylinder speimens was also used for elasti modulus and Poisson s ratio testing aording to ASTM C 469. Beam speimens, 4.5 by 6 by 11 in. (114 by 152 by 279 mm) reinfored with No. 4 steel bars, were made for testing orrosion resistane aording to ASTM G 109. Sine two anode bars are required to measure the polarization resistane, the speimens were modified from the desription in ASTM G 109. Four No. 4 steel bars were plaed in eah speimen instead of three bars. This onfiguration is illustrated in Figure 3.3. Twelve beams were produed for the mixtures C1 to C6, D1 to D6, SF1 to SF7, and L1 to L6, while only four were produed for the other mixtures. The additional beams for the ontrol, DCI, SF, and latex-modified mixtures failitated periodi measurements of hloride onentration, permeability, and ph Preparation The oarse aggregates for the main bath and butter bath of a partiular mixture were weighed out and soaked in water for 24 hours prior to mixing to ensure that the oarse aggregates were saturated. Both the Maui dune sand and the rushed basalt sand were plaed in an oven at 110 C for 48 hours to obtain zero-moisture-ontent fine aggregates. This drying allowed the moisture ontent of the fine aggregate to be arefully ontrolled. The steel reinforing bars used in the speimens were pikled in a 10% sulfuri aid solution for 10 minutes. Then, the bars were leaned by wire brushing. A layer of 31

43 No. 4 bar Figure 3.3. Details and dimensions (in (mm)) of beam speimens. 32

44 eletroplater s tape was used to over three inhes at eah end of eah bar. The taped bars were then plaed in the molds so that 1.5 inhes (38 mm) of the bar were proteted within eah end of the beam speimen. The position of the bars is shown in Figure Mixing proess Fine aggregates were removed from the oven, weighed out for both the butter bath and the main bath, and plaed in bukets. These bukets were overed so that the fine aggregates did not absorb moisture from the air as they ooled. Fine aggregates were allowed to ool for three to four hours prior to mixing. The soaked oarse aggregate was dumped in a wire-mesh sieve to drain the exess water. The oarse aggregate was then weighed prior to mixing. Water gained by soaking the oarse aggregate was aounted for when weighing out the mixing water. Mixing was onduted aording to ASTM C Casting speimens Fresh onrete was plaed in prepared ylinder molds with three equal layers of onrete. Eah layer was rodded 25 times with a in. (16 mm) diameter steel rod. Fresh onrete was also poured into beam molds in two lifts. Eah lift was onsolidated by a vibrator. Caution was taken during vibrating to avoid over-onsolidation Proess after uring period Approximately 24 hours after asting, the speimens were taken out of the molds. The ends of eah reinforing bar in beam speimens were taped one more time with 33