steel slag aggregate in concrete.pdf

US AND INTERNATIONAL PERSPECTIVES ON THE USE OF STEEL SLAG AGGREGATE IN 1 PORTLAND CEMENT CONCRETE 2 3 Brad Fronek 4 Student 5 Civil & Environmental Engineering Department 6 Cleveland State University 7 1960 E. 24th Street 8 Cleveland, Ohio 44115 9 Email: [email protected] 10 11 Paul Bosela, P.E., Ph.D. 12 Professor 13 Civil & Environmental Engineering Department 14 Cleveland State University 15 1960 E. 24th Street 16 Cleveland, Ohio 44115 17 Tel: 216-687-2597 18 Fax: 216-687-5395 19 Email: [email protected] 20 21 Norbert Delatte, P.E., Ph.D. (Corresponding Author) 22 Professor and Chair 23 Civil & Environmental Engineering Department 24 Cleveland State University 25 1960 E. 24th Street 26 Cleveland, Ohio 44115 27 Tel: 216-687-9259 28 Fax: 216-687-5395 29 Email: [email protected] 30 31 Submission Date: November 11, 2011 32 Number of Words: 5,938 33 Number of Figures: 0 34 Number of Tables: 0 35 Equivalent Number of Words: 5,938 36

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TRB 2012 Annual Meeting Paper revised from original submittal.

Fronek, Bosela, and Delatte 2

ABSTRACT 1 The issue of sustainability in the built environment is of increasing importance, particularly in the transportation 2 sector. Slags from the iron and steel industries can be used in some cases to replace natural aggregates in 3 construction. In this research laboratory investigations of the use of steel slag as a portland cement concrete (PCC) 4 aggregate were reviewed. Much of this research has taken place outside of the United States. Some limited field 5 cases of the use of steel slag in pavements were also found. At least two of these resulted in dramatic pavement 6 failures, but it is not known whether the slag used in those applications had been properly aged as required by 7 modern specifications. Research on the use of steel slag aggregate in PCC has been carried out in Spain, Germany, 8 Canada, Italy, India, and Saudi Arabia. Although there have been some limited field applications, virtually all of the 9 research has been in the laboratory. Much of this work has shown that properly aged steel slag can be non-10 expansive when used in PCC. When evaluating these research results, it is important to carefully consider the 11 properties of the slags used, because they may be very different from slags produced in the U.S. due to differences in 12 sources or industrial processes. Several State Department of Transportation specifications were reviewed, and they 13 generally do not permit the use of steel slag as a PCC aggregate. Steel slag represents a very small part of the total 14 aggregates currently used, but it is an alternate material that should be considered where it makes economic sense. 15

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INTRODUCTION 1 The issue of sustainability in the built environment is of increasing importance, particularly in the 2

transportation sector. Many current approaches, such as the United States (US) Green Building Councils well 3 known Leadership in Energy and Environmental Design (LEED) program (1), focus on the energy and 4 environmental performance of a completed facility, or recycling or reusing building materials, or reducing 5 construction waste. The use of steel and other metallic slags may have an important place in sustainability. 6

Meeting the global demand for concrete in the future is becoming more challenging with each passing year. 7 Since more than three quarters of the volume of concrete is commonly composed of aggregates and the Earths 8 resources are finite, finding suitable alternatives to natural aggregates is becoming increasingly important. 9 According to some estimates after the year 2010 the global concrete industry will annually require 8 to 12 billion 10 metric tons of natural aggregates (2). As stated by the United States Geological Survey, during the past 25 years the 11 production of crushed stone has increased at an average annual rate of about 3.3 percent. Production of sand and 12 gravel, which until 1974 exceeded that of crushed stone, has increased at an annual rate of less than 1 percent. Based 13 on these numbers, by 2020 US production of crushed stone, which is expected to increase by more than 20 percent, 14 will be about 1.6 billion metric tons, while production of sand and gravel will be just under 1.1 billion metric tons, 15 an increase of 14 percent. In essence the amount of crushed stone to be produced in the next 20 years will equal the 16 quantity of all stone produced during this century, about 36.5 billion metric tons (3). 17

Slags from the iron and steel industries are sometimes erroneously classified, and often looked upon, as 18 industrial waste materials. In actual fact, these by-products can be valuable and extremely versatile construction 19 materials. The history of slag use in road building dates back to the time of the Roman Empire, some 2000 years 20 ago, when broken slag from the crude iron-making forges of that era was used in base construction (4). 21

The objective of this research project was to support the Federal Highway Administration (FHWA) Office 22 of Pavement Technology by summarizing literature, research files, test standards, specifications, case studies, and 23 other sources to provide guidance to state highway agencies, steel-slag producers and suppliers, and paving 24 contractors concerning the potential use of steel slag as an aggregate in concrete for paving applications. 25

26 OVERVIEW OF SLAG 27

Slag is a broad term used to signify metallic and non-metallic by-products of the steel making process. 28 Iron blast furnace slag (BFS) is a by-product of the production of iron from iron ore or pellets in a blast furnace. It 29 is formed when iron ore or pellets, coke and a lime flux are melted in a blast furnace. The molten iron produced is 30 either cast into products or used later in the production of steel. The lime chemically combines with the aluminates 31 and silicates of the ore and coke ash, and this resultant by-product material is referred to as blast furnace slag. The 32 molten blast furnace slag may be cooled in different ways, resulting in various products. Air-cooled blast furnace 33 slag (ACBFS) is a rock-like material used in fill and embankments, as a road base, or for concrete aggregates, 34 concrete sand, glass insulation wool, as a filter medium, and as a leveling material. Water cooling results in 35 granulated blast furnace slag, which has highly cementitious properties. It is often called slag cement and is used 36 as a cement replacement for portland cement, glass making, concrete block manufacturing, filtration medium, and 37 soil amendment (4). 38

The US Geological Survey reported Although data on U.S. slag production are unavailable, the range of 39 output is estimated as having increased by about 30% to about 11 to 15 million tons in 2010, owing to a restart of 40 many of the iron and steel furnaces that had been idled at least part time in 2009. Better slag availability led to a 41 modest increase in slag sales in 2010, although volumes remained constrained by continued low levels of 42 construction spending. An estimated 15 million tons of iron and steel slag, valued at about $290 million (f.o.b. 43 plant), was sold in 2010. Iron or blast furnace slag accounted for about 60% of the tonnage sold and had a value of 44 about $250 million; nearly 85% of this value was granulated slag. Steel slag produced from basic oxygen and 45 electric arc furnaces accounted for the remainder (5). 46

As defined by the American Society for Testing and Materials (ASTM), steel slag is a non-metallic product 47 consisting primarily of calcium silicates and ferrites combined with fused oxides of iron, aluminum, manganese, 48 calcium, and magnesium. It is a by-product of steel making produced during the separation of the molten steel from 49 impurities in steel-making furnaces. When using the Basic Oxygen Furnace, 75 150 kg of steel slag is produced 50 per one tonne of steel. About 65 80 kg of steel slag is created per one tonne of steel produced by utilizing an 51 Electric Arc Furnace (6). 52

Steel slag is produced during the separation of the molten steel from impurities in Basic Oxygen or Electric 53 Arc furnaces. The slag occurs as a molten liquid and is a complex solution of silicates and oxides that solidifies 54 upon cooling. Virtually all steel is now made in integrated steel plants using a version of the basic oxygen process or 55 in specialty steel plants using an electric arc furnace process. Steel slag produced in a Basic Oxygen furnace is 56



referred to as basic oxygen steel making slag (BOS) or steel furnace slag. Steel slag produced in an electric arc 1 furnace is referred to as electric arc furnace slag (EAF) or steel furnace slag. Steel furnace slag can be blended with 2 other products such as granulated slag and fly ash to produce pavement material, and is also used as an aggregate in 3 asphalt pavement, as a soil conditioner, and for unconfined construction fill. It also has agricultural and 4 environmental applications. 5

BOS and EAF slag are typically somewhat heavier than BFS and most natural aggregates. Steel slag also 6 differs from blast furnace slag in that free calcium and magnesium oxides are not completely consumed in the steel 7 slag, and subsequent hydration results in deleterious expansion characteristics. In addition, various grades of steel 8 are produced, which result in corresponding variances in the resulting steel slags. Worldwide, almost 100% of BFS 9 is recycled, while about 80% of steel slag is recycled. The expansion characteristic of the steel slags is one of the 10 main differences, and barriers, to its construction use. Expansion can lead to breaking apart and failure of PCC, and 11 expansion of cement treated base layers such as econocrete can lead to large cracks in asphalt surface layers. 12 13 USE IN THE UNITED STATES 14

According to the National Slag Association (NSA) (6), current uses of steel slag include: 15 Bituminous/ asphalt paving 16 Manufacture of portland cement 17 Railway aggregate 18 Roadway bases, and 19 Agricultural soil amendment 20

Use of steel slag as an aggregate in concrete is not cited. 21 22 Laboratory Studies 23 Over several years laboratory research was carried out at Cleveland State University to evaluate the use of 24 steel slag as an aggregate for PCC. Slag in varying percentages was used to replace both coarse and fine aggregate. 25 The slag used in the research had been aged by the supplier. It was found that satisfactory fresh and hardened 26 properties of the PCC could be obtained. One advantage of steel slag for use as a base material or as hot mix asphalt 27 aggregate is its high inter-particle friction. However, the friction was detrimental to use as a PCC aggregate, since 28 that impeded workability and required the addition of water reducers to attain satisfactory hardened properties if 29 high slag percentages were used. Limited testing of expansion characteristics was carried out, and the concrete 30 made with aged steel slag did not appear to be expansive (7, 8, 9, 10). 31 32 Field Case Studies 33 Field case studies of concrete pavements with steel slag aggregate have been very limited, and only two 34 were found in the course of this research. Both were located in Florida. A portion of I-75 near Tampa was opened 35 to traffic between 1980 and 1982. It consisted of 9 inches (230 mm) of concrete pavement over 6 inches (150 mm) 36 of econocrete base. Within six months of opening the last section of the pavement distress was observed. The 37 conclusions of the investigation were that the problem was primarily poor drainage. However, the use of expansive 38 steel slag aggregate in the concrete was also blamed for the distress on part of the project, and longitudinal cracks as 39 much as 2 inches (50) mm wide extending for hundreds of feet or meters were observed (11). It is not known what 40 aging process, if any, was used for the slag. 41

Erlin and Jana noted that The reactions of free lime (CaO, hard-burned lime) and magnesia (MgO, 42 periclase) with water result in the formation of epizet (Ca(OH)2, strained calcium hydroxide) and brucite (Mg(OH)2, 43 magnesium hydroxide), with respective solid volume increases of 91.7 and 119.6 % (12) 44 Erlin and Jana also show a photograph of Thrust faults in an asphalt shoulder flanking a concrete 45 pavement expanding laterally due to electric furnace slag aggregate that contained free lime and periclase in an 46 econo-crete subbase (concrete lean in portland cement) (2003) The location shown in the photograph is unknown 47 (12). 48 At about the same time, similar problems were observed with pavement over econocrete base at the Tampa 49 airport. Professor Ernest Barenberg of the University of Illinois did an investigation of the excessive longitudinal 50 joint opening in the runways and found the opening was due to expansion of the slag concrete used in the base layer. 51 The solution was to tear it all out and replace it with a more conventional stabilized material (Ernest Barenberg, 52 personal communication). 53 These case studies, strictly speaking, were not of concrete pavement but of the similar econocrete base. In 54 each case, the pavement failure mechanism was the same, with wide longitudinal cracks. This distress is difficult to 55



repair without complete replacement of the pavement down through the expansive econocrete base layers, and is 1 therefore of considerable concern to owners. 2 3 State DOT specifications 4 As part of this research, state materials specifications for Ohio, Indiana, West Virginia, Pennsylvania, 5 Michigan, and Illinois were reviewed. These specifications were reviewed because these are either states with 6 significant steel slag production or are located close to those states. 7 8 Ohio 9 In Ohio, steel slag may be used for asphalt concrete base course, but not for surface course or for PCC. 10 Steel slag as an aggregate is covered in section 703 of the Ohio Department of Transportation (ODOT) spec book. 11 Among these specifications are those concerning the use of steel slag as an aggregate. Section 703.14D discussed 12 with the aging and stock piling of the slag. Fine aggregates and coarse aggregates for asphalt concrete can be found 13 in section 703.04 for concrete base and section 703.05 for intermediate and surface courses. In both of these 14 sections sand, gravel and air-cooled slag are mentioned but steel slag is not. Section 703.01E states that open hearth 15 (OH), BOF, EAF steel slag aggregate must conform to 703.04, 703.05 material specifications. It then states a letter 16 of certification that covers the shipment of steel slag must be provided with each shipment that ensures the quality of 17 the slag as well as quality control documents from the processor(13). Processing and quality control requirements 18 are contained in ODOT Supplement 1071 (14) 19 20 Indiana 21 Section 904 deals with the specifications for aggregates. Section 904.02 deals with the use of fine 22 aggregates. It lists natural sand for PCC in decks and bridges, natural sand, crushed limestone and ACBFS for PCC 23 for other construction. For hot asphalt mix, the specification list natural sand or manufactured sand, and it says, 24 Steel furnace slag is permitted only with steel furnace slag coarse aggregate. Section 904.03 deals with coarse 25 aggregates and list quality classification. The use of steel slag in PCC is not addressed (15). 26 27 West Virginia 28 Division 700 is the materials section that addresses hydraulic cement, fine aggregate, and coarse aggregates 29 in West Virginia. Section 702 contains requirements for fine aggregates. Section 702.3 states that fine aggregates 30 must meet requirements of ASTM D 1073 for asphalt mixtures and 702.5 lightweight fine aggregate for structural 31 concrete use requirements of ASTM C 330. Section 703 contains the specifications for coarse aggregates. 703.3.1-32 steel slag defines the classification and requirements for the steel slag. It states that the steel slag must be stockpiled 33 and maintained wet for at least 6 months and be rendered inert to minimize the possible expansion. After the six 34 months of aging an expansion test must be completed before its use. 35 When the steel slag is used in hot asphalt mix, the expansion test is waived. The mixture may not contain 36 more than 50% by weight of the coarse aggregate and cannot be used as a coarse aggregate in a single mix. The 37 expansion test can also be waived for shoulders and road stabilizers where it is not confined. Section 703.3.1 38 concludes with the statement, Steel slag shall not be used in any item where the expansion might be detrimental. 39 Such items include, but not necessarily limited to, the following: aggregate for Portland cement concrete, backfill 40 around drainage structures, piers, abutments, walls, etc. (16). 41 42 Pennsylvania 43 Section 703 is the specification requirements for aggregate uses in Pennsylvania (17). 703.1 deals with the 44 use of fine aggregates and states that steel slag may be used as an aggregate for bituminous concrete mixtures. It 45 outlines the requirements for stockpiling and weathering as well as the testing in accordance with Pennsylvania Test 46 Method No. 130 (18). The maximum volumetric expansion must be less than 0.50%. Section 703.1 also states, 47 Fine aggregate manufactured from steel slag may not be used in cement concrete or mortar mixtures. 48 Materials section 703.2 contains the requirements for coarse aggregates. Under section 703.2, item 4 deals 49 with steel slag as a coarse aggregate. Slag must be soaked in water before or during the stockpile operation. The 50 slag aggregate is stockpiled and weathered for 6 months before being tested. The slag aggregate can be used for 51 shoulders, selected material surfacing and in bituminous concretes. It is also stated in this section that, Aggregate 52 manufactured from steel slag is not acceptable for pipe or structural backfill or in cement concrete (17). 53 54 Michigan 55



The section of material requirements that deals with aggregates for Michigan Department of Transportation 1 (DOT) is section 902. This section outlines the testing methods and types of aggregates. Steel slag is defined in 2 section 902.02 A-2 as a synthetic by-product from BOF, EAF or open hearth furnaces. Section 902.03 contains the 3 requirements for PCC and discusses natural aggregates as well as BFS. In item A - slag coarse aggregates, BFS is 4 allowed to be used if it meets certain requirements but there is no mention of steel furnace slag in this section either. 5 Under section 902.04 Coarse aggregates for HMA mixtures; natural aggregates as well as BFS and steel furnace 6 slag are discussed. Steel slag is not allowed as an aggregate in portland concrete cement since it is omitted in 7 section 902.03 (19). 8 9 Illinois 10 Section 1000 of the Illinois Department of Transportation specifications contains the requirements for the 11 materials for Portland cement and blended hydraulic cement. Section 1004.01 covers coarse aggregate materials. 12 Some approved aggregates consist of gravel, chert gravel, crushed stone, wet bottom boiler slag, crushed slag from 13 air cooled blast furnace slag, and crushed steel slag from OH, BOF or EAF processes. Section 1004.02 covers 14 coarse aggregates for PCC. Section 1004.02 states that the aggregates must conform to the requirements of section 15 1004.01. It also states that the aggregates shall be gravel, crushed gravel, crushed stone, crushed concrete, crushed 16 slag or crushed sandstone. Section 1004.03 lists the types of aggregates that are approved for use in bituminous 17 courses in item A. Some of the approved aggregates are crushed gravel, crushed sandstone, crushed slag and 18 crushed steel slag. Therefore steel slag is not allowed to be used as an aggregate for PCC since it is not specified in 19 the material specifications contained in section 1004.02 (20). Illinois does have a slag producer self-testing program 20 (21). 21 22 INTERNATIONAL STUDIES AND RESULTS 23 Research on the use of steel slag aggregate in PCC has been carried out in Spain, Germany, Canada, Italy, 24 India, and Saudi Arabia, as well as in other countries. Although there have been some limited field applications, 25 virtually all of the research has been in the laboratory. The following summary includes all countries that were 26 found to have published studies on use of steel slag aggregate in PCC. 27 28 Spain 29 Polanco et al. (22) reported on the use of EAF slag and Ladle Furnace Slag (LFS) in hydraulic concrete. 30 The properties studied in their research were the concretes durability and resistance to external agents like freezing 31 and thawing cycles, wetting and drying cycles, potential expansion in hot water and climate chamber aging without 32 chemical activators or additives. 33 The coarse and fine samples of EAFS contained less than 0.1% of MgO and 1% of free CaO while the LFS 34 had a free MgO range of 3 to 4% and content of free lime of 10 to 20%. This study used five different mixtures that 35 ranged from a sample with 25% EAF sand (fine aggregate) mixed with 25% limestone sand and no LFS to a sample 36 that contained 30.6% EAFS sand, 10.2% of LFS and no limestone sand. All the samples used in this study 37 contained approximately 40% by weight of coarse EAFS aggregate. 38

The initial compressive strength at 28 days ranged from 31.5 MPa to 60.4 MPa. The porosity range was 39 14.3 % to 18.5% with a water penetration depth that ranged from 36 mm to 68 mm. The results of the freezing and 40 thawing test showed an acceptable surface appearance in 4 out of 5 samples and a change in compressive strength 41 that ranged from a gain of 10.4% to a loss of 78.4%. The results of the wetting and drying test showed all samples 42 with an acceptable surface appearance and a variation in compressive strength of a -26.7% to a positive strength gain 43 of 6.9%. The results from the wet chamber showed a surface appearance as acceptable and an expansion range of 44 negative 0.12% to 0.00% which is below the acceptable value of 0.20%. The results of the climatic chamber test 45 showed the first three samples with acceptable surface appearance and a change in length that ranged from -0.09% 46 to +0.04%. The final two samples had severe damage to the surface appearance and an expansion in length of 2.39 47 and 0.94% respectively. 48 The magnesium oxide in form of periclase in the cement can cause unsoundness in concrete if its content is 49 higher than 6% of cement weight and if its particle size is smaller than 5 m. If the particle size is higher than this 50 value but does not exceed the limit of 15 m , the periclase content should be reduced to 2%. Finally, the authors 51 state that if the particle size is larger than 15 m , the content must be under 1.2% of cement weight and larger than 52 30 m, under 1%. In this study periclase was found mainly in the LFS and to a smaller degree in the EAFS. 53

The concrete mixtures with EAF slag as an aggregate and LFS as a fine filler showed good mechanical 54 strength. The durability of the cement containing LFS should not be considered positive since there was a loss of 55



strength in all mixtures when compared to the control mixture. The long-term expansion of the mixtures was found 1 to be within acceptable range. The periclase has a detrimental effect when the LFS is too high. 2 Other work on this topic has also been carried out in Spain (23, 24). Other research from Spain, reported 3 in 2010, evaluated the use of two types of foundry sand (FS), EAFS and BFS as aggregates in concrete. Only the 4 EAFS will be discussed further in this paper. The slump, compressive strength, tensile splitting strength, modulus of 5 elasticity, sorptivity, length change and high temperature exposure were reported on in two separate stages. Stage 6 one used high water-cement ratio and stage two contained medium water cement-ratio concrete. 7 The EAFS samples contained 25%, 50% and 100% aggregate by volume. The same effective w/c ratio was 8 determined and used in this study in order to determine the effect the aggregate has on the cement. The EAFS 9 contained 21.77% CaO and contained 6.14% MgO by volume. The expansion of the EAFS samples were 10 determined at 14 days and found to be less than 1% and therefore the materials were found to be non- expansive 11 materials. A minimum amount of additive was added to the first two samples but not the third EAFS sample. The 12 concrete made with low amounts of slag had similar slump test results to ordinary Portland cement (OPC) but the 13 third sample had considerable reduced workability of the concrete. Due to the higher w/c ratio in stage 1, the 14 hardened concrete properties obtained were low and the concrete from stage 2 that had the highest hardened 15 properties were made with the EAFS. The splitting tensile strength and modulus of elasticity obtained was similar 16 to conventional concrete. For the first 12 weeks the OPC and the concrete with 50% EAFS aggregate experienced 17 the highest expansion of approximately 1.5% and from 12 to 56 weeks the length of the samples remain constant 18 (25). 19 20 Germany 21

The use of steel slag for various construction applications in Europe was reviewed in 1996. The two types 22 of steelworks slags discussed in this article are BOF slag and EAF slag. The chemical, mineral, physical 23 characteristics as well as the environmental aspects of the two types of slag are discussed. The physical properties 24 given in this paper are bulk density, resistance to impact, absorption of water, Los Angeles abrasion resistance, 25 polished stone test, compressive strength and expansion by volume. 26

The use of dolomite rather than lime was shown to result in a higher content of MgO. In previous studies, 27 the amount of CaO and free MgO occur as a precipitate in the steel making process which has no effect on the 28 volume stability and they also occur as an undissolved particle which is a major factor. According to the author, the 29 spongy free lime is the most important factor of the free lime and in MgO rich steel slag, the Magnesio-wusite with 30 MgO contents above 70% is the most important factor. When using slag as an aggregate, a free lime content up to 31 7% can be used for unbound applications and 4% for bituminous pavements. When slags have not been weathered 32 the steam test was developed and proposed as a standard method for testing steel slag aggregates for expansion. 33

The use of steel slag in PCC is contingent upon the ability of the aggregate to rapidly form a ridged bond 34 which is a requirement for volume stability. For this reason, it is only used in nonstructural applications like slabs or 35 paving blocks for breakwaters. Work in Austria has shown it is possible to use it as an aggregate in concrete floors 36 and concrete road construction (26). 37

A 2001 study focused on the integrity and volume stability of PCCs that contain steel slag coarse 38 aggregates. The feasibility of using steel slag in a confined application is found by comparing the allowable stress 39 of a material with the expansion force of the steel slag particles. The expansion forces of a known volume of slag 40 can then be used to find the expansive force of a single slag particle. There were two testing methods used in the 41 evaluation of the cements in this study the expansion force test and the autoclave disruption test. This study used 42 3 different BOF slags and one Nickel slag, but only the BOF slag properties will be discussed further in this paper. 43 The 3 BOF samples had a particle size of 20 mm and the range of CaO was 35.1% - 40.6% and the range of MgO 44 was 8.8% to 11.3%. 45

The maximum expansion force of a single slag particle for each BOF sample was 806 N, 556 N, and 1609 46 N. Under the autoclave test, the first two samples expansion forces did not cause any unacceptable surface distress, 47 however in the third sample the expansion force of 1609 N caused surface pop-out which was deemed unacceptable. 48 The surface tension of the three samples was 0.64 MPa, 0.57 MPa and 1.28 MPa respectively. 49

The maximum expansion force and the calculated surface tension stress of the slag particle can be used to 50 determine if the slag can be used as a coarse aggregate in a confined application. It is stated that even with positive 51 results of strength and volume stability, each slag should be checked for each use. The author also states, At this 52 stage, it is imperative that only special quality slag, of clearly proven suitability, is considered for concrete aggregate 53 and confined application uses (27). 54

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Canada 1 According to 2002 research, the Ministry of Transportation of Ontario, Canada banned the use of steel slag 2 in asphalt concrete several years ago due to the expansion problems. Ladle slag is derived from the further refining 3 of steel that originated from a BOF or EAF furnace. The ladle slag used in this study resulted from an EAF 4 production. This study uses three samples of ladle slag, one passing the 100 sieve, one passing the 200 sieve and the 5 final sample passing the 325 sieve. 6 A chemical analysis was performed and all three samples had very similar composition. The content of 7 CaO decreased slightly and the MgO, F, and SO3 increased slightly as the fineness decreased. The CaO content 8 ranged from 55.9 to 57% and the MgO content ranged from 3.2 to 4.7%. With the high free CaO content, the slag 9 fines cannot be used in replacement of Portland cement since it has a high potential for soundness problems. X-ray 10 diffraction (XRD) was used to identify the mineral content of the ladle slag. The free lime content could not be 11 determined from the XRD but Ca(OH)2 was identified. The slag fines showed very little cementitious properties 12 when mixed with water. However, the cementitious properties increased significantly when chemical additives were 13 used and as the fineness of the slag increased (28). 14 15 Italy 16 Research in Italy in 2009 was conducted with an unspecified type of steel slag as an aggregate. The slag 17 used in the study was weathered outside for 5 months and then kept wet for an additional 15 days in the laboratory. 18 The focus of this research was to show that by selecting a proper sort of slag particles, addition of optimized amount 19 of super plasticizer, it is possible to produce mortars that have with good compressive strength in the presence of 20 limited amount of low cost cements. 21 The samples prepared for this study contained varying amounts of cement to slag ratios with a coarse 22 aggregate between 2500 and 5000m, a medium aggregate between 500 and 2500 m and a fine aggregate of less 23 than 500 m. XRD was used in the determination of the different compounds of the slag. The CaO content range 24 was 37.9 to 65.% and the MgO range was 1.8 to 11. %. The medium and coarse slags exhibited the same patterns 25 by XRD but the fine slag aggregate showed significant difference from the medium aggregate. Free lime was not 26 detected by XRD analysis so ethylene glycol method was used to confirm the absence of the free lime. The 27 presence of free MgO was not detected in the samples as well. 28 There was no linear relationship between the amounts of super plasticizer added to the mixture and the 29 compressive strength achieved. The apparent limit for the improvement of the material properties was 2%. The 30 range of expansion of the different samples was from 0.028% to 0.019%. The results showed that using the super 31 plasticizer and the appropriate slag particle size, w/c and c/s, an adequate compression strength at 28 days can be 32 achieved. In order to determine the optimum water the c/s ratio and the w/(c+ slag fine fraction) must be considered 33 (29). 34 35 India 36 The use of both EAF slag and GGBFS together in a cementitious manner was investigated in this research. 37 The EAF slag came from a steel plant located in Western India. The slag was cooled by both the spraying of water 38 and air. Once the slag was received it was melted again in a graphite crucible in the laboratory. The two slags as 39 well as the clinker were examined under XRD, X-ray fluorescence and a scanning electron microscope in order to 40 determine the chemical composition, microstructure and phase analysis. The GGBFS was mixed with EAF to form 41 a blended cement. 42 The CaO content in the clinker was recorded to be 65.7%, which was twice that of the EAF slag, and the 43 MgO content in the clinker was 2.1 %. The MgO content in the untreated slag was 12%, and 21.4% in the treated 44 slag. The iron oxide was reduced in the untreated slag from 24.1 to 1.2% by weight from melting which accounts 45 for the increase in the MgO in the slag. The compressive strength of the received slag and treated slag and the 46 blended mixture of EAFS and GGBFS was approximately equal to that of the control specimen. The treatment of 47 the slag improved the Pozzolanic strength by 4 times from 2 MPa to 8 MPa. A reactivity of merwinite phase in the 48 presence of lime and tobermorite-gel like phase formation on hydration was observed in the study. The treatment of 49 the EAF slag provided it with cementitious and pozzolanic characteristics (30). 50 51 Saudi Arabia 52 The slag used in this research was produced by an EAF and stored outside, crushed and then graded. This 53 study focused on the slag being used as a course aggregate in Portland cement mixtures to obtain results for strength 54 and shrinkage properties. The chemical makeup of the slag consisted of 20-40% CaO and 7 to 12% of MgO by 55 weight. The presence of free lime was not detected by chemical analysis of the EAFS. The different specimens 56



were subjected to one of the three different curing conditions of immersing in water at 21C, moderate temperature 1 of 28C and relative humidity (RH) of 45% and high temperature of 55 C and RH of 10%. 2 The results expressed in this study are the averages of three specimens under the same condition. The 3 results for the compressive strength of the slag concrete showed it had similar strength as the gravel concrete. It was 4 noted by the author that there was a minor loss in compressive strength of the specimens from the third experiment 5 type and this might have been caused by micro cracks resulting from expansive elements still present in the steel 6 slag. There was an increase in the stiffness of the slag concrete and could be easily seen in the stress strain diagram. 7 The flexural strength values were also found to be slightly higher than that of the gravel specimens. The shrinkage 8 of the slag concrete was substantially lower that of the gravel concrete and could be attributed to the higher modulus 9 of elasticity, as well as the angularity and honeycomb surface of the slag. The results have shown that the slag as a 10 coarse aggregate in the concrete did not have negative effects on the short term properties of the concrete (31). 11 12 CONCLUSIONS 13 As natural aggregate supplies are depleted, pressures to use alternative materials such as steel slag will 14 increase. However, the risk of failure due to expansive reactions may obviously outweigh the benefits attained. The 15 case studies in Florida provide a clear cautionary tale. 16 On the other hand, methods of processing and aging slag have advanced considerably in the decades since 17 those failures. Several state Departments of Transportation already have specifications or special provisions to 18 ensure that steel slag is aged so as to be non-expansive. 19 Much of the research into the use of steel slag as an aggregate in PCC has been conducted outside of the 20 United States. Much of this work has shown that properly aged steel slag can be non-expansive when used in PCC. 21 When evaluating these research results, it is important to carefully consider the properties of the slags used, because 22 they may be very different from slags produced in the US due to differences in sources or industrial processes. 23 Even if steel slag aggregate is considerably cheaper than natural aggregates, agencies will continue to be 24 reluctant to use it for PCC in pavements and other similar applications unless it can be demonstrated that proper 25 aging can significantly reduce or eliminate the risk of damage due to expansion. This would, of course, also require 26 test methods and specifications so that potentially harmful material can be identified. 27 28 ACKNOWLEDGEMENTS 29

This study is based upon work supported by the Federal Highway Administration under contract DTFH61-30 10-Q-00125 Feasibility of Expanding Use of Steel Slag as a Concrete Pavement Aggregate. The conclusions 31 expressed herein are the conclusions of the authors and not necessarily those of the Federal Highway 32 Administration. The authors gratefully acknowledge this support. 33 34 REFERENCES 35 36 1 U.S. Green Building Council. http://www.usgbc.org. Accessed July 26, 2011 2 Tu, T.Y.; Chen, Y.Y.; and Hwang, C.L., Properties of HPC with Recycled Aggregates, Cement and Concrete Research, V.36, 2006, pp. 943-950. 3 Tepordei, Valentin V., Natural Aggregates Foundation of Americas Future, www.nationalatlas.gov/articles/geology/a_aggregates.html. Accessed July 19, 2008. 4 Lewis, D., 182-6 Properties and uses of slag [Online] / auth. NSA // national Slag Association. - http://www.nationalslag.org/archive/legacy/nsa_182-6_properties_and_uses_slag.pdf. 5 Van Oss, H.G., Iron and Steel Slag, Mineral Commodity Summaries, U.S. Geological Survey, January 2011. 6 National Slag Association (NSA) (undated) Steel Slag: A Premier Construction Aggregate, http://www.nationalslag.org/ 7 Obratil, Patel, Bosela, and Delatte, Effect of Steel Slag Replacement on Fresh and Hardened Properties of Concrete, paper presented at 87th Annual Meeting of the Transportation Research Board, Washington D.C., 2007. 8 Bosela, Delatte, Obratil, and Pastorelle, Fresh and Hardened Properties of Paving Concrete with Steel Slag Aggregate, 9th International Conference on Concrete Pavements, ISCP, San Francisco, California, August 2008. 9 Obratil, Patel, Bosela, and Delatte, Examination of Steel Slag as a Replacement for Natural Aggregates in Concrete Paving Mixtures, paper presented at 88th Annual Meeting of the Transportation Research Board, Washington, D.C., 2009. 10 Patel, J. (2008) Broader Use of Steel Slag Aggregates in Concrete, Masters Thesis, Cleveland State University



11 Design Related Distress in Concrete Pavements [Article] / auth. Armaghani Jamshid M., Larsen Torbjorn J. and Smith Lawrence L. // Florida's Interstate 75: A Case Study. - [s.l.] : Concrete International, August 1, 1988. - 8 : Vol. 10. 12 Forces of Hydration that can Cause Havoc in Concrete [Report] / auth. Erlin Bernard and Jana Dipayan. - [s.l.] : Concrete International, 2003. 13 State of Ohio Department of Transportation Columbus, Ohio. Construction and Material Specifications, January 2011. 14 Ohio Department of Transportation Supplement 1071, 2010, Quality Control Requirements For Steel Slag Aggregate Producer/Processors 15 Indiana Department of Transportation, Standard Specification, 2012 16 West Virginia Department of Transportation, 2010, Standard Specifications Roads and Bridges 17 Commonwealth of Pennsylvania Department of Transportation, 2011, Publication 408/2011 18 State of Pennsylvania (1995), PA Test method No. 130, Method of Test for Evaluation of Potential Expansion of steel slags. 19 Michigan Department of Transportation, 2003, Standard Specifications for Construction 20 State of Illinois, 2007, Standard Specifications for Road and Bridge Construction 21 State of Illinois Policy Memorandum, 2008, Slag Producer Self-Testing Program 22 Juan A. Polanco, Juan M. Manso, Jess Setin, and Javier J. Gonzlez (2011), Strength and Durability of Concrete Made with Electric Steelmaking Slag, ACI Materials Journal, March-April 2011, Title no. 108-M22. 23 Juan M Manso, Javier J Gonzalez and Juan A Polanco, "Electric Arc Furnace Slag in Concrete", Journal of Materials in Civil Engineering, ASCE, November 2004. 24 Juan M Manso, Juan A Polanco, Milagros Losanez and Javier J Gonzalez, "Durability of Concrete made with EAF Slag as Aggregates", Cement and Concrete Composite, 2006. 25 Properties of Concrete using Metallurgical Industrial By- Products as Aggregates [Journal] / auth. Etxeberria M. [et al.] // Construction and Building Materials. - [s.l.] : Elsevier Ltd., 2010. - Vol. 24. - pp. 1594-1600. - (Spain). 26 Use of Steelworks Slag In Europe [Journal] / auth. Geiseler J.. - [s.l.] : Elsevier Science Ltd., 1996. - 1-3 : Vol. 16. - (Germany). 27 Products of Steel Slags an Opportunity to Save Natural Resources [Journal] / auth. Motz H. and Geiseler J. // Waste Management. - [s.l.] : Elsevier Science Ltd., 2001. - Vol. 21. - pp. 285-293. - (Germany). 28 Characteristics and Cementitious Properties of Ladle Slag Fines from Steel Production [Journal] / auth. Shi Caijun // Cement and Concrete Research. - [s.l.] : Elsevier Ltd., 2002. - Vol. 32. - pp. 459-462. - (Canada). 29 Steelmaking Slag as Aggregate for Mortars: Effects of Particle Dimension on Compression Strength [Journal] / auth. Faraone Nicola [et al.] // Chemosphere. - [s.l.] : Elsevier Ltd., 2009. - Vol. 77. - pp. 1152-1156. - (Italy). 30 Cementitious and Pozzolanic Behavior of Electric Arc furnace Steel Slags [Journal] / auth. Muhmood LuckMan, Vitta Satish and Venkateswaran D. // Cement and Concrete Research. - [s.l.] : Elsevier Ltd., 2009. - Vol. 39. - pp. 102-109. - (India). 31 Utilization of Local Steelmaking Slag in Concrete [Journal] / auth. Al-Negheimish Abulaziz I, Al-Sugair Faisal H. and Al-Zaid Rajeh Z.. - [s.l.] : King Sand University, 1997. - 1 : Vol. 9. - (Saudi Arabia).


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