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Effect of electric arc furnace dust (EAFD) on properties of asphalt cement mixture
Resources, Conservation and Recycling 70 (2013) 38–43
Contents lists available at SciVerse ScienceDirect
Resources, Conservation and Recycling journal homepage: www.elsevier.com/locate/resconrec
Effect of electric arc furnace dust (EAFD) on properties of asphalt cement mixture Mohammad A.T. Alsheyab a,∗ , Taisir S. Khedaywi b,1 a International Research Center for Water, Environment and Energy (Salt) and the Department of Water and Environmental Engineering (Al-Huson College), Al-Balqa’ Applied University, Jordan b Department of Civil Engineering, Philadelphia University (On Sabbatical Leave from JUST), Jordan
a r t i c l e
i n f o
Article history: Received 8 March 2012 Received in revised form 7 October 2012 Accepted 23 October 2012 Keywords: Electric arc furnace EAFD Asphalt cement Solidification/stabilization Penetration index Road construction
a b s t r a c t Electric arc furnace dust (EAFD) is one of the by-products of steelmaking industry which has been classified as hazardous due to containing some heavy metals such as Zinc, Cobalt, Copper, Lead or Cadmium. This research aims at solving the problem of this hazardous waste by solidification/stabilization through mixing it with asphalt cement to be used for road construction. EAFD was used as an additive to the asphalt concrete mixtures with five percentages (0%, 5%, 10%, 15% and 20%) by volume of binder. Penetration, ductility, specific gravity, softening point, flash point, fire point and rotational viscosity were analyzed. It was found that while the penetration and ductility were decreasing with the increase of EAFD concentration in the binder, specific gravity, softening point, flash point, fire point and rotational viscosity were increasing. Finally it has been concluded that the results are promising for dual achievement (1) to solve an environmental problem and (2) to use the EAFD for road construction. © 2012 Elsevier B.V. All rights reserved.
1. Introduction The use of Electric Arc Furnace technology in the steelmaking industry has been increasing considerably over the last four decades, it increased from being 14% in 1970 to 34% in 1998 of the total technologies used for steel production (Sofilic´ et al., 2004). As a result of this increase, it has been reported that many pollutants are released to atmosphere during the steelmaking process when using this technology such as dust, carbon and nitrogen oxides and organic compounds where the amount of dust generated per ton of steel product is estimated to be 15–20 kg. The world generated electric arc furnace dust (EAFD) per year is estimated to be around 3.7 million tons (Néstor and Borja, 2003). This dust is classified by the European Waste Catalogue and the Environmental Protection Agency as a hazardous waste, not disposable in the environment, because it contains hazardous, leachable elements such as zinc, lead or cadmium (Guézennec et al., 2005; Cubukcuoglu and Ouki, 2009; Pavao et al., 2009). Fig. 1 shows formation of EAFD from the steelmaking process. It has been also reported that the recycling of these hazardous metals is still expensive and therefore alternatives should be analyzed and investigated; one of these alternatives is the waste
∗ Corresponding author. Tel.: +962 777584811. E-mail addresses: [email protected] (M.A.T. Alsheyab), [email protected] (T.S. Khedaywi). 1 Tel.: +962 2795588657; fax: +962 27201074. 0921-3449/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.resconrec.2012.10.003
immobilization techniques to prevent the free movement of these hazardous elements in the solid waste. There are three major types of immobilizing techniques: (1) the temporary containment technique, (2) cost effective solidification/stabilization techniques and (3) permanent techniques (Pavao et al., 2009; Jay et al., 2003). It has been reported that EAFD is treated in different ways, such as: (1) recovery of valuable metals (iron, zinc and lead) before land disposal (MacRay, 1985), (2) additive to cement/concrete industry (Vargas et al., 2006; LIST., Paluchewiczz, 2007; Holter and Malinowska, 2005), (3) glass-ceramic industry (LIST., Paluchewiczz, 2007; Kavouras et al., 2007) and (4) additive to asphalt cement ˇ (STUrM et al., 2009). An estimation study of the environmental impacts of cement and asphalt with EAFD was conducted and showed that EAFD can be safely used as a component in asphalt and cement mixtures. This study will focus on using the technology of solidification/stabilization to prevent migration and exposure of contaminants from the EAFD by mixing a binding agent with the hazardous EAFD waste. These binders could be organic binders that include asphalt, organophilic clay, oractivated carbon; and inorganic binders that may include cement, fly ash, lime, phosphate, soluble silicates, or sulfur. This study will focus on using asphalt as ˇ the binding agent (Selih et al., 2004). Many researchers indicated that it is possible to use additives to improve the performance of asphalt cement mixtures. There are a number of asphalt additives (or modifier) in the market. Terrel and Epps (1998) classified modifiers which can be used in bituminous mixtures. The generic classification of asphalt
M.A.T. Alsheyab, T.S. Khedaywi / Resources, Conservation and Recycling 70 (2013) 38–43
39
Table 1 Properties of asphalt.
Fig. 1. Formation of EAFD from the steelmaking process (Guézennec et al., 2005).
modifiers are crushed fines, lime, portland cement, fly ash, carbon black, sulfur, lignin, natural rubber, styrene-butadiene (SB), styrene–butadiene–styrene (SBS), recycled tires, polyethylene, polypropylene, ethyl-vinyl-acetate (EVA), polyvinyl chloride (PVC), rock wool, polyester, fiberglass, manganese salts, lead compounds carbon, calcium salts, recycling and rejuvenating oils, hardening and natural asphalt, amines, and lime. Carbon black was used as mineral filler in a study by Rostter et al. (1977). They concluded that due to the fineness of the carbon black, it became part of the asphalt when completely dispersed in the asphalt. This increases the viscosity of the asphalt unless fluxing oil is used, which also aids in dispersion of the carbon black throughout the asphalt. Goetzce and Monismith (1978) reported on analytical study of the applicability of asphalt rubber for reducing reflecting cracking. Asphalt–rubber interlayer was found to reduce predicted crack tip stresses which should result in reducing reflective cracking of over layer. Khedaywi et al. (1987) have studied the effect of limestone dust on the properties of asphalt cement and shown that limestone dust caused a decrease in the penetration and the ductility values with the increase in dust concentration in the binder. The softening point and the specific gravity were increasing with the increase of limestone dust concentration in the binder. Khedaywi and Abu-Orabi (1989) have studied the effect of oil shale ash, rubber ash, husk ash, and polyethelene on properties of asphalt cement. They concluded that penetration and ductility of the binder are inversely proportional with the increased amount of these additives in the binders. Also the softening point of these binders is directly proportional with the added amount of additives in the binder. Specific gravity of the binder is directly proportional with the added amount of ashes and inversely proportional with the added amount of polyethylene in the binder. Khedaywi et al. (1993) have investigated the effect of rubber on properties of asphalt concrete mixtures. Results indicated that asphalt–rubber concrete mixtures have lower stability and higher flow than do asphalt concrete mixtures without rubber. Al- Massaeid et al. (1994) have evaluated the effect of olive husk on properties of bituminous concrete. They concluded that the olive husk material improved workability and stability and reduced the optimum binder content of bituminous mixes. Khedaywi et al. (1996) conducted a study on the effect of phosphate slimes on properties and performance of asphalt–cement and asphalt concrete mixtures. The results showed that the increase of phosphate slime showed an increase then a decrease in Marshall
Property
Value
ASTM method
Penetration (0.1 mm) 25 ◦ C, 100 g, 5 s Ductility (cm) at 25 ◦ C Specific gravity at 25 ◦ C Softening point (◦ C) Flash point (◦ C) Fire point (◦ C) Rotational viscosity (Mpa s)
67 110 1.01 50.3 312.5 318 330
D5 D 113 D 70 D 36 D 92 D 92 D 4402
Stability, air voids increased, and no improvements in the moisture susceptibility of asphalt concrete mixtures. In his study, utilization of the indirect tensile test to evaluate the effectiveness of additives on moisture sensitivity of asphalt concrete mixtures, Khedaywi (1992) concluded that 1.0% lime slurry additive was the best additive to use with asphalt–crushed limestone concrete mix and 2.0% lime slurry additive was the best additive to use with asphalt–valley gravel concrete mixture. 2. Objectives The main objectives of this research are as follows: • To investigate the feasibility of using the EAFD as an additive to asphalt cement. • To analyze the effect of this EAFD on the properties of asphalt cement. • To check the applicability of the EAFD–asphalt mixture for road construction; surface treatments for roads, airfields and other trafficked areas. 3. Material used 3.1. Asphalt cement One penetration of asphalt cement 60–70 grade of asphalt cement was used in this study. Asphalt was provided by Jordan Petroleum Refinary Company in Zarqa/Jordan, and it is widely used in flexible pavement construction. The physical properties of this asphalt cement are shown in Table 1. 3.2. Electric arc furnace dust (EAFD) EAFD was provided by United Iron and Steel Manufacturing Company in Jordan and it was characterized at the laboratories of the Royal Scientific Society in Jordan. The results of analysis are summarized in Table 2, where it shows that the major components are ferric oxide (Fe2 O3 = 32%) and zinc oxide (ZnO = 29%). All Table 2 EAFD characterization. Compound
Percentage
Fe2 O3 ZnO Al2 O3 Cu2 O SiO2 Loss on ignition @ 1000 ◦ C CaSO4 CaCl2 CaO NaCl K2 O MgO Others
32 29 1.28 0.7 4 11.63 3.43 1.91 1.4 5.79 2.7 4.66 1.5
40
M.A.T. Alsheyab, T.S. Khedaywi / Resources, Conservation and Recycling 70 (2013) 38–43
Fig. 2. Penetration test experiment.
samples of electric arc furnace dust used in this research were passing no. 200 sieve.
4. Laboratory work 4.1. Preparation of EAFD–asphalt binder It has been decided to study different volume percentages of EAFD–Asphalt binder, the studied percentages are: 0, 5, 10, 15 and 20% of EAFD by volume of binder. It has been realized that percentages of EAFD more than 20% were difficult to mix with asphalt. For each experiment, the corresponding weight to each volume percentage for both the asphalt and EAFD was prepared. The asphalt was heated while adding the corresponding volume of EAFD with mixing to guarantee a homogeneous mixture for each experiment. Mixtures were left to cool down to ambient temperature to be ready for testing.
4.2. Penetration test (ASTM D 5) The penetration test is an empirical measure of asphalt consistency. The test consists of allowing a prescribed needle, weighted to 100 g to bear on the surface of the asphalt cement, at 25 ◦ C, for 5 s, as shown in Fig. 2. The distance, in units of 0.1 mm, penetrated by the needle into the EAFD–asphalt mixture is taken as the measurement. The penetration characteristic practically measures the softness of asphalt and therefore, binders with high penetration numbers (called “soft”) are used for cold climates while asphalt binders with low penetration numbers (called “hard”) are used for warm climates.
4.3. Ductility test (ASTM D 113) It is a measurement of asphalt binder stickiness by stretching a standard-sized briquette of asphalt binder to its breaking point, conducted at only one temperature (25 ◦ C). More important than the stretched distance is its presence or absence. Binders with high degree of ductility are more affected by temperature.
4.4. Specific gravity (ASTM D 70) Because the specific gravity of asphalt binders changes with temperature, specific gravity tests are useful in making volume corrections based on temperature. The specific gravity at 15.6 ◦ C is commonly used when buying/selling asphalt cements. A typical specific gravity for asphalt is around 1.03.
Fig. 3. Softening point experiment.
4.5. Softening point (ASTM D 36) The softening point is defined as the temperature at which a bitumen sample can no longer support the weight of a 3.5-g steel ball. Fig. 3 illustrates the softening point experiment. 4.6. Flash and fire points (ASTM D 92) Performed on the original binder, the flash point of binder is measured to ensure the binder is safe to work with at production temperatures. Flash point is the temperature to which a binder may be safely heated without instantaneous flash in the presence of an open flame. 4.7. Rotational viscosity test (ASTM D 4402) A rotational viscometer is used to evaluate the high temperature workability of binder. This ensures that the binder is sufficiently fluid when pumping and mixing. In addition, the viscosity measured is used to establish the temperature–viscosity plot for a binder type. 5. Test results, analysis and discussion Six parameters were analyzed in this research in order to investigate the effect of EAFD on the properties of asphalt and its applicability for road construction. These parameters are specific gravity; softening point; ductility; flash and fire points; penetration and rotational viscosity. Four volumes of EAFD (5%, 10%, 15% and 20%) were investigated, taking the 0% as the baseline for comparison. The results (Illustrated in Fig. 4) as expected showed that the specific gravity was increasing with the increase of EAFD percentage, the highest specific gravity was 1.348 at 20% EAFD. If compared with the baseline (0%), the increase of specific gravity was 11%, 22%, 27% and 33% at 5%, 10%, 15% and 20% of EAFD, respectively. The equation y = −0.0004x2 + 0.0254x + 1.0096 is best representative for
M.A.T. Alsheyab, T.S. Khedaywi / Resources, Conservation and Recycling 70 (2013) 38–43 1.6
400 Flash Point Fire Point Poly. (Flash Point) Poly. (Fire Point)
1.4 1.2
380
1
Temperature (°C)
Specefic Gravity
41
0.8 0.6 0.4 0.2
360
340
0 0
5
10
15
20
320
% EAFD by volume of binder Fig. 4. Effect of EAFD on specific gravity.
300 0
5
58
10
15
20
% EAFD volume by binder
Softening Point ( ° C)
57
Fig. 7. Effect of EAFD on flash and fire points.
56 55 54 53 52 51 50 49 0
5
10
15
20
% EAFD by volume of binder Fig. 5. Effect of EAFD on softening point.
the obtained results with correlation factor of R2 = 0.997, where y represents the specific gravity and x represents the %volume of EAFD in the binder. The softening point was also increasing with the increase of EAFD as shown in Fig. 5. Results were best represented by the equation y = 0.0071x2 + 0.1831x + 50.157 with correlation factor R2 = 0.94 where y refers to softening point and x to the volume of EAFD. The third investigated parameter was the ductility whose results are illustrated in Fig. 6. It has been realized that ductility was decreasing with the increase of EAFD%; the decreasing equation can be represented by y = 0.3757x2 − 11.524x + 104.09 with correlation factor of R2 = 0.94, where y represents the ductility and x the volume of EAFD. The ductility has been reduced in comparison with 0% baseline 61%, 73%, 78% and 83%, respectively.
The other parameter that was investigated was the flash and fire points, shown in Fig. 7. It has been realized that both parameters were increasing with the volume increase of EAFD. The flash point results can be represented by the equation y = 0.1971x2 − 0.9229x + 312.16 with correlation factor R2 = 0.96 and the fire point can be represented by y = 0.1971x2 − 0.9629x + 317.46 with R2 = 0.95. In both equations x represents the volume of EAFD and y represents the flash and the fire points, respectively Penetration was the other investigated parameter. Results are shown in Fig. 8 where it shows that penetration values were reducing with the increase of EAFD volume in the mixture. The following exponential equation y = 65.97e−0.0286x was the best representative for the relation between penetration and the volume of dust. The last parameter investigated in this study was the rotational viscosity. The rotational viscosity was increasing with the increase of EAFD volume in the mixture as shown in Fig. 9. The results can be represented in the equation y = 0.7629x2 + 18.403x + 371.14 with correlation factor R2 = 0.945, where y represents the rotational viscosity and x represents the volume of EAFD in the mixture. The increasing factors were 1.7, 1.9, 2.2 and 3.3 times of the rotational viscosity of asphalt at 0% volume of EAFD, respectively. The penetration index (PI) is a measure of the way the binder’s consistency (penetration value) changes with temperature. The obtained results were compared with the typical values for specific use shown in Table 3.
120
Penetration(0.1mm) 25 °C, 100g, 5s
70
Ductility (cm) , 25 °C
100 80 60 40 20
65 60 55 50 45 40 35 30
0 0
5
10
% EAFD by volume of binder Fig. 6. Effect of EAFD on ductility.
15
20
0
5
10
% EAFD by volume of binder Fig. 8. Effect of EAFD on penetration.
15
20
Rotational Viscosity (MPa.s)
42
M.A.T. Alsheyab, T.S. Khedaywi / Resources, Conservation and Recycling 70 (2013) 38–43
1200
6. Conclusions
1000
1. The addition of EAFD to asphalt cement produced appropriate mixture with asphalt properties suitable for road construction. This was proved by the values of Penetration Index for all studied samples, which was between −2 and +2 for all of them, according to ASTM D946/D946M – 09a. 2. From the environmental point of view, the stabilization/solidification of EAFD by mixing it with asphalt would be an excellent option to get rid of this hazardous material to be used in road construction. 3. The EAFD–asphalt binder would be more suitable for cold weathers as the penetration was increasing with the increase of % EAFD by volume of binder. 4. The studied mixtures showed that the produced binders are safer than the asphalt alone as the flash and fire points got increased with the increase of %EAFD. 5. According to the obtained results of penetration at 15% and 20%, the mixtures would be suitable for crack filling of flexible and rigid pavement as well as for roofing. 6. Due to the suitability of using EAFD with asphalt binder and the fact that it is safe from the environmental point of view, it is recommended to conduct a study on the real application of the asphalt mixture with EAFD in road construction. 7. Results showed that there is a potential of saving asphalt cement amounts equivalent to the added amounts of EAFD which will be otherwise landfilled, this means that there would be a considerable savings of money depending on the asphalt prices as well as the EAFD addition cost and a reduction of the volume of EAFD to be disposed of.
800 600 400 200 0 0
5
10
15
20
% EAFD by volume of binder Fig. 9. Effect of EAFD on rotational viscosity.
Table 3 Penetration Index for different bitumen types. Bitumen type
PI
Blown bitumen Conventional paving bitumen Temperature susceptible bitumen
>2 −2 to +2 <−2
The PI can be determined by connecting the penetration value with the softening point for each studied volume of EAFD in the binder mixture, as shown in Fig. 10. The obtained values for PI lie between −2 and +2 and all around 0. This means that the EAFD–asphalt binder mixtures are normal and suitable for road construction (Hobson and Pohl, 1975).
Acknowledgments Authors are grateful to Abdulhameed Shoman Fund for Supporting Scientific Research for funding this project and United Iron and Steel Manufacturing Company in Jordan, in particular to Eng. Mohammad Shawabkeh for their cooperation and providing the research project with the necessary samples of EAFD.
References
Fig. 10. Penetration Index value for studied binders.
Al-Massaeid H, Hamed M, Khedaywi T. Empirical evaluation of olive husk in asphalt cement binder and bituminous concrete. Transportation Research Record 1436, TRB, National Research Council, Washington, DC; 1994. p. 124–132. ASTM D946/D946M – 09a. Standard Specification for Penetration-Graded Asphalt Cement for Use in Pavement Construction. Cubukcuoglu B, Ouki SK. The use of alternative constituents in cement-based solidification/stabilization of electric arc furnace dust. In: Proceedings of the 7th international conference on sustainable management of waste and recycled materials in construction, WASCON; 2009. Goetzce NV, Monismith CL. An analytical study of the applicability of rubber pavements. Berkeley: Deportment of Civil Engineering, University of California; 1978. Guézennec A-G, Huber J-C, Patisson F, Sessiecq P, Birat J-P, Ablitzer D. Dust formation in electric arc furnace: birth of the particles. Powder Technology 2005;157(1–3):2–11. Hobson GD, Pohl W. Modern petroleum technology. 4th ed. Britain: Applied Science Publ.; 1975. Holter M, Malinowska A. The reduction of harmfulness of heavy metals from electric arc furnace dust. Hutnik-Wiadomosci hutnicze 2005:7–8 [in Polish]. Jay N, Meegoda AS, Ezeldin, Hsai-Yang F, Hilary I. Waste immobilization technologies. Practice Periodical of Hazardous, Toxic and Radioactive Waste Management 2003;7(46)., http://dx.doi.org/10.1061/(ASCE)1090-025X(2003)7:1(46) [13 pages]. Kavouras P, Kehagias T, Tsilika I, Kaimakamis G, Chrissafis K, Kokkou S, et al. Glassceramic materials from electric arc furnace dust. Journal of Hazardous materials 2007;A139. Khedaywi T. Utilization of the indirect tensile test to evaluate the effectiveness of additives on moisture sensitivity of asphalt concrete mixtures. Indian Highway, India; August 1992. p. 31–37. Khedaywi T, Abu-Eisha S, Taqieddin S. Effect of phosphate slimes on properties and performance of asphalt cement and asphalt concrete mixes. Dirasat, Natural and Engineering Sciences 1996;23(2):170–9.
M.A.T. Alsheyab, T.S. Khedaywi / Resources, Conservation and Recycling 70 (2013) 38–43 Khedaywi T, Tamimi A, Al-Masaeid H, Khamaiseh K. Laboratory investigation of properties of asphalt rubber concrete mixtures. Transportation Research Record 1417, TRB, National Research Council, Washington, DC; January 1993. p. 93–98. Khedaywi T, Abu-Orabi S. Effect of oil shale ash, rubber ash, husk ash, and polyethylene on properties of asphalt cement. Journal of Petroleum Research, Scientific Research Council 1989;8(2):193–206. Khedaywi T, Abu-Orabi S, Al-Rashdan Z. Effect of limestone dust collector fines on properties of asphalt cement. Journal of Petroleum Research, Scientific Research Council 1987;6(2):53–62. LIS T., Paluchewicz Z. The utilization of steel-making dusts in the glass-making industry. Hutnik-Wiadomosci hunticze 2007;5 [in Polish]. MacRay DR. Electric arc furnace dust disposal recycle and recovery. Pittsburgh, PA: Center for Metals Production; 1985, CMP Report, 85-2. Néstor GG, Borja GEV. The situation of EAF dust in Europe and the upgrading of the Waelz process. Waste Treatment and Clean Technology 2003;99(2):1511–20, ISSN: 0210-5621. Pavao B, De Vargas AS, Masuero AB, Dal Molin DC, Vilela AC. Influence of electric arc furnace dust (EAFD) in alkali-activated fly ash binder. In: Proceedings of the
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11th international conference on non-conventional materials and technologies (NOCMAT’09); 2009. Rostter F, White R, Dannenberg E. Carbon Black as a Reinforcing Agent for Asphalt, vol. 46. USA: AAPT; 1977. p. 326. ˇ Pavˇsiˇc P, Makaroviˇc M, et al. The use ˇ J, Ducman V, Mladenoviˇc A, Sever SA, Selih of waste materials in building and civil engineering. Materials Technology Ljubljana 2004;38(1–2):79–86 [in Slovenian]. ˇ Novosel-Radoviˇc V, Jenko M. CharSofilic´ T, Rastovˇcan-Mioˇc A, Cerjan-Stefanovic´ S, acterization of steel mill electric arc furnace dust. Journal of Hazardous Materials 2004;B109:59–70, ISSN: 0304-3894. ˇ STUrM, Milaˇciˇc r. MUrko S. vaHˇciˇc T, Mladenoviˇc a. STrUPi-ˇsUPUT M, j. sˇ cˇ anˇcar j. The use of EAF dust in cement composites: assessment of environmental impact. Journal of Hazardous Materials 2009;166:277–83. Terrel RL, Epps JA. Using additives and modifiers in hot mix asphalt. National Asphalt Pavement Association Quality Improvement Series 1998;114. Vargas AS, Masuero AB, Vileia ACF. Investigations on the use of electric-are furnace dust (EAFD) in Pozzolan-modified Portland cement 1 (MP) pastes. Cement and Concrete Research 2006;36.
Contents lists available at SciVerse ScienceDirect
Resources, Conservation and Recycling journal homepage: www.elsevier.com/locate/resconrec
Effect of electric arc furnace dust (EAFD) on properties of asphalt cement mixture Mohammad A.T. Alsheyab a,∗ , Taisir S. Khedaywi b,1 a International Research Center for Water, Environment and Energy (Salt) and the Department of Water and Environmental Engineering (Al-Huson College), Al-Balqa’ Applied University, Jordan b Department of Civil Engineering, Philadelphia University (On Sabbatical Leave from JUST), Jordan
a r t i c l e
i n f o
Article history: Received 8 March 2012 Received in revised form 7 October 2012 Accepted 23 October 2012 Keywords: Electric arc furnace EAFD Asphalt cement Solidification/stabilization Penetration index Road construction
a b s t r a c t Electric arc furnace dust (EAFD) is one of the by-products of steelmaking industry which has been classified as hazardous due to containing some heavy metals such as Zinc, Cobalt, Copper, Lead or Cadmium. This research aims at solving the problem of this hazardous waste by solidification/stabilization through mixing it with asphalt cement to be used for road construction. EAFD was used as an additive to the asphalt concrete mixtures with five percentages (0%, 5%, 10%, 15% and 20%) by volume of binder. Penetration, ductility, specific gravity, softening point, flash point, fire point and rotational viscosity were analyzed. It was found that while the penetration and ductility were decreasing with the increase of EAFD concentration in the binder, specific gravity, softening point, flash point, fire point and rotational viscosity were increasing. Finally it has been concluded that the results are promising for dual achievement (1) to solve an environmental problem and (2) to use the EAFD for road construction. © 2012 Elsevier B.V. All rights reserved.
1. Introduction The use of Electric Arc Furnace technology in the steelmaking industry has been increasing considerably over the last four decades, it increased from being 14% in 1970 to 34% in 1998 of the total technologies used for steel production (Sofilic´ et al., 2004). As a result of this increase, it has been reported that many pollutants are released to atmosphere during the steelmaking process when using this technology such as dust, carbon and nitrogen oxides and organic compounds where the amount of dust generated per ton of steel product is estimated to be 15–20 kg. The world generated electric arc furnace dust (EAFD) per year is estimated to be around 3.7 million tons (Néstor and Borja, 2003). This dust is classified by the European Waste Catalogue and the Environmental Protection Agency as a hazardous waste, not disposable in the environment, because it contains hazardous, leachable elements such as zinc, lead or cadmium (Guézennec et al., 2005; Cubukcuoglu and Ouki, 2009; Pavao et al., 2009). Fig. 1 shows formation of EAFD from the steelmaking process. It has been also reported that the recycling of these hazardous metals is still expensive and therefore alternatives should be analyzed and investigated; one of these alternatives is the waste
∗ Corresponding author. Tel.: +962 777584811. E-mail addresses: [email protected] (M.A.T. Alsheyab), [email protected] (T.S. Khedaywi). 1 Tel.: +962 2795588657; fax: +962 27201074. 0921-3449/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.resconrec.2012.10.003
immobilization techniques to prevent the free movement of these hazardous elements in the solid waste. There are three major types of immobilizing techniques: (1) the temporary containment technique, (2) cost effective solidification/stabilization techniques and (3) permanent techniques (Pavao et al., 2009; Jay et al., 2003). It has been reported that EAFD is treated in different ways, such as: (1) recovery of valuable metals (iron, zinc and lead) before land disposal (MacRay, 1985), (2) additive to cement/concrete industry (Vargas et al., 2006; LIST., Paluchewiczz, 2007; Holter and Malinowska, 2005), (3) glass-ceramic industry (LIST., Paluchewiczz, 2007; Kavouras et al., 2007) and (4) additive to asphalt cement ˇ (STUrM et al., 2009). An estimation study of the environmental impacts of cement and asphalt with EAFD was conducted and showed that EAFD can be safely used as a component in asphalt and cement mixtures. This study will focus on using the technology of solidification/stabilization to prevent migration and exposure of contaminants from the EAFD by mixing a binding agent with the hazardous EAFD waste. These binders could be organic binders that include asphalt, organophilic clay, oractivated carbon; and inorganic binders that may include cement, fly ash, lime, phosphate, soluble silicates, or sulfur. This study will focus on using asphalt as ˇ the binding agent (Selih et al., 2004). Many researchers indicated that it is possible to use additives to improve the performance of asphalt cement mixtures. There are a number of asphalt additives (or modifier) in the market. Terrel and Epps (1998) classified modifiers which can be used in bituminous mixtures. The generic classification of asphalt
M.A.T. Alsheyab, T.S. Khedaywi / Resources, Conservation and Recycling 70 (2013) 38–43
39
Table 1 Properties of asphalt.
Fig. 1. Formation of EAFD from the steelmaking process (Guézennec et al., 2005).
modifiers are crushed fines, lime, portland cement, fly ash, carbon black, sulfur, lignin, natural rubber, styrene-butadiene (SB), styrene–butadiene–styrene (SBS), recycled tires, polyethylene, polypropylene, ethyl-vinyl-acetate (EVA), polyvinyl chloride (PVC), rock wool, polyester, fiberglass, manganese salts, lead compounds carbon, calcium salts, recycling and rejuvenating oils, hardening and natural asphalt, amines, and lime. Carbon black was used as mineral filler in a study by Rostter et al. (1977). They concluded that due to the fineness of the carbon black, it became part of the asphalt when completely dispersed in the asphalt. This increases the viscosity of the asphalt unless fluxing oil is used, which also aids in dispersion of the carbon black throughout the asphalt. Goetzce and Monismith (1978) reported on analytical study of the applicability of asphalt rubber for reducing reflecting cracking. Asphalt–rubber interlayer was found to reduce predicted crack tip stresses which should result in reducing reflective cracking of over layer. Khedaywi et al. (1987) have studied the effect of limestone dust on the properties of asphalt cement and shown that limestone dust caused a decrease in the penetration and the ductility values with the increase in dust concentration in the binder. The softening point and the specific gravity were increasing with the increase of limestone dust concentration in the binder. Khedaywi and Abu-Orabi (1989) have studied the effect of oil shale ash, rubber ash, husk ash, and polyethelene on properties of asphalt cement. They concluded that penetration and ductility of the binder are inversely proportional with the increased amount of these additives in the binders. Also the softening point of these binders is directly proportional with the added amount of additives in the binder. Specific gravity of the binder is directly proportional with the added amount of ashes and inversely proportional with the added amount of polyethylene in the binder. Khedaywi et al. (1993) have investigated the effect of rubber on properties of asphalt concrete mixtures. Results indicated that asphalt–rubber concrete mixtures have lower stability and higher flow than do asphalt concrete mixtures without rubber. Al- Massaeid et al. (1994) have evaluated the effect of olive husk on properties of bituminous concrete. They concluded that the olive husk material improved workability and stability and reduced the optimum binder content of bituminous mixes. Khedaywi et al. (1996) conducted a study on the effect of phosphate slimes on properties and performance of asphalt–cement and asphalt concrete mixtures. The results showed that the increase of phosphate slime showed an increase then a decrease in Marshall
Property
Value
ASTM method
Penetration (0.1 mm) 25 ◦ C, 100 g, 5 s Ductility (cm) at 25 ◦ C Specific gravity at 25 ◦ C Softening point (◦ C) Flash point (◦ C) Fire point (◦ C) Rotational viscosity (Mpa s)
67 110 1.01 50.3 312.5 318 330
D5 D 113 D 70 D 36 D 92 D 92 D 4402
Stability, air voids increased, and no improvements in the moisture susceptibility of asphalt concrete mixtures. In his study, utilization of the indirect tensile test to evaluate the effectiveness of additives on moisture sensitivity of asphalt concrete mixtures, Khedaywi (1992) concluded that 1.0% lime slurry additive was the best additive to use with asphalt–crushed limestone concrete mix and 2.0% lime slurry additive was the best additive to use with asphalt–valley gravel concrete mixture. 2. Objectives The main objectives of this research are as follows: • To investigate the feasibility of using the EAFD as an additive to asphalt cement. • To analyze the effect of this EAFD on the properties of asphalt cement. • To check the applicability of the EAFD–asphalt mixture for road construction; surface treatments for roads, airfields and other trafficked areas. 3. Material used 3.1. Asphalt cement One penetration of asphalt cement 60–70 grade of asphalt cement was used in this study. Asphalt was provided by Jordan Petroleum Refinary Company in Zarqa/Jordan, and it is widely used in flexible pavement construction. The physical properties of this asphalt cement are shown in Table 1. 3.2. Electric arc furnace dust (EAFD) EAFD was provided by United Iron and Steel Manufacturing Company in Jordan and it was characterized at the laboratories of the Royal Scientific Society in Jordan. The results of analysis are summarized in Table 2, where it shows that the major components are ferric oxide (Fe2 O3 = 32%) and zinc oxide (ZnO = 29%). All Table 2 EAFD characterization. Compound
Percentage
Fe2 O3 ZnO Al2 O3 Cu2 O SiO2 Loss on ignition @ 1000 ◦ C CaSO4 CaCl2 CaO NaCl K2 O MgO Others
32 29 1.28 0.7 4 11.63 3.43 1.91 1.4 5.79 2.7 4.66 1.5
40
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Fig. 2. Penetration test experiment.
samples of electric arc furnace dust used in this research were passing no. 200 sieve.
4. Laboratory work 4.1. Preparation of EAFD–asphalt binder It has been decided to study different volume percentages of EAFD–Asphalt binder, the studied percentages are: 0, 5, 10, 15 and 20% of EAFD by volume of binder. It has been realized that percentages of EAFD more than 20% were difficult to mix with asphalt. For each experiment, the corresponding weight to each volume percentage for both the asphalt and EAFD was prepared. The asphalt was heated while adding the corresponding volume of EAFD with mixing to guarantee a homogeneous mixture for each experiment. Mixtures were left to cool down to ambient temperature to be ready for testing.
4.2. Penetration test (ASTM D 5) The penetration test is an empirical measure of asphalt consistency. The test consists of allowing a prescribed needle, weighted to 100 g to bear on the surface of the asphalt cement, at 25 ◦ C, for 5 s, as shown in Fig. 2. The distance, in units of 0.1 mm, penetrated by the needle into the EAFD–asphalt mixture is taken as the measurement. The penetration characteristic practically measures the softness of asphalt and therefore, binders with high penetration numbers (called “soft”) are used for cold climates while asphalt binders with low penetration numbers (called “hard”) are used for warm climates.
4.3. Ductility test (ASTM D 113) It is a measurement of asphalt binder stickiness by stretching a standard-sized briquette of asphalt binder to its breaking point, conducted at only one temperature (25 ◦ C). More important than the stretched distance is its presence or absence. Binders with high degree of ductility are more affected by temperature.
4.4. Specific gravity (ASTM D 70) Because the specific gravity of asphalt binders changes with temperature, specific gravity tests are useful in making volume corrections based on temperature. The specific gravity at 15.6 ◦ C is commonly used when buying/selling asphalt cements. A typical specific gravity for asphalt is around 1.03.
Fig. 3. Softening point experiment.
4.5. Softening point (ASTM D 36) The softening point is defined as the temperature at which a bitumen sample can no longer support the weight of a 3.5-g steel ball. Fig. 3 illustrates the softening point experiment. 4.6. Flash and fire points (ASTM D 92) Performed on the original binder, the flash point of binder is measured to ensure the binder is safe to work with at production temperatures. Flash point is the temperature to which a binder may be safely heated without instantaneous flash in the presence of an open flame. 4.7. Rotational viscosity test (ASTM D 4402) A rotational viscometer is used to evaluate the high temperature workability of binder. This ensures that the binder is sufficiently fluid when pumping and mixing. In addition, the viscosity measured is used to establish the temperature–viscosity plot for a binder type. 5. Test results, analysis and discussion Six parameters were analyzed in this research in order to investigate the effect of EAFD on the properties of asphalt and its applicability for road construction. These parameters are specific gravity; softening point; ductility; flash and fire points; penetration and rotational viscosity. Four volumes of EAFD (5%, 10%, 15% and 20%) were investigated, taking the 0% as the baseline for comparison. The results (Illustrated in Fig. 4) as expected showed that the specific gravity was increasing with the increase of EAFD percentage, the highest specific gravity was 1.348 at 20% EAFD. If compared with the baseline (0%), the increase of specific gravity was 11%, 22%, 27% and 33% at 5%, 10%, 15% and 20% of EAFD, respectively. The equation y = −0.0004x2 + 0.0254x + 1.0096 is best representative for
M.A.T. Alsheyab, T.S. Khedaywi / Resources, Conservation and Recycling 70 (2013) 38–43 1.6
400 Flash Point Fire Point Poly. (Flash Point) Poly. (Fire Point)
1.4 1.2
380
1
Temperature (°C)
Specefic Gravity
41
0.8 0.6 0.4 0.2
360
340
0 0
5
10
15
20
320
% EAFD by volume of binder Fig. 4. Effect of EAFD on specific gravity.
300 0
5
58
10
15
20
% EAFD volume by binder
Softening Point ( ° C)
57
Fig. 7. Effect of EAFD on flash and fire points.
56 55 54 53 52 51 50 49 0
5
10
15
20
% EAFD by volume of binder Fig. 5. Effect of EAFD on softening point.
the obtained results with correlation factor of R2 = 0.997, where y represents the specific gravity and x represents the %volume of EAFD in the binder. The softening point was also increasing with the increase of EAFD as shown in Fig. 5. Results were best represented by the equation y = 0.0071x2 + 0.1831x + 50.157 with correlation factor R2 = 0.94 where y refers to softening point and x to the volume of EAFD. The third investigated parameter was the ductility whose results are illustrated in Fig. 6. It has been realized that ductility was decreasing with the increase of EAFD%; the decreasing equation can be represented by y = 0.3757x2 − 11.524x + 104.09 with correlation factor of R2 = 0.94, where y represents the ductility and x the volume of EAFD. The ductility has been reduced in comparison with 0% baseline 61%, 73%, 78% and 83%, respectively.
The other parameter that was investigated was the flash and fire points, shown in Fig. 7. It has been realized that both parameters were increasing with the volume increase of EAFD. The flash point results can be represented by the equation y = 0.1971x2 − 0.9229x + 312.16 with correlation factor R2 = 0.96 and the fire point can be represented by y = 0.1971x2 − 0.9629x + 317.46 with R2 = 0.95. In both equations x represents the volume of EAFD and y represents the flash and the fire points, respectively Penetration was the other investigated parameter. Results are shown in Fig. 8 where it shows that penetration values were reducing with the increase of EAFD volume in the mixture. The following exponential equation y = 65.97e−0.0286x was the best representative for the relation between penetration and the volume of dust. The last parameter investigated in this study was the rotational viscosity. The rotational viscosity was increasing with the increase of EAFD volume in the mixture as shown in Fig. 9. The results can be represented in the equation y = 0.7629x2 + 18.403x + 371.14 with correlation factor R2 = 0.945, where y represents the rotational viscosity and x represents the volume of EAFD in the mixture. The increasing factors were 1.7, 1.9, 2.2 and 3.3 times of the rotational viscosity of asphalt at 0% volume of EAFD, respectively. The penetration index (PI) is a measure of the way the binder’s consistency (penetration value) changes with temperature. The obtained results were compared with the typical values for specific use shown in Table 3.
120
Penetration(0.1mm) 25 °C, 100g, 5s
70
Ductility (cm) , 25 °C
100 80 60 40 20
65 60 55 50 45 40 35 30
0 0
5
10
% EAFD by volume of binder Fig. 6. Effect of EAFD on ductility.
15
20
0
5
10
% EAFD by volume of binder Fig. 8. Effect of EAFD on penetration.
15
20
Rotational Viscosity (MPa.s)
42
M.A.T. Alsheyab, T.S. Khedaywi / Resources, Conservation and Recycling 70 (2013) 38–43
1200
6. Conclusions
1000
1. The addition of EAFD to asphalt cement produced appropriate mixture with asphalt properties suitable for road construction. This was proved by the values of Penetration Index for all studied samples, which was between −2 and +2 for all of them, according to ASTM D946/D946M – 09a. 2. From the environmental point of view, the stabilization/solidification of EAFD by mixing it with asphalt would be an excellent option to get rid of this hazardous material to be used in road construction. 3. The EAFD–asphalt binder would be more suitable for cold weathers as the penetration was increasing with the increase of % EAFD by volume of binder. 4. The studied mixtures showed that the produced binders are safer than the asphalt alone as the flash and fire points got increased with the increase of %EAFD. 5. According to the obtained results of penetration at 15% and 20%, the mixtures would be suitable for crack filling of flexible and rigid pavement as well as for roofing. 6. Due to the suitability of using EAFD with asphalt binder and the fact that it is safe from the environmental point of view, it is recommended to conduct a study on the real application of the asphalt mixture with EAFD in road construction. 7. Results showed that there is a potential of saving asphalt cement amounts equivalent to the added amounts of EAFD which will be otherwise landfilled, this means that there would be a considerable savings of money depending on the asphalt prices as well as the EAFD addition cost and a reduction of the volume of EAFD to be disposed of.
800 600 400 200 0 0
5
10
15
20
% EAFD by volume of binder Fig. 9. Effect of EAFD on rotational viscosity.
Table 3 Penetration Index for different bitumen types. Bitumen type
PI
Blown bitumen Conventional paving bitumen Temperature susceptible bitumen
>2 −2 to +2 <−2
The PI can be determined by connecting the penetration value with the softening point for each studied volume of EAFD in the binder mixture, as shown in Fig. 10. The obtained values for PI lie between −2 and +2 and all around 0. This means that the EAFD–asphalt binder mixtures are normal and suitable for road construction (Hobson and Pohl, 1975).
Acknowledgments Authors are grateful to Abdulhameed Shoman Fund for Supporting Scientific Research for funding this project and United Iron and Steel Manufacturing Company in Jordan, in particular to Eng. Mohammad Shawabkeh for their cooperation and providing the research project with the necessary samples of EAFD.
References
Fig. 10. Penetration Index value for studied binders.
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