DIGEST 2006 - Sabita

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undertaken on a trial section consisting of a 13,2mm single seal, with steel slag as an aggregate on the south bound lane and shoulder, and dolerite as an aggregate on the north bound lane and shoulder. The results are presented in Table 4. The results indicate that the steel slag aggregate provides a more skid resistant surface than the corresponding dolerite aggregate. Environmental considerations Today we have an obligation to consider the impact of our actions on the environment, especially with regard to preservation and sustainability. By using steel slag as an aggregate, the environment is reaping a two-fold benefit. The most obvious environmental advantage is the preservation of precious natural resources, and Carriageway Steel slag (southbound) Dolerite (northbound) Lane/position Shoulder Outer wheel path Inner wheel path Shoulder Outer wheel path Inner wheel path Ave. grip no. 0.62 0.62 0.71 0.56 0.59 0.59 Std. dev. 0.0381 0.0355 0.0336 0.0171 0.0157 0.0164 Minimum 0.50 0.51 0.56 0.52 0.50 0.53 Maximum 0.77 0.75 0.79 0.62 0.62 0.62 90 th percentile 0.58 0.59 0.68 0.55 0.57 0.56 Table 4: Grip Tester Friction Measurements Performance As can be seen from the above testing, the steel slag asphalt mix complies with normal design criteria and indicates that this aggregate can be effectively used to improve the properties of an asphalt mix. Because site conditions may not always be emulated by laboratory testing, in-service assessment was carried out, and this has indicated that, to date, the performance of the mix on the road has been satisfactory, with no problem areas evident. another benefit is a reduced need to dispose of the material in landfill sites. There is however one negative perception associated with the use of steel slag aggregates, and this is the leaching of chemicals from the slag aggregate into the groundwater and resultant negative impacts on the environment. However, studies undertaken in Germany have shown that this leaching of chemical elements is insignificant in terms of environmental impact, and should not be considered an issue of concern in terms of environmental health and sustainability. 79
Conclusions From the results presented, it can be seen that steel slag produces a high quality aggregate, which can yield a number of benefits in terms of improved skid resistance, resistance to permanent deformation and durability. Road owners, road users and the environment benefit from the use of steel slag as an aggregate in the road construction industry. Steel slag aggregate is indeed a valuable commodity to the road construction industry, and should be considered as a viable alternative aggregate in the road construction industry. References 1. Asphalt Institute: Mix design methods for asphalt concrete and other hot mix types. MS-2. Sixth edition. 2. Asphalt Institute: Superpave mix design, Superpave series No. 2 (SP-2). Third edition 2001. United States of America. 3. Colarado Department of Transportation: Contract No. CMS 804-99. January 2001: Development of a new high performance asphalt mix for 1-70 through Greenwood Canyon. CTL/Thompson Inc. Colarado. 4. Committee of State Road Authorities. TRH8:1987. Selection and design of hot mix asphalt surfacings for highways. South Africa. 5. European conference on slags. Marseilles 25-27 March 1988. Proceedings: The steel slags, characteristics and properties. Dr Ing. H Motz. 6. Euroslag: Engineering of Slags, A Scientific and Technological Challenge. 2nd European Slag Conference. 9-11 October 2001 Dusseldorf. Proceedings: Progress in the utilisation of steel slags in the UK. G.H.Thomas: Thomas Research Services Ltd. United Kingdom. 7. Euroslag: Engineering of Slags, A Scientific and Technological Challenge. 2nd European Slag Conference. 9-11 October 2001 Dusseldorf. Proceedings: EAF Slag in Aspahlt. N.Jones – Steelphalt. United Kingdom. 8. Hot mix asphalt design Project. September 2001. Interim guidelines for the design of hot mix asphalt in South Africa. 9.http://www.tfhrc.gov/hnr20/recycle/ waste/ssa3.htm 10. http://www.tfhrc.gov/hnr20/recycle/ waste/ssa1.htm 11. Ohio Department of Transportation. November 1993. Report No. FHWA/OH-94/004. Precipitate potential of highway subbase aggregates. J.D.Gupta and W.A Kneller. 12. Oregon Department of Transportation. State Research Project #511. April 2000. Steel slag in hot mix asphalt concrete. Final report. L. Hunt and G.E. Boyle. 13. Steelmaking Slag Technical Committee. 1993. Steel Slag Aggregates Use in Hot Mix Asphalt Concrete. Final Report, prepared by John Emery Geotechnical Engineering Limited. USA. 14. Transportation Research Board. National Cooperative Highway Research Programme, Synthesis of Highway Practice 199. Recycling and use of waste materials and by-products in highway construction. R.J. Collins and S.K. Ciesielski, Washington DC 1994. 15. United States of America. National Cooperative Highway Research Program Synthesis of Highway Practice 199, Transportation Research Board. 1994. Recycling and Use of Waste Materials and By-Products in Highway Construction. Collins, R. J. and S. K. Ciesielski. Washington DC. 80
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DIGEST 2006
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Mission Sabita’s plans and action
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4. Innovation The use of steel slag
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1 Valediction
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economic growth. In addition to str
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one of the world leading trade orga
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Choosing road surfaces: Bitumen, gr
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we can economically test a possible
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oads. These considerations influenc
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double that for two-lane surfaced r
Page 21 and 22: elative fluctuation by increasing o
Page 24 and 25: Optimising resource utilisation: Ag
Page 26 and 27: COSHEC in 2007: Health and safety i
Page 28 and 29: designed to assist road authorities
Page 30 and 31: • Obtain endorsement and commitme
Page 32 and 33: • institution of Sabita safety tr
Page 34 and 35: Towards an informed industry: Updat
Page 36 and 37: versions of some of Sabita’s earl
Page 38 and 39: from texture treatments to overlays
Page 40 and 41: South Africa's education system: A
Page 42 and 43: environment and red tape on small a
Page 44 and 45: Figure 2. Matric result trends the
Page 46 and 47: professional work, within the conte
Page 48 and 49: Assessing Teachers are often unclea
Page 50 and 51: 3 HG learners in a class of 40 SG).
Page 52 and 53: The following observations may be m
Page 54: documented successful maths and sci
Page 57 and 58: public awareness programme to illus
Page 59 and 60: Surge in SAT's knowledge transfer a
Page 61 and 62: organisation. With the improvement
Page 63 and 64: accomplished through self-study. Th
Page 65 and 66: 4 Innovation
Page 67 and 68: calcium oxide is not fully hydrated
Page 69 and 70: oad construction. As mentioned prev
Page 71: M ix type Coars e continuous Coarse
Page 76 and 77: itumen emulsion or foamed bitumen,
Page 78 and 79: operations, as well as to advance a
Page 81 and 82: Fischer-Tropsch wax bitumen modifie
Page 83 and 84: Viscosity The significant influence
Page 85 and 86: Figure 3: Layer temperature profile
Page 87 and 88: easily formed and shaped where nece
Page 89 and 90: Achieving cost-efficiency through t
Page 91 and 92: Graded stone seals The seals that a
Page 93: Figure 6 illustrates how the stone
Page 96 and 97: decided rather to use the old TRH8
Page 98 and 99: ecommendations (R69/97 for bitumino
Page 100 and 101: compositional fractions (See Table
Page 102 and 103: PRADO analysis. Large quantities of
Page 104 and 105: HMA research programme: Forensic in
Page 106 and 107: Conclusions The following conclusio
Page 108 and 109: test programme, will seek to develo
Page 111 and 112: Out of the box thoughts on traditio
Page 113 and 114: Or more appropriately, a lone thar
Page 115 and 116: seal, and everybody's happy! Or wer
Page 118 and 119: The status quo on landfill sites: D
Page 120: In August 2004 a status quo report
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Bond coats Bond coats were first us
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peak value of 1,2 J/cm 2 . Typical
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promote the breaking of the emulsio
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Bitumen stabilised materials: A per
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Figure 2: DSR testing at comparativ
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Revision of Technical Guideline 1 (
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º introducing upper limits on some
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void loss due to embedment and aggr
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Alternatives to coal tar products:
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you don’t measure” might have b
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gradually increased from approximat
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Conclusions MC 30 cutback bitumen
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Towards industry self-regulation: T
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Figure 2: Accidents involving heavy
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RTMS standards for transport operat
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operators as part of their quality
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• System installation i.e. applic
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Notes 169
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Advertiser Index Advertiser Page Co
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Sabita Video Training Aids Video se
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Associate Members Africon Engineeri
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DIGEST 2006 - Sabita

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