Table 2.4 Uses of secondary materials in 1990
2.6.3 Expected development
The UK Department of the Environment has put its very substantial weight behind the use of secondary aggregates and, in its Guideline for Aggregates (DOE, 1994), it is relying on greatly increased use of secondary aggregates as part of its long-term strategy to meet aggregate demand. However, the actual amount of secondary materials employed in the future will depend on:
• further research;
• improved data on the specifications required for, and the suitability of, the product
2.7 CONCLUSION
This chapter has considered the problem faced by the Engineer of trying to predict aggregate performance in order to provide the public with a safe and longer-lasting road surface. Rather than supply a set of answers, its aim has been to increase awareness of the complexities of aggregate performance and the limitations of current selection methods.
It has also introduced future European test methods which will cause fundamental changes to British specification requirements. Finally, as aggregate is a naturally occurring product and prone to change, can its future assessment against a recipe specification be allowed to continue?
2.8 REFERENCES
Manual of Contract Documents for Highway Works. Her Majesty’s Stationery Office, London. Volume 1: Specification for Highway Works (MCHW 1).
Association Franchise de Normalisation (1982) Aggregates—Characteristics of Aggregates Intended for Road Works. Norme Française Homo-Logueé NF P18–321, May 1982. Association Française de Normalisation, Paris.
Aggregates Committee, The (1992) Aggregates for Pavements. Frost-Resistance Test. V-209, Reykavik, Iceland.
Anon (1996) Analysis of the markets and prospects for aggregates, ready-mixed concrete, asphalt and lime in 16 European cuntries, BDS Marketing & Research, May.
British Aggregates & Construction Materials Industries (1994) Why Quarry, Quarrying:
An Introduction. Information Sheet 1, British Aggregates & Construction Materials Industries, London.
British Aggregates & Construction Materials Industries (1996) A Question of Balance—
Recycling, British Aggregates & Construction Materials Industries, London.
British Standards Institution (1985a) Testing Aggregates. Part 103: Methods for Determination of Particle Size Distribution, Section 103.1: Sieve Tests. BS 812: Part 103.1:1985, British Standards Institution, London.
British Standards Institution (1985b) Testing Aggregates. Part 105: Methods for Determination of Particle Shape, Section 105.1: Flakiness Index. BS 812: Part 105.1:
1985, British Standards Institution, London.
British Standards Institution (1989a) Testing Aggregates. Part 121: Methods for Determination of Soundness. BS 812: Part 121:1989, British Standards Institution, London.
British Standards Institution (1989b) Testing Aggregates. Part 114: Methods for Determination of the Polished-Stone Value. BS 812: Part 114:1989, British Standards
for differing applications;
• promotion of the qualities of the various materials; and
• possibly, an acceptance by the end user of an increased degree of risk.
Institution, London.
British Standards Institution (1990a) Testing Aggregates. Part 112: Methods for Determination of Aggregate Impact Value (AIV). BS 812: Part 112:1990, British Standards Institution, London.
British Standards Institution (1990b) Testing Aggregates. Part 110: Methods for Determination of Aggregate Crushing Value (ACV). BS 812: Part 110:1990, British Standards Institution, London.
British Standards Institution (1990c) Testing Aggregates. Part 111: Methods for Determination of 10% Fines Value (TFV). BS 812: Part 111:1990, British Standards Institution, London.
British Standards Institution (1990d) Testing Aggregates. Part 113: Methods for Determination of Aggregate Abrasion Value (AAV). BS 812: Part 113:1990, British Standards Institution, London.
British Standards Institution (1992) Hot Rolled Asphalts for Roads and Other Paved Areas; Part 1, Specification for Constituent Materials and Asphalt Mixtures; Part 2, Specification for Transport, Laying and Compaction of Rolled Asphalt. BS 594: Part 1:1992, BS 594: Part 2:1992, British Standards Institution, London.
British Standards Institution (1993) Coated Macadam for Roads and Other Paved Areas;
Part 1, Specification for Constituent Materials and for Mixtures; Part 2, Specification for Transport, Laying and Compaction. BS 4987: Part 1:1993, BS 4987: Part 2:1993, British Standards Institution, London.
British Standards Institution (1995) Testing Aggregates. Part 2: Methods for Determination of Density. BS 812: Part 2:1995, British Standards Institution, London.
Bullas, J.C. and G.West (1991) Specifying Clean, Hard and Durable Aggregate for Bitumen Macadam Roadbase, Department of Transport TRRL Research Report 284, Transport and Road Research Laboratory, Crowthorne.
Comité Européen de Normalisation (1991a) Method of Test for the Determination of Resistance to Wear of Aggregates: Micro-Deval Test. Draft European Standard CEN/TC 154/SC6/N136E, Comité Européen de Normalisation TC 154/TC 154.
Comité Européen de Normalisation (1991b) Method of Test for the Determination of Resistance to Impact of Aggregates: Schlagversuch, Draft European Standard CEN/TC 154/SC6/N135E, Comité Européen de Normalisation TC 154/TC 154.
Comité Européen de Normalisation (1991c) Method of Test for the Determination of Resistance to Fragmentation of Aggregates: Los Angeles Test. Draft European Standard CEN/TC 154/SC6/N134E, Comité Européen de Normalisation TC 154/TC 154.
Comité Européen de Normalisation (1991d) Method of Test for the Determination of Resistance to Freeze/Thaw. Draft European Standard CEN/TC 154/SC6/N148E, Comité Européen de Normalisation TC 154/TC 154.
Comité Européen de Normalisation (1995) Tests for Geometric Properties of Aggregates, Part 12: Assessment of Fines—Methylene Blue Test. Draft European Standard prEN 933–12, Comité Européen de Normalisation TC 154/WG.
Craig, C. (1991) A Study of the Characteristics and Role of Aggregate Dust on the Performance of Bituminous Materials, DPhil Thesis, Department of Civil Engineering
and Transport, University of Ulster.
Curtis, C.W., R.L.Lytton and C.J.Brannan (1992) Influence of Aggregate Chemistry on Absorption and Desorption of Asphalt, 71st Annual Meeting, Transportation Research Board, Washington DC.
Defence Works Services (1995) Marshall Asphalt for Airfield Pavement Works; Hot Rolled Asphalt and Coated Macadam for Airfield Pavement Works, Defence Works Functional Standards, Her Majesty’s Stationery Office, London.
Department of the Environment (1994) Guidelines for Aggregates, MPG6, Her Majesty’s Stationery Office, London.
Knight, B.H. (1935) Road Aggregates, Their Use and Testing, The Roadworkers’
Library, Volume III, Edward Arnold & Company, London.
Laboratoire Central des Ponts et Chausées (1963) Adhesion test on vialit plate, Bulletin de Liaison Ponts et Chausées 4, Laboratoire Central des Ponts et Chausées, Paris.
Lebas, A. and A Maldonado (1989) Un Centre d’Essais Lourds au Service de la Recherche et de la Promotion dans l’Industrie des Carriers, Bulletin Liaison Laboratoire Ponts et Chaussées 160, Feb.–Mar., Laboratoire Central des Ponts et Chausées, Paris, 37–42.
McCool, P.D. (1990) Rational Design Method for Surface Dressing, DPhil Thesis, University of Ulster.
Perry, M. (1996) A Study of the Factors Affecting the Polishing of Gritstone Aggregate, DPhil Thesis, University of Ulster.
Property Services Agency (1987) Standard Specification Clauses for Airfield Pavement Works; Part 4. Bituminous Surfacing, Property Services Agency, Croydon.
Sorby, H.C. (1880) On the Structure and Origin of Non-Calcareous Rocks, Proceedings of the Geological Society, 36, Geological Society, London, 46–96.
Thompson, A., J.R.Greig and J.Shaw (1993) High Specification Aggregates for Road Surfacing Materials, Technical Report, Department of the Environment, London.
Wentworth, C.K. (1922) The shape of beach pebbles, Geological Survey, Professional Paper 131, Geological Society, London, 75–102.
Woodside, A.R. (1981) A Study of the Characteristics of Roadstones with Particular Reference to Polishing and Skidding Resistance, MPhil Thesis, University of Ulster.
Woodside, A.R. and W.D.H.Woodward (1984) The Methylene Blue Absorption Soundness Test, Internal Report, Department of Civil Engineering, University of Ulster.
Woodside, A.R. and W.D.H.Woodward (1993) Assessing surfacing aggregate performance—is clean, hard and durable enough? Municipal Engineer, Proceedings of
the Institution of Civil Engineers, Institution of Civil Engineers, London, 151–5.
Woodside, A.R., W.Given, W.D.H.Woodward and M.Megaw (1993) The relationship of unbound aggregate fines to pavement performance, Proceedings of Euroflex 1993;
European Symposium on Flexible Pavements, Lisboa, Portugal.
Woodside, A.R., W.D.H.Woodward, B.Kelly and C.Lycett (1993) Assessing the factors which influence the permeability and strength of a porous asphalt, Proceedings of 5th Eurobitume Congress, Stockholm, 623–6.
Woodside, A.R., W.D.H.Woodward, T.E.I.Russell and R.A.Peden (1996) The relationship between aggregate mineralogy and adhesion to aggregate, Performance and Durability of Bituminous Materials, Proceedings of Symposium, University of Leeds, Mar., E & FN Spon, London.
Woodward, W.D.H. (1995) Laboratory Prediction of Surfacing Aggregate Performance, DPhil Thesis, University of Ulster.
Zingg, T.H. (1935) A contribution to the analysis of coarse gravel, Schweizerische Mineralogische und Petrographische Mitteilungen, 15, 133–40.
CHAPTER 3 Binders
P.J.Green, BP Research
3.1 INTRODUCTION
By the middle of the nineteenth century, the problem of dust generated by the horse-drawn traffic in towns was causing much concern (section 1.1). However, the change from horse-drawn to motor vehicles not only greatly exacerbated the dust problem but also placed new demands on the smoothness and durability of the road surface. This led to serious attention being given to the materials used in the construction of streets and roads.
The availability of a regular supply of tar from local coal gas works provided one of the first materials for treating the previously unbound aggregates in streets and pavements. Later, rock asphalt and Trinidad lake asphalt were the sources of bitumen first used to bind mixtures of aggregates in road building in the modern style. By the turn of the century the potential of petroleum as a readily available source of low-cost, high-quality bitumen was being exploited on a small scale. From then to the present day, a range of petroleum bitumens have been developed and used in materials for use in road construction.
A general classification of binders for asphalt materials and surface treatments is shown in Figure 3.1. The most widely used of these in increasing importance are coal tars, natural asphalts and petroleum bitumens.
3.2 TAR
Coal tar was one of the first materials tried for suppressing the dust generated from the traffic on unbound roads. It was originally the by-product of the carbonization of coal during the production of town gas and coke. However, the production and widespread use of natural North Sea gas since the 1970s has meant that the main source of coal tar at the present time is from coke production for the steel and smokeless fuel industries.
Coke is produced either by the destructive distillation of coal at about 1000 °C or carbonization at lower temperatures (600 °C to 750 °C) for smokeless fuel production.
The vapours from these processes are condensed and become the crude tars which must be refined further to obtain products suitable for use as road binders. Fractional