Slag Aggregates for antiskid road pavements

Introduction

The road construction industry is characterized by the consumption of large quantities of natural aggregates. The recycling and re-use of alternative, environmental-friendly raw materials is necessary and this is characterised as an essential step towards sustainable and viable development.
The continuously growing requirements in road safety have imposed higher standards in road construction, and specially in motorway construction. Among the factors that are determinant for the final quality of the road pavement, one of the most important is the quality of the aggregates used in the bituminous mixture. The steel slag is currently the most widely used road aggregate in the EU.

Aggregate for antiskid wearing course 5-12MM	Aggregate for antiskid wearing course 12-16MM	Aggregate for road pavement

The main reasons that led to the use of steel slag in road construction are the following:

EAF slag aggregates pose a serious competition to natural aggregates. They present excellent mechanical and physical properties and have proved their appropriateness as hard, coarse aggregates for the manufacture of antiskid layers. By their use, the behaviour of paving is improved considerably in terms of durability, skid resistance, contributing at the same time in the construction of a safe road network.
Road safety, being of major importance, sets road construction specifications at very high standards, particularly in the construction of highways.

The European use of slag dates back to 1880 when the first concrete blocks with slag aggregates were introduced. Since then the evolution in slag recycling has been gradually increasing, with the increase in the production of steel demand and, as such, the increase in slag production.
AEIFOROS S.A. has been involved in hard aggregate production from electric arc furnace (EAF) steel slag since 2001. The EAF slag is an industrially-produced stone, which, after the proper processing, makes an excellent material for the antiskid course in road pavement construction; the use of it, is part of steel industry best practices, internationally recognized and  applied in many European countries.
Meeting the highest standards for aggregate production and showing remarkable environmental concern, the company AEIFOROS S.A. operates today three state-of-the-art slag aggregates production facilities, two in Greece and one in Bulgaria. About 250.000 tons of EAF slag are annually processed in those three facilities while the total production capacity reaches 450.000 tons.
The quality of hard aggregates produced in our facilities is our main priority, and is ensured through staff experience, our know-how and the excellence and consistency of production organization.
AEIFOROS S.A. is one of the few companies in Greece that produces slag aggregates for bituminous mixtures and skid-resistant courses for motorways and highways, airfields and other trafficked area, certified according to CE ELOT EN 13043. Furthermore, the Quality Management System of the enterprise has been assessed and found in conformity with the requirements of the standards ELOT EN ISO 9001:2000. AEIFOROS' hard aggregates have also received the first price in the category "Ecological Product" in the greek competition of the European Business Awards for the Environment in 2006.

Product properties

The main advantage of EAF slag aggregates is the excellent mechanical properties that fully satisfy both international and domestic specifications for incorporation into bituminous mixtures for skid resistant layers and surface treatments.

One of the main factors that determine the final quality of a highway is the use of proper aggregates in the final surfacing. The most common aggregate for this skid resistant course in EU is Electric Arc Furnace Slag.

The use of such aggregates for highway construction offers the advantage that newly constructed roads are of equivalent quality and safety with those of other European countries and contributes in the manufacturing of a safer road network. In a nutshell the advantages are

Furthermore, when compared to natural aggregates, EAF slag aggregates present the advantage of quality stability and constant chemical composition since the raw material is produced during the controlled industrial process of steel manufacturing.
Tests have been carried out in public and private laboratories. Over 30 different bituminous mixture studies have been carried with AEIFOROS slag aggregates for the construction of hundreds of kilometers of motorways, highways and airfields in Greece.

Uses

The production of coarse aggregates for road construction from EAF slag is financially viable for the producer and economically attractive to the customer since it is an abundant and accessible solution. The environmental benefits from the use of Electric Arc Furnace slag aggregates in road construction are the following;

Some major highway projects where AEIFOROS slag aggregates have been used are the following:

Thin surfacing (2,5cm thickness) Egnatia Motorway	Skid resistant asphaltic concrete being layed on P.A.Th.E highway

Since 2005 AEIFOROS SA, pioneer in the production of coarse aggregates from EAF Slag, has strongly supported the recognition of the value of utilising EAF slag in environmental, social and economical level. The production and use of slag aggregates is an innovation in Bulgaria and a lead of AEIFOROS S.A. The Electric Arc Furnace (EAF) Slag is an industrially-produced artificial aggregate, which after suitable treatment, constitutes an excellent material for the manufacture of antiskid layers in the road construction industry. This practice, although internationally recognized and applied in most European countries for many years has only in recent years begun to establish itself in Greece. The production and use are friendly to the environment, while contributing in the manufacture of safer highways.

AEIFOROS' hard aggregates for bituminous mixtures are certified with CE marking according to EN 13043 and have been used in all major highways in Greece. The main advantage of AEIFOROS aggregates is the excellent mechanical properties. It is hard, durable, compression and impact resistant material with great frictional resistance.