Qatar finds eco-friendly solution to steel slag stockpile

Qatar has found an environment-friendly solution to its large stockpile of steel slag, aggregating more than 1.6mn tonnes, by planning to utilise it in the construction sector, especially for roads, in view of the fast-paced infrastructure development taking place ahead of hosting the 2022 FIFA World Cup.A well-researched move – undertaken by TRL (the UK Transport Research Laboratory), in collaboration with the Ministry of Municipality and Environment (MME), Ashghal and Qatar Steel – would reduce the dependence on the imported aggregate and hence savings in foreign exchange.The pilot project, marking a forward step in Qatar’s continuing efforts to achieving sustainable development and environment protection, was yesterday disclosed by Ashghal president Dr Saad bin Ahmed bin Ibrahim al-Mohannadi in the presence of Dr Mohammed bin Saif al-Kuwari, Assistant Undersecretary for Laboratories and Standardisation at MME.The process includes refining the iron from impurities that float on the top of melted steel in the form of slag, which is then transported, tipped, and quenched with treated water and left to air-cool and weathering for one-year. After weathering, the slag is processed by crushing and removal of residual metal, by electro-magnets, before use in construction.“Qatar is mainly relying on imported aggregate… Developing high value aggregate from the steel slag has major environmental, economic and social benefits, including reduced dependence on imported materials, increased use of local materials, reduced carbon emission associated with imported materials, and cost savings,” Qatar Steel managing director and general manager Ali bin Hassan al–Muraikhi said.Qatar Steel has accumulated large quantities of steel slag from its factory in Mesaieed, exceeding more than 350,000 tonnes annually with stockpiles amounting to over 1.6mn tonnes.To avoid land disturbance and waste accumulation, the Industries Qatar subsidiary had appointed TRL to identify a potential market for the use of steel slag in the construction. It reviewed local and global information on the use of slag products in construction, development of asphalt and concrete products made with steel slag, and the potential use of fine slag aggregate to replace dune sand in improving the properties of unbound sub-base materials for road construction.The full-scale trial roads were constructed at Qatar Steel site in 2016 to demonstrate the successful use of steel slag in the various road construction layers of asphalt base and unbound sub-base. In addition, pre-cast concrete elements of crash barriers, soakaways, manholes, kerbstone and solid blocks were produced to demonstrate high-value applications in the concrete industry.In view of the large benefits, TRL has recommended quality production of slag aggregate, certification of slag products by the authorities including MME and Ashghal, development of case studies and the inclusion in the next update to the Qatar construction specification.“The implementation plan will provide more confidence in the use of slag in real projects and enhance its effective uptake by the construction industry, to support the government initiatives of sustainable development and green construction,” Qatar Steel said.