The use of ladle furnace slag in soil stabilization Juan M. Manso a,⇑ , Vanesa Ortega-López a , Juan A. Polanco b , Jesús Setién c a Dept. of Civil Engineering, EPS University of Burgos, Calle Villadiego s/n, 09001 Burgos, Spain b Dept. Materials and Geotechnics, University of Cantabria, Avenida de los Castros s/n, 39006 Santander, Spain c Div. Materials Science and Engineering, University of Cantabria, Avenida de los Castros s/n, 39005 Santander, Spain highlights " Ladle furnace slag is a useful by-product for the improvement of natural clayey soils. " Mixtures of soil with LFS have volumetric stability and good bearing capacity. " The curing time of LFS–soil mixes is longer than that of ordinary lime–soil mixes. " The durability of LFS–soil mixes is better than that of ordinary lime–soil mixes. article info Article history: Received 13 July 2012 Received in revised form 7 September 2012 Accepted 25 September 2012 Available online 5 December 2012 Keywords: Ladle furnace slag Reducing slag Clayey soil Soil stabilization Swelling Bearing capacity abstract Natural clayey soils have often to be stabilized by mixing them with certain materials, such as cement, lime, or similar products, so that they acquire the necessary properties for civil works. Some industrial by-products can also be used for this purpose, among which steelmaking slags. Our research studies the properties of Ladle Furnace Slag (LFS) and the characteristics of several clayey soils susceptible to improvement with additions of this by-product. The behaviour of the different soil and slag mixes was similar to the behaviour of the soil and lime mixtures reported in the literature. The results of a series of test report improvements in various geotechnical properties, such as the plasticity index, expansive- ness, bearing capacity and durability. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Natural soil stabilization is a classic problem in civil engineer- ing, when it is necessary to prepare a subbase or foundation bed with natural soils upon which to construct light foundations or transportation infrastructure such as roadbeds, railroads, or air- ports. The function of the grading roadbed is to provide geometric regularity, lineal continuity and adequate transmission of loads to the subjacent ground. Grading roadbeds may be prepared in differ- ent ways; this study examines the construction of a surface layer, in which the natural soil, if of poor quality, may be efficiently improved. An outstanding problem in geotechnical engineering has in- volved improvements to the bearing capacity of clayey soils and the achievement of volumetric stability when they show expansive behaviour in the presence of water [1]. For decades, various proven industrial products (lime, Portland cement) have been used, in or- der to achieve levelled areas of acceptable surface quality for civil works, although they are currently considered to incur high eco- nomic and environmental costs [2–5]. Nevertheless, when mixed with a clayey soil, various industrial by-products are able to transform its properties. In this way, cheap materials or compounds capable of activating light pozzolanic activity, ionic exchanges and the flocculation of clay can be used for the improvement of soft natural soils. The most prominent are Ground Granulated Blast Furnace Slag (GGBFS) [6], fly ashes from coal burning [7] and cement kiln dust [8–14]. Bottom ashes from coal burning [15], municipal solid waste incinerator ashes [16,17] and small proportions of chemical activators that improve the binding capacity of the soil [18] are also used, but to a lesser extent. Most of the aforementioned by-products may be sourced in a dusty form, which makes their application in large proportions mixed with natural soils considerably easier and more economi- cally viable. Slags from iron and steel manufacture have long been regarded as useful materials in building and civil works. Relevant studies 0950-0618/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.conbuildmat.2012.09.079 ⇑ Corresponding author. Tel.: +34 947259076/634255862; fax: +34 947259478. E-mail addresses: jmmanso@ubu.es (J.M. Manso), vortega@ubu.es (V. Ortega- López), polancoa@unican.es (J.A. Polanco), setienj@unican.es (J. Setién). Construction and Building Materials 40 (2013) 126–134 Contents lists available at SciVerse ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat