Influence of high temperature on the properties of concretes made with industrial by-products as fine aggregate replacement _ Isa Yüksel a, * , Rafat Siddique b , Ömer Özkan c a Department of Civil Engineering, Zonguldak Karaelmas University, 67100 Zonguldak, Turkey b Department of Civil Engineering, Thapar University, Patiala, Punjab 147 004, India c Faculty of Technical Education, Sakarya University, 54187 Sakarya, Turkey article info Article history: Received 28 May 2008 Received in revised form 14 June 2010 Accepted 19 June 2010 Available online 13 July 2010 Keywords: High temperature Bottom ash Concrete Fine aggregate Granulated blast-furnace slag Replacement abstract Influence of high temperature on the properties of concrete containing non-ground granulated blast-fur- nace slag (GBFS) and coal bottom ash (BA) as fine aggregate was presented. Six series of concrete mix- tures were prepared by partially replacing fine aggregate separately with GBFS and BA. Replacement percentages were between 10 and 50% with an increment of 10% by dry weight of fine aggregate. Then 0.2% polypropylene fibres (PP) were added to last three mixtures that has the same mixture with the first three series. The first series is control concrete, the second series contained GBFS and the third series con- tained BA. All the concrete specimens were exposed to 800 °C temperature at the age of 90 days. Tests were conducted to determine loss in weight, compressive strength, and dynamic modulus of elasticity. Also surface crack observations were conducted with microscope. Test results showed that it is possible to partially replace fine aggregate with GBFS or BA even if such concretes were to be subjected to high temperature response. Performance of BA concrete was found to be better than GBFS as replacement material. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Various types of solid wastes or industrial by-products, such as coal bottom ash (BA) and blast-furnace slag have found extensive use in cement and concrete. Coal bottom ash is a coarse sand to fine gravel size material, collected at the bottom of the boiler, is generally used as a low cost replacement material either as a base material in road construction or as a replacement material in Port- land cement [1]. Blast-furnace slag, a non-metallic product consist- ing of silicates and alumina-silicates of calcium, comes from the blast-furnace production of iron from ore through the process of water jetting and water-immersing the molten blast-furnace slag for granulation [2]. Numerous studies were carried out to investi- gate strength and durability properties of cement and concrete including ground blast-furnace slag or coal bottom ash as an admixture. High temperature causes dramatic physical and chemical changes resulting in the deterioration of the concrete [3,4]. Although concrete is recognized as an excellent thermal-resistant material among various construction materials, critical deteriora- tion of concrete is observed when it is exposed to high temperature like as in the case of fire. A number of physical and chemical non- reversible changes occur in concrete when subjected to high tem- perature. Concrete damage due to high temperatures includes weight loss, reductions in strength and modulus of elasticity, and formation of cracks and large pores [5]. Fire resistance of concrete is affected by factors like the type of aggregate and cement used in its composition, the temperature and duration of the fire, size of structural member, and moisture content of concrete [6–9]. Assessment of fire-damaged concrete usually starts with visual observation of color change, crazing, cracking, and spalling [10]. Low void ratio causes a decrease of resistance against fire in con- crete. The effect of high temperature on the concrete was re- searched in many studies. It was observed that normal and high strength concrete loses 60% of initial compressive strength when they are exposed to 800 °C [11]. Like the strength, high tempera- ture also made similar effect to modulus of elasticity [12]. In an- other study, concretes were exposed to 300, 600 and 900 °C and it was observed that it lost mechanical properties at 600 °C and loses its all properties at 900 °C [13]. Yüksel et al. concluded that resistance to high temperature and surface abrasion are positively affected durability properties if GBFS and BA are used as an aggre- gate replacement material in concrete [14]. Explosive spalling of concrete due to high temperature should be prevented. Many investigations have been carried out, which re- vealed that the application of polypropylene (PP) fibres in concrete may considerably reduce the amount of spalling [15,16]. PP fibres 0950-0618/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.conbuildmat.2010.06.085 * Corresponding author. Tel.: +90 372 2575448; fax: +90 372 2574023. E-mail addresses: yukselisa@yahoo.com, yuksel@karaelmas.edu.tr ( _ I. Yüksel). Construction and Building Materials 25 (2011) 967–972 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat