Building and Environment 42 (2007) 3060–3065 Wet and dry cured compressive strength of concrete containing ground granulated blast-furnace slag Cengiz Duran Atis - Ã , Cahit Bilim Engineering and Architecture Faculty, Civil Engineering Department, Cukurova University, 01330 Balcali-Adana, Turkey Received 23 August 2005; received in revised form 13 July 2006; accepted 24 July 2006 Abstract This paper reports a part of an ongoing laboratory investigation in which the compressive strength of ground granulated blast-furnace slag (GGBFS) concrete studied under dry and wet curing conditions. In the study, a total of 45 concretes, including control normal Portland cement (NPC) concrete and GGBFS concrete, were produced with three different water-cement ratios (0.3, 0.4, 0.5), three different cement dosages (350, 400, 450 kg/m 3 ) and four partial GGBFS replacement ratios (20%, 40%, 60%, 80%). A hyperplasticizer was used in concrete at various quantities to provide and keep a constant workability. Twelve cubic samples produced from fresh concrete were de-moulded after a day, then, six cubic samples were cured at 2272 1C with 65% relative humidity (RH), and the remaining six cubic samples were cured at 2272 1C with 100%RH until the samples were used for compressive strength measurement at 28 days and three months. Three cubic samples were used for each age and curing conditions. The comparison was made on the basis of compressive strength between GGBFS concrete and NPC concrete. GGBFS concretes were also compared within themselves. The comparisons showed that compressive strength of GGBFS concrete cured at 65%RH was influenced more than that of NPC concrete. It was found that the compressive strength of GGBFS concrete cured at 65%RH was, at average, 15% lower than that of GGBFS concrete cured at 100%RH. The increase in the water-cementitious materials ratios makes the concrete more sensitive to dry curing condition. The influence of dry curing conditions on GGBFS concrete was marked as the replacement ratio of GGBFS increased. r 2006 Elsevier Ltd. All rights reserved. Keywords: Concrete; Ground granulated blast-furnace slag; Curing; Compressive strength 1. Introduction Granulated blast-furnace slag is defined as the glassy granular material formed when molten blast-furnace slag is rapidly chilled as by immersion in water [1–3]. Fast cooling results with minimum crystallization and converts the molten slag into fine aggregate sized particles (smaller than 4 mm), composed of predominantly noncrystalline material [1]. Due to its high content of silica and alumina in an amorphous state, GGBFS shows pozzolanic behavior similar to that of natural pozzolans, fly ash and silica fume [1]. Blast-furnace slags have been widely utilized as ingredients in cement or concrete with potential hydrauli- city from the point of view of effective use industrial by- products [4]. Erdogan [1] reported that the use of granulated blast- furnace slag as finely divided mineral admixture in NPC concrete mixes was initiated in South Africa in 1953. The use of GGBFS in concrete increases the workability, reduces bleeding of fresh concrete or mortar. It improves strength, reduces heat of hydration, reduces permeability and porosity, reduces the alkali–silica expansion [1,4–7]. Regarding influence of curing conditions, Ramezanian- pour and Malhotra [8] stated that ‘‘if the potential of concrete with regards to strength and durability is to be fully realized, it is most essential that it be cured adequately. The curing becomes even more important if the concrete contains supplementary cementing materials such as fly ash, or ground, granulated blast-furnace slag or silica fume, and is subjected to hot and dry environments immediately after casting’’. ARTICLE IN PRESS www.elsevier.com/locate/buildenv 0360-1323/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2006.07.027 Ã Corresponding author. Fax: +90 322 338 6126. E-mail address: cengiz@cukurova.edu.tr (C. Duran Atis -).