Improvement of concrete properties using granulated blast furnace slag sand

A high volume of ground granulated blast furnace slag (GGBS) or granulated blast furnace slag (BFS) can enhance the resistance of concrete to freezing and thawing without the use of air-entraining (AE) agents. Furthermore, it can also enhance the resistance of concrete to chloride ion penetration and sulfuric acid attack, although the mechanism of improvement differs. In particular, BFS can reduce time-dependent strains, such as drying shrinkage strain and creep strain. The use of granulated blast furnace slag, either GGBS or BFS, promotes the durability of concrete structures by improving the mechanical properties of cementitious materials. Some of the concrete properties that are improved by the incorporation of BFS are presented in this paper. The detailed improvement mechanism of BFS has not yet been clarified. However, it is clear that it depends on the chemical reactions involving BFS and thus a critical time is required for BFS to hydrate in order to improve concrete properties. It takes four weeks to achieve high resistance to freezing and thawing by using BFS without the addition of an AE agent; use of a thickening agent can further shorten this curing period to one week. This paper is an English translation from a previous work by the authors [Ayano et al., (2014). “Resistance to freezing and thawing attack of concrete with blast furnace slag fine aggregate.” Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures), 70(4), 417-427 (in Japanese)] and [Jariyathitipong et al., (2013). “Improvement of resistance to sulfuric acid attack of concrete by use of blast furnace slag sand.” Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures), 69(4), 337-347 (in Japanese)].