Copper slag is a by-product yielded from a copper refinery. The annual amount of copper slag in Japan is two million tons. The copper slag has been used for cement material, sand blasting, reclamation and so on. However, most of the copper slag is stacked high as waste since the production exceeds demand. This study on the application of copper slag as fine aggregate for concrete has been started with the expectation of large amounts of consumption. Many researchers have already found it possible to use a copper slag as a concrete aggregate. However, it also has been clear that the concrete with copper slag has some problems. One of them is excess bleeding attributed to the glassy surface of copper slag. Another problem is the delay of setting time of concrete with copper slag nevertheless it produced at the same refinery. The delay of setting time is more than one week in some cases although the durability in concrete is not affected by it. In this paper, the strength, setting time and durability of concrete with copper slag is clarified. It is shown that the delay of setting time does not have a negative influence on durability. Furthermore, the solution will be given in this paper.
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.
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