jailcd2019-050: Suppression Effect of Fly-Ash on Delayed Expansion of Raw LD Converter Slag

Abstract

Steelmaking slags (SMSs) were by-produced 12.6 million tons a year in Japan. The effective use of SMSs are hindered, because free lime (f-CaO) and free magnesia (f-MgO) contained in a part of SMSs have properties of expansion and collapse by reaction with water. In the current circumstances, most SMSs have kept as bad stocks in the steelworks area. The solution of the expansion problem of SMSs makes a big contribution in effective utilization of resources and realization of sustainable development goals (SDGs).
We have prepared the concrete based on fly-ash (FA) cement with Linz-Donawitz converter slag (LDS; the slag which is a type of SMSs and contains large amount off-MgO) without aging treatment as fine aggregate (LDS mortar), and investigated the effect of suppressing the expansion of LDS mortar.
In order to clarify the expansion mechanism by LDS, observation of microstructure by Scanning electron microscopy  (SEM)  with  Energy  Dispersive  X-ray  Spectroscopy  (EDX)  and  measurement  of pore  size distribution by mercury porosimetry were carried out.