Reactivity Assessment of Modified Ferro Silicate Slag by R3 Method

Pithchai Pandian Sivakumar,Nele De Belie,Elke Gruyaert,Stijn Matthys

doi:10.3390/app11010366

Pithchai Pandian Sivakumar, Nele De Belie + Show 2 more

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https://doi.org/10.3390/app11010366

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Journal: Applied sciences	Publication Date: Jan 1, 2021
Citations: 19	License type: CC BY 4.0

Affiliation: Ghent University, KU Leuven, Ablynx (Belgium)

Abstract

Traditional methods to track the reactivity of supplementary cementitious materials (SCMs) and their contribution to the hydration mechanism mostly use Portland Cement (PC) as an activator. Alternatively, a novel method to assess the reactivity of SCMs called R3 was recently presented. This novel method uses lab grade chemicals such as portlandite (CH), K2SO4, KOH, and CaCO3 to activate the SCM by resembling the pH of the alkaline pore solution created by PC. By using this method, the reactivity of the SCM can be easily quantified from measured heat release, bound water content, and CH consumption. The primary objective of the current study is to apply the novel methodology to analyze the reactivity of Modified Ferro Silicate (MFS) Cu slag benchmarked against siliceous fly ash (FA), ground granulated blast-furnace slag (GGBFS), and inert quartz filler. GGBFS showed the highest cumulative heat release and bound water content due to its latent hydraulic behavior. Determination with XRD analysis of the major phase of the R3 model MFS slag paste showed the participation of Fe in the hydration mechanism by forming Fe-AFm. R3 paste with GGBFS showed the presence of hydrotalcite/Al-AFm, whereas FA showed the presence of ettringite (AFt) as their crystalline reaction products. The experiments also indicate that the MFS slag acts as a reactive pozzolanic material with an acceptable performance in heat release, bound water content, and CH consumption, and can be used as SCM to make concrete. With the possibility of using MFS slag as SCM to replace part of PC, sustainability and circular economy can be fairly well achieved.

Highlights

Copper (Cu) is one of the most vital metals used in a wide range of thermal applications and electrical wiring
fly ash (FA) is an amorphous rich by-product synthesized during the coal combustion that is mainly composed of fine particulates which are collected by the electrostatic precipitator
Note that the mechanism governing ground granulated blast-furnace slag (GGBFS) reactivity explained through chemicals such as portlandite (CH) consumption and bound water cannot be considered as decisive, and the results should be interpreted with caution by accounting the results shown in Sections 3.2.2 and 3.2.3

Summary

Introduction

Copper (Cu) is one of the most vital metals used in a wide range of thermal applications and electrical wiring. Cu metal is usually synthesized by pyro-metallurgical refining of Cu ore such as chalcopyrite (CuFeS2) or bornite (Cu5FeS4) [1,2]. Due to the improved technological facilities and state of the art on smelter and refining processes, industries focus on the use of metal scraps as recyclable materials to synthesize Cu metal. During the smelting and refining of Cu ore or Cu rich metal scraps into Cu metal, a slag is obtained as a by-product [2]. This by-product is produced in high volume, as the production of 1 ton of Cu metal usually generates approximately 2.2–3.0 tons of Cu slag. Cu slag (the term Cu slag in the literature refers to its origin, rather than its mineralogy, which is mainly a siliceous amorphous phase) is widely used in abrasive tools, roofing granules, cutting tools, glass, and in the cement and concrete industry [3]

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