Evaluation of coppe slag as aggregate addition on properties of cementitious matrix

Cézar Augusto Casagrande,Ana Cecília De Nóbrega,Lidiane Fernanda Jochem,Diego Deyvison Dos Santos

doi:10.1590/s1517-707620200004.1189

Cézar Augusto Casagrande, Ana Cecília De Nóbrega + Show 2 more

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https://doi.org/10.1590/s1517-707620200004.1189

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Abstract

This work aims the performance of concretes copper slag-added evaluated in fresh state by slump test and in hardened state by compression strength in 7 and 28 days of cement hydration, durability indexes as water absorption and binder efficiency by cement index. In fresh state, the results showed that the samples with copper slag presented lower slump than the reference sample. In hardened state, with 30% of copper slag addition, the compression strength was reduced only by 9% and 8% in comparison with the control series, for 7 and 28 days, receptively. Also, for 28 and 48 days of cement hydration, the water absorption showed lower values in the series with copper slag, indicating a beneficial performance of this waste in the cementitious matrix. Also, the binder efficiency was verified in the work. As the higher the slag in the mixture, lower was the cement consumption and, consequently, higher was the efficiency of the cement, resulting in a low increased in the cement index. The control series, at 28 days of cement hydration, achieved 11 kg·m-3·MPa-1 while the 30% copper slag-added series achieved 12 kg·m-3·MPa-1, which is only 9% higher than series with no consumption of copper slag, indicating a great performance of the copper slag in this cementitious matrix. Keywords: copper slag; cementitious matrix; replacement; concrete.

Highlights

Copper slag is a waste derived from the production of copper alloys, where more than 30 million tons are generated annually around the world [1]
The are some causes that may result in lower workability performance, as the higher the aggregate presence in the mixture, the higher is the necessity of the admixtures or water to guarantee the same workability of the control series
It is worth mentioning that the copper slag (CS) was add on mass, and has a specific gravity about 50% higher than the natural river sand (NS), this leads to a reduction in binder volume as the replacement level increases

Summary

Introduction

Copper slag is a waste derived from the production of copper alloys, where more than 30 million tons are generated annually around the world [1]. It is a product composed of less than 3% of copper, partially amorphous and when composed of calcium oxide, aluminum, magnesium and, mainly, silica in appropriate proportions, may have interesting pozzolanic properties for the cementitious matrix [2]. One of the most popular approaches is to improve the dosage of concrete by manipulating its constituents [6, 7] Another widely used alternative is the progressive consumption of synthetic and organic additives in order to reduce cement consumption per unit volume [8]. One approach that is increasingly being employed is the partial replacement of cement and or aggregates by some industrial waste or byproduct, as slag, ash, bricks, clays, glass, kaolinite, heavy metals, organic waste and others [9-17]

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