Production and Characterization of Concrete Paving Blocks Containing Ferronickel Slag as a Substitute for Aggregates

Abstract

The present work aims to investigate the potential valorization of ferronickel slag (FNS) as a substitute for aggregates in the production of H-shaped concrete paving blocks (CPB). FNS is a byproduct of the pyrometallurgical treatment of laterites for the recovery of Ni as ferronickel; its size distribution ranges within the specified limits for use as aggregates replacement, as shown by granulometric tests. Three compositions were prepared: a reference, containing only ordinary raw materials (CPBRef) and two others containing 10 wt% (CPB10) and 20 wt% (CPB20) aggregates replacement by FNS. Approximately 1000 blocks were produced in pilot scale for each composition. All mixtures were tested after 28 days of curing, in accordance with European Standard BS EN 1338 to determine water absorption, abrasion resistance, compressive and tensile/splitting strength. Spectral reflectance was measured on a UV–Visible-NIR spectrophotometer between 250 and 2500 nm, while thermal conductivity was determined by using a thermal conductivity analyzer. CPB morphological characteristics and microstructure were examined by scanning electron microscopy. Although it was found that limestone (LS) aggregates replacement by FNS relatively impaired the quality of the resulting CPB to a certain extent, the paving blocks using 10 wt% FNS met the minimum requirements specified by BS EN 1338 standard.