Production of concrete paving blocks (CPB) utilising electroplating residues – evaluation of mechanical and micro-structural properties

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Abstract

The objective of this study was to use electroplating waste [blasting dust (BD) and electroplating sludge] for the production of concrete paving blocks (CPBs) by means of the solidification/stabilisation technique and to characterise the mechanical and micro-structural properties of CPBs. Granulometric tests showed that electroplating residues have a size range that allows their use as aggregates. Blocks were produced with compositions of 5, 10, 15, 20 and 25% BD and electroplating sludge, and reference blocks (REF) were produced without the addition of residues. Blocks were cured for 7, 14, 28, 60 or 90 days. The blocks produced with 5%, 10% and 15% BD had compression resistances at 28 days of 42.60 MPa, 37.57 MPa and 35.6 MPa, respectively, all of which are above the Brazilian limits for paved areas to be used by light vehicles (35 MPa). In contrast, the specimens produced with electroplating sludge behaved differently, probably due to their water/agglomerate ratio and the limited interaction of the cement matrix with the aggregate, which influenced the observed compression resistance values. Only the blocks manufactured with 5% electroplating sludge showed resistance values above the limit established by Brazilian standards (35.43 MPa), but the values were inferior to those of the reference block (37.35 MPa). Therefore, the characteristics of the electroplating residues (BD and electroplating sludge) are acceptable as raw materials in civil construction. The solidification/stabilisation technique also appeared to be quite promising for the incorporation of electroplating residues into cement matrix for the fabrication of CPBs. © 2012 Canadian Society for Chemical Engineering

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