Use of gasification residues in compacted concrete paving blocks

Research was done to determine the possible uses of fine-grained solid gasification residues in concrete products. Due to the residues' chemical composition, compacted concrete paving blocks were studied as one viable non-structural application of adding the residue. Six different residues were tested in the laboratory at up to 25% replacement by dry weight of either cement or aggregate. After these preliminary laboratory tests, one residue Was used in full-scale field tests at the Lakan Betoni factory where 10 and 15% of straw-derived residue Was used as a cement replacement. Tensile strength, compressive strength, resistance to freezing-thawing cycles, absorption and leaching were evaluated. The addition of the residue improved the workability of the concrete, provided a beneficial dark coloring and did not adversely affect most properties. The freeze-thaw resistance should be improved by reducing the factory compaction effort to ensure sufficient void space. (c) 2005 Elsevier Ltd. All rights reserved.