Feasibility of lightweight materials manufactured from inorganic residues containing calcium by autoclaving technique in a commercial scale plant

This study investigates the feasibility of lightweight materials manufactured from filter residues collected from a commercial paper-mill sludge gasification plant (referred as filter residues) by using an autoclaving technique. To assess the characteristics of tested lightweight materials, the experimental conditions were controlled the various blended ratios (sand and cement) and curing types (natural curing and autoclaving), respectively. In the case of 1:1 blended ratio of filter residues and sand, 15% cement addition ratio and natural curing conditions, the bulk density and compressive strength of manufactured lightweight materials were all in compliance with criteria of CNS 8905 code for applying the C-class building hollow concrete block. Meanwhile, the moisture buffering capacity of manufactured lightweight materials was complied with the criteria of first-class moisture controlled materials in Japan. The toxic metals concentrations by toxicity characteristics leaching procedure (TCLP) were lower than the regulation thresholds in Taiwan. That is, the manufactured hollow concrete block was satisfied for environmental safety requirement. In summary, it can be concluded that the manufactured lightweight materials were all in compliance with the relevant criteria and has the potential for production and development in a commercial scale plant.