Recycling of paper sludge powder for achieving sustainable and energy-saving building materials

Abstract Calcium silicate board materials (CSBM), as a new environmental friendly and energy-saving building material, have been widely used in the construction of ceiling and insulation panel. This study aims to investigate the feasible utilization of two kinds of paper sludge powder, paper sludge ash (PSA) and alkali recovery paper sludge (ARPS), as the supplementary materials to develop a sustainable CSBM with low water-cement ratio. The experimental results indicate that single addition of 30% PSA or 20% ARPS can improve the flexural strength of CSBM effectively because a moderate addition of paper sludge can decrease the porosity. Meanwhile, the addition of PSA or ARPS notably reduces the thermal conductivity of the CSBM and DSC-TG analysis present a better thermal stability before 650 °C. Furthermore, the reinforcing capability of the hybrid PSA/ARPS to CSBM is investigated using response surface methodology (RSM). In conclusion, the utilization of paper sludge powder presents a great potential to develop sustainable and energy-saving CSBM with enhanced flexural strength and reduced water absorption.