Properties of Waste Paper Sludge Ash (WPSA) as cement replacement in mortar to support green technology material

Waste Paper Sludge Ash (WPSA) is a waste material collected from the Paper Industry. WPSA is used as cement replacement in producing mortar and was investigated on its chemical, physical and mechanical properties. Construction material with natural resources now become limited and causes of air pollution and environmental problems. WPSA becomes a new innovation material that can be used as material for masonry to support the green technology due to less presence of sulphate at only 0.57% of the total weight. Carbon dioxide (CO₂) and Sulphur dioxide emission also can be reduced since less cement productivity is involved. The chemical and physical properties of the WPSA were determined by comparing it with the Ordinary Portland Cement (OPC). As the result of testing, it shows that WPSA is similar to the chemical properties of OPC and the water absorption of the mortar is 27.05%. However the total percentage of the three combinations of SiO₂, Al₂O₃ and Fe₂O₃ was 45% and expected to possess low pozzolanic reactivity (50%). WPSA was used in mortar with proportions of 50%, 60%, 70%, 80%, 90% and 100% as cement replacement by volume along with sand and water in fix quantity. An additional control mix mortar without WPSA was also prepared. The compressive strength of each mortar mix was also determined on 3, 7, 28 and 60 days. Results show that the compressive strength increased with increasing curing age for all concrete mixes and the compressive strength decreases with increasing WPSA in the mortar. The inclusion of 50% WPSA can gain favorable strength mortar at 16.4 MPa. Meanwhile 70% and 100% replacement can be adopted for economical environmental mortar to suit lower strength mortar construction at 12.5 MPa and 7.7 MPa respectively.