Fabrication of a non-cement binder using slag, palm oil fuel ash and rice husk ash with sodium hydroxide

• Published in: Construction & building materials 2013-12, Vol.49, p.894-902
• Main Authors: Karim, M.R., Zain, M.F.M., Jamil, M., Lai, F.C.
• Format: Article
• Language: English
• Subjects: Analysis; Binders (Materials); Chemical activator (NaOH); Chemical properties; Non-cement binder; Pozzolanic materials (slag, palm oil fuel ash, rice husk ash); Properties; Sodium hydroxide
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2013.08.077

•A new non-cement binder (NCB) is developed as a supplement of cement.•NCB is fabricated using slag, POFA and RHA with NaOH at ambient temperature.•Four different mix ratios of slag, POFA and RHA were designed to fabricate the NCB.•NaOH is the key element that contributes as a binding agent in developing NCB.•NCB could be used as a sustainable binder (alternative of cement) in the near future. The aim of the study is to fabricate a new non-cement binder (NCB) using slag, palm oil fuel ash (POFA) and rice husk ash (RHA). To activate these materials, sodium hydroxide (NaOH) was used at 2.5%, 5.0% and 7.5% by weight of NCB. Four different mix ratios of the slag, POFA and RHA were designed to fabricate the NCB. Mortar-prisms of NCB were cast using water-to-binder ratio of 0.5 and 0.6 with required superplasticizer. Mortar specimens were immersed in a water bath at 25±2°C for curing. NCB was tested for its consistency, setting time, flow, flexural and compressive strengths. XRD, SEM and FTIR analyses of NCB-mortars were also obtained. The results revealed that the consistency, setting time, flow and strength of NCB-paste/mortars are greatly influenced by the mix proportion and fineness of constituent materials of NCB, and NaOH doses. NCB-mortar containing 42% slag, 28% POFA and 30% RHA with 5% NaOH achieves the highest compressive strength of 40.68MPa and a flexural strength of 6.57MPa at 28days. From the FTIR analysis, NCB-mortars are observed to have silica–hydrate bond with sodium or other inorganic metals (i.e., sodium–silica–hydrate–alumina gel). Therefore, NCB could be fabricated from the aforementioned materials.