Abstract

Recycling industrial waste material as construction material to minimize production of ordinary Portland cement could solve arising industrial waste management problems and increase environmental sustainability. This study focused on the incorporation of wood biomass ash in combination with silica fume in blended cement. In this study, physical and chemical properties of high calcium wood ash (HCWA) and densified silica fume (DSF) were thoroughly characterized. Results indicated that HCWA is an active hydraulic binder material as it is rich in calcium carbonate and quicklime content. Fresh concrete properties showed HCWA-DSF blended cement pastes have marginally higher standard consistency and significantly longer setting times as compared to pure cement paste. Additionally, hard concrete properties, such as mechanical strength, water absorption, air permeability and chloride resistance properties of mortar were also investigated. Enhancement in the compressive and flexure strength of mortar was observed for mortar mixes containing DSF and HCWA. The incorporation of HCWA at level of cement replacement ranging between 4 to 12% in combination with 7.5% of DSF was observed to significantly improve the chloride resistance of mortar mixes produced.

Key words: High calcium wood ash, ternary blended cement, mechanical strength, durability, recycling.

Abbreviation

HCWA, high calcium wood ash; DSF, densified silica fume; XRD, X-ray diffraction pattern; XRF, X-Ray Fluorescence; ASTM, American Society of Testing Materials; LOI, loss on ignition; CP, cement paste; C-S-H, calcium silicate hydrate; OPC, ordinary Portland cement; PC, Portland cement.