Effect of fly and bottom ash mixture from combustion of biomass on strength of cement mortar

Abstract

The preliminary results of fly and bottom ash mixture form combustion od biomass (80% of tree waste and 20% of palm kernel shells) for the produce of ceramic mortars has been presented. Currently, bio- ash from fluidized bed are deposited in landfills. Use of this ash to production of cement mortar instead of sand will reduce the consumption of the mineral resources. The chemical composition of this waste materials was determined using X-ray fluorescence (spectrometer ARL Advant ‘XP). Cement mortar were made using CEM I 42.5 R. The ash were added in an amount 20% of cement weight (in different proportions of fly and bottom ash). The results showed, that the compressive strength (after 28 days) of cement mortar containing ash is higher regardless of the type of ash mixture used. The highest compressive strength (increased by 7.0% compared to the control sample) was found for cement mortars in which the ratio of fly ash to bottom ash was 10/90. This mortars also showed the highest frost resistance (after 150 cycles freezes and unfreeze). The largest decrease the compressive strength (over 18.7%) after the frost resistance test. While cement mortars in which the ratio of fly ash to bottom ash was 90/10 showed the highest frost resistance (after 150 cycles freezes and unfreeze).