Improvement of Compressive Strength of Mortar from Unground Palm Oil Fuel Ash
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Abstract
This research aimed to study the compressive strength of mortar incorporating low-calcium fly ash and unground palm oil fuel ash as partial replacements for hydraulic cement at replacement levels of 20%, 30%, and 40% by weight. The ratios between fly ash and palm oil fuel ash were varied at 30:70, 50:50, and 70:30 by weight. Compressive strength was determined at curing ages of 14, 28, and 56 days. In addition, the effect of activating the mixtures with sodium hydroxide (NaOH) solution at different concentrations was investigated. The results showed that, at the same replacement level of pozzolanic materials, increasing the proportion of palm oil fuel ash resulted in a decrease in compressive strength. Moreover, increasing the NaOH concentration up to 1.0 molar enhanced the compressive strength of the mortar, with a more pronounced effect observed in mixtures containing lower cement content. However, when the NaOH concentration reached 1.5 molar, the compressive strength of the mortar decreased.
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