Durability of high performance concrete containing palm oil fuel ash

The use of pozzolans, either naturally occurring or artificially made, has been in practice since the early civilisation. Of the artificial pozzolans, fly ash is the most commonly used globally. With the rise in the demand for high performance concrete in recent years, however, the demand for such pozzolanic materials is also increasing steadily. Perhaps the latest addition to the ash family is palm oil fuel ash (POFA); a waste material obtained on burning palm oil fibre and palm kernel shell as fuel in palm oil mill boilers that has recently been identified as a good pozzolanic material. This paper illustrates some test results on the performance behaviour of concrete incorporating POFA as a partial replacement of ordinary Portland cement (OPC). The durability aspects considered in this study are resistance to heat rise, carbonation, and resistance to aggressive chemicals like chloride and acid attack. Experimental investigation on resistance to heat rise demonstrates that the partial replacement of OPC by POFA is advantageous in controlling temperature rise. As compared with the specimens prepared form OPC alone, concrete specimens made with POFA exhibited much better resistance to attack by chloride ions and acid solution. It is the pozzolanic behaviour of the ash that has been credited for the excellent performance against such aggressive environments. Interestingly, the depth of carbonation was not influenced by the replacement of OPC as only a little difference in each value of carbonation between OPC and POFA concrete specimens has been detected.