Peat soil treatment using POFA

Abstract

Palm oil fuel ash (POFA) is a by-product from palm oil mill. It is found that this ash contains pozzolanic which possess cementitious properties that enable it to replace cement. This leads to this research to study the possibility of POFA to replace Ordinary Portland Cement (OPC) in stabilizing peat soil. POFA which were collected from Bukit Kerayong was dried than sieved through 445 µm sieve. In order to get fineness POFA, ash which passes through 445 µm sieve were then grinded. As for the peat soil, it was dug out approximately 0.5m from the surface of Sungai Belankan, Sepang. It was first heated up in the oven and sieved to remove the large fibres. Several series of physical properties test were conducted in this study. The tests conducted were liquid limit test, specific gravity test, particle size distribution test, compaction test, organic content test and moisture content test. On top of that, the classification for peat soil was found as low to medium degree of decomposition, which is according to von Post scale, it can be classified as H4. The peat has high amount of moisture content which is 211%. For engineering properties which is also the main objective for this test, an unconfined compression test was conducted for a total of 15 samples with 38mm of diameter and 76mm of height. These samples were divided into four groups named P0, P1, P2, P3 and P4 with 0% additive, 30%OPC, 20%OPC + 10%POFA, 15%OPC + 15%POFA and finally 10%OPC + 20%POFA respectively. Each group experienced 3 different curing periods of 0, 7 and 14 days and named as A,B and C respectively. Based from the deviator stress vs. axial strain graph, the highest recorded UCS value is 128 kPa which was tested on sample P2C. It was even higher than the value of P1C which is 92.1 kPa. Hence, it shows that there are possibilities for POFA as one of a pozzolanic material to replace cement in peat soil stabilization.