**2.1 Material**

POC sand as well as natural sand were utilised in this study. POC sand was used as replacement of natural sand. Palm oil clinker (POC) sand was obtained by crushing POC chuck obtained from the palm oil processing plants in Johor. The POC sand that passed 2.36 mm sieve according to ASTM C33 [23] was selected. **Figure 4** shows the grading of the POC compared with that of natural river sand. POC sand has a smaller size than the natural sand but both still well graded and can be used for the mixture. This is implying that surface area of PO is higher than that natural sand. In the SEM micrographs experiment, POC sand show craters between 14 μm to 61 μm and micro pores with diameters between 12 μm and 15 μm (**Figure 5**). POC sand has more porosity of 6% compared to natural river sand of only 3%.
