Geotechnical performance of tropical laterite soil using palm oil fuel ash and activator magnesium oxide stabilizer

Agricultural by-products waste, such as palm oil fuel ash (POFA) and magnesium oxide (MgO) activator, were utilized to achieve the chemical stabilization of laterite soil. This approach is environmental friendly as it aims at eliminating the potential hazards related to improper waste disposal methods and decreasing greenhouse gas emission generated by cement production to enhance the compressive strength of the soil. In this work, different percentages of additives ranging between (10% and 40%) with the addition of MgO between (2.5%and10%) were incorporated into the examined soil and cured at room temperature. Unconfined compressive strength (UCS) test, flexural strength (FS) test, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis were conducted to examine the stabilized soil samples. The results showed that UCS values of LS-POFA-MgO sample increased up to 3.56 and 5.05 MPa after 7 and 28 curing days when the POFA-MgO was used at a ratio of 30:10, respectively. An increase of approximately 17 times greater than the untreated soil was also found. The FS LS-POFA-MgO showed a significant increase, exhibiting an enhanced peak behavior, thereby reducing deflection with brittleness. The findings were also substantiated by the pozzolanic activity enhancement of the former composition, as validated by the EDX patterns and SEM analyses. Therefore, the use of POFA based MgO activator is effective in addressing some soil issues and selecting the best soil mixtures. Furthermore, the soil's compressive strength improved significantly, making it suitable for utilisation as a material for the pavement base.