Synthesis of sustainable lightweight foamed concrete using palm oil fuel ash as a cement replacement material

The replacement of conventional ordinary Portland cement with industrial by-products to produce cellular lightweight foamed concrete can have economic and environmental benefits. The performance of using a palm oil industrial by-product, namely, palm oil fuel ash (POFA), as a cement replacement material was investigated with proportions of 10, 20, and 30% to achieve a targeted oven-dry density of 1300 kg/m3. Tests on compressive & splitting tensile strengths, water absorption, porosity, and sorptivity were carried out and analysed. Further, the microstructural analyses through X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) were conducted to correlate the test results. Non-destructive tests of ultrasonic pulse velocity and electrical resistivity tests were used for investigating the quality of concrete and corrosion resistivity. The results revealed that a replacement with 20% POFA produced slightly better performance compared to other mixes. A density reduction of about 43% with a replacement of 30% POFA was achieved in the development of non-structural foamed concrete. A reduction in compressive strength was noticed beyond 20% of POFA replacement and this could be attributed to the high amount of LOI, and porous nature of POFA; even though the UPV test results showed the foamed concrete as doubtful quantity the use of POFA as a sustainable material could be envisaged in such non-structural concrete. Furthermore, the SEM images shows the appearance of micro-cracks when 30% POFA was used. Moreover, the XRD results show a slight reduction in the intensity of the peaks of the crystalline phases when a higher quantity of POFA was used.