Roles of superabsorbent polymers (SAPs) and palm oil fuel ash (POFA) on the strength, cost analysis and CO2 emission of lightweight concrete: Comparison with aluminum-based aerated concrete

Abstract

This work investigated the effects of superabsorbent polymers (SAPs) as pore-forming agent and palm oil fuel ash (POFA) as sand replacement (0–100 % by weight) on the strength, economic feasibility, and CO2 emissions for lightweight concrete production. The product properties were compared with the traditional aerated concrete (with aluminum powder), which aimed to shed light on the use of SAPs and POFA for manufacturing a more sustainable lightweight concrete. The use of POFA to replace sand increased the cost of production by approximately 1–7% and CO2 emissions by approximately 3–12 % due primarily to the transportation of the POFA from the oil palm fuel power plant, which could be avoided if produced on site of or near the power plant. The use of SAPs in the preparation of the lightweight concrete led to a reduced compressive strength compared to the aerated concrete, especially in the autoclaved samples, calculated as 15–33 % for 28 days and 44–56 % for autoclaved curing, possibly due to a collapse of the porous structure under high temperature and pressure. These drawbacks could be eliminated if the natural SAPs in the form of fine particle size were treated with Ca2+ in agro-waste ash so as to facilitate and enhance the pozzolanic reaction during the curing phase. The fossil-based SAPs could then be replaced with the organic-based ones, which would be a more sustainable construction material for a lower-carbon society. However, further investigations into other aspects of these materials should be conducted.

Keywords

• Palm oil fuel ash
• Lightweight concrete
• Superabsorbent polymers