Sustainable Binder Strategies: Comparative Effects of Palm Oil FuelAsh in High-Volume GGBS Concrete
DOI:
https://doi.org/10.47363/t6y5ww27Keywords:
Hydraulic Lime, Hydrated Lime, Ordinary Portland Cement, Portland-Limestone Cement, Concrete, Ground Granulated Blast Furnace Slag, Palm Oil Fuel Ash, Compressive StrengthAbstract
Concrete faces persistent challenges to its durability, performance, and sustainability, including cracking from thermal and shrinkage stresses, chemical degradation, freeze-thaw damage, and the high carbon footprint of cement production; workability, curing, and maintenance further complicate its use.
This study evaluates the combined use of POFA and GGBS as partial cement replacements to improve sustainability and mechanical performance, identifies methodological gaps in typical POFA characterisation, and demonstrates that modest POFA additions in high-volume GGBS binders can reduce CO2e while mitigating early-age strength limitations of latent hydraulic systems.
POFA was introduced at 0-6% replacement in 1% increments within an 80% GGBS binder matrix across four secondary binders: ordinary Portland cement, Portland-limestone cement, natural hydraulic lime, and calcium air-lime. Compressive and flexural strengths were measured at 7, 14, 28, and 91 days using a 1:1:2 aggregate mix and water binder ratio of 0.40; water submersion and ambient curing were compared at 28 and 91 days.
Incorporation of POFA in GGBS/CEM I composites yielded compressive strengths above C30/37 MPa, a 16.6% increase over the control, and improved workability. Optimal POFA contents for peak flexural strength were binder dependent: 2-3% for GGBS/CEM I, 5% for GGBS/CEM II and GGBS/CL90,and 6% for GGBS/NHL5, implicating filler effects, particle packing, latent hydraulicity, and secondary pozzolanic reactions in microstructural refinement.
Mixes were highly curing-sensitive with strength variations up to 33% resulting in a compressive strength ranking CEM I > CEM II > CL90 > NHL5,while CEM II and NHL5 showed similar responses to POFA. Significant compositional variability in both the chemistry and morphology of POFA was evident in the literature and this sample, underscoring the need for fraction-specific chemical and mineralogical characterisation. These results indicate that carefully optimised, low-level POFA additions to high-volume GGBS binders can enhance performance and reduce clinker demand, supporting more sustainable cementitious formulations.
