Assessing the applicability of rice husks ash as an alternative to clinker in cement manufacture

Abstract

The widespread use of Portland cement (PC) in the construction industry has led to significant environmental impacts, including high carbon dioxide emissions and depletion of non-renewable resources. This has raised concerns about the sustainability of PC and the need for alternative binders with lower carbon emissions. Agricultural and industrial waste materials, such as rice husk ash (RHA), have shown potential as partial replacements for cement due to their suitable chemical composition and abundance. RHA possesses pozzolanic properties, making it an attractive option for reducing the demand for PC and its associated greenhouse gas emissions. However, the utilization of RHA in cement manufacture requires careful consideration of its physiochemical properties, burning techniques, and optimal processing methods. Furthermore, the potential of RHA-blended cement to meet the required physical and mechanical properties of concrete needs to be evaluated. This study aims to assess the applicability of RHA as an alternative to clinker in cement manufacture. The specific objectives include determining the physiochemical properties of RHA and clinker, investigating the physiochemical properties of cement made, and evaluating the physical and mechanical properties of concrete made with RHA-blended cement.The tests carried out included compressive strength of cement and concrete, setting time, consistency,specific gravity and fineness. All cement samples satisfied the ASTM standards of type P cement (ASTM C-595-03) except 50% replacement at 7 days curing and both 40% and 50% at 28 days curing. An increase in the RHA content showed an increase in the compressive strength at 7days curing for only 10%, 20%, 30% RHA replacements and the percentage increase in strength was 11.1%, 15.8% and 5.9% respectively. The 40% and 50% replacements showed a decrease in strength at 7days curing at 6.7% and 23.1% respectively. At 28days curing, 10% RHA replacement had a compressive strength of 25N/mm2 which is higher than that of the control sample (23N/mm2) compared to all other replacements that had lower compressive strength than the control sample (22 N/mm2 for 20%RHA, 21 N/mm2 for 30%RHA, 18 N/mm2 for 40%RHA and 16 N/mm2 for 50%RHA).This study highlights the potential of RHA as a sustainable additive in cement production, promoting cleaner and more environmentally friendly practices in the rice and construction industries.