Potential Mixture of POFA and SCBA as Cement Replacement in Concrete – A Review

Concrete is an important material used in all kind of building construction and ordinary Portland cement (OPC) is one of an important element in the production of concrete. However, the production of cement causes a problem because of high CO2 emission to atmosphere. The manufacture of 1 tonnes of cement would produce approximately released 1 tonnes of CO2. So, the need to search another material that can replace a cement with same properties and environmental friendly are crucial. The suitable material to replace cement has to be a pozzolanic materials. This is because pozzolanic materials has cementitious properties and high silica content. Palm oil fuel ash (POFA) and sugarcane bagasse ash (SCBA) are the material that suitable to replace cement because of high silica content. The use of POFA and SCBA in concrete has been studied by many researcher and it has been proved to improve the mechanical strength of the concrete either in normal concrete, high strength concrete or lightweight concrete. This paper would discuss the overview of the previous study on the cement replacement by POFA and SCBA and the potential of the both materials to be mix together to improve its properties. The chemical element which will be the focus point is SiO4, MgO, CaO and SO3, while the physical and mechanical properties such as workability, specific gravity, compressive strength and tensile strength will also be reviewed

Potential use of sugar cane bagasse ash as sand replacement for durable concrete

The increasing urban development, led by concrete, requires a higher availability of materials and energy, and it will be responsible for a high waste generation. To face the exploitation of natural resources, the use of fossil fuels and the reduction of waste disposal, new environmental-friendly strategies emerge accomplishing the circular economy principles. In this research, the use of poor reactive agro-industrial ashes as sand replacement in cement-based materials is investigated. Poor reactive sugar cane bagasse ashes (fly and bottom ash -SCB FA and SCB BA, respectively) from a power plant in Dominican Republic have been used in substitution rates of 10%, 20% and 30% of weight of sand. Physico-chemical characteristics of ashes are investigated and correlated to the performance of the bio-concretes. SCB FA showed being an enhancer of durability-related properties of the concrete even with high content of silica in form of quartz, due to the capability of modifying the microstructure of the concrete and an additional binding capacity of chlorides ions. Durability-related tests (open porosity test, electrical resistivity test, capillary absorption test and chloride migration test) have been conducted at 28, 60, 90 and 240days. Direct correlations exist when compared chloride migration resistance against porosity and electrical resistivity in concretes with SCB FA, not so for capillary absorption. This demonstrates the inadequacy of establishing conclusions about durability performance of bio-concretes based on durability tests when run independently. The use of agro-industrial ashes as substitutes of natural aggregates not only reduces the consumption of natural sand but can deliver bio-concretes with potential benefits in terms of compressive strength and durability

Characterization of sugarcane bagasse ash as a potential supplementary cementitious material: Comparison with coal combustion fly ash

This study aims to evaluate the potential of sugarcane bagasse ash (SCBA) as a supplementary cementitious material (SCM) in terms of composition. Using coal-combustion fly ash (CFA) as the benchmark, SCBA is characterized thoroughly using multiple tools to determine and compare particle size, particle morphology, chemical composition, glass content, element distribution and chemical status. It is found that SCBA has fine particle size (d50 = 6.76 μm, compared to 2.2 μm of CFA), high glass content (78.5 wt%, compared to 81 wt% of CFA), and relatively stable chemical composition, making it a potential effective SCM. The glass content of SCBA is dominated by amorphous silica (77.2%, compared to 53.6% of CFA), which can lead to formation of secondary calcium silicate hydrates in pozzolanic reactions. However, SCBA contains no spherical glass grains but many porous grains, which may compromise the workability of fresh-state cement-based materials. Another two detriments of SCBA are high carbon and potassium contents, which could potentially interfere the performance of cement-based materials. However, due to their existence forms (i.e., either light or dissolvable, as revealed by X-ray photoelectron spectroscopy), these detrimental effects can be mitigated through washing. A literature-survey based analysis shows that the ash samples adopted in this study are representative, so the conclusions drawn from this study are generally meaningful