Manufacturing of compressed stabilized earth bricks (CSEB) using aluminium dross

Loo, Yi Xin (2022) Manufacturing of compressed stabilized earth bricks (CSEB) using aluminium dross. Final Year Project, UTAR.

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Abstract

Carbon dioxide (CO2) is a greenhouse gas whose atmospheric concentration is increased year by year and reflects a significant impact on the global. Compressed stabilized earth block (CSEB) is one of the masonries units, which is energyefficient, high strength and environmentally friendly as compared to fired brick. Cement is the major stabilizer in casting CSEB, but cement manufacturing factory is one of the major emission sources of CO2. At the same time, the growth of population all over the world, it indicates the growth of the various type of factories. However, the growth of factories not only brings the growth in the economy but also the challenges disposal of waste generated safely for the ecological balance. In addition, aluminium factories are the major source of aluminium dross (AD) generation. It is a challenge to safely dispose of AD because it is considered a hazardous waste that will reflect a lot of environmental issues and even human health problems. The most common way to dispose of is through landfill, but leachate from the landfill might bring a lot of disadvantages to the environment and affect humans indirectly. Hence, to solve the issues due to cement used in CSEB and AD, AD is suggested to replace the cement used in CSEB fabrication. It can reduce the cement usage and also solve the amount of AD to be disposed of. The objectives of this research are (i) to fabricate CSEB with partial replacement of cement by aluminium dross powder for sustainable purpose, (ii) to evaluate the engineering properties and durability of the fabricated CSEB and (iii) to elucidate the feasibilities of aluminium dross as part of the cement substitution in CSEB. The cement replacement percentage for this research was ranging from 0 to 35 % of AD. All the CSEB specimens with 28 days of curing process were tested to identify their engineering properties through bulk density test, compressive strength test, water absorption test, porosity test, air permeability test and microstructure analysis. In this research, the most suitable cement replacement percentage is 15 % (CAD-15) at 28 days of curing and indicates a 5.499 N/mm2 of compressive strength which is most similar to 5.512 N/mm2 of purely cementstabilized specimen although the optimum replacement is 10 % of AD. The 28thday compressive strength and water absorption rate of the CSEB specimen with 5, 10, 15, 20, 25, 30 % replacement are within the recommended limit of 3 N/mm2 and 15 % respectively except for the CSEB with 35 % of AD substitution (CAD-35). The main mechanism that influences the mechanical properties is the formation of calcium silicates hydrates (C-S-H) and calcium aluminate hydrates (C-A-H) gel from the reaction between pozzolanic reaction and cement hydration process. Formation of these gels contribute to the bonding between soil matrixes and consequently reduce the pores and capillaries formation. The more the bond formed, the density and strength will be higher. Consequently, the water absorption, porosity and air permeability will be much reduced. Therefore, after the optimum replacement percentage, the bond between soil matrixes started to become weaker and thus showed a lower strength. In addition, for CSEB with 30 % of cement replacement (CAD-30), since its strength and water absorption were within the recommended standard, therefore, it had been used for cost feasibility study. From the analysis, CAD-30 had resulted a higher profit earn as compared to CS. Hence, based on the results obtained, fabrication of CSEB with the incorporation of AD will promote in reduction of air pollution and mitigate thev11 problem caused during the conventional brick firing process and cement manufacturing process. Furthermore, CSEB also solved the waste management problems and landfill capacity issues, thus promoting a more sustainable environment.

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