Indian Journal of Science and Technology
Year: 2019, Volume: 12, Issue: 14, Pages: 1-16
Jeffrey Ken B. Balangao1* and Maria Sheila K. Ramos2
1Department of Arts and Sciences, University of Science and Technology of Southern Philippines-Oroquieta Campus, Mobod, Oroquieta City, 7207 Misamis Occidental, Philippines; [email protected]
2Department of Chemical Engineering and Technology, College of Engineering and Technology, MSU-Iligan Institute of Technology, 9200 Iligan City, Philippines;
*Author for correspondence
Jeffrey Ken B. Balangao
Department of Arts and Sciences, University of Science and Technology of Southern Philippines-Oroquieta Campus, Mobod, Oroquieta City, 7207 Misamis Occidental, Philippines. Email: [email protected]
Objecive: To investigate the influences of CaO/SiO2 ratio, % aluminum addition and curing time to the resulting compressive strengths of produced Autoclaved Aerated Concretes (AACs) with fly ash from a coal power plant in Misamis Oriental, Philippines as an initial activity prior to optimization using Response Surface Methodology. Methods: The production of each AAC sample was based on a Box-Behnken experimental design of the Response Surface Methodology using the parameters: CaO/SiO2 ratio, % aluminum addition and curing time. After which, compressive strengths were obtained from these AACs following the ASTM C 109 method. X-ray Diffraction (XRD) was used to determine tobermorite phases in the samples which are the main binding phases in them. Findings: Compressive strengths of the produced AACs ranged from 2.866 to 11.843 MPa which passed the ASTM C 1693 requirement. The presence of tobermorite in all samples was a good indication for these amenable strength values. These values were observed to pass the requirement at all ranges of CaO/SiO2 ratio and lower % aluminum addition and curing time applied. According to the ANOVA for reduced cubic model, among the production parameters, only the curing time had a significant effect to the resulting compressive strengths since p-value < 0.05 but it had an inverse effect since it had a negative coefficient estimate. However, only the CaO/SiO2 ratio had a positive effect as it had a positive coefficient estimate. The interactions between factors AB (CaO/SiO2 ratio-% aluminum addition) and AC (CaO/SiO2 ratio-curing time) had significant positive effects since their p-values were lesser than 0.05 and their coefficient estimates were positive. Improvement: It is recommended to conduct Scanning electron microscopy for the samples to view micrographs and validate the XRD results. The use of other production parameters like fly ash-to-cement ratio, water-to-cementitious materials ratio, curing temperature etc. and the determination of other functional properties such as flexural strength, impact strength, fire- and sound- proof properties among others are also recommended.
Keywords: Autoclaved Aerated Concrete, Compressive Strength, Fly Ash, Production, Tobermorite, X-ray Diffraction
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