Molar ratio mixture design for optimising compressive strength of kaolinitic cement

• Published in: Materials technology (New York, N.Y.) N.Y.), 2011-11, Vol.26 (5), p.243-250
• Main Authors: Hwang, C L, Kuo, C K, Wang, E H
• Format: Article
• Language: English
• Subjects: Amorphous materials; Cements; Compressive strength; Exploitation; Optimization; Polymerization; Portland cements
• ISSN: 1066-7857; 1753-5557
• DOI: 10.1179/175355511X13110717549314

The production of conventional cementitious materials is causing further deterioration of the environment. Metakaolin, a geopolymeric cement, is an inorganic amorphous material that is an effective ecological alternative to ordinary cement. It has been 20 years since its exploitation. However, the hardening mechanism of geopolymer polymerisation somewhat differs from that of ordinary Portland cement. Taking into consideration four principal variables in molar ratios and liquid/solid ratios, this study used a correlational approach to identify the optimum mixture design to obtain maximum compressive strength comparable to in situ conditions. The mole values of three basic chemical constituents SiO sub(2), Al sub(2)O sub(3) and M sub(2)O (M represents a positive ion of metal) in metakaolin were found to be equal to 0.9, 0.93 and 0.54 respectively. Under scanning electron microscopy, the images of specimens showing complete polymerisation were observed to reveal the foundations of strength establishment. The mixture design and the mix procedure are reported herein to ensure quality control and promote the utilisation of metakaolin cement. The design formulae of the metakaolin mixtures are provided, and two-dimensional phase diagrams are recommended in this paper. Through a standardised design approach, it is expected that the geopolymer will become an important part of sustainable development in the twenty-first century.