Optimization of metakaolin-based Geopolymer Composite using Sisal Fibers, response Surface Methodology, and Canonical Analysis

In the present context, geopolymer appears as an ecologically viable alternative compared to Portland cement, due to lower CO2 emissions rate. The objective of this work is to study reinforced geopolymer pastes with elongated sisal fibers by means of parameters such as flexural strength. For this, metakaolinwas used as an aluminosilicate source material in addition to a combination of sodium silicate and sodium hydroxide as the activator solution. The influence of the independent variables sisal fiber percentage, molar ratio between activator and metakaolin, and the curing time was evaluated through an experimental design. The statistical model of central composite planning was used to optimize the results obtained. The best value for the modulus of rupture was of approximately 9.3 MPa, obtained with 2 days curing, with the activator/metakaolin ratio of 0.59 and percentage of sisal fiber de 4.34.