Geopolymer mix in accordance to design of experiment (DOE) method

Abstract

This paper presents an experimental study conducted to assess the capability of using DOE method to achieve particular targeted strength for geopolymer concrete. Targeted strength of 30 MPa, 40 MPa and 60 MPa were used in this study. Cube samples with dimension of 100 mm were used for compressive strength test. Similar DOE method calculation as in normal concrete mix were calculated for all the raw material ratios in geopolymer concrete mix. Parameters such as characteristic strength, standard deviation (s), margin (m), target mean strength (fm), free-water/cement ratio (w/c), slump, relative density of aggregate (SSD), concrete density (D), percentage grading of fine aggregate passing 600 μm sieve, and proportion of fine aggregate were determined according to the respective concrete mix design. However, only characteristic strength, fm and w/c varied in each targeted strength mix design while the other parameters were kept constant. In order to yield geopolymer concrete, the used of cement and water in DOE form were fully substituted with the used of fly ash and alkaline activator respectively. Final strength gained from test result for the respective 30 MPa, 40 MPa and 60 MPa were 74.6 MPa, 84.5 MPa and 97.7 MPa. Therefore, it was noted that geopolymer mix yielded higher strength compared to the targeted strength by using the DOE method calculation.