Experimental investigations and fuzzy logic modeling of compressive strength of geopolymers with seeded fly ash and rice husk bark ash

In the present work, compressive strength of inorganic polymers (geopolymers) made from seeded fly ash and rice husk bark ash has been predicted by adaptive fuzzy logic. Different specimens, made from a mixture of fly ash and rice husk bark ash in fine and coarse form together with alkali activator made of water glass and NaOH solution, were subjected to compressive strength tests at 7 and 28 days of curing. The curing regime was different: one set cured at room temperature until reaching to 7 and 28 days and the other sets were oven cured for 36 h at the range of 40–90 °C and then cured at room temperature until 7 and 28 days. A model based on fuzzy logic for predicting the compressive strength of the specimens has been presented. To build the model, training and testing using experimental results from 120 specimens were conducted. The data used as the inputs of fuzzy logic model are arranged in a format of six input parameters that cover the percentage of fine fly ash in the ashes mixture, the percentage of coarse fly ash in the ashes mixture, the percentage of fine rice husk bark ash in the ashes mixture, the percentage of coarse rice husk bark ash in the ashes mixture, the temperature of curing and the time of water curing. According to these input parameters, in the fuzzy logic model, the compressive strength of each specimen was predicted. The training and testing results in fuzzy logic model have shown a strong potential for predicting the compressive strength of the geopolymer specimens.