Screening of Factors Influencing Phosphate-Based Geopolymers Consolidation Time, Using Plackett-Burman Design

摘要

In this paper, Plackett-Burman design was employed for screening factors influencing phosphate-based geopolymers consolidation time, through comparing the differences between each factor at two levels. This design screens 9 factors through 12 experiments. Considered factors are: Si/P molar ratio, curing temperature, heating time, calcination of used aluminosilicate precursor, mold's condition, aluminosilicate particle size, chemical composition of aluminosilicate precursor, pH and acidic solution. Results show that curing temperature, calcination of aluminosilicate precursor, mold's condition and aluminosilicate particle size factors are responsible for 97.79% of the consolidation time variation. The most significant effect is attributed to curing temperature, with a contribution of 73.46%. This factor presents a negative effect. Thus, its increase generates the decrease of consolidation time. This result can be explained by the endothermic character of the geopolymeric reaction. In fact, the increase of the curing temperature activates the reaction which accelerates the kinetics of consolidation. The impact of the other factors like Si/P molar ratio, the heating time, nature of aluminosilicate precursor, pH values and the acidic solution is very small and it can be neglected, in the studied conditions. These factors did not present a kinetics influence and they haven't a direct effect on the consolidation time.