Compressive strength of functionally graded geopolymers: Role of position of layers

In the present paper, compressive strength of functionally graded geopolymeric (FGG) specimens was studied. FGG samples were prepared by casting two different geopolymeric mixes. Several FGG structures were made by changing volume fractions of the two geopolymeric mixtures in a specific specimen. Compressive strength of FGG specimens was measured in such way that the direction of functionally graded layer was parallel to the direction of applied load. The obtained results indicated that the strength of FGG specimens was higher than that anticipated from the rule of mixtures. The highest positive deviation was related to the specimen with FGG layer in the middle of specimen. It was concluded that the position of functionally graded layer is the controlling factor of strength of FGG specimens.