Chemically graded geopolymer under flexural loading: experimental modelling

Abstract

In this paper, a functionally graded solution is proposed for stress distribution in functionally graded geopolymers under flexural loading with the load direction parallel to the gradient direction. A functionally graded geopolymer specimen is made by sequential pouring and subsequent vibration of two different mixtures of alkali activated pastes into appropriate moulds. Diffusion of the two mixes into each other during vibration and an early age curing process causes chemically graded distribution of the constituent oxides. Because of the variation of the elastic modulus in functionally graded specimens, the stress distribution pattern is related to its pseudo-strain function through different equations. According to the considered functions for both the modulus of elasticity and pseudo-strain, different equations are proposed to predict the flexural strength of functionally graded geopolymers. The best performance model is acquired by adopting an inverse tangent for variation of strain in the deflected beam and the exponential function for variation of the modulus of elasticity in the functionally graded region.