Alkali-activated concretes (AAC) are emerging as sustainable alternatives to Portland cement concrete (PCC) due to their substantially lower carbon emissions; however, their fatigue behaviour requires further investigation. This study numerically evaluates the monotonic and fatigue performance of fly ash-based AAC in comparison with PCC of comparable strength. Three-point bending under monotonic loading is first simulated using ABAQUS/CAE. A two-dimensional notched beam specimen of size 262.5 mm × 75 mm with a centrally located bottom notch of 15 mm × 3 mm is modelled. Two strength grades of AAC and corresponding PCC mixes are analysed. Ultimate load, mid-span deflection, and crack mouth opening displacement are obtained from history outputs. The monotonic response is then used to define constant-amplitude cyclic loading for fatigue analysis, with load ranges of 20-80% and 25-95% of the ultimate load. Structural responses under cyclic loading are examined and compared. Since finite element modelling cannot directly capture the complete fatigue life of quasi-brittle materials, fatigue resistance is approximated using the number of cycles associated with the initial rapid deformation stage, assumed to represent 10% of the total fatigue life. From the observed results, AAC performed higher fatigue strength with respect to the PCC, highlighting its potential for sustainable constructions.
Anand et al. (Wed,) studied this question.