FRACTURE PROPERTIES OF ALKALI ACTIVATED MORTARS

In this paper, three different coal fly ash-based alkali activated mortars are studied. The three different mortars are obtained using the same binding system but different types (i.e. silica sand or expanded perlite) and sizes of aggregates. Small-scale beams are constructed together with additional specimens for material characterization. The small-scale beams are notched and loaded in a three-point bend setup to investigate the fracture properties of the three mixtures. The setup utilized follows the draft of the ACI 446 report on the fracture testing of concrete. The fracture energy is determined from the work of fracture and results highly dependent on the type of aggregate rather than its dimension. Digital image correlation is employed to obtain the displacement and therefore strain components on the side surface of the specimens in order to investigate the crack propagation and determine the size of the fracture process zone, which appears to be similar to the one of a cement-based mortar.