This paper aims to evaluate the effect of replacement of aggregate by recycled one on fracture response of selected composites. These are hemp fibre reinforced cement-based composites. Four different mixtures were prepared: in reference one, the only natural aggregate was used whereas in the other three mixtures, the natural aggregate was replaced by recycled one in the amount of 10, 25 and 50 %, respectively. All mixtures contained hemp fibres with a length of 10 mm in the dosage of 1 % by volume. In order to determine the selected mechanical fracture characteristics of the investigated composites, three-point bending fracture tests were carried out on prismatic specimens with nominal dimensions 40 × 40 × 160 mm3 provided with an initial notch. During the whole course of the testing, the loading process was governed by a constant displacement increment of 0.02 mm/min. The vertical displacement (midspan deflection) was measured using the inductive sensor mounted on a special measurement frame placed on the specimens. The fracture tests were terminated when the midspan deflection reached 0.5 mm. The mechanical fracture parameters were obtained through a direct evaluation of the fracture test data via the effective crack model and the work-of-fracture method. The paper shows that composites with a higher dosage of recycled aggregate (25 and 50 wt%) achieve similar values of mechanical fracture properties, so this replacement can be recommended.
