Petrographical characteristics as an indicator of physico-mechanical properties of concrete aggregate

The physical and mechanical properties of concrete designed to a C40 mix using 6.5 mm and 10.0 mm aggregate from Montenegro and Malta respectively were investigated. Ultrasonic pulse velocity (UPV) and compressive strength (CS) tests corroborated findings in the literature. The coarseness of aggregate was found to be of primary technological importance: CS increased with increasing aggregate size. Although UPV in all the tests was between 3.5 km/s and 4.5 km/s – that is the concrete quality was of good grade – the CS of the control cubes for the 6.5mm and 10.0mm coarse aggregate mixtures was 27 N/mm² and 39 N/mm² respectively. The homogeneity of the concrete was affected by the physical and mechanical properties of the aggregate, including its size, but its petrological texture was also a significant parameter. The petrological characteristics of the aggregate severely affected the load-bearing capacity of the concrete. These characteristics had a significant bearing on the physico-mechanical properties of the hardened concrete. (paper)