Effect of low quality aggregates on the mechanical properties of lightweight concrete

Ignimbrite is one of the pyroclastic volcanic rock formations. Its soundness, lightness and shape workability are the most advantageous properties. These properties get its usage since prehistoric ages as construction materials, like bricks and caves. This kind of pyroclastic volcanic rock exists all over the world, particularly in volcanic and high seismicity provinces. Some physical and mechanical properties of ignimbrite rock samples are obtained in order to interpret influence of aggregate strength on concrete produced and for comparing with other lightweight aggregate concretes. The ignimbrite and pumice are used as crushed aggregate in the present work. The aggregate concentration of concrete specimens is designed in four different groups by using 0, 25, 50, 75 and 100% ignimbrite and pumice, as a proportion of aggregate volume with the same water cement ratio of 0.6 and the dosage of 300 kg/m(3) lightweight concrete manufactured. All concrete specimen groups are settled in steel formworks and water cured for 7, 14 and 28 days. According to the pumice and perlite like lightweight concretes, the ignimbrite concretes had higher strength. So, its usage as a construction material like lightweight concrete, brick or panel is more advantageous in producing cheap anti-seismic constructions. Therefore, ignimbrite concretes lighter the building, get less earthquake loads and behave better than gas, pumice or perlite concrete. Another advantage of ignimbrite is its occurrence in active fault zones (earthquake areas) all over the world.