Expanded obsidian as a soil aerator, its porosity, physical and mechanical characteristicsArtsruni Safaryan, Tamara Sarkisyan, Tatevik Paytyan, Marine Kalantaryan and Armine BaghdagyulyanE3S Web Conf., 175 (2020) 09019DOI: https://doi.org/10.1051/e3sconf/202017509019