Materials and technologies in construction and architecture IV : selected peer-reviewed full text papers from the 4th International Scientific Conference 'Construction and Architecture: Theory and Practice of Innovative Development' (CATPID 2021 - Part I) : selected peer-reviewed papers from the 4th International Scientific and Technical Conference 'Construction and Architecture: Theory and Practice of Innovative Development' (CATPID 2021 - Part I), July 1-5, 2021, Nalchik, Russia