TY JOUR TI TECHNICAL CONDITION OF PRECAST BEAMS WITH THE USE OF EXPANDED LIGHTWEIGHT CONCRETE HOLLOW-CORE SLABS KW expanded lightweight concrete KW hollow-core slab KW durability KW defects KW strengthening JO Bulletin of Belgorod State Technological University named after. V. G. Shukhov AU Smolyago, G.A. AU Drokin, S.V. AU Dronov, A.V. AU Belousov, A.P. AU Pushkin, S.A. AU Smolyago, E.G. PY 2019 IS 4 PB Belgorod State Technological University named after V.G. Shukhov