TY JOUR TI THE EFFECT OF ASTRALENES ON THE FIRE RESISTANCE AND STRENGTH CHARACTERISTICS OF CONCRETE IN A HYDROCARBON FIRE KW concrete KW astralenes KW fire resistance KW hydrocarbon fire KW residual strength JO Scientific and analytical journal «Vestnik Saint-Petersburg university of State fire service of EMERCOM of Russia» AU Pylaeva, E.A. PY 2026 IS 2026 PB Saint-Petersburg University of State Fire Service of Emercom of Russia