The investigation of expanded polystyrene creep behaviour

¹ Moscow state university of civil engineering, Yaroslavskoye shosse, 26, Moscow, Russia, 129337
² Scientific Institute of Thermal Insulation Vilnius Gediminas Technical University (VGTU), 10223 Saulėtekio al. 11, Vilnius, Lithuania

^* Corresponding author: science-isa@yandex.ru

Abstract

The results obtained in long-term testing under constant compressive stress of the cut from the Slabs EPS 50/100 and EPS 150 with the density ranging from 15 to 24 kg/m³, which were manufactured by the same manufacturer by foaming EPS solid granules (beads) in closed volume. The creep strain of the above described specimens was used as a criterion for estimating the deformability of the EPS slabs under long-term compressive stress. It was measured using special stands EN 1606, maintaining constant stress during the fixed time interval t_n=122 days. Creep strains were determined by the methods described in EN 1606 for constant stress σ_c=0.35σ_10% (compressive stress σ_10% was determined in accordance with EN 826:2013. The long-term compressive stress measurement error did not exceed 1 %, while the creep strain measurement error was not larger than 0,005 mm. The tests were conducted at the ambient temperature of (23±2)°С and relative humidity of (50±5) %.The long-term constant compressive load σ_c=0.35σ_10%. The method of mathematical and statistical experimental design optimization models taking into account the thickness of specimens is proposed to determine the creep compliance I_c (t_n) the creep strain ε_c (t_n) and predictive point estimate of creep strain ε_c (T). Graphical interpretation of the abstained models is also presented. It should be noted that the abstained equations may be used in practice for estimating the creep strains at time t_n=122 days and predictive estimates of ε_c (T) for the load time of 10 years.