The investigation of expanded polystyrene creep behaviour

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/m 3 , 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 e c ( t n ) and predictive point estimate of creep strain e 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 e c ( T ) for the load time of 10 years.