Creep of expanded polystyrene under constant compressive stress

Abstract

For the first time, the summarized data obtained in the long-term 5.5 year testing of expanded polystyrene under constant compressive stress, σc = (0.2÷0.45) σ10%, have been presented. The book also provides the predictions of deformations caused by creep under constant long-term compression, which were made for long periods of time (10, 20 and 50 years), and the determined confidence intervals of prediction. Special attention is paid to the methods of determining confidence intervals for obtaining the predictive creep values for expanded polystyrene. The data presented in this part of the book may be of practical and theoretical interest because the data found in the literature on the topic are rather controversial. Moreover, the experimental investigation of the relaxation of stresses in time from 1 to 25% under fixed constant compressive strains is described. Physical relationships between creep and time (or stress relaxation – time), which were obtained experimentally under constant compressive stress σc (in parts of σ10% equal to 0.25, 0.35, 0.45 or ε0 = const, respectively), have been used in the investigation. The tables presenting the results of the experiments, which make them more easily understood by the readers, and the bibliography on the considered problem, are also given.