Study of the relationship of oxides in the composition of alkaline alumosilicate binder on its module of elasticity
Journal Title: Вісник Одеської державної академії будівництва та архітектури - Year 2018, Vol 1, Issue 73
Abstract
One of the solutions to improve environmental and fire safety of glued wooden materials is to replace organic glues by inorganic binders of the R2O – Al2O3 – SiO2 – H2O system. However, the latter have the increased rigidity (low elasticity) compared to wood, the value of which is influenced, first of all, by the composition of the binder. Differences in coefficients of thermic expansion of the glue itself and glued materials can result in the occurrence in the glued connection of inner stresses. These stresses can destroy the connections before any external loads are applied. Internal stresses are especially dangerous at use temperatures below 0 ºС. These inner stresses can be eliminated to some extent by changing a design of the glued connection, by using glue with the lower modulus of elasticity or by bringing the value of modulus of elasticity to that of the wood. The organic resin-based glues are known to have the following values of modulus of elasticity: made with phenol- formaldehyde resin 3…5 GPa, resorcinol-formaldehyde resin 1…2.6 GPa, carbamide-formaldehyde 3.5…5.5 GPa, melamine- formaldehyde 3…4.5 GPa, whereas a pine, the most widely used in construction, is characteristic of the modulus of elasticity between 6 and 12 GPa. The work presents the results of the study of the influence of the ratio of basic oxides of the binder on its modulus of elasticity in bending after solidification at T = 125 °C. Using a symmetric non-compositional three-level experimental design of the second order (Box–Behnken design) under which the following ratio of oxides, these were: Na2O/Al2O3 = 0.6…1.0, SiO2/Al2O3 =3.9…5.0 and H2O/Al2O3 = 14…20 were taken as variables, the regression equations of the values of modulus of elasticity in bending were obtained. The results allowed to conclude that its optimal value, close to the modulus of elasticity of the pine (12…12.8 GPa), can be achieved with the following ratios: Na2O/Al2O3 = 0.6…0.8, SiO2/Al2O3 = 3.9, and H2O/Al2O3= 7…20.
Authors and Affiliations
P. , Kryvenko, S. , Guzii
Keywords
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