PSI - Issue 81

Oleksandr Matviiuk et al. / Procedia Structural Integrity 81 (2026) 493–498

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physical treatment methods (Abolore et al. (2025); Pinchevska and Zavialov (2020); Albrektas et al. (2020); Rowell et al. (2025); Heitner et al. (2010)). Previous studies by the authors have investigated the influence of water and acidic environments on the mechanical properties of untreated wood (Roshchuk et al. (2024); Homon et al. (2023); Matviiuk et al. (2025); Janiak et al. (2023)). However, the behavior of polymer-modified wood under prolonged exposure to water environments remains insufficiently studied.

Nomenclature σ с,agr,w,mod

wood stress;

relative strain of wood;

u с,agr,w,mod

short-term compressive strength of wood;

f c,0,d

modulus of elasticity of wood; relative critical strain of wood; relative ultimate strain of wood; relative residual strain of wood.

E 0

u c,0,d u c,u u c,fin

The aim of this study is to conduct experimental investigations of spruce and ash wood specimens modified with silor under axial compression parallel to the grain after prolonged exposure to water environment, and to determine the main mechanical characteristics at the pre-critical and post-critical stages of deformation. 2. Methods of experimental research The experimental research program was designed to investigate the effect of modification by the polymer composition Silor using autoclave impregnation on the mechanical properties of structural wood subjected to short-term axial compression parallel to the grain under service conditions in water environments. To achieve the stated scientific and applied objective, test specimens with dimensions of 30 × 30 × 120 mm were manufactured. Two wood species were selected for the full -scale experimental study: ash with strength class D35 and spruce with strength class C30, in accordance with DBN B.2.6-161:2017 and Eurocode 5:2004. The age of the wood was approximately 35 – 40 years. The scope of the experimental investigations is presented in Table 1.

Table 1. Scope of experimental investigations

Number of specimens, pcs

Wood age, years

Wood species Immersion time, days

Loading rate, mm/min

At moisture content of 12%

Spruce

- -

40 40

1.5 1.5

5 5

Ash

Water-impregnated specimens (moisture content > 30%)

Spruce

28 28

40 40

1.5 1.5

5 5

Ash

Specimens modified with Silor polymer composition

Spruce

- -

40 40

1.5 1.5

5 5

Ash

Silor-modified specimens immersed in water

Spruce

180 180

40 40

1.5 1.5

5

Ash 5 Test specimens were prepared in accordance with the recommendations for sampling and testing in the form of prismatic elements (DSTU 3129:2015). The specimens represented prismatic structural wood elements with a total height of 120 mm and a cross- sectional area of 30 × 30 mm (Fig. 1). The wood was selected with an annual ring width of 2-3 mm, first-grade quality, free from destructive defects and decay. To reduce the scatter of test results, each group of five twin specimens was manufactured from identical wood material, meaning that all prismatic elements within a group were cut from the same initial timber blank. Prior to specimen preparation, the wood blanks were conditioned to a standard moisture content of 12% through the following stages. At the first stage, air drying was performed under a shelter with ensured air circulation in both vertical and horizontal directions between layers for a period of two months. At the second stage, the lumber was placed in a drying chamber and further dried using a convective thermal method at a temperature of 40 °C until the target mo isture content was achieved, which required