PSI - Issue 81

Orest Polishchuk et al. / Procedia Structural Integrity 81 (2026) 316–320

319

3. Research results and discussion Cubes of all series were tested under a one-time, short-term load regime until failure.

Combined reinforcement in studies involving different types of fibers has a positive effect on the compressive strength of fiber reinforced concrete. The compressive strength of fiber-reinforced concrete samples was one strength class higher compared to the control concrete mix. The use of polypropylene fiber increased the compressive strength of fiber-reinforced concrete on average by 9% at the age of 7 days and by 15% at the age of 28 days compared to unreinforced concrete. The use of steel fiber increased compressive strength on average by 13% at 7 days and by 18% at 28 days compared to unreinforced concrete. The strength values of the investigated concretes and fiber-reinforced concretes were experimentally determined after 12 months of exposure in aggressive environments (Figs. 3 and 4).

60

50

40

30

20

10

0

pH=7, water pH=3, acid CEM І, without fiber CEM І, PFs CEM І, PFs+SFs CEM ІІ, without fiber CEM I І, PFs CEM І I, PFs+SFs pH=13, alkaline pH=5, kerosene

Fig. 3. Graphical dependence during compression testing of 10 × 10 × 10 cm cubes without considering the size (scale) factor (0.95) and with a coefficient of variation of 13.5 on the aggressive environment after 12 months of exposure, MPa.

60

50

40

30

20

10

0

CEM І, without fiber

CEM І, PFs

CEM І, PFs+SFs CEM ІІ, without fiber

CEM I І, PFs CEM І I, PFs+SFs

pH=7, water

pH=13, alkaline pH=5, kerosene pH=3, acid

Fig. 4. Compressive strength of concretes without considering the size (scale) factor (0.95) and with a coefficient of variation of 13.5 of different compositions under the action of various aggressive effects after 12 months of exposure, MPa.