The paper deals with soil improvement using polyester fibres of length 70mm mixed in soil SC as random reinforcement in amount of 0.5%, 1.0% and 1.5%. Improvement of soil was measured by direct shear tests, using shear box of size 0.3m x 0.3m x 0.15m. It will be shown that for tested soil, optimal amount of fibres is 1.0%, when increase of angle of internal friction was up to 6.0o (from 45.3o to 51.3o) and increase of cohesion was up to 17.5kPa (from 0kPa to 17.5kPa) in comparison with soil without fibres

Using materials from recycling is a key part of decreasing present-day waste. It is optimal for recycled material to be used in environmental protection. This paper presents the application of geotextile ropes in erosion protection of a slope of a gravel pit. To protect the slope, thick ropes with a diameter of 120 mm made from wool and a mixture of recycled natural and synthetic fibers were used. After 47 months from installation, soil and rope specimens were taken from the slope parts with inclinations 1:1 and 1:1.8, and their physical and mechanical properties were determined. Direct shear tests were applied to determine the soil shear strength parameters in state at sampling and at I_c = 0 (unconsolidated and consolidated). Based on the obtained soil shear strength parameters, the loads on the ropes were determined, taking into account also unfavorable hydraulic conditions and compared to rope strength. It was shown that even after 47 months from installation, rope tension strength was higher as tension forces were induced in the ropes in every case. At present, whole slopes in protected sections are stabilized, without rills and gullies.

When improving soil shear strength using various materials, determination of the improvement rate is a key issue and can be carried out using a direct shear test (DST). However, many standards for DST require only three specimens in the test and do not deal with test result uncertainty. In this study, shear strength parameters of clay of intermediate plasticity (CI) and sandy clays (CS1, CS2) improved with the addition of polyester fibres of 70 mm in length in amounts of 0.5%, 1.0%, and 1.5% of dry soil mass were obtained using DST with a shear box of size 0.3 m × 0.3 m × 0.08 m. The results show that using fibres provides significant improvement and the number of tested specimens (three or four) in DST has a significant impact on the obtained values of shear strength parameters. It is not recommended to carry out DST with only three specimens. The analysis of uncertainty shows that covariance between correlated input quantities (normal stresses and shear stresses) has a negligible influence on result uncertainty. The worst-case estimated uncertainties are very high and should not be applied. Analysis of the state of the fibre surface before and after shearing using scanning electron microscopy (SEM) shows that suitable fibre scratch resistance may be the reason for the large improvement.

Changes in climatic conditions in the world often affect the variability of water relations and soil erosion. Observed phenomena lead to removal of the most valuable soil surface layer from slopes, washout of minerals, deterioration of slope structure and also destruction of protective vegetation. Geotextiles are used to protect slopes from effects of erosion. Depending on the type of used raw material as well as production technology, geotextiles are used for long-term or temporary protection (biodegradable). Biodegradable geotextiles under influence of atmospheric factors undergo gradual decomposition. The substances released as a result of decomposition cause soil fertilization, which promotes development of protective vegetation. The aim of the research is to assess impact of exploitation time on selected physical, mechanical and hydraulic properties of innovative geotextiles in form of meandrically arranged Kemafil ropes made of wool and recycled fibers installed on slope in Jasienica Economic Zone in Międzyrzecze. The research was carried out in the Laboratory of Geosynthetics and Textile Products of the University of Bielsko-Biala in accordance with the applicable European standards. Nonwovens used for production of geotextiles were tested before installation, as well as after 6 and 12 months from their installation. Geotextiles reduce speed of rainwater flowing down from the surface of slope and store its excess. Waste raw materials used for production of geotextiles enable products effectively protecting slope against water erosion.