Abstract This article presents experimental results from fatigue tests in form of load-controlled cyclic tension-swelling, i.e. repeated tensile loads and alternating tension–compression on high-strength polyethylene-reinforced SHCC, subjected to a sinusoidal loading regime with a fixed upper load limit and variable lower stress levels, corresponding to zero, moderate and high compression depending on the load regime. To assess material degradation, crack development and opening were determined using DIC during the cyclic tests. Electron microscopy of the fracture surfaces reveal different load-dependent degrees of material deterioration. Together with the results from DIC, a stable basis for the discussion of the material’s performance under the employed loading regimes is provided. The analysis revealed a decrease of the maximum number of loading cycles with increasing compressive stress leading to a more severe deterioration of the material that is reflected in both the mechanical performance and crack development.

Abstract The crushing of the glass fiber-reinforced polymer (GFRP) previously separated from the other wind-turbine-blade materials produces a waste with minimum contents of deformable particles of balsa wood and polymers, being mainly composed of GFRP-composite fibers. This residue is named selectively crushed wind-turbine blade (SCWTB). This research evaluates the impact of adding up to 6.0% by volume of SCWTB on the deformability, load-bearing capacity and energy absorption of concrete subjected to compression, bending, and indirect-tensile stresses. SCWTB increased the failure strain of concrete in the direction parallel to a compression load, although it led the failure and fracture strains to match. However, the strain increase from failure to fracture was 2000–3000 µε in the transverse direction to loading, so concrete with SCWTB was load-bearing after failure. GFRP-composite fibers’ stitching effect was more noticeable under bending stresses. Thus, 1.5% vol. and 6.0% vol. SCWTB resulted in almost the same bending failure stress in concrete, around 6.1–6.2 MPa, and contents from 3.0 and 6.0% vol. SCWTB provided load-bearing capacity in simple and notched-specimen bending, respectively. In addition, the low content of deformable particles in SCWTB increased the deflection increment from failure to fracture in bending, although the presence of such particles augmented energy absorption. No SCWTB content provided load-bearing capacity under indirect-tensile stresses, although it did increase pre-failure deformability. In general, the energy absorbed by concrete increased by up to 43% when adding SCWTB, the use of up to 6.0% of this waste being recommended to increase the ductility of concrete. Graphical abstract

Abstract Polymer concrete is increasingly used in high-precision machine tools due to its excellent damping properties, thermal stability, and reduced environmental impact. However, its low tensile strength and stiffness limit its use in structural or dynamically loaded components. This study examines the mechanical enhancement of polymer concrete through the integration of prestressed continuous carbon fiber reinforcements. Specimens with embedded carbon fiber rovings prestressed up to 470 MPa were fabricated and tested under three-point bending and uniaxial compression loading. Bending strength increased by up to 35 % and bending stiffness by 16 %, with significant gains occurring beyond a prestress level of 70 – 110 MPa. CT imaging confirmed that prestressing delayed crack initiation and limited propagation. Under compressive loading parallel to the fiber direction, strength increased by up to 8 %, though the effect diminished at higher prestress levels. A reduction in compressive strength was observed for transverse loading, attributed to matrix discontinuities and stress redistribution. The results demonstrate that prestressed fiber integration significantly improves the structural performance of polymer concrete, offering enhanced load capacity and failure resistance. These findings lay the foundation for broader application of polymer concrete in load-bearing components and support the development of hybrid systems combining mechanical efficiency with design flexibility.