| Popis: |
The paper summarizes selected results of an extensive experimental investigation, in which high-strength strain-hardening cement-based composites (HS-SHCC) made with different high-performance polymer fibers were investigated in terms of mechanical behavior under and after exposure to elevated temperatures of 105 °C, 150 °C and 200 °C. Besides the ultra-high molecular-weight polyethylene (UHMWPE) fibers, which are commonly used in HS-SHCC, high-modulus poly(p-phenylene-2,6-benzobisoxazole) (PBO-HM) fibers have been analyzed, since they exhibit a considerably higher temperature resistance in comparison to UHMWPE fibers. In contrast to the expectations, the in-situ and residual tension experiments at temperatures of up to 150 °C showed that the high-strength SHCC reinforced with UHMWPE fibers yielded considerably superior performance and less pronounced decrease of the mechanical properties compared to the composites made with PBO-HM fibers. Furthermore, the SHCC made with UHMWPE fibers showed a significant recovery after being cooled down, while the SHCC made with PBO-HM fibers exhibited a limited recovery; the degradation was proportional to the temperature increase. The 200 °C treatment led to brittle failure of both composites with dramatically reduced tensile strength and with low recovery after specimen cooling in the residual experiments. |
