The adhered mortars in recycled aggregates (RA) may lower the performance of the\nconcrete, by for instance reducing its strength and durability, and by cracking. In the present study,\nthe effect of nylon fiber (NF) on the permeability as well as on the mechanical properties of concrete\nincorporating 100% RA was experimentally investigated. Concrete was produced by adding 0, 0.6 and\n1.2 kg/m3 of NF and then cured in water for a predetermined period. Measurements of compressive\nand split tensile strengths, ultrasonic pulse velocity and total charge passed through concrete were\ncarried out, and the corresponding test results were compared to those of concrete incorporating\ncrushed stone aggregate (CA). In addition, the microstructures of 28-day concretes were examined\nby using the FE-SEM technique. The test results indicated that recycled coarse aggregate concrete\n(RAC) showed a lower performance than crushed stone aggregate concrete (CAC) because of the\nadhered mortars in RA. However, it was obvious that the addition of NF in RAC mixes was much\nmore effective in enhancing the performance of the concretes due to the crack bridging effect from\nNF. In particular, a high content of NF (1.2 kg/m3) led to a beneficial effect on concrete properties\ncompared to a low content of NF (0.6 kg/m3) with respect to mechanical properties and permeability,\nespecially for RAC mixes.
Loading....