Abstract:
The use of Engineered Cementitious Composite (ECC) in sprayed applications presents promising prospects but imposes higher demands on material performance. A hybrid fiber-reinforced ECC (HECC) incorporating polyethylene (PE) fibers and basalt fibers (BF) was developed for sprayed applications. The study investigated the influence of different fiber types and dosages on the workability of HECC through flowability tests, thereby defining a sprayable performance range. The mechanical properties of sprayed HECC were examined using direct tension tests and compressive strength tests. Additionally, interface pull-off tests were conducted to evaluate the bond performance of HECC sprayed onto existing concrete under various conditions. The results indicated that the flowability of HECC is predominantly influenced by the more flexible and aggregating PE fibers. When the fiber dosage is excessive, leading to a flowability below 150 mm, the material becomes unsuitable for sprayed application. The sprayed HECC retains the characteristics of multi-point cracking and strain hardening, with increased spraying pressure enhancing its mechanical properties. Under various conditions, the bond strength of HECC at the interface approached that of existing concrete, achieving more than 80% of the strength obtained through press-mud construction.