Sprayable ECC Technology

(Movie for sprayable ECC)

Engineered cementitious composite suitable for wet-mix shotcreting (sprayable ECC) in the fresh state, while maintaining tensile strain-hardening behavior in the hardened state, has been developed by employing a parallel control of micromechanics-based design and rheology-based design. In the development concept of sprayable ECC, micromechanics is adopted to properly select the matrix, fiber, and interface properties to exhibit strain-hardening and multiple cracking behaviors in the composites. Within the pre-determined micromechanical constraints, the fluid properties are controlled by the rheological process design to develop flocculations between cementitious particles at a proper rate. The pumpability and sprayability of ECC mix are then realized by the controlled rheological properties of fresh matrix and the uniform dispersion of fibers. A series of spray and deformability tests show the excellent pumpability, sprayability, and rebound property of the sprayable ECC. Subsequent uniaxial tensile tests demonstrate that the mechanical performance of sprayed ECC using wet-mix shotcreting process is comparable to that of ECC cast with external consolidation, for the same mix design.

Spraying ECC onto Vertical Surface

45 mm Thickness of Sprayed ECC Layer (Vertical Surface)

Spraying ECC onto Overhead Surface

25 mm Thickness of Sprayed ECC Layer (Overhead Surface)

Similar Uniaxial Tensile Behavior of Sprayed and Cast ECC (Same Mix)