Wet curing of newly placed concrete is certainly important. Your 10-day cure sounds great. Properly placed shotcrete against a properly prepared construction joint will provide concrete that acts monolithically and will not be a “cold joint” as is common in cast concrete. There are three key factors for joint preparation:
- The joint must be roughened. This should be done when the crew finished for the day using a stiff broom or raking with a trowel.
- On the subsequent shoot the surface should be cleaned (usually using a high pressure, pressure washer).
- Before shooting bring the surface to a saturated surface dry (SSD) condition. SSD means the pores of the concrete have been filled with water but there is no running water on the surface.
Following these 3 steps are essential for creating a monolithic, watertight joint. Here’s a link to an article on why shotcrete doesn’t have cold joints: https://shotcrete.org/wp-content/uploads/2020/05/2014Spr_TechnicalTip.pdf
Quality shotcrete placement requires a well-designed concrete mixture, proper equipment, attention to the surface prep, proper placement techniques, and curing. One aspect that can help you ascertain the nozzleman’s expertise is to require they have a current American Concrete Institute Shotcrete Nozzleman Certification. You can verify an individual’s certification status at: https://www.concrete.org/certification/verifyacertification.aspx?d=Ask