How to Finish Shotcrete to Look Like Stucco

Plaster and stucco are commonly used to finish dull surfaces, such as concrete and masonry, to give them texture, color and depth. Since shotcrete is essentially concrete that has been blasted onto a surface with a pump, it falls under the category of materials that may be spruced up with a quick application of plaster. Once your shotcrete structure or surface has been fully dried and cured, apply plaster to make it look like a stucco wall.

Tri-sodium phosphate
Stiff-bristled scrub brush
Garden hose with misting nozzle
Portland cement
Masonry cement
Sand
Trowel
Plaster rake
Finishing trowel

Instructions

- 1
  Wash the shotcrete surface thoroughly with tri-sodium phosphate, hot water and a stiff-bristled scrub brush. This is especially important if the shotcrete is older and has collected dirt and other debris. Mix 1/4-cup tri-sodium phosphate into a gallon of hot water. Rinse the shotcrete with a garden hose.
- 2
  Mix equal parts of Portland cement and masonry cement. Blend in four parts sand for every one part of the cement mixture.
- 3
  Add enough water to the cement and sand mixture it has the consistency of peanut butter. Test the mixture by scooping some onto a trowel then holding the trowel at a 45-degree angle. If the plaster stays on the trowel, it is thick enough to use -- otherwise, add more dry ingredients until it passes the trowel test.
- 4
  Spray the shotcrete surface lightly with the garden hose fitted with a misting nozzle if it has dried while you were preparing the cement. The wall should be slightly damp, but not dripping wet.
- 5
  Work with a partner to apply the plaster -- this can be done by hand or with trowels. Scoop the plaster onto the shotcrete surface and press it into any cracks, grooves or other imperfections to ensure complete coverage.
- 6
  Smooth the plaster over with a trowel. Spread the plaster thinly until it is about 3/8-inch thick. Run a plaster rake over the plaster in a horizontal or diamond pattern.
- 7
  Allow the plaster to dry completely. Test the plaster with your thumb -- the plaster should resist dents but can be scratched by a fingernail.
- 8
  Moisten the plaster with the garden hose and the misting attachment. As with the first misting, the surface should be moist but not dripping wet.
- 9
  Spread another layer of plaster over the moistened surface with the trowel. Use the same process you used with the initial layer of plaster but spread the second layer to a thickness of about 1/4-inch.
- 10
  Give the plaster some texture by moving a finishing trowel over the surface. Use circular, crescent-shaped, zigzag or wavy patterns until you achieve the desired appearance. Stand several feet back from the surface to check your progress and ensure that the texture is attractive.

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