Ray asked about using a hopper to spray cement material onto worn concrete slabs.
Question (from Ray): Hi, I would like to use a hopper to spray cement material to fix concrete slabs that have lost some of their top coat, as I believe it would be easier than troweling or using a squeegee and perhaps the pressure would cause the mortar to better attach to the concrete surface, thank you.
Answer: The surface has to be prepped well first. A good pressure washing will remove dust, dirt, and loose concrete and will also open up the pores of the slab for better bonding. Let the surface dry out mostly (slightly damp is fine) before starting the repair.
Spraying with a hopper can definitely save time and help with coverage, but you’ll still need to trowel the material after spraying to get it smooth and even. Keep your mix rich (higher cement content) for stronger adhesion and a cleaner finish. Using a bonding agent or replacing some of your mix water with an acrylic admix will also improve adhesion and overall durability.
Apply the material in thin coats rather than one heavy layer, since thicker applications are more likely to crack or delaminate. After placing the mix, you can give the surface a light broom or texture to blend it in with the surrounding slab.
Finally, don’t forget curing! Mist the surface with water or cover it so it doesn’t dry out too fast. Proper curing makes a big difference in how long the repair will last, too. Good Luck!
