The cement in the sprayed concrete mix acts as a “glue” which binds and embeds the aggregate particles together through the cement matrix. The cement lime is also the main lubricant for delivery of the sprayed concrete. Cement is hydraulic setting and therefore partly responsible for the mechanical properties of the set concrete. However, here there is an additional central requirement over and above its use in structural concrete. Cement for sprayed concrete must always start to set extremely quickly, give good bonding capability and high very early strength.
Cement which does not react well when combined with setting accelerators or with slow-reaction admixtures in combined cements is not particularly suitable for the production of sprayed concrete for stabilization.
The cement content is in general 300 - 450 kg/m3. It is depending on the spraying process and the shotcrete requirements.