904.07.05.04 – “The concrete…

904.07.05.04 – “The concrete shall be placed in its final position and to its full depth in a continuous placing operation without interruption.” Tremie placements do not have a “continuous flow of concrete at 15 m³/h”, since there are times when the concrete supply switches from one truck to another. This fact must be acknowledged by the standard since it is not reasonable to reject the concrete for short stoppages in flow. As long as the concrete hasn't set, there is no detrimental impact, and retarders are often used in these types of applications.

904.07.08.02 – Project CA’s have rejected the use of fog misting on conventional concrete placements to prevent plastic shrinkage cracking and to control the evaporative moisture loss from the surface of the concrete on low relative humidity days with high wind. The standard needs to acknowledge the use of fog spraying for all concrete, not just HPC. Change the title to “Fog Misting of High Performance and Conventional Concrete”. Fog misting is a concrete construction "best practice" to control plastic shrinkage and the MTO should not be banning an industry best practice just because of the potential for uneducated constructors to work the water back into the surface inappropriately. You need to deal with the inappropriate practice by noting that "fog spraying shall be stopped whenever water begins to puddle on the surface and concrete finishing operations shall not be initiated until the water sheen is no longer on the surface of the concrete".