When using Sonocrete, the concrete hardens faster. This means faster stripping or a reduction in cement – our desired effects. But these effects have a flip side: The workability of the concrete. Faster hardening concrete could be hard before it reaches the moulds.
Workability has been a core challenge for us over the last months. With the effect of cavitation from the power ultrasound, the C-S-H phases in the concrete grow at an increased pace – sometimes too fast to handle. We had several tests in the lab and in plants where the concrete became too hard too early.
To improve this, we worked on several parameters – from the duration of the ultrasound treatment to the stirring speed in our tank.
The aim is to fine-tune our process in a way that we can have the concrete open for as long as needed, and then to give a very sharp increase in hardening – almost like hitting a “stiffen” button once it is in the moulds.
With most recipes, we are now reaching workability times of 30 to 90 minutes.