I would / have cut trunks up of the lower end of the diameter of yours with my Msa200 and it is fast cutting but, only 8 cuts per charge of an AP300 battery.
A rotary mower that relies on blades lifting the cutting through a chute into a grass box wouldnt be much use unless running at governed speed especially if wet
If you used Ncl5 for your lime crete it will loose most if not all of its breathability as it cures.
Adhere-vit is probably product for you....Did you lay the limecrete over foamed glass aggregate?
https://www.lime.org.uk/adhere-vit.html