Replaster - need a new brush?

I am going to have my shotcrete pool replastered in a month or so. I have had it for two years and the builder is doing this as the plaster is failing. The finish is a diamond brite type of plaster. The bristles on the brush I have now are pretty frayed. I thought this might be a good thing for new plaster, but I am not sure. What do the experts here think?

Does anybody have an opion on this? I will probably buy a new one anyway, but I would like to know if the frayed bristles of a used brush are better for new diamond brite.

C'mon warm weather...