Cement and flyash can be mixed in pneumatic conveying pipe at controlled rate to very high accuracies but it is not a cheap solution. Mixing from the tanker will not work as the material discharge from the tanker will not be at a controlled rate. You will need cement and flyash both in silos to mix them using pneumatic conveying no other mixer is required and the blending is very good. I know of a facility in South East UK on a cement plant which is currently doing that. If you need to know the supplier of that equipment then PM me and i will tell you the name. ■