Patent ID: 6969476

Claim:
A method for manufacturing a concrete product in a substantially horizontal slip-form casting process using two or more different grades of concrete mix, in which method concrete mix is fed into a slip-form mold of a defined cross section moving progressively in the casting process so as to give a concrete product of a desired shape, whereby two or more different grades of concrete mix can be used in the product cast in accordance with the method wherein batches of the different concrete mix grades are metered in predetermined amounts into a feeder hopper of a slip-form casting machine at predetermined instants during progress of slip-form casting process, wherein at an instant of changing the grade of concrete mix, the feeder hopper of the casting machine still contains a certain amount of a preceding grade prior to delivery of a next grade of concrete mix into the feeder hopper, an amount of concrete mix remaining in the feeder hopper is measured, distance covered in casting is measured and the delivery of concrete mix is controlled based on the measurement results of the amount of remaining concrete mix and the distanced covered in casting.