i. Truck mounted mixers also know as transit mixers are very popular and have replaced the dumpers and agitator cars used earlier to transport fresh concrete from the batching plant to the site.

ii. Transit mixers of capacity 4 to 12 cum mounted on truck chassis are available.

iii. These mixers are not very efficient and need long mixing duration depending on the extent of dryness in the mix.

iv. Their function is mainly to keep the mix in an agitated condition. With the development of twin fin process mixer, the transit mixers have become more efficient.

v. These mixers in addition to the outer spirals have two opposed inner spirals. The outer spirals convey the mix materials towards the bottom of the drum while the opposed mixing spirals push the mix towards the feed opening.

vi. The repeated counter current mixing process is carried out within the mixer drum.

vii. A number of special nozzles provided on the lower side of inner mixing spirals, precisely and uniformly spray water on the mix under pressure along the entire length of the drum.

viii. This results in through mixing of the entire drum contents within a short time.

ix. Hence, production of high quality structural concrete in the transit mixer is possible at a faster rate.