A continuous mixer that is installed in the bed of a dump truck. The mixer has a hopper for cement, a pair of belts to move the other mixing materials, and a chute with an auger for mixing the cement and mixing materials with water and depositing the mixture where desired. The hopper stands upright in the bed when the bed is down and tilted at about 45° when the bed is up. An auger at the bottom of the hopper feeds cement to an opening at the bottom of the hopper, The belts sit below the hopper and are oriented with the belts parallel to the ground during operation, The belts feed mixing materials from the bed to a mixing chute below the belts. An auger combines the dry materials and water to form the concrete as they travel the length of the chute to the discharge end.