while in transit. The quality and characteristics of the mix shall conform in every respect to the requirements for concrete mixed at the site, Concrete shall be delivered to the site within 1 hour after the addition of mixing water. The number of revolutions of the mixer shall be not less than 4 revolutions of the drum per minute nor greater than a peripheral velocity of 22 feet per minute. Any ad- ditional mixing shall be not more than 250 revolutions at mixing and agitating speed combined. The agitating speed for any type of transit mixer shall be not less than 2 nor more than revolutions per minute, Truck mixers generally shall be operated within the limits of the capacity and speed of rotation designated by the manufacturer. 5-13. PREPARATION FOR PLACING: Water shall be removed from excavations before concrete is deposited. Any flow of water shall be diverted through proper side drain and shall be removed by methods which will avoid washing over the freshly deposited concrete. Hardened concrete, wood chips and shavings and other debris, shall be removed from the interior of the forms, and all hardened concrete and foreign materials from the inner surfaces of the mixing and conveying equipment. Wood forms, unless lined, shall be oiled or, except in freezing weather, wetted with water in advance of pouring so that joints will tighten and prevent seepage of cement grout from the mix. Reinforcement shall be secured in position, inspected and approved by the Engineer before starting the pouring of concrete. Runways, or other means approved by the Engineer, shall be provided for wheeled equipment to convey the concrete to the points of deposit, The equipment used to deposit concrete shall not be wheeled over the reinforcement, nor the runways be supported on reinforcement. 5-14. EXPANSION AND CONTRACTION JOINTS: Expansion and cor.traction joints shall be constructed at such points and of such design as are indicated on the drawing. The expansion Joint materials, as specified in other sections of the specifications, shall be installed as indicated on drawings and subject to the approval of the Engineer. In no case shall the reinforcement, corner protection angles, or other fixed metal items, embedded in or bonded into the concrete, be run continuous through an expansion joint, except 4s shown on the drawings. Reinforcement steel shall continue through contraction joints as shown on the drawings. &. Joints Between Slabs on Earth and Vertical Surfaces: Joints between slabs on earth and vertical surfaces shall be of premolded expansion-joint-filler strips. Unless otherwise noted, or specified, such joints shall be 5-10