installed with close joints, Joint marks shall be smoothed off and all blemishes removed, leaving finished surfaces smooth and unmarred, subject to approval by the Engineer, 5-21. CONCRETE FLOOR FINISHES: Concrete floor slabs shall be finished as hereinafter described. The dusting of wearing surfaces with dry cement will not be permitted. In preparing base slabs for the various finishes, the slabs shall be struck off true at the required level below the elevation or grade of the finished floors, as shown on the drawings. Floors shall be level except that where drains occur the floors shall be pitched thereto. Finishes as bélow specified are called for in Finish’ Schedules or in notes on the drawings. a. Smooth Integral Cement Finish: All cement fin- ish floors shall have &@ smooth integral cement finish applied as follows: The finish coat shall be not less than 1/2 inch thick, applied after screeding while the concrete is still green, but after all surface water has disappeared (not more than 30 to 45 minutes). The mix shall be 1 part Portland cement, 1 part fine aggregate and 2 parts coarse aggregate. sieve, The fine aggregate shall pass a 1/4 inch mesh not more than 5 per cent shall pass a 100-mesh sieve and not more than 10 per cent shall pass a 50-mesh sieve, The coarse aggregate shall be graded from 1/8 inch to 3/8 inch, with at least 95 per cent passing a 3/8 inch sieve and not over 10 per cent passing a No. 8 sieve. The water shall not exceed 5 gallon per sack of cement. shall be screeded to a true and even surface, The finish then floated and troweled smooth. No floating or troweling of the surfacé shall be done while the finish coat is wet or sloppy. After having set sufficiently to ring the trowel, the work shall be given a second troweling and burnishing. b. Wood Float Finish: Exterior slabs so noted shall be finished by tamping with special tools to force aggregate away from the surface, then screeding with straightedges to bring the surface to required line as shown on the drawings. While the concrete is still green, but has hardened sufficiently to bear the cement finisher's weight, the surface shall be floated with a wood float to a true and uniform plane with no coarse aggregate visible. Dusting, to absorb surface water, will not be permitted, ¢. Floors Receiving Asphalt-Tile Flooring: Floors receiving asphalt-tile flooring shall be as specified in paragraph a. above, except that the finish coat may be com- posed of 1:1-1/2:3 mix of cement, fine and coarse aggregate, and the surface left after the first troweling, second troweling and burnishing. 5-14 omitting th«