FLOORS FOR MILL BUILDINGS. 



33 



s. ivm and shall be retained on the No. 20 screen. Dust shall be excluded. The sand for the 

 base shall U rl.-an ami sharp. The aggregate for the base shall be of broken stone or gravel and 

 shall pass a J in. ring. 



Base. -On a thoroughly tamped and compacted subgrade the concrete for the base shall be 



laid .UK! thoroughly tamped. The base shall not be less than 2\ in. thick. Concrete for the 



hall IK- thoroughly mixed with sufficient water so that some tamping is ri-quired to bring 



the moisture to the surface. If old concrete is used for the base the surface shall be roughened 



" Lirn * Mortar. '?" Plank 



TIMBER FLOOR ON CINDERS 



,' I Matched Mapfe, Longitudinal 

 " , Transverse!. 



fit 



fix Tonguedde Grooved Mapfe 







^Cinders ' ^ **4 " W-P- Nailing 5 trip 



(t>) TIMBER FLOOR ON CINDERS 



,r", 



f/z P/Bnk, Longitudinal 

 '"?- PJank, Transverse 



\ rR>* Concrete oF Tar orAspha/l; 

 *"3* 'Concrete 



(c) TIMBER FLOOR ON TAR CONCRETE 



f I' Mapfe, Longitudinal 

 / ,'*>" Hemlock, Diagonaf 

 f f Hemlock, Transverse 



J^ \? RooFing Pitch 

 "-Compacted Earth 

 (d) TIMBER FLOOR ON TAR CONCRETE 



,*/ Pitch and Sand, I :$ 

 ( ; '4"*4"x8 "Map/e Block, fain Vertical 



*~-4? Port /and Cement Concrete- 

 (e) TIMBER FLOOR ON CONCRETE 



tl" Wearing Surface, /' Port/and 

 Cement Mortar 





^6" Tar - Grave/ Concrete 

 (F) TIMBER BLOCKS ON TAR CONCRETB 



'&" A'n" /" 



( *~~" ' *^ Concrete-J^ 



Cinders, well drained 

 ? Portland Cement Corrcrete f l&6 



(g) CONCRETE FLOOR 



FIG. 25. EXAMPLES OF 



' ' ... ..'... y 



' Tin Gutter 

 (h) CONCRETE SHOP FLOOR 



GROUND SHOP FLOORS. 



and thoroughly cleaned so that the new mortar will adhere. The roughened surface of old con- 

 crete shall then be thoroughly wet so that the base will not draw water from the finish when the 

 latter is applied. Before scrubbing the base with grout the excess water shall be removed. 



Finish. With old concrete the surface of the base shall first be scrubbed with a thin grout 

 of pure cement, rubbed in with a broom. On top of this, before the thin coat is set, a coat of 

 finish mixed in the proportions of one part Portland cement, one part stone broken to pass a J in. 

 ring, and one part sand shall be troweled on using as much pressure as possible, so that it will 

 take a firm bond. After the finish has been applied to the desired thickness it should be screeded 

 and floated to a true surface. Between the time of initial and final set it shall be finished by 



4 



