(_b) Blue--ultramarine blue, Phthalocyanine blue, 



(c) Red- -red iron oxide, 



Cd) Brown- -brown iron oxide, raw and burnt amber, 



(e) Cream or buff--yellow iron oxide, 



(f) Green--chromium oxide, phthelocyanine green, and 



(g) White--titanium dioxide, 



5. Preparation of Concrete Mixes . 



There are standard methods for selecting proportions for concrete made 

 with aggregates of normal density and of workability suitable for usual 

 cast-in-place construction. The methods provide a first approximation of 

 proportions and are intended to be checked by trial batches in the labora- 

 tory or field and adjusted, as necessary, to produce the desired character- 

 istics of the concrete. 



a. Selection of Mix Proportions . The procedure for selection of mix 

 proportions given in this section is applicable to normal weight concrete. 

 Estimating the required batch weights for the concrete involves a sequence 

 of logical, straightforward steps which, in effect, fit the characteristics 

 of the available materials into a mixture suitable for the work. Regard- 

 less of whether the concrete characteristics are prescribed by the speci- 

 fications or are left to the individual selecting the proportions, estima- 

 tion of a total batch weight per cubic unit of concrete can best be accom- 

 plished by referring to the table used in (7) below. 



(1) Choice of Slump . If slump is not specified, a value appro- 

 priate for the work can be selected from Table 10. The slump ranges shown 

 apply when vibration is used to consolidate the concrete. Mixes of the 

 stiffest consistency that can be placed efficiently should be used. 



Table 10. 



Recommended slumps for various types 

 of construction. 



Types of construction 



Slump (mm) 



Maximum - 1 - 



Minimum 



Reinforced foundation walls and footings 

 Plain footings, caissons, and substruc- 

 ture walls 

 Beams and reinforced walls 

 Building columns 

 Pavements and slabs 

 Mass concrete 



76 



76 



102 



102 



76 



51 



25 



25 

 25 

 25 

 25 

 25 



a May be increased 25 mm for methods of consolidation other than 

 vibration. 



95 



