APPENDIX C-Continued 



TABLE 5.3.4(a)— RELATIONSHIPS BETWEEN 



WATER-CEMENT RATIO AND COMPRESSIVE 



STRENGTH OF CONCRETE 



Compressive strength 

 at 28 days, psf 



Water-cement raUo 



, by weight 



Non-alr-entralned 



Alr-entrainod 



6000 



0.41 



_ 



5000 



0.48 



0.40 



4000 



0.57 



0.48 



3000 



0.68 



0.5B 



2000 



0.82 



0.74 



•Values are estimated average strengths for concrete contain- 

 ing not more than the percentage of air shown In Table 5JJ. 

 For a constant water -cement ratio, the strength of 

 Is reduced as the air content is Increased. 



Strength Is ba^ed on 6x12 In. cylinders 

 at 73.4 ± 3 F (23 ± 1.7 C) In accordance with Section 9(b) of 

 ASTM C 31 for Making and Curing Concr£te Compressit 

 and Flexure Test Specimens in the Field. 



Relationship assumes maximum size of ^ 



1 in.; for a given source, strength produced lor 

 cement ratio will Increase as m ' 

 decreases; see Sections 3.4 and 5J^. 



TABLE 5.3.4(b)— MAXIMUM PERMISSIBLE 



WATER-CEMENT RATIOS FOR 



CONCRETE IN SEVERE EXPOSURES* 



ed 28 days 



of aggregate about ',« to 

 ■ *or a given water- 

 :|ze of aggregate 







Structure 





ously or frequently 



exposed to 



Type of structure 



and exposed to 







freezing and thawingt 



or sulfates 



Thin secUons (railings. 







curbs, sills, ledges. 







ornamental work) and 



0.45 



0.40: 









1 In. cover over steel 







All other structures 



OJSO 





"Based on report of ACI Committee 201. "Durability of Con- 



pTevIously cited. 



C 150) is used. 



TABLE 5.3.6— VOLUME OF COARSE AGGREGATE 

 PER UNIT OF VOLUME OF CONCRQSE 



Maximum size 

 of aggregate. 



Volume of dry-rodded coarse aggregate* 

 per unit volume of concrete for 

 different fineness moduli of sand 



2.40 



2.60 



2.80 



3.00 



',i 



0.50 



0.48 



0.46 



0.44 



•.i 



0.59 



0.57 



OiS 



0.53 



% 



0.66 



0.«4 



0.62 



0.60 



1 



0.71 



0.68 



0.67 



0.65 



Hi 



0.75 



0.73 



0.71 



0.69 



: 



0.78 



0.76 



0:74 



0.7J 



3 



0.82 



0.80 



0.78 



0.76 



a 



0.87 



0.85 



0.83 



0.81 



dry-rodded condition 



al reinforced construction For less workable 



Ing, they may be reduced up to 10 percent. 



5.3.7 Step 7. Estimation oj jine aggregate 

 content. At completion of Step 6, all ingredients 

 of the concrete have been estimated except the 

 fine aggregate. Its quantity is determined by 

 difference. Either of two procedures may be em- 

 ployed: the "weight" method (Section 5.3.7.1) or 

 the "absolute volume" method (Section 5.3.7.2). 



TABLE 5.3.7.1— FIRST ESTIMATE OF 

 WEIGHT OF FRESH CONCRETE 



requirements for strength and durability, the 

 mixture must be based on whichever criterion 

 leads to the larger amount of cement. 



The use of pozzolanic or chemical admixtures 

 will affect properties of both the fresh and hard- 

 ened concrete.* 



5.3.6 Step 6. Estimation oj coarse aggregate 

 content. Aggregates of essentially the same maxi- 

 mum size and grading will produce concrete of 

 satisfactory workability when a given volume of 

 coarse aggregate, on a dry-rodded basis, is used 

 per unit volume of concrete. Appropriate values 

 for this aggregate volume are given in Table 

 5.3.6. It can be seen that, for equal workability, 

 the volume of coarse aggregate in a unit volume 

 of concrete is dependent only on its maximum 

 size and the fineness modulus of the fine ag- 

 gregate. Differences in the amount of mortar re- 

 quired for workability with different aggregates, 

 due to differences in particle shape and grading, 

 are compensated for automatically by differences 

 in dry-rodded void content. 



The volume of aggregate, in cubic feet, on a 

 dry-rodded basis, for a cubic yard of concrete is 

 equal to the value from Table 5.3.6 multiplied by 

 27. This volume is converted to dry weight of 

 coarse aggregate required in a cubic yard of con- 

 crete by multiplying it by the dry-rodded weight 

 per cubic foot of the coarse aggregate. 



PROPORTIONS FOR NORMAl MZ HEAVYWEIGHT CONCRETE 





First estimate of c 

 lb per ci 



oncrete -rljht, 

 1 yd- 



of aggregate, in. 



Non-alr-entralned 



Air-entrained 

 concrete 



H 



3840 



3690 



',i 



3890 



3760 



•4 



3960 



3840 



1 



4010 



3900 



l',4 



4070 



3960 



2 



4120 



4000 



3 



4160 



4040 



6 



4230 



4120 



•Values calculated by Eq 

 richness (550 lb of cement pe 

 aggregate specific gravity of 2.7. W, 

 values for 3 to 4 In. slump In T" 

 mated weight may be refined 

 formation is available: for 

 water from the Table 5.3.3. 

 the weight per cu yd 15 lb 

 100 lb diflerence in cemen 

 yd IS lb 

 egate spedl 

 eight 100 lb 



of medium 



Tables 5.3.3. If desire 



550 lb correct 



the concrete 



5.3.7.1 If the weight of the concrete per 

 unit volume is assumed or can be estimated from 

 experience, the required weight of fine aggregate 

 is simply the difference between the weight of 

 fresh concrete and the total weight of the other 

 ingredients. Often the unit weight of concrete is 

 known with reasonable accuracy from previous 

 experience with the materials. In the absence of 

 such information, Table 5.3.7.1 can be used to 

 make a first estimate. Even if the estimate of 

 concrete weight per cubic yard is rough, mixture 

 proportions will be sufficiently accurate to per- 



324 



