APPENDIX C-Continued 



The concrete has a measured slump of 5 cm and unit 

 weight of 2390 kg/m'. It is judged to be satisfactory 

 from the standpoint of workability and finishing prop- 

 erties. To provide proper yield and other characteristics 

 for future batches, the following adjustments are made: 

 AZ.2.9.1 Since the yield of the trial batch was 



49.04/2390 = 0.0205 m^ 



and the mixing water content was 2.70 (added) + 0.34 

 (on coarse aggregate) + 0.86 (on fine aggregate) = 3.90 

 kg, the mixing water required for a cubic meter of con- 

 crete with the same slump as the trial batch should be 



A2.2.10.2 Rc-estimated water for same slump as 

 trial batch: 



2.70 + 0.34 + 83 _ ,„, . 

 0.0202 ^ 



Mixing water required for slump of 8 to 10 cm: 



192 + 8 = 200 kg 



A2.2.10.3 Adjusted cement content for increased 

 water: 



200/0.62 = 323 kg 



A2.2.I0.4 Adjusted coarse aggregate require- 

 ment: 



As indicated in Al.5.2.9.1, this amount must be in- 

 creased another 8 kg to raise the slump from the 

 measured 5 cm to the desired 8 to 10 cm range, bring- 

 ing the total mixing water to 198 kg. 



A2.2.9.2 With the increased mixing water, ad- 

 ditional cement will be required to provide the desired 

 water-cement ratio of 0.62. The new cement content 

 becomes 



198/0.62 = 319 kg 



A2.2.9.3 Since workability was found to be satis- 

 factory, the quantity of coarse aggregate per unit 

 volume of concrete will be maintained the same as 

 in the trial batch. The amount of coarse aggregate per 

 cubic meter becomes 



1146 

 1.02 



; 1124 kg dry 



1124 X 1.005 = 1130 kg SSD" 



A2.2.9.4 The new estimate for the weight of a 

 cubic meter of concrete is the measured unit weight of 

 2390 kg/m'. The amount of sand required is, therefore 



2390 - (198 + 319 -|- 1130) = 743 kg SSD 

 or 



743/1.007 = 738 kg dry 



The adjusted basic batch weights per cubic meter of 

 concrete are 



Water (net mixing) 



198 kg 



Cement 



319 kg 



Coarse aggregate (dry) 



1124 kg 



Fine aggregate (dry) 



73a kg 



A2.2.10 Adjustments of proportions determined on 

 an absolute volume basis follow a procedure similar 

 to that just outlined. The steps will be given without 

 detailed explanation: 



A2.2.10.1 Quantities used m the nominal 02 m^ 

 batch are 



Walrr (added) 



Coarse aggregate 

 Fine aggregate (u 

 Total 



2 70 kg 

 SMkg 

 23 SO kg 

 16.81 kg 

 4S.3S kg 



Measured slump 5 cm; unit weight 2390 kg/m»; yield 

 48.35/2390 = 0.0202 m'; workability o.k. 



= 1163 kg wet 



1163/1.02 = 1140 kg dry 



A2.2.10.S The volume of ingredients other than 

 air in the original trial batch was 



= 0.0039 m 

 = 0.0018 IT 

 = C086 n 

 = 0.0059 n 

 0.0202 r 





1000 





5.64 



* 



3.15 X lOOO 



aggregate 



23.04 



2.68 X 1000 



sgregate 



15.58 



2.64 X lOOO 



Since the yield was also 0.0202 m^, there was no air in 

 the concrete delectable within the precision of the unit 

 weight test and significant figures of the calculations. 

 With the proportions of all components except fine 

 aggregate established, the determination of adjusted 

 cubic yard batch quantities can be completed as fol- 

 lows: 



Volume of cement 



Weight of fine 

 aggregate (dry basis) 



= 0.728 1 

 a.728 = 0.2721 



2.64 X 1000 = 718 kg 



The adjusted basic batch weights per cubic meter of 

 concrete, then, are: 



Water (net mixing) 200 kg 



Cement 323 kg 



Coarse aggregate (dry) 1140 kg 



Fine aggregate (dry) 718 kg 



These differ only slightly from those given in Para- 

 graph A2.29.4 for the method of assumed concrete 

 weight. Further trials or experience might indicate 

 small additional adjustments for either method. 



*Saturatcd-njrfaee-dry 



PROPORTIONS FOR NORMAL AND HEAVYWEIGHT CONCRETE 



334 



