2. Determine the batch quantities for a concrete mix design (Non-air entraining) that is to have a 28-day compressive st

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2 Determine The Batch Quantities For A Concrete Mix Design Non Air Entraining That Is To Have A 28 Day Compressive St 1 (125.39 KiB) Viewed 31 times

2. Determine the batch quantities for a concrete mix design (Non-air entraining) that is to have a 28-day compressive strength of 4000 psi. A slump of 3 in. is desirable. Assume the specific gravity of cement is 3.14 and one sack weights 94lbs. Also assume that the unit weight of water = 62.4 lb/ft". Use the design Tables 5.4 and 5.5 as provided in class. The following descriptions apply to the coarse and fine aggregates: Coarse Aggregates: Sieve No. 4 to 1 in., Rounded shape Absorption (%) = 0.15 Specific Gravity (bulk dry) = 2.71 Specific Gravity (bulk saturated surface dry) = 2.74 Dry-rodded unit weight (lb/ft?) = 101.2 Fine Aggregate: Fineness modulus = 2.7 Absorption (%) = 0.72 Specific Gravity (bulk dry) = 2.42 Specific Gravity (saturated surface dry) = 2.46
TABLE 5-4 DRY-RODDED VOLUME b/b. OF COARSE AGGREGATE (ANY TYPE) PER UNIT VOLUME OF CONCRETE Fine Sand Medium Sand Coarse Sand Fireness Modulus of Sand Size of Coarse 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 Aggregate (Square-opening Laboratory Sieves) Values for b/bo · No. 4 to in 0.59 0.58 0.57 0.56 0.55 0.53 0.52 No. 4 to 1 in. 0.66 0.65 0.64 0.63 0.62 0.61 0.60 0.59 No. 4 to 1 in. 0.71 0.70 0:69 0.68 0.67 0.66 0.65 0.64 No. 4 to 1 in. 0.75 0.73 0.72 0.71 0.70 0.69 0.68 No. 4 to 2 in. *0.78 0.77 0.76 . 0.75 0.74 0.13 0.72 0.71 No. 4 to 2 in 0.80 0.79 0.78. 0.77 0.76 0.75 0.74 0.73 From A. T. Goldbeck and J. E. Gray, "A Method of Proportioning Concrete for Strength, Workability, and Durability," Bull. 11, National Crushed Stone Association, Nov. 1953. "For concrete that is to be assisted in place by internal vibration under very rigid inspection, increase tabulated values of blbo approximately 10%. 0.54 ..0.74 1 in. 40. . TABLE 5-5 NON-AIR-ENTRAINING STRUCTURAL CONCRETE CEMENT FACTORS REQUIRED FOR 28-DAY COMPRESSIVE STRENGTHS LISTEDs, b Size of Coarse Aggregate (Square- opening Laboratory Sieves): No. 4 to No. 4 to No. 4 to No. 4 to No. 4 to No. 4 to 1 in. & in. 1 lin. 2 in. 2 in Slump (in.): 3 6 3 6 3. 6 3 6 3 6 3 6 Water (gal yd of concrete) Angular 42 44 40 42 38 36 38 35.37 34 36 coarse aggregate Rounded 38 40. 36. 38 34 36. 32 34 31 33 30 32 coarse aggregate 28-Day Compressive Strength (psi) Cement (Sacks/YP of. Concrete) 2000 4.6 4.8 4.4 4.6 4.2 4.4 4.0 4.2 3.9 4.0 3.8 3.9 2500 5.0 5.2 4.8. 5.0 4.5 4.8 4.2 4.5 4.1 4.3 4.0 4.2 3000 5.4 5.7 5.2 :5.4 4.9 5.2 4.6 4.9 4.4 4.7 4.3 4.6 3500 5.9 6.3 5.6 5.9 5.3 5.6 5.0 5.3 4.9 5.2 4.8 5.0 4000 6.5 6.9 6.2 6.5 5.8 6.2 5.5 5.8 5.4 5.7 5.2 5.5 4500 7.2. 7.5 6.8 7.1 6.4 6.8 6.1 6.4 5.9 6.3 5.7 6.1 5000 8.1 8.5 7.7 . 8.1 .7.3.7.7 6.9 7.3 6,7 6.5 6.9 Entrapped air (approx. %) 2.5 2 1.5 1 1 From A. T. Goldbeck and J. E. Gray. "A Method of Proportioning Concrete for Strength, Workability, and Durability," Bull. 11. National Crushed Stone Association, Nov. 1953.. For concrete to be assisted in place by intemal vibration, use 3-in. slump and decrease tabulated water contents by approxi- mately 4 gal. No reduction in cement factor is suggested. This is waler actually effective as mixing water. 7.1.