Proporti

Proporti - D esigning and P r opor tioning Nor mal C oncr...

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Designing and Proportioning Normal Concrete M ixtures
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Proportioning Factors in the Proportioning of Quality Concrete Mixtures Workability Durability Strength Appearance Economy
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Proportioning Materia ls Cement Supplementary Cementing Materials Water Aggregate Admixtures Fibers
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Proportioning
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Proportioning Mix Characteristics Strength Water-cementing materials ratio Aggregate size and volume Air content Slump and workability Water content Cementing materials content and type Admixtures
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Proportioning Requirements for Exposure Conditions Exposure condition Maximum w/c-ratio by mass Min. strength, f' c , MPa (psi) No freeze-thaw, deicers, aggressive substances Select for strength, workability, and finishing needs Select for structural requirements Concrete with low permea- bility; exposed to water 0.50 28 (4000) Concrete exposed to freezing and thawing in a moist condition or deicers 0.45 31 (4500) For corrosion protection for 0.40 35 (5000)
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Requirement for Concrete Exposed to Sulfates Sulfate exposu re (SO 4 ) in soil, % by mass 4 in water, ppm Cement type Maximu m w/c- ratio, by Minimu m strengt h, f' c , MPa (psi) Negligible Less than 0.10 Less than 150 No special type required Moderate 0.10 to 0.20 150 to 1500 II, MS, IP(MS), IS(MS), P(MS), I(PM) (MS), I(SM) (MS) 0.50 28 (4000) Severe 0.20 to 2.00 1500 to 10,000 V, HS 0.45 31 (4500)
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Relationship between W/C-Ratio and Strength Compress ive strength at 28 days, M Pa Water-cementitious materials ratio by mass Non-air- entrained concrete Air-entrained 45 0.38 0.30 40 0.42 0.34 35 0.47 0.39 30 0.54 0.45 25 0.61 0.52 Metric Metric
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Relationship between W/C-Ratio and Strength Compress ive strength at 28 days, psi Water-cementitious materials ratio by mass Non-air- entrained concrete Air-entrained 7000 0.33 6000 0.41 0.32 5000 0.48 0.40 4000 0.57 0.48 3000 0.68 0.59 Inch-Pound Inch-Pound
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Proportioning Compressive Strength Vs. W/C- Ratio
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Bulk Volume of Coarse Aggregate M aximum size of aggregate, mm (in.) Fineness modulus of sand 2.40 2.60 2.80 3.00 9.5 (3/8) 0.50 0.48 0.46 0.44 12.5 (1/2) 0.59 0.57 0.55 0.53 19 (3/4) 0.66 0.64 0.62 0.60 25 (1) 0.71 0.69 0.67 0.65 37.5 (1 1/2) 0.75 0.73 0.71 0.69 50 (2) 0.78 0.76 0.74 0.72
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Proportioning Bulk Volume of Coarse Aggregate
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Proportioning Absolute Volume of Coarse Aggregate per m 3 of Concrete Given:0.46 m 3 of coarse aggregate Bulk density = 1567 kg/m 3 , rodded Relative density = 2.65 Water = 1000 kg/m 3 0.46 m 3 • 1567 kg/m 3 = 715.5 kg Absolute volume = 715.5/(2.65 • 1000) = 0.27 m 3 So the coarse aggregate is 27% of the absolute volume of the concrete 1 m3 0.46 m3
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Proportioning Absolute Volume of Coarse Aggregate per yd 3 of Concrete 1 yd3 0.46 yd3 Given:0.46 yd 3 of coarse aggregate Bulk density = 98 lb/ft 3 , rodded Relative density = 2.65 Water = 62.4 lb/ft 3 0.46 • 27 = 12.4 ft 3 12.4 • 98 = 1215 lb Absolute volume = 1215/(2.65 • 62.4) = 7.35 7.35/27 = 0.27 So the coarse aggregate is 27% of the absolute volume of the concrete
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Proportioning Air Content and Aggregate Size
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Water and Air Requirements for Different Slumps and Sizes of Aggregate Water, kilograms per cubic meter of concrete, for indicated sizes of aggregate Slump, mm 9.5 m m 12.5 mm 19 m m 25 m m 37.5 50 m m 75 15 0 m m 25 to 50 207 199 190 179 166 154 130 113 75 to 100 228 216 205 193 181 169 145 124 150 to 175 243 228 216 202 190 178 160 Approximate amount of entrapped air in non-air-
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This note was uploaded on 12/15/2011 for the course CM 217 taught by Professor Rogers,m during the Fall '08 term at BYU.

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Proporti - D esigning and P r opor tioning Nor mal C oncr...

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