Question

Determine the batch weights needed for all materials for a 10 yd³ batch given the following information. Show all work for partial credit.

Slump = 4 inch maximum

w/cm = 0.45

Cementitious content = 525 lbs/yd³

Slag content = 30% by weight

Fly ash content = 30% by weight

CA (limestone) specific gravity (SSD) = 2.49

FA (sand) specific gravity (SSD) = 2.58

Cement (type I) specific gravity = 3.14

Slag (grade 100) specific gravity = 2.86

Fly ash (class C) specific gravity = 2.59

Air content = 1.0 percent (non-air entrained)

CA absorption = 1.0%

CA moisture content = 2.5%

FA absorption = 1.5%

FA moisture content = 3.3%

Aggregate Volume: 55% CA, 45% FA

Material	Uncorrected batch weights for 1 yd3	Corrected batch weights for 1 yd3	Batch weights for 10 yd3
Portland Cement
Slag
Fly Ash
Water
Coarse Aggregate
Fine Aggregate

Answer 1

Ans) To get slump of 4in , M20 should be preferred

Ratio for M20(by volume) = 1 : 1.5 : 3

Cement content = 525 lb/yd³

Cement weight per yd³ = 525 lb

W/C = 0.45

Water weight = 0.45 x 525

= 236.25 lb/yd³ x 1 yd³

= 236.23 lb

Volume of water = 236.23/(62.4 x 27) = 0.14 yd³

Volume of cement per yd³ = mass / density

Density = SG of cement x density of water

Volume of cement = 525 / ( 62.4 x 27 x 3.14)

= 0.1 yd³

CA volume per cubic yard = 3 x 0.1 = 0.3 yd³

Density of CA = SG x Density of water

= 2.49 x 62.4 = 155.38 lb/ft³ or 4195.26 lb/yd³

Density = mass /volume

mass of CA = density x volume

= 4195.26 x 0.3

= 1259 lb  

FA volume per cubic yard = 3 x 0.1 = 0.3 yd³

Density of FA = SG x Density of water

= 2.58 x 62.4 = 161 lb/ft³ or 4347 lb/yd³

Density = mass /volume

mass of FA = density x volume

= 4347 x 0.15

= 652 lb

Volume of air per yd³ = 1%= 0.01 yd³

Weight of slag = 0.30 x 525 = 157.5 lb

Volume of slag = 157.5 / (2.86 x 62.4 x 27)

= 0.032 yd³

Weight of fly ash = 0.30 x 525 = 157.5 lb

Volume of slag = 157.5 / (2.59 x 62.4 x 27)

= 0.036 yd³

Corrected mass :

Corrected mass of water = 236.23 + (0.01 x 1259) + (0.015 x 652)

= 236.23 + 22.37

= 258.6 lb

Corrected mass of CA = 1259 - (0.025 x 1259)

= 1227.525 lb

Corrected mass of FA = 652 - (0.015 x 652)

= 642.22 lb

  

Material	Uncorrected batch weight	Corrected batch weight (lb) per yd3	Batch weight (lb)for 10yd3
Portland cement	526	526	5260
Slag	157.5	157.5	1575
Fly Ash	157.5	157.5	1575
Water	236.23	258.6	2586
Coarse Aggregate	1259	1227.525	12275.25
Fine Aggregate	625	642.22	6422.2