Step-1: Choice of slump Slump,mm

Type of construction Maximum Minimum

If slump is not specified, a value appropriate for the work can Reinforced Beam 100 25
be selected from Table 6.3.1. The slump ranges shown apply Reinforced Column 100 25
when vibration is used to consolidate the concrete. Mixes of
Reinforced Wall 100 25
the stiffest consistency that can be placed efficiently should
Reinforced Slab and Stair 75 25
be used.
Reinforced Foundation 75 25

1/5 the minimum dimension of

Step-2: Choice of maximum size of aggregate structural members
1/3 the thickness of a slab
Large nominal maximum sizes of well graded aggregates
have less voids than smaller sizes. Hence, concretes with the
Available
larger-sized aggregates require less mortar per unit volume of Three-fourths of the space between
aggregate=25m
concrete. Generally, the nominal maximum size of aggregate reinforcing bars
m
should be the largest that is economically available and
consistent with dimensions of the structure

Non AIR -ENTERAINED CONCRETE

Step-3: Estimation of mixing water Slump (mm) 9.5mm 12.5mm 19mm 25mm 37.5mm 50mm 75mm 150mm
The quantity of water per unit volume of concrete required to 20 to 50 207 199 190 179 166 154 130 113
produce a given slump is dependent on: the nominal 75 to 100 228 216 205 193 181 169 145 124
maximum size, particle shape, and grading of the
aggregates; the concrete temperature; the amount of 100 to 175 243 228 216 202 190 178 160 0
entrained air; and use of chemical admixtures. More than 175 0 0 0 0 0 0 0 0

Step-4: Selection of water-cement or water-cementitious

materials ratio
Relationship b/n Water Cement Ratio
Water - Cement Ratio by Weight
Compressive strength at 28 days (Mpa) Fck
40 0.42
35 0.47
30 0.54
25 0.61
20 0.69
15 0.79

Step-5: Calculation of cement content

The required cement is equal to the estimated mixing-water content (Step 3) divided by the water-
cement ratio (Step 4).

Step-6: Estimation of coarse aggregate content Fineness Modulus

Nominal maximum size of
2.4 2.5 2.6 2.7 2.8 2.9 3
Volume of dry-rodded coarse aggregate per unit volume of aggregate
concrete for different coarse aggregates and fineness moduli 9.5 0.5 0.48 0.46 0.44
of fine aggregates 12.5 0.59 0.57 0.55 0.53
19 0.66 0.64 0.62 0.6
25 0.71 0.69 0.67 0.65
37.5 0.75 0.73 0.71 0.69
50 0.78 0.76 0.74 0.72
75 0.82 0.8 0.78 0.76
150 0.87 0.85 0.83 0.81

Step-7: Estimation of fine aggregate content

Table: 6First Estimate of Weight of Fresh Concrete
Maximum size of aggregate, mm First estimate of concrete weight, kg/m3
Air-entrained
Non-air entrained concrete
concrete
10 2285 2190
12.5 2315 2235
20 2355 2280
25 2375 2315
40 2420 2355
50 2445 2375
70 2465 2400
150 2505 2435

UM=10Ga(100-A)+CM(1-Ga/Gc)*WM(Ga-1)

UM Unit mass of fresh concrete Kg/m3

Weighted average specific gravity of
Ga combined fine and coarse
aggregate,bulk,SSD
Gc Specific gravity of cement
A Air Content, percent
WM Mixing Water Requirement Kg/m3
CM Cement Requirement Kg/m3

The water content of the concrete

Step-8: Adjustment for moisture aggregate will be affected by the moisture
content of the aggregate.
coarse aggregate %
fine aggregate %

Modification water add Total amount of water-(sand+agg)

 Concrete Mix design Based on ACI
Concrete Mix design for C40/50 trial mix Crushed Agg. (00)
Cement Type = OPC Cubical Strength = 50 Mpa Cement Content (kg/m3)= 500.00
A - Specification Requirement
Parameters Requirement
Required Ave. Compressive Strength Fcu 50 N/mm2
Required Cement Content 500.00 Kg/m3
Water / Cement Ratio 0.35 ACI 211-1-81 Table A-1.5.3.4(a)
Slump Required (mm) 25-75
B - Laboratory quality test result of the ingredients
The quality test result of water quality for construction, Flakiness Index,Grading, Unit Weight, Specific Gravity & Water absorption for fine & course
aggregate including silt content of sand.
Cement used is OPC from Dangote Cement Factory
C - Laboratory Design Data's Values
Entrapped air content Determined accordance with Table A.1.5.3.3 of ACI = 1.5%
Bulck Specific Gravity of Coarse Aggregate 25mm size = 2.88
Specific Gravity of Fine Aggregate = 2.66
Specific Gravity of Cement = 3.15
Water absorption of Coarse Aggregate 25 mm size = 1.25
Natural Moisture of coarse Aggregate 25mm size = 1.00
Water absorption of Fine Aggregate = 10.00
Natural Moisture of Fine Aggregate = 2.10
Dry rodde Unit Weight of Course Aggregate = 1,647.00 Kg/m3
Loose uint weight of Course Aggregate = 1,505.00 Kg/m3
Loose uint weight of Fine Aggregate = 1,632.00 Kg/m3
Loose Uint weight of Cement = 1,380.00 Kg/m3
Fineness Modules(FM) = 2.80
D - Determination of Target Mean Strength
The cubical target average mean Compressive strength at 28 days is given by the following (ACI )
Equation :
Target mean strength (Ts) = fck + 8.3
Where Ts = Target mean strength
fck = Characteristic Cubical Compressive Strength of Concrete at 28 day's = 50 N/mm2
So From the above Equation target mean strength = 58.3 N/mm2
The quantity of coarse aggregate estimated from ACI 211-1-81 Table A- 1.5.3.6 for a finesse modules of 2.9 and 25mm Nominal size of coarse aggregate , the
table indicates the volume of Coarse aggregate to be used on dry -
roaded basis is 0.66 m3
Therefore the required dry mass for coarse aggregate calculated as
Total Coarse Aggregate by Mass = 1087.0 Kg

2
 F - Determination of Cement Content

The concrete will be non-air entrained , from table A1.5.3.3,the estimated mixing water for required slump and Nominal Size is :
Nominal Size (mm) Slump (mm) Estimating Mixing Water(Kg)
25 25-75 175
Cement Content = Free water content / (Water/cement)
Cement Content = 500.00 kg
G - Determination of Mixing water excluding absorption of aggregates( from table A1.5.3.3,)
Estimated Mixing Water = 175 kg
H1 - Determination of Fine Aggregate by mass basis
From ACI 211-1-81 Table A1.5.3.7.1
The mass of a cubic meter of non air-entrained concrete made with aggregate having a nominal maximum size of 25mm is
estimated to be = 2380 Kg

The mass already Known are :

Water = 175.0 Kg
Cement = 500.00 Kg
Coarse Aggregate (25mm) = 1087.02 Kg
Total = 1762.0 Kg
Thus Mass of Fine Aggregate = 618.0 Kg
In Volume Bases
Volume of water = 0.1750 m3
Solid Volume of Cement = 0.1587 m3
Solid Volume of Coarse Aggregate (25mm) = 0.3774 m3
Volume of entrapped air = 0.0200 m3
Total Volume except Volume of Fine Aggregate = 0.7312 m3
Solid Volume of Fine Aggregate = = 0.2688 m3
H 2-2 - Batch masses per meter cube of Concrete
Water = 175 Kg
Cement = 500.00 Kg
Coarse Aggregate 25mm = 1087.02 Kg
Fine Aggregate = 617.98 Kg
Batch masses per cubic meter of concrete calculated on the two basis are compared below
Based on Estimated 1m3 Concrete Mass,
Concrete Ingredients Kg
Water 175.00
Cement 500.00
Fine Aggregate 617.98
Coarse Aggregate 1087.02

The Trial batch Preparation based on estimated concrete mass basis is as follows
Thus the adjusted net trial batch in SSD aggregate basis becomes

3
 ( i ) - Trial Batch in SSD aggregate basis

Water Free Water

Aggregate Type Natural Moisture
Absorption Required %

Coarse Aggregate 25mm 1.000 1.250 0.250

Fine Aggregate 2.100 10.000 7.900
Mass of additional water added due to absorbtion of aggrigate in Kg are :

Aggregate Type Free Water (Kg)

In Coarse Aggregate (25mm) 2.72
In Fine Aggregate 48.82
Total 51.54
Thus the total mass of water added including absorbed water = 227 kg
Adjusted weight of Aggregate in (kg ) thus becomes ,
Aggregate Type Adjusted mass (Kg)
Coarse Aggregate (25mm) 1084
Fine Aggregate 569
Thus the adjusted net trial batch in SSD aggregate basis becomes
Aggregate Type Adjusted mass (Kg)
Water 227
Cement 500
Coarse Aggregate (25mm) 1084
Fine Aggregate 569

Slump 28 days Characterstic Cubical Strength 28 Days Target 7 Days Target

Cement Content (Kg) Cement Type
in(mm) (N/mm2) Strength (N/mm2) Strength (N/mm2)

500.00 OPC 25-75 50.00 58.30 34.98

Proportion of Fine & Coarse Aggregate per a bag of Cement

Quantity per Bag (50Kg ) Loose Unit weight (Kg/m3) Loose Volume of Aggregate per a
Parameter Adjusted
Quantity (Kg) bag of cement (50Kg) in m3
Water 226.5 226.54 22.65 0.022653797
Cement 500.0 500.00 50 0.0362318841
Fine Aggregate 569.2 569.16 56.9 1632.0 0.0348749743
Coarse Aggregate C/A (02)= 80% 867.44 86.7 1505.0 0.0576373395
Coarse Aggregate C/A (01)= 20% 216.86 21.7 1505.0 0.0144093349
Total 1295.70 2,380.00 238.00 Volume of Aggr. (m ) 3
0.17
Number of bag of cement in cubic meter of Concrete 10.0

4
 N.B Determination of Adimxture for per cubic meter of concrete

Admixture to be added for 1m3 concrete which consume =500kg cement per1m3 concrete 1.0% Or 5.0 Lt/m3
mix 0.5%-2%

Where Ts = Targeat mean strength

fck = Characteristic Compresive Strength at 28 day's 40 N/mm2
s = Standard Deviation 4.5
y = Statical Value 1.65

So From the above Equation Cylinderical targeat mean strength 47 N/mm2

The Equivalent Cubical targeat mean strength = 1.25(35) 59 N/mm2

So From the above Equation Cubical targeat mean strength 59 N/mm2

5
 750

1500

1.30

1110

555.00
60

Parameter Adjusted Quantity (Kg)

Water 110.00 160.00 50.00
Cement 500.00 500 - 175.00
Fine Aggregate 630.00 610.00 (20.00) 43.75 (380.00)
Coarse Aggregate 02 900.00 865.00 (35.00) 131.25
Coarse Aggregate 01 230.00 244.56 14.56
Chemical 6.00 0 (6.00)
2,376.00 (2,376.00)