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Specifications for Quantities of Concrete

I. Class A
All superstructures and heavily reinforced sub-structures. The important part of the
structures included are slabs, beams, girders, columns, arch ribs, box culverts,
reinforced abutments, retaining walls, reinforced footings, pre-cast piles and cribbing

Mixture: (1: 2: 4)
Portland cement: 9 bags per cu. m.
Fine Aggregates: 0.50 cu. m + 10% waste per cu. m. – (angular – 0.54)
Coarse Aggregates: 0.77 cu. m. + 5% waste per cu. m. – (angular – 0.68)
Maximum water-cement ratio: 0.53
Minimum compressive strength: 3,000 psi (20.7 MPa)
Size of coarse aggregates: 37.5mm (1 ½ inches)
Slump: 50-100mm (2-4 inches)

II. Class B
Footings, pedestals, massive pier shafts, pipe bedding and gravity walls, unreinforced or
with only small amount of reinforcement

Mixture: (1: 2 ½: 5)
Portland cement: 8 bags per cu. m.
Fine Aggregates: 0.45 cu. m + 10% waste per cu. m. – (angular – 0.52)
Coarse Aggregates: 0.82 cu. m. + 5% waste per cu. m. – (angular – 0.73)
Maximum water-cement ratio: 0.58
Minimum compressive strength: 2,400 psi (16.5 MPa)
Size of coarse aggregates: 50mm (2 inches)
Slump: 50-100mm (2-4 inches)

III. Class C
Thin reinforced sections, railing and for filler in steel grid floors.

Mixture: (1: 3:6)

Portland cement: 9.5 bags per cu. m.
Fine Aggregates: 0.53 cu. m + 10% waste per cu. m. – (angular – 0.59)
Coarse Aggregates: 0.70 cu. m. + 5% waste per cu. m. – (angular – 0.68)
Maximum water-cement ratio: 0.55
Minimum compressive strength: 3,000 psi (20.7 MPa)
Size of coarse aggregates: 12.5mm (1/2 inches)
Slump: 50-100mm (2-4 inches)

Prepared by: Engr. Christopher B. Patrimonio, MBA, MEngCE

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IV. Class D or P
Pre-stressed concrete structures and members

Mixture: (1: 2: 3)
Portland cement: 11 bags per cu. m.
Fine Aggregates: 0.44 cu. m + 10% waste per cu. m. – (angular – 0.47)
Coarse Aggregates: 0.68 cu. m. + 5% waste per cu. m. – (angular – 0.65)
Maximum water-cement ratio: 0.49
Minimum compressive strength: 5,000 psi (34.47 MPa)
Size of coarse aggregates: 19mm (3/4 inches)
Slump: 100mm (4 inches)

 Based on 40 kg of cement per bag and 21-26 L of water per cu. m.

Compressive strength of concrete

Days % Compressive strength

3 40 - 50
7 65 - 75
14 85 - 90
28 90 - 99

Sample Computations

Work description: Concrete works

Structure: Foundation

Quantity: 180 cu. m.

Problem: Determine the quantity for cement, fine and coarse aggregates and water.

Solution:

* For Class B mixture for rounded

a. Quantity of cement, QC
QC = 8 x 180 = 1,440 bags

b. Quantity of fine aggregates, QFA

QFA = (0.45 cu. m. + 0.10 waste per cu. m.) x 180 = 99 cu. m.

c. Quantity of coarse aggregates, QCA

QFA = (0.82 cu. m. + 0.05 waste per cu. m.) x 180 = 156.6 cu. m.

d. Quantity of water, QW
QW = 26 x 180 = 4, 680 L

Prepared by: Engr. Christopher B. Patrimonio, MBA, MEngCE

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Masonry Works

Concrete Hollow Blocks (CHB)

Number of CHB = area x 12.5 x 1.05 (breakage)

Number of Cement (bags)

4” CHB = area x 12.5 / 32
6” CHB = area x 12.5 / 14
8” CHB = area x 12.5 / 10

Quantity of Sand (cu. m.) = bags of cement x 0.80

Rebars (spacing in meters)

Vertical Horizontal LM/SM

0.60 0.60 3.6
0.80 0.80 3.2
0.80 1.00 2.8
1.00 1.00 2.4
1.00 1.20 2.3

Sample Computations

Work description: Masonry works

Type of blocks: 6” CHB
Quantity: 238 sq. m.
Rebars: 0.80 m. x 0.80 m.
Problem: Compute quantity of sand, rebars and CHB

Solution:

a. Quantity of sand for 6” CHB

Cement (bags) = 238 x 12.5 / 14 = 212.5 say 213 bags
Sand (cu. m.) = 213 x 0.08 = 17.04 say 17.5 cu. m.

b. Quantity of rebars for 0.80 m. x 0.80 m.; LM/SM = 3.2

Length of bar = 238 x 3.2 = 761.6 say 762 m.
No. of bars = 762 m. x 1 bar / 6 m. = 127 pcs of 6 m. rebars

c. Number of 6” CHB
CHB (pcs) = 238 x 12.5 x 1.05 = 3,123.75 say 3,124 pcs

Prepared by: Engr. Christopher B. Patrimonio, MBA, MEngCE

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Removal of Forms and Falsework

Minimum Percentage of
Location Minimum Time
Design Strength
Centering under girders, beams frames or arches 14 days 80%
Floor slabs 14 days 70%
Walls 1 day 70%
Columns 2 days 70%
Sides of beams and all other vertical surfaces 1 day 70%

Recommended Slumps for Various Types of Concrete Construction

Slump, cm
Types of Construction
Maximum Minimum
Reinforced foundation walls and footings 8 2
Plain footings, caissons, and substructure wall 8 2
Beams and reinforced walls 10 2
Building columns 10 2
Pavements and slabs 8 2
Mass concrete 8 2

Grading Requirements for Fine Aggregates

Sieve Mass Percent Passing
9.5 mm (3/8 in) 100
4.75 mm (No.4) 95-100
2.36 mm (No.8) -
1.18 mm (No.16) 45-80
0.600 mm (No.30) -
0.300 mm (No.50) 5-30
0.150 mm (No.100) 0-10
0.075 mm (No. 200) 3 maximum

Grading Requirements for Coarse Aggregates

Standard Alternate US
Class A Class B Class C Class P Class Seal
mm Standard
63 2-1/2" 100
50 2" 100 95-100
37.5 1-1/2" 95-100 100
25 1" - 35-70 100 95-100
19 3/4" 35-70 - 100 95-100 -
12.5 1/2" - 10-30 90-100 - 25-60
9.5 3/8" 10-30 - 40-70 20-55 -
4.75 No.4 0-5 0-5 0-15 0-10 0-10
0.075 No.200 0-1 0-1 0-1 0-1 0-1

Prepared by: Engr. Christopher B. Patrimonio, MBA, MEngCE

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Classes and Uses of Concrete

CLASS A: All superstructures and heavily reinforced substructures. For slabs, beams, girders, arch
ribs, box culvert, reinforced footings, precast piles and cribbing.
CLASS B: Footings, pedestals, massive pier shafts, pipe bedding, and gravity walls, unreinforced or
with only a small amount of reinforcement.
CLASS C: Thin reinforced sections, railings, and for filler in steel grid floors.
CLASS P: Pre-stressed concrete structures and members.
Seal: Concrete deposited in water

Composition and Strength of Concrete for Use in Structures

Minimum
Designated
Compressive
Size of
Minimum Maximum Strength of 150
Consistency Coarse
Cement Water - mm X 300 mm
Range in Aggregates,
Class Content Per Cement Ratio Concrete
Slump mm Square
m3 Kg (bag*) Kg/Kg Cylinder
(inch) Opening, Std.
Specimen at 28
mm
days
MN/m2(PSI)
50-100 37.5-4.75 20.7
A 364 (9.1) 0.53
(2-4) (1 1/2”-No.4) (3,000)
50-100 50 - 4.75 16.5
B 320(8.0) 0.58
(2-4) (2”-No.4) (2,400)
50-100 12.5-4.75 20.7
C 380 (9.5) 0.55
(2-4) (1/2”-No.4) (3,000)
100max. 19.0-4.75 37.7
P 440(11) 0.49
(4)max (3/4”-No.4) (5,000)
100-200 25 - 4.75 20.7
Seal 380 (9.5) 0.58
(4-8) (1”-No.4) (3,000)

Prepared by: Engr. Christopher B. Patrimonio, MBA, MEngCE