2. SUB-TOPIC
1-1 Plain and Reinforced
Concrete
1-2 The Principles of concrete
mixing
1-3 The Unit of Measure
1-4 Concrete Proportion
3. 1-1 Plain and Reinforced
concrete
Plain Concrete is an artificial stone
as a result of mixing cement, fine
aggregates, coarse aggregates
and water.
Reinforced Concrete is a concrete
with reinforcement properly
embedded in such manner that the
two materials act together in
resisting forces.
4. The Different types of Concrete
Used in Construction:
Ordinary Portland cement
Rapid Hardening Portland cement -
Blast Furnace or Sulfate Cement
Low Heat Portland Cement
Portland Pozzolan Cement
High Alumina Cement “aluminous
cement or cement fundu”
5. The Main Composition of
Cement:
1.6 to 65% Lime
18.0 – 25% Silica
3.0 – 8% Alumina
3.0 – 5% Iron oxide
2.0 – 5% Magnesia
1.0 – 5% Sulfur Oxide
6. AGGREGATES
COARSE AGGREGATES
such as crushed stone, crushed gravel or natural gravel
with particles retained on 5mm sieve.
FINE AGGREGATES –
such as crushed stone, crushed gravel, sand or natural
sand with particles passing on a 5 mm sieve.
Size of aggregates – for coarse aggregate
(gravel), the maximum nominal size varies from
40, 20, 14 or 10 mm diameter.
7. 1-2 The Principles of Concrete
Mixing
1. Workability
2. Strength
3. Durability
4. Economy
8. The proportion that will be finally adopted in
concrete mixing has to be established by actual
trial and adjustment processes to attain the
desired strength and quality of concrete required
under the ff. procedures:
1. The water cement ratio is first determined at
the very first hour of mixing to meet the
requirements of strength and durability.
2. The cement-aggregate ratio is then chosen and
established to satisfy the workability
requirements.
9. The ACI requirements
1. Fresh concrete shall be workable.
2. Hardened concrete shall be strong
enough to carry the design load
3. Hardened concrete could withstand the
condition to which it is expected to
perform.
4. Concrete should be economically
produced.
10. Concrete Mixture
a. Designed Mixture
Where the contractor is responsible in
establishing proportion that will achieve required
strength and workability as specified in the plan
b. Prescribed Mixture
Where the designing engineer specify the
mixture proportion.
12. Table 1-1 Conversion from inches to
meter
Number Accurate
value
Approxima
te value
Number Accurate
value
Approximat
e value
1 .0254 .025 10 .2540 .250
2 .0508 .050 11 .2794 .275
3 .0762 .075 12 .3048 .300
4 .1016 .100 13 .3302 .325
5 .1270 .125 14 .3556 .350
6 .1524 .150 15 .3810 .375
7 .1778 .175 16 .4064 .400
8 .2032 .200 17 .4318 .425
9 .2286 .225 18 .4572 .450
13. Number Accurat
e value
Approximat
e value
Number Accurate
value
Approximat
e value
19 .4826 .475 30 .7620 .750
20 .5080 .500 31 .7874 .775
21 .5334 .525 32 .8128 .800
22 .5588 .550 33 .8382 .825
23 .5842 .575 34 .8636 .850
24 .6096 .600 35 .8890 .875
25 .6350 .625 36 .9144 .900
26 .6604 .650 37 .9398 .925
27 .6858 .675 38 .9652 .950
28 .7112 .700 39 .9906 .975
29 .7366 .725 40 1.016 1.00
14. 1-4 CONCRETE
PROPORTION
Proportioning concrete mixture is done in
two different ways; by weight or by
volume method.
Mixture
Class
Proportion Cement in
Bag
Sand
cu. M.
Gravel
cu. m
40kg 50kg
AA 1 : 1 ½ : 3 12.0 9.5 .50 1.0
A 1 : 2 : 4 9.0 7.0 .50 1.0
B 1 : 2 ½ : 5 7.5 6.0 .50 1.0
C 1 : 3 : 6 6.0 5.0 .50 1.0
TABLE 1- 2 Concrete Proportion