1. Concrete and Admixtures
Reported by:
Morales, Zani Gamaliel F.
Odiame, Yeoj C.
Submitted to:
Arch. Sylvester, Seño D.
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

2. History / Origin of Concrete
• Concrete comes from the Latin word "concretus" (meaning compact or
condensed), the perfect passive participle of "concrescere", from "con-"
(together) and "crescere" (to grow).
• Modern tests show that opus cae-menticium
had as much compressive strength as modern
Portland-cement concrete (ca. 200 kg/cm2).
Two important details:
1. Its mix consistency is fluid and homogeneous, allowing it to be
poured into forms rather than requiring hand-layering together with the
placement of aggregate.
2. Integral reinforcing steel gives modern concrete assemblies great
strength in tension, whereas Roman concrete could depend only upon the
strength of the concrete bonding to resist tension.
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

3. History / Origin of Concrete
• The baths of Caracalla in Rome are
just one example.
• Some have stated that the secret of
concrete was lost for 13 centuries
until 1756, when the British engineer
John Smeaton pioneered the use of
hydraulic lime in concrete, using
pebbles and powdered brick as
aggeregate.
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

4. Difference
• Roman Conrete
– Made of quicklime , pozzolana and an aggregate of pumice during the Roman Empire (old
concrete used by the Romans, did not use any steel reinforcing bars)
– Widespread use of concrete in Roman structures
• Freed Roman construction from restrictions of stone and brick materials
• Allowed for revolutionary new designs in terms of structural complexity and dimensions
– Had much compressive strength as modern Portland cement
– Tensile strength is lower without steel reinforcement
– Mix consistency requires hand layering together with placement of aggregate that consisted of
rubble
– Depend upon the strength of concrete bonding to resist tension
• Modern structural concrete
- Mix consistency is fluid and homogenous
- Could be poured into forms
- Integral reinforcing steel gives modern concrete assemblies great
strength in tension
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

5. Chemical Admixture
Chemical Admixtures are materials in the form of powder or fluids that
are added to the concrete to give it certain characteristics not
obtainable with plain concrete mixes. In normal use, admixture
dosages are less than 5% by mass of cement and are added to the
concrete at the time of batching/mixing.
Types of Admixtures
• Accelerators - speed up the hydration (hardening) of the concrete.
• Retarders – slow the hydration of concrete.
• Plasticizers – increase the workability of plastic or fresh concrete.
• Pigments – can be used to change the colour of concrete, for aesthetics.
• Air-entraining agents - stop formation of air bubbles in concrete, used in
freezing locations.
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

6. Concrete mixture and proportions
Mixture Class Proportion Cement in Bag Sand Gravel
Cement : 40 kg 50 kg Cubic Meter Cubic Meter
Sand : Gravel
Class AA 1:1½:3 12 9.5 0.5 1.0
Class A 1:2:4 9.0 7.0 0.5 1.0
Class B 1:2½:5 7.5 6.0 0.5 1.0
Class C 1:3:6 6.0 5.0 0.5 0.1
Compressive Strength (pounds per sq. inch) of Mixture and their Application /
Usage
a. Class AA - - 4000 PSI (retaining walls, concrete under water)
b. Class A - 3500 PSI (beams, slabs, footings, columns)
c. Class B - 3000 PSI
d. Class C - 2500 PSI (planboxes, non-critical areas)
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

7. Concrete mixture and proportions
Note: Commercially-available Portland cement bags come in 40kg and 50kg quantities
Mixture Class Proportion Cement in Bag Sand Gravel
Cement : 40 kg 50 kg Cubic Meter Cubic Meter
Sand : Gravel
Class AA 1:1½:3 12 9.5 0.5 1.0
Class A 1:2:4 9.0 7.0 0.5 1.0
Class B 1:2½:5 7.5 6.0 0.5 1.0
Class C 1:3:6 6.0 5.0 0.5 0.1
Meaning: Class AA concrete Meaning: Class AA concrete using 40 kg Portland
has 1 part Cement, 1.5 parts cement bag (bought from hardware), will be
Sand and 3 parts Gravel in equivalent to 12 bags of 40-kg Portland cement +
terms of proportion. 0.5 cubic meters (m3) of sand + 1.0 cubic meter
(m3) of gravel in terms of quantity

8. How to compute for the mixture proportion
1. Determine the length, width and depth of the space you’d
like to fill with concrete, in inches.
2. Multiply the length, width and depth.
3. Divide the result by 12 to determine the cubic feet for
concrete needed.
4. Divide number of cubic feet by 0.45 if you plan on using 60
pound bags of concrete mix. If you’re using 80 pound bags of
concrete mix, divide by 0.6.
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

9. How to compute for the mixture proportion
Another method:
1. Measure the length and width in feet of the space to be filled with
a tape measure. Multiply these measurements to arrive at the
square footage of the space.
2. Measure the depth in feet of the space to be filled. Multiply this
measurement by the square footage number. This will give you
the number of cubic feet of concrete you will need to buy.
3. Divide the number of cubic feet by three to arrive at the number
of cubic yards of concrete to be mixed and poured. Some
companies will sell concrete by the cubic foot; you can buy it
without the extra step.
4. Add a cubic foot or yard to the number before purchasing to allow
for errors. Because pouring concrete is a permanent form of
construction and difficult to fix once it's done, it is usually better
to have a little too much concrete than not enough.
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

10. Differentiation
Concrete – is a composite construction material
composed primarily of aggregate, cement and sand. It is
also widely used for making architectural structures,
foundations, pavements etc.
Cement – is a binder, a substance that sets and hardens
independently, and can bind other materials together.
Therefore, cement and concrete can be differentiated in
such a way that cement is just one of the 3 main
ingredients to create a concrete.
CONCRETE AND MIXTURES
Morales, Zani Gamaliel F. / Odiame, Yeoj C.
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00

11. Differentiation
Grout – is generally composed of a mixture of water,
cement, sand, often colour tint, and sometimes fine
gravel.
Plaster (cement) – is a mixture of suitable plaster, sand,
Portland cement, and water which is normally applied to
masonry interiors and exteriors to achieve a smooth
surface.
Therefore Grout is used in flooring in between while
Plaster (cement) is used in exterior / interior wall to have
a smooth surface.
CONCRETE AND MIXTURES
Odiame, Yeoj C. / Morales, Zam
BUILDING TECHNOLOGY – 1 / 10:00 – 11:00