TYPES OF CONCRETE AND THEIR WEIGHT
Lightweight concrete- is classified into three types depending upon the kind of aggregates used in
mixing, which predetermines their weight.
a. Low density concrete- is employed for insulation t-- purposes whose unit weight rarely exceeds 50
pounds per cubic foot or 800 kg/m 3
b. Moderate-strength concrete - with unit weight from 960 to 360 kg. per cubic meter with a
compressive strength of 70 to 176 kg. per square centimeter is usually used to fill over light gage steel
floor panels
c. Structural concrete - has somewhat the same characteristics as that of medium stone concrete and
weighs from 90 to 120 pounds per cubic foot or 1440 to 1920 kg/ cu.m.
Medium stone concrete is also known as structural concrete weighing from 145 to 152 pounds per cubic
foot generally assumed to be 150 pounds per cubic foot or 3300 kg/cum
Heavyweight concrete - is used for shielding against gamma and radiation in nuclear reactor and other
similar structure. This is also used as counter weight for a lift bridge. The contents. of heavyweight
concrete are cement, heavy iron ores, crushed rock, steel scraps, punching’s or shot (as fine) is also
used.
WEIGHT OF HEAVYWEIGHT CONCRETE
The weight of the heavyweight concrete depends upon the kind of aggregate used in mixing:
1. Heavy rock aggregate - weighs 200 to 300 pounds per cu. ft. or 3,200 kg/cu. m.
2. Iron pa.1chings added to high density ores- 4,325 kg/ cum
3. Ores and steel - 330 lb/cu. ft or 5,300 kg/cum
TESTS
Concrete should undergo tests specially those made of various proportions few days or weeks before
the actual construction. The Building Officials has the right to order the testing of any materials used in
concrete construction to determine if the concrete con82 forms with the quality specified. The complete
records of the tests shall be maintained and made accessible for inspection during the progress of the
work and for a period of 2 years aner all and shall be preserved by the inspecting Architect or Engineer
for reference purposes.
Consistency - refers to the state of fluidity of freshly mixed concrete.
1. Slump Test ·- this method of test requires a fabricated metal.
2. Compression Test: This type of test is the process applied in determining the strength of
concrete
REINFORCED CONCRETE FLOOR SYSTEM
A floor system of a building refers to the beam, girder and floor slab. The floor slab carries both
live and dead load. Live load refers to the human occupants and other movable and moving
objects on the floor. Dead load refers to all fixed object and the weight of the slab itself.
BEAM AND GIRDER
Beam is the structural member supporting the transverse load with each end and resting on a
support. Girder is the term applied to a beam that supports one or more smaller beam.
Beam is classified as
1. Simple Beam – Refers to a single span beam supported at its end without restraint at
the support. Restraint means a rigid connection or anchorage on he support.
2. Continuous Beam – term applied to a beam that rest on more than to supports.
3. Semi – Continuous Beam – refers to a beam with two span with or without restraint at
the two extreme ends.
Cantilever Beam is supported on one end and the other end projecting beyond the support or
wall.
T-Beam When the floor slab and beams are poured with concrete simultaneously to produce a
monolithic structure where the portion of the slab at both sides of the beam serves as flanges
of T-beam.
TYPES OF REINFORCED CONCRETE SLAB
ONE WAY SLAB – common type of reinforced concrete floor system made of solid slab
supported by two parallel beams.
TWO WAY SOLID SLAB – supported on four sides where the floor panel is nearly square in plan
is generally economical to employ the two directions reinforcing bars place at right angle with
each other.
RIBBED FLOOR SLAB – consists of small adjacent T-Beam where in the open spaces between the
ribs are filled with clay tile, gypsum tiles or steel forms.
FLAT SLAB – rectangular slab directly supported by columns without beam or girders.
REINFORCE CONCRETE STAIRWAYS
The simplest form of reinforce concrete stairway is the inclined slab supported at the end of the
beams provided with steps on its upper surface.
PRECAST AND PRESTRESSED CONCRETE
PRECAST CONCRETE
The introduction of pre-cast concrete construction was brought by cost factor that has
increased considerably faster than most industrial products affected by the large amount of
onsite labor involved in the traditional methods of construction.
Precast Concrete has the following advantages:
1. Mass production of standardized and repetitive units.
2. Least labor cost per unit due to mechanized series of production
3. Used of unskilled labor
4. Less construction time
5. Better quality control and higher strength of concrete
6. Construction free of defects and weather conditions
TYPES OF PRECAST STRUCTURES
WALL PANEL –
3.
