Part 2 Flashcards
mixture of fine aggregates or sand, coarse aggregates or gravel,
cement, water, and/or admixtures. These materials when properly
mixed and proportioned, make a plastic or monolithic form that can be
molded into a predetermined size, shape, and volume
CONCRETE
Concrete comes from the latin word ________ which means, _________
which is a concise description of the binding of loose particles into a
single mass.
Concretus, growing together
Paste
a. Cement
b. Water
Mineral Aggregate
a. Coarse Aggregate
b. Fine Aggregate
Composition of concrete by volume of cement, water, and aggregate
7-14%
15-20%
66-78%
Cementitious material includes Portland Cement, blended cements,
ground granulated blast furnace slag, fly ash, silica fume, metakaolins,
and other materials having cementitious properties. Cement as the
hydrated paste is the binder of concrete.
Cement
give volume to the concrete because they occupy
maximum space in the total volume of concrete.
Aggregates
indispensable because it is required for reaction of hydration.
But its use should be restricted to minimum as possible considering the
requirement for chemical reaction with cement and workability only.
Water
Is an optional ingredient which is used depending on the specific
purpose. It is used to modify some of the properties of concrete such as
setting time, workability or surface finishing characteristics. However, it
must be noted that admixture should not be used to compensate for
bad quality of concrete instead it should be used as a supplement for
good construction.
admixture
those materials which contributes Silica (SiO3
), Alumina (Al2O3
) and
Iron Oxide (Fe2O3
) to the clinker, it includes clay, shale, blast furnace
slag, iron ore and sand.
Argillaceous Raw Materials
those material which contributes Lime (CaO) and Magnesia (MgO) to
the clinker, it includes limestone, chalk, marls, and marine (oyster
shells)
Calcareous Raw Materials
a material that sets or hardens by chemical
reaction with water in air.
Hydraulic Cement
a hydraulic cement produced by pulverizing
cement clinker and gypsum (calcium sulfate).
Portland Cement
a hydraulic cement consisting of two or more inorganic
constituents (at least one of which is not a portland cement or
portland cement clinker) which separately or in combination
contribute to the strength gaining properties of the cement.
Blended Cement
a blended hydraulic cement consisting of an
intimate and uniform blend of portland cement or portland blast-
furnace slag cement and fine pozzolan produced by intergrinding
portland cement clinker and pozzolan, in which the amount of
pozzolan constituent is within specified limits.
Portland-Pozzolan Cement
For general concrete construction use when the special properties
specified for any other type are not required
T-1
For general concrete construction, Moderate Sulfate resistance or
moderate heat of hydration cement
T-II
For general concrete construction, High early strength cement
T-III
For general concrete construction, Low heat of hydration cement
T-IV
For general concrete construction, High sulfate resistance cemen
T-V
For general construction use when the special properties specified for
any other type are not required
T-I (White Portland Cement)
For general concrete construction use, Moderate sulfate resistant and
moderate heat of hydration cement
Three color bands
BRIGHT YELLOW (T-IP)
For general concrete construction use when special characteristics
attributed to the larger quantities of pozzolan in the portland-pozzolan
cement are not required.
wo color bands
BRIGHT YELLOW (T – I(PM))
For general concrete construction use not requiring high early
strength, sulfate resistant, Low Heat of hydration cement
One color band
BRIGHT YELLOW (T - P)
For general concrete construction, Moderate sulfate resistant and
moderate heat of hydration cement
Two color bands
BLUE COLOR (T-IS)
For general concrete construction not requiring high early strength,
sulfate resistant, Low Heat of hydration cement
One color band blue color (T-S)
Primarily used in masonry and plastering construction
One color band
Two color bands
Three color bands (T – N, T – S, T – M)
The condition by which the cement paste, mortar or concrete
mix starts to lose its plasticity and gain a certain degree of
rigidity
Setting of Cement
The condition by which the mortar or concrete starts to
develop and gain its strengtht
Hardening of Cement
It is the chemical reaction that takes place when portland cement
and water are mixed together. The hydration reaction is considered
complete at 28 days.
Hydration
The quantity of heat that are liberated (exothermic) from the
reaction of cement with water.
Heat of Hydration
the concrete should be workable and free from segregation and
bleeding.
plastic
state
the separation of coarse aggregates (stones)
and bleeding is the separation of cement paste from the main mass
Segregation
considered to be the most important and is taken as an index of its
overall quality.
compressive strength
This method covers determination of the density
of hydraulic cement. Its particular usefulness is in
connection with the design and control of
concrete mixtures.
Standard Method of Test for Density of Hydraulic Cement
(AASHTO T-133 / ASTM C 188)
defined as the
mass of a unit volume of the solids.
density of hydraulic cement
Both strength and permeability are influenced by fineness.
Increasing the fineness substantially increase the rate of
hydration.
FINENESS (AASHTO T-128 / ASTM C 184)
To determine whether or not the hydraulic cement under test
meets the air-entraining or non-air-entraining requirements of
the applicable hydraulic cement specification.
Controls the ability to withstand cycles of freezing and thawing.
AIR CONTENT (ASTM C 185)
To determine the amount of water required to
prepare hydraulic pastes for testing.
Normal Consistency (ASTM C187)
generally assumed to
affect concrete workability.
Cement consistency
Measures the penetration resistance of
cement paste or mortar.
To ensure that the cement does not produce
abnormal setting time or to test the reaction
of cement and chemical admixture.
TIME SETTING Using Vicat Needle
(AASHTO T-131 ASTM C 191)
refers to the stiffening of the cement paste or the change from
plastic state to a solid state.
Setting
mainly develop by a selective hydration of tricalcium
aluminate (C3A) and tricalcium silicate (C3S) and is accompanied by
temperature rises in the cement paste;
Setting
corresponds to a rapid rise
Initial set
corresponds to the
peak temperature.
final set
Provides an index of potential delayed
expansion caused by hydration of free lime
(CaO)or MgO or both.
SOUNDNESS DETERMINATION BY AUTOCLAVE EXPANSION
(AASHTO T-107 / ASTM C 151)
This method is used to determine the compressive
strength of hydraulic cement that will be used to
determine compliance with specifications.
It also provides an excellent indication of the overall
quality of hydraulic cement.
COMPRESSIVE STRENGTH of Hydraulic Cement mortars using
2-in. or (50mm) Cube Specimen
(AASHTO T-106 / ASTM C 109)
the weight percentage lost
when Portland cement is heated at 950±50°C
was added in cement specification to prevent
the addition of carbonate minerals such as
limestone and dolomite.
LOSS ON IGNITION (LOI) ASTM C114
The limits is set in order to prevent adulteration or
contamination of cement with siliceous and
argillaceous components.
All Portland cements contains ____ from silicate
impurities of gypsum(CaSO4) added during the
final grinding process.
INSOLUBLE RESIDUE (IR)
regulates the initial setting and
hardening reactions that take place
during hydration. above a certain optimum %
causes a decrease in strength and
an increase in expansion.
SULFUR TRIOXIDE (SO₃)
______ is being limited because of concern about
expansion that can occur if free ______ as periclase
hydrates to form Mg(OH)₂ at room temperature.
MAGNESIA (MgO)
a freshly mixed
material which can be molded into a shape. The relative
quantities of cement, aggregates and water mixed
together, control the properties of concrete in the wet
state as well as in the hardened state.
Fresh concrete or plastic concrete
a broad and subjective term
describing how easily freshly mixed concrete can be
mixed, placed, consolidated, and finished with
minimal loss of homogeneity. ‘Workability’ means
the behavior of the fresh concrete during mixing,
handling, delivery, and placement at the point of
placing and then during compaction and finishing of
the surface. It is a measure of the deformity of the
fresh concrete. It is defined by measurable numbers
Concrete workability
defined as mass of water
divided by the mass of cement in a mix.
Water-cement ratio
As aggregate surface area increases, more cement paste is
needed to cover the entire surface of aggregates.
Aggregate Size, Shape and Surface.
Some materials such as a super plasticizers reduce attraction
between cement and aggregate particles, allowing mixes that
can be flowable without the negative strength and segregation
effects of too much water.
Admixtures
a measure of the workability of the
concrete. This test is done at the point of placement.
Slump
controlled by the amount of water that is
batched into the concrete. __________ is increased as
water is added to a batch of concrete. There are
chemical admixtures (Water reducing) that can
increase the ______ chemically, without the
addition of extra water.
slump
is most widely used test for checking
workability of fresh concrete. Though we use this
test to measure workability actually it does not
define workability of concrete.
Slump test
Classification of slumping
• Collapse Slump
• Shear Slump
• True Slump
the specimens may be
conveyed to the laboratory for final cure. Specimen identity will be
noted along with the date and time the specimen was made.
After 24 - 48 hours of initial curing
Done in such a manner that at no time during the prescribed period will the concrete lack ample moisture and temperature control, so that hydration can continue to develop
Curing
