Part 2 Flashcards by Catherine Cordova

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

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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

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Paste

a. Cement
b. Water

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Mineral Aggregate

a. Coarse Aggregate
b. Fine Aggregate

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Composition of concrete by volume of cement, water, and aggregate

7-14%
15-20%
66-78%

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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

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give volume to the concrete because they occupy
maximum space in the total volume of concrete.

Aggregates

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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

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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

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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

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those material which contributes Lime (CaO) and Magnesia (MgO) to
the clinker, it includes limestone, chalk, marls, and marine (oyster
shells)

Calcareous Raw Materials

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a material that sets or hardens by chemical
reaction with water in air.

Hydraulic Cement

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a hydraulic cement produced by pulverizing
cement clinker and gypsum (calcium sulfate).

Portland Cement

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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

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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

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For general concrete construction use when the special properties
specified for any other type are not required

T-1

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For general concrete construction, Moderate Sulfate resistance or
moderate heat of hydration cement

T-II

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For general concrete construction, High early strength cement

T-III

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For general concrete construction, Low heat of hydration cement

T-IV

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For general concrete construction, High sulfate resistance cemen

T-V

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For general construction use when the special properties specified for
any other type are not required

T-I (White Portland Cement)

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For general concrete construction use, Moderate sulfate resistant and
moderate heat of hydration cement

Three color bands
BRIGHT YELLOW (T-IP)

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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))

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For general concrete construction use not requiring high early
strength, sulfate resistant, Low Heat of hydration cement

One color band
BRIGHT YELLOW (T - P)

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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

Part 2 Flashcards

(62 cards)