CHEMISTRY CONCRETE PERTEMUAN 06 Matakuliah: S0372 – Kimia Teknik Sipil Tahun: Ganjil 2007/2008.

CHEMISTRY CONCRETE PERTEMUAN 06

Matakuliah : S0372 – Kimia Teknik SipilTahun : Ganjil 2007/2008

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CHEMISTRY CONCRETE

• Aggregate.• Additional Materials.

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AGGREGATE

Aggregate content in concrete mixture usually very high. Pursuant to experience, the aggregate composition gyrate 60 - 70% from concrete mixture weight.Although its function only as filler, but because its big enough composition, this aggregate even also become important.Aggregate which is used in concrete mixture can in the form of natural aggregate or artificial aggregate.In general aggregate can be differentiated pursuant to its size measure, that is harsh aggregate and smooth aggregate.

Bina Nusantara Classification aggregate pursuant to source of material.

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Things required to paid attention to relate to usage of aggregate in concrete mixture :1. Air Volume

Air which there are in concrete mixture will influence the process of concrete, especially after formed its of cement pasta.

2. Solid Volume.Density of aggregate volume will influence weight fill and concrete become.

3. Specific gravity aggregate.Specific gravity aggregate will influence mixture proportion in weight as control.

4. Absorbtion.Absorbtion have an in with to specific gravity.

5. Rate irrigate surface of aggregate.Rate irrigate surface of aggregate have an in with usage of mixing moment water.

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ADDITIONAL MATERIALS.

Admixture is enhanced materials into concrete mixture at the time of or during mixing take place.

Function of this materials is to denature from concrete in order to become more suited for certain work, or to cost effective.

Admixture in Standards Definition of Terminology Relating to Concrete and Concrete Aggregates is defined as material besides water, aggregate, hydraulic cement which mixed in enhanced mortar or concrete before or during squealer take place. used Additional materials to modify the nature of and characteristic of concrete, for example to be able to, it is easy to be done, thrift or for the purpose of other like thrift of energy.

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Additional Type Materials.

In general additional materials which used in concrete can be differentiated to become 2 that is chemical admixture and additional materials which have the character of mineral (additive).

Additional materials of admixture enhanced by squealer moment and or moment pelaksaan of moulding (placing) while additional materials which have the character of mineral enhanced by squealer moment executed.

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Additional Materials of Chemistry :

1. Type A “Water – Reducing Admixtures”

Is materials add lessening needed to water yield concrete with certain consistency.

Materials add reducing of water can come from organic materials nor inorganic mixture for concrete without air (non-air-entrained) or with air in the case of lessening content irrigate mixture.

Besides materials add this can be used to modify time fastener of mortar or concrete as impact change of cement water factor.

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Composition of materials mixture add this classified in general become 5 class:a. Acid of Lignosulfonic and salt content.b. Modification and sour generation of salt content and

lignosulfonic.c. Hydroxylated carboxylic acids and its salt content.d. Modification hydroxylated carboxylic acids and its salt content.e. Other material like :

Inorganik material, example : zinky, salt, barracks, posfat, chloride

Acid of Amino and its generation Karbonhidrat, sour sugar and polisakarin. Polymer mixture, like ether, generation of melamic, naptan,

silicon, hidrokarbon-sulfat.

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2. Type B “Retarding Admixtures”

Retarding admixtures [is] materials add functioning to pursue time fastener of concrete. Its use to delay time fastener of concrete (setting time) for example because hot wheater condition, or lengthen time for condensation to avoid cold joints and avoid impact degradation of fresh concrete moment at the time of moulding executed.

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3. Type C “Accelerating Admixtures”

Accelarating Admixtures is materials add functioning to quicken cordage and development of strength early concrete.

This materials is used to lessen the the duration draining time (hidrasi) and quicken attainment of strength at concrete.

Most famous Admixtures Accelerating is chloride calcium. functioning Other materials as accelerator for example is salt compound like chloride, bromide, carbonate, silicate and sometimes other organic compound like tri-etanolamin.

Maximum dose is 2% from used cement weight.

Grouply materials add this divided to become three : (1) Organic condensation salt, (2) Organic condensation mixture, (3) Material of miscellaneous.

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4. Type D “Water Reducing and Retarding Admixtures”

Is materials add double-duty that is lessening the amount of water of pencampur needed to yield concrete with certain consistency and pursue cordage early.

This extant to materials almost everything melt. Water which implied in this materials will become the part of concrete mixture water. Become in the plan irrigate this have to be enhanced as total water weight in concrete mixture.

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5. Type E “Water Reducing and Accelerating Admixtures”Is materials add double-duty that is lessening the amount of water of pencampur needed to yield concrete which [is] its certain consistency and quicken cordage early.

6. Type F “Water Reducing, High Range Admixtures”Is materials add functioning to lessen the amount of water of pencampur needed to yield concrete with certain consistency, counted 12% or more.

7. Type G “ Water Reducing, High Range Retarding Admixtures”Is materials add functioning to lessen the amount of water of pencampur needed to yield concrete with certain consistency counted 12% or more as well as utk pursue cordage of concrete.

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Additional Materials of Mineral (Additive)Additional materials of this mineral more used to improve;repair performance depress concrete, so that additional materials of this mineral tend to to have the character of cementation.Some additional materials of this mineral is :pozzolan, fly ash, slag, and silica fume.Some advantage of usage of additional materials of this mineral for example :

a. Repairing performance of workability.b. Lessening heat.c. Lessening the expense of work of concrete.d. Heightening endurance to sulphate attack.e. Heightening endurance to attack reaction of alkali-silikaf. Heightening concrete age.g. Heightening strength depress concrete.h. Heightening is durabel of concrete.i. Lessening decrease.j. Lessening absorpsion and porosity irrigate in concrete.

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a. Fly ash stone smolder

Fly ash defined as smooth item result of tilery residu or embers stone powder. Fly ash can be differentiated to become two, that is fly ash normal which yielded from tilery of stone or anthracite smolder ash and bitomius fly class of C yielded of stone smolder type of lignite or of subbitumeus. Dusty fly class of C pregnant possibility of chalk ( lime ) more than 10% weight.

Chemical Compound Type F Type C

Trioksida Sulfur ( SO3 ), max % 5 5

Water Content, max % 3 3

Losing of heat, max % 6^ 6

Usage up to 12% still permitted if there is repair of result or performance test laboratory show that way.

Oksida Silika (SiO2) + Oksida Alumina (Al2O3) + Oksida besi

(Fe2O3), minimum 10%70 50

Chemical Content of Fly ash

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b. Slag

Slag represent result of residu combustion of high kiln. Definition of Slag in ASTM. C.989 is product of non-metal representing material in form of refinement, granular result of combustion is later; then made cool, for example by plunging it in water.

Factor to determine the nature of cementation in slag is chemical composition, alkali concentration and reaction to system, obstetrical of glass in slag, softness, and temperature of yg generated by during hydration process take place.

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c. Silika Fume

Silica fume is material of pozzollan smooth, where more silica composition witch yielded from high kiln or rest of silicon production or of alloy silicon iron (known as aliance between microsilika with silica of fume).

Usage of silica of fume in concrete mixture meant to yield concrete with strength depress high, for example for the column of wall or structure shift, concrete or pre-cast.

Usage of silica of fume range from 0 – 30% to improve; repair strength characteristic and is durabel concrete with water factor cement equal to 0.34 and 0.28 with or without materials of superplastisizer value and of slump 50mm.

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Chemical Weight in %

SiO2 92 - 94

Karbon 3 - 5

Fe2O3 0.10 - 0.50

CaO 0.10 - 0.15

Al2O3 0.20 - 0.30

MgO 0.10 - 0.20

MnO 0.008

K2O 0.1

Na2O 0.1

Physics Weight in %

Spesific gravity 2.02

Mean particle size measure of um. 0.1

Get away sieve of No. 325 in % 99

Acidity of pH ( 10% water in slurry) 7.3

Chemical Compound Silika Fume