1Chapter 2: Portland Cement (cont.)

Tests on Portland Cement

Lab. Department is consider the main department for

cement industry to determine the

(Physical, Chemical, Mechanical)

properties of cement.

2Physical properties Chemical properties

Fineness: (Blaine method).Affect at (rate of hydration, bleeding, durability, gypsum quantity, etc)

1- Composition: (raw materials)(Fe2o3, Mgo, Al2o3, Sio2, Cao)To know proportions and compare with standard specifications.

Consistency: (VICAT needle, Glimore Needle)

2- Composition: (Mill materials)Before entering kiln, determined (Fe2o3, Mgo, Al2o3, Sio2, Cao)To know proportions and compare with standard specifications.

Setting Time: (mixing, initial setting, final setting, initial hardening, final hardening)Times- Factors affecting setting time are: (Fineness, Water, cement age, Heat, cement components)

3- Composition: Raw cement (Clinker) analysis determine some factors and compare it with standard.(Silica factor, Hydraulic factor, K factor, etc)

Soundness(Cement Swelling): 4- Composition: (ready cement analysis)-to know un effective materials cao.-(Fe2o3, Mgo, Al2o3, Sio2, Cao)-(C3S, C2S, C3A, C4AF) according to Begue.

Heat of Hydration: (thermo couple)

- False set and flash set.

- Compressive strength.

- Loss on ignition

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The relative quantities of each of these phases affects:

setting time rate of strength development overall strength durability colour

It is important, then, to know the composition of the cement.

Chemical Properties of Portland Cement

T Chemical analysis

Compound composition Chemical limits

& Hydraulic Cements Tests on Portland, Blended & Hydraulic Cements

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5Compound Composition: (ready cement analysis)

To know un effective materials, free cao (must be less than 1%). To determine major comp. (Fe2o3, Mgo, Al2o3, Sio2, Cao). To calculate (C3S, C2S, C3A, C4AF) according to Begue.

To determine Loss on ignition.(heated the sample to 1000C then calculate weight before and after ignition)

6Compound Composition: (Raw cement -Clinker- analysis):

To determine free cao (must be less than 1%). To determine some factors and compare it with standard .

(Silica factor, Hydraulic factor, K factor, etc)

1- Silica factor (S.F.):

4)(1.2Fe2o3Mgo

2si o

2- Hydraulic factor (H.F):

0.6)-.5(CMgo

2si o

03232

ao

oFeoAl

If H.F is very small the volume of the cement paste will increase which

lead to destroy the cement paste, but, if H.F is very high the cement

paste will be milled.

3- K factor calcium- (Kyool):

95)%-0(

9327.0321.128.2

*100 oFeoAlSioCaoK

4- A to F factor (A/F):

4)-(

13232

oFeoAl

7Physical Properties of Portland Cement

FinenessSoundnessConsistencySetting timeFalse set and flash setCompressive strengthHeat of hydrationLoss on ignitionDensityBulk densitySulfate expansion

Fineness

Fineness of cement is also important; it affects:

rate of hydration (rate of hydration increases with increasing fineness) rate of setting (setting time decreases with increasing fineness) -increase hydration-

durability (ASR) (high cement fineness reduces the durability of concrete to freeze )

rate of carbonation during storage cost rate of gypsum addition (increased fineness required a grate amount of gypsum )

bleeding (Increasing fineness tend to decrease the amount of bleeding )However, later strength is not directly affected.

8Blaine Fineness Apparatus

9Soundness

The main purpose of the soundness test is to assess the possible

risk of late expansion due to hydration of un combined calcium

oxide and/or magnesium oxide. The test uses apparatus known as

Le Chatelier apparatus, which magnifies any expansion during

heating to a value that can be measured.

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consistency

The main purpose of the consistency test is to determine the required quantity of water to obtain a standard or homogeneous past ,and water quantity is enough to hydration process.

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Setting time

The time it takes for a cement to stiffen to a standard value after addition of water is commonly known as the set time. The test involves mixing cement with water and then measuring its resistance to penetration of a standard probe at varying intervals of time, until a certain value is reached.

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Factors affecting setting time:

(Fineness w/c ratio cement age Heat cement components)

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Early stiffening (False set & Flash set)

False set refers to the rapid development of rigidity without the

evolution of much heat.

Flash set (quick set) refers to the rapid development of rigidity

without the evolution of considerable heat.

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