Cement Physical testing methods

Chapter 2: Portland Cement (cont.)

Tests on Portland Cement

Lab. Department Department is consider consider the main main department for cement industry to determine the

(Physical Physical,, Chemical Chemical,, Mechanical) proper propertie ties s of cement. cement.

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Physical properties

Chemical properties

Fineness: (Blaine method).  Affect at (rate of hydration, bleeding, durability, gypsum quantity, …etc) Consistency: (VICAT needle, Glimore Needle)

1- Composition: (raw materials) (Fe2o3, Mgo, Al2o3, Sio2, Cao) To know proportions and compare with standard specifications. 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 3- Composition: Raw cement (Clinker) analysis  determine setting, final setting, initial hardening, final hardening)Times some factors and compare it with - Factors affecting setting time are: standard. (Fineness, Water, cement age, (Silica factor, Hydraulic factor, K Heat, cement components) 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 2

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

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Compound composition

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Chemical limits

& Hydraulic Cements Tests on Portland, Blended & Hydraulic Cements

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Compound Composition: (ready cement analysis) 

To know un effective materials, free cao (must be less than 1%).

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To determine major comp. (Fe2o3, Mgo, Al2o3, Sio2, Cao).

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To calculate (C3S, C2S, C3A, C4AF) according to Begue.

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

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

To determine free cao (must be less than 1%).

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To determine some factors and compare it with standard . (Silica factor, Hydraulic factor, K factor, …etc )

1- Silica factor (S.F.):

o 2 (1. 2 Mgo Fe2o3 

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2- Hydraulic factor (H.F):

o

2



l 2o3  Fe2o3

(0. 5- . 6



Mgo C ao

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):  K  

100*Cao 2.8Sio2 1.1 l 2o3  0.7

4- A to F factor (A/F): l 2o3 ( 1  Fe2o3

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e2o3

(90- 95 )%

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Physical Properties of Portland Cement 

Fineness

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Soundness

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Consistency

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Setting time

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False set and flash set

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Compressive strength

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Heat of hydration

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Loss on ignition

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Density

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Bulk density

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Sulfate 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-

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

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rate of carbonation during storage

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cost

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rate of gypsum addition (increased fineness required a grate amount of gypsum )

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bleeding (Increasing fineness tend to decrease the amount of bleeding )

However, later strength is not directly affected.

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Blaine Fineness Apparatus

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Soundness 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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