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14 Properties of Cement: Physical & Chemical Properties of Cement

 

CEMENT MAY BE PRESCRIBED AS A MATERIAL WITH ADHESIVE AND COHESIVE PROPERTIES, WHICH MAKE IT CAPABLE OF BONDING MINERAL FRAGMENTS INTO A COMPACT WHOLE.

We will discuss the properties of cement in this article.

Cement is the composition of the following:

IngredientPercentage in cement
Lime60-65
Silica17-25
Alumina3-8
Magnesia1-3
Iron oxide0.5-6
Calcium Sulfate0.1-0.5
Sulfur Trioxide1-3
Alkaline0-1

 

The durability and strength of cement depend upon the components present in it.

 


 

  1.  Properties of Cement  

The properties of cement can be categorized into two types, namely physical properties & chemical properties.

 

 Properties of Cement

 


 

 

A. Physical Properties of Cement  

 

1. Fineness 

It is the biggest factor in the strength of cement. Higher fineness leads to higher strength.

Higher fineness denotes more area for cement-water reaction increasing strength.

Fineness in cement is achieved by grinding the clinker during the process of production.

 

2. Soundness

The capacity of not changing of properties of the material, like volume change; when water is added to it, is soundness.

Material with high soundness has a higher strength. So cement should also have high soundness.

Cement should be the cause of high soundness in mortar and concrete.

A few reasons for unsoundness are :

1. Excessive use of Gypsum in cement.

2. Excess of Lime

3. Burned Less

4. Excessive magnesia content

Some of the tests carried out to ensure the soundness are:

a. Le Chatelier Test

b. Autoclave Test

 

3. Consistency

Uniformity in the nature of the material leads to higher consistency. So, cement should have high consistency.

In other words, the flowing ability of cement paste is called consistency.

Vicat Test is carried out to measure the consistency of cement.

 

4. Setting Time

When water is added to the cement, it hardens and sets.

Setting time may depend upon the uniformity of cement, water-cement ratio, presence of admixtures, etc.

The initialsetting time of the cementshould not be less, and the final setting time should not be high.

 

The bestinitial and final setting timefor cement is given as:

Initial Setting Time: 30-45 Minutes

Final Setting Time: Below 10 Hours

 

5. Heat of hydration

The chemical reaction between cement and water is called the heat of hydration.

When water is added to cement, heat is generated. This can affect cement quality because excessive hydration leads to undesired strength.

Hydration depends upon the water-cement ratio, uniformness, temperature of curing, etc.

The heat of hydration is mainly affected by C3S and C3A.

 

6. Strength of Cement

Compressive, tensile, and flexural strength plays a vital role in the durability and quality of cement.

Factors affecting the strength of cement are:

a. Water-cement ratio of a mix.

b. Cement-fine aggregate ratio

c. Curing conditions

d. Size and shape of a specimen

e. The manner of molding and mixing

f. Loading conditions

g. Age of cement

 

7. Compressibility

Cement has high compressive strength. Thus, it provides stability and durability to the structure.

 


 

B. Chemical Properties of Cement

 

a. Lime

If the lime is used more than 65 %, it may result in the problem of expansion.

 

b. Alumina

Excess use of alumina quickens the setting time but weakens the cement bonding.

 

c. Sulfur Trioxide

If more Sulfur Trioxide is used, the cement becomes unsound.

 

d. Iron oxide

It is also called Ferric Oxide. It is responsible for the color of the cement.

 

e. Silica

Silica provides high compressive strength, abrasion resistance, and bond strength to cement.

 

f. Alkaline

The high amount of alkali use leads to difficulty in the regulation of setting time, and the low amount leads to discoloration of cement.

 

g. Magnesia

If the magnesia is used in high amounts, it results in unsoundness and uneconomical.

 


 

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