What is Expansive cement?
It is a special type of
cement, when its mixed with water, it forms a paste that tends to increase in
volume to a much higher degree than Portland cement paste after setting. Its cement
mortar or concrete is compensated for compression losses.
In this post, we study in
detail the production, properties, types and applications of Expansive cement.
Production
of Expansive Cement
The manufacturing process
of this type of cement is similar to that of Portland cement, but the raw
materials used to make the clinkers are different. First, lime and clay form at
about 2,600 degrees Fahrenheit and clinkers, and in the next set, lime, calcium
sulfate and bauxite combine to form sulfolaminate clinkers at a temperature of
2300 degrees Fahrenheit. These two clinkers are bonded together to form
expandable cement. When this cement is exposed or mixed with water, the amount
of sulfoaluminate expands.
 |
| Fig 1: Use of expansive cement mortar in grouting of anchor bolts. |
PHYSICAL PROPERTIES OF EXPANSIVE CEMENT
Tab 1: Properties of Expansive Cement
PROPERTIES | VALUE |
Setting Time | 75 min |
Air Content | 12 % |
7 days expansion | |
Min | 0.04 |
max | 0.10 |
Compressive strength | |
7 days | 14.7 Mpa |
28 days | 24.5 Mpa |
TYPES OF EXPANSIVE CEMENT
Extensive cement is divided into 3 types depending on
the type of compound mixture used in the cement,
(1) TYPE K EXPANSIVE CEMENT
A mixture of portland cement,
anhydrous tetra calcium trialuminate sulfate (c4a3s), calcium sulfate (caso4),
and lime (cao).
(2)
TYPE M EXPANSIVE CEMENT
Interground
or blended mixtures of portland cement and calcium sulfate suitably
proportioned.
(3)
TYPE S EXPANSIVE CEMENT
A
portland cement containing a high computed tricalcium aluminate (C3A) content
and an amount of calcium sulfate above the usual amount found in portland
cement.
APPLICATIONS
OF EXPANSIVE CEMENT
1. This type of cement is used in large, continuous and large floor slabs
without joints
2. It works well for filling holes in foundations and for forming
stronger self-stressed concrete than conventional Portland cement concrete.
3. Pre-compressed concrete components for bridges and buildings are made
using this material.
4. Used to construct water-retaining structures and to repair damaged
concrete surfaces.
5. Used in anchor bolts grouting.
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