Surkhi is the powered form of over burnt bricks or the clay balls.
If surkhi is used instead of fine aggregate in the preparation of mortar then it is said to be surkhi mortar.
This mortar can be prepared by mixing surkhi and cement (or lime) with water in a mortar mill.
It is mostly used while constructing dams, brick masonry in buildings, aqueducts, bridges, etc.
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Evidence has shown that the use of surkhi and surkhi mortar was started before the 2nd century BC. ( Source: IndianExpress NewsPaper)
Surkhi mortar was used even during the 19th century.
In the 19th century, surkhi mortar was used for the construction of masonry in the upper Ganga Canal in Uttar Pradesh, Vani Vilas Sagar Dam, etc.
1.2. Strength & Quality of Surkhi Mortar
The mortar prepared from surkhi varies in quality since the raw materials like clay or lime occurred in nature are widely varying in quality.
Even since the beginning of the use of surkhi mortar for the different constructions; many kinds of research and studies have been carried out by engineers for determining the strength, characteristics and the qualities of the materials used for the preparation of mortar.
Strength characteristics of surkhi mortar depend upon the following:
a. The physical and chemical composition of lime or cement or surkhi.
b. Mineralogical composition of surkhi.
c. Degree of the burning of lime or cement or surkhi.
d. Fineness of surkhi.
e. Mix proportion.
f. The period of grinding and curing of mortar.
1.3. Methods of Grinding
The required quantity of lime or cement is poured into the mixer and water is added to make the uniform paste of lime or cement.
Then surkhi in the required proportion is added and the mixture is further ground till a uniformly mixed mortar is obtained.
The quantity of water used for the preparation of mortar is adjusted to obtain a workable mortar.
1.4. Types of Surkhi Mortar
3 types of surkhi mortar are commonly used. They are:
1.4.1. Surkhi-Lime Mortar
The mixture of lime, surkhi and water is said to be the surkhi-lime mortar.
This mortar has a low heat of hydration. It sets very slowly.
1.4.2. Surkhi-Cement Mortar
It is the mixture of cement, surkhi and water in definite proportion.
This mortar is commonly used. It also has a high heat of hydration and high setting time.
|Read Also: Cement Mortar & Grades of Cement Mortar|
1.5. Advantages of Surkhi Mortar
a. There is a global sand shortage. So, surkhi mortar can be used as an alternative.
b. The constituents of this mortar do not segregate.
c. It has a low heat of hydration.
d. It is more impervious than cement mortar of proportion leaner than 1:3.
e. It is more resistive to alkalis and salt solutions.
f. It is slow in setting and therefore it can be used for work up to a period of six hours of its preparation without disturbing the efficiency of mortar.
1.6. Disadvantages of Surkhi Mortar
a. Compared to ordinary mortar it is more subjected to shrinkage.
b. It has low compressive strength as compared to ordinary cement mortar.
c. It sets slowly.
a. Can we use surkhi mortar in permanent constructions?
Ans: Yes, we can use surkhi mortar for small scale permanent structures. Generally, this mortar is not used for large scale constructions although it was used in the construction of heavy structures in past.
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