Surkhi Mortar: Definition, Uses, Tests

Surkhi Mortar
Surkhi Mortar


Surkhi Mortar’s main constituent is surkhi which is a waste material produced by powdering burnt bricks and has pozzolanic properties; it also enhances the waterproofing capabilities therefore used in the manufacturing of concrete as well as mortar.

Also, Read: Self Compacting Concrete

There are several pieces of evidence that shows the use of surkhi in construction before the 2nd century B.C

Pozzolanic materials are those materials that have cementitious properties within themselves.

When surkhi mixed with water it reacts and releases calcium hydroxide at the time of hydration. Due to pozzolanic properties in surkhi it utilized in India by mixing it with cement concrete.

Surkhi is economical, eco-friendly as well as has significant properties that it can easily use in the civil engineering industry.
It is used in concrete at the time of hydration to reduce its temperature.

It shows a remarkable change in the compressive strength of concrete when mixed in it, but It has more shrinkage than ordinary concrete.

By adding sukhi in concrete we decrease its initial strength, but it obtains final strength for a very long time The properties of surkhi are wide, and it has various use according to its property.

Addition of surkhi in cement concrete results in increment in plasticity and decrement in bleeding and segregation.

Surkhi which is used in construction should not retain more than 10% of its total weight in INDIAN STANDARD Sieve No.9.

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Surkhi Mortar

  • Surkhi mortar is a mortar formed by mixing surkhi instead of sand in mortar, or it is mixed according to the design mix of mortar.
    As it is more durable and has more strength than conventional sand mortar. It is economical and availability is more than sand in the market.
  • In surkhi mortar proportion of surkhi is 10 – 30% of the cement.
  • Surkhi mortar can be used as an alternative option for sand in civil engineering as shortage of sand is a global problem that can be rectified by the surkhi.
  • Surkhi mortar also reduced the effect of alkalies and salts on the concrete as it affects the final setting time of concrete and which causes the delay in its strength.
  • The segregation does not occur in the constituent of the mortar due to more cohesive force between the particles of the mortar. It also has a low heat of hydration than conventional concrete.
  • Surkhi Mortar has more initial setting time than ordinary cement mortar. It also has more shrinkage than ordinary concrete. Which sometimes results in excessive loss of moisture in concrete and cracks.

Read more:- Self Compacting Concrete

Types of Surkhi Mortar

Surkhi-Cement Mortar

Surkhi-cement mortar is formed by surkhi cement and sand. The proportion of surkhi should not be less than 10% of the weight of the cement. It is the most commonly used mortar in the Civil Engineering industry.

Surkhi-Lime Mortar

Surkhi-Lime Mortar is formed by the mixing of surkhi lime and sand. Which results in more water retention in the mortar and gives larger coverage at the time of construction of masonry.

Read more:- What is Shoring? Its types and Uses

Uses of Surkhi Mortar

Surkhi Mortar is used for all construction work like masonry work foundation work. it is suitable for both sub-structure work as well as super-structure work but cannot be used as plastering work or any type of external work because it gets disintegrate with time.

Uses of Surkhi Concrete

Surkhi Concrete is formed by mixing Stone dust, Surkhi, Cement, Aggregate and water.

Surkhi Concrete is much more economical than conventional concrete as it used to make concrete bricks as well as used in constructions of dams and heavy structures as it is not a standardized material it is not used widely in construction.

Read more:- Type of foundations and its types

Tests on Surkhi Mortar / Surkhi Concrete

Water Absorption Test

Water Absorption Test is a test used to find out the rate of water absorption in Surkhi Concrete as well as in Surkhi Mortar.

The sample should be oven dried in 115 degrees until the sample attains its constant weight.

Then immersed in water for 24 hours, and it should not absorb water more than 20% of the total weight of the sample.

Water Absorption Test Formula in percentage by

Weight = (W2-W1/W2)x 100

Soundness Test

Soundness Test is done in concrete bricks or in concrete cubes by striking two samples with each other as they must be producing metallic sound without causing any damage or crack in each other.

Hardness Test

Hardness Test is used to find the durability of any sample of concrete by making a scratch on its surface by any metallic object.

If the scratch is more than the sample is not durable and if the scratch or an impression is less or have no impression on the sample it’s a durable sample.

Read More:- What is Superelevation? It’s importance, Design & Analysis. – CivilLatest

Structural Test

Structural Test are the test which is used to determine the structural formation of any sample.

The Concrete sample is taken then crushed and analyze properly whether it is homogenous or does it have any lumps in it or not, or it has any voids in it.

If the sample does not have any voids and has homogenous formation and not have any lumps then the sample is passed in the structural test which means, it’s a durable and structurally sound sample.

Read More:- Lateral Stability of Structures – CivilLatest

Efflorescence Test

Efflorescence Test is a test used to determine the presence of alkali material in a sample.

In this test the sample it put in an apparatus in which its one end is immersed in water up to 2.5 cm and have another appratus same quantity of water is filled without sample immersed in it.

And put the whole arrangement at room temperature or at 30 degrees temperature to allow evaporation till whole water gets evaporated.

If the sample does not have a whitish layer on its surface, then the sample does not contain any alkali. And if a white layer visible on 10% of the sample’s surface then the sample is permissible and can be used.

If the White layer is presented on 50% of the sample’s surface then the sample is moderately affected by alkalies. And if it is more than that it is severely affected by alkalies.

Compressive Strength Test

Compressive Strength Test is a test that is used to determine the compressive strength of the sample. A compression Testing Machine is used in this test.

A preconditioned sample is taken then put that sample in a machine and 14 N/MM/Min load is applied to the sample till failure.

The compressive strength of the sample is determined on specimens after 7 days, 14 days, 28 days after the construction of specimens.

Closing Phrase

This is all about surkhi mortar if you have any queries regarding this article, please leave a comment below.

Please stay at home and be safe!

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By Shivansh Sharma

Shivansh Sharma is a Civil Engineer who is a Structural Engineering enthusiast, Blogger, and learner. Pursuing M. Tech (Structural Engineering). His project portfolios include 3 Residential projects and 1 commercial project. His knowledge of Rehabilitation of structures, Concrete, Steels and construction techniques allows him to help clients to meet their needs. Being a nature lover If he isn't working you will probably find him in the garden with his plants.


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