Surkhi (Brick Dust) – Its Characteristics, Applications, Concrete Mix Ratio and Manufacturing Process

What is Surkhi in construction?

Surkhi is utilized as a substitute for sand, cement and mortar. It is also used as fine aggregate in lime mortar and has practically a similar capability to sand however it gives some strength and hydraulicity. Sometimes it is also known as brick dust. 

Surkhi is made by crushing to powder consumed bricks, brickbats, blocks or consumed mud; under-consumed or over-consumed blocks ought not to be utilized, nor blocks containing a high extent of sand. At the point when the dirt is particularly scorched for making into surkhi, an expansion of 10 to 20 per cent of fast lime will work on its quality; little earth balls are made for consumption.

Surkhi for mortar might be produced using somewhat under-consumed blocks, and ground extremely fine; this will work on the hydraulicity of fat lime. Surkhi should be very much blended with lime, ideally in a mortar factory. (Test for under-consumed blocks is that they shouldn’t break up in water). Surkhi mortar acquires strength whenever left submerged in water.

Also Read: Different Types of Mortar and Grout

Characteristics of Surkhi

Some of the characteristics of Surkhi are:

1. Where sand isn’t accessible or is expensive, surkhi is used as an alternative in the preparation of ready-mix lime mortar. This generally comprises broken brickbats. When these are not free in bulk quantities, round bundles of the earth are made, and burned into a furnace grounded to a fine powder.
2. Broken or grinded stone is additionally utilized but it must be free from every extra proportion of fine particles like dust.
3. The best surkhi is made of mud containing 10 to 20 % of lime kankar and this must be under-burned. Mud containing practically zero lime should be completely burned to draw out the superior quality of surkhi from it.
4. Surkhi must not be utilized in lime mortar for plaster, since it is probably going to deteriorate after some time because of damaging the environment.

Application of Surkhi

Applications of Surkhi can be found in the following:

1. Admixture

Surkhi is utilized as an admixture to lime or concrete as it gives a few strengths and pressure-driven properties to it. It additionally makes it denser which builds the compressive strength of cement.

2. Cement Mortar

A piece of concrete is changed by surkhi while utilizing surkhi in mortar. Surkhi in concrete mortar grants strength and water-powered properties to the mortar.

3. Cement Concrete

A piece of concrete is changed by surkhi while getting ready mix cement concrete. As the hydration of concrete returns, lime is freed, which response with surkhi to give thick, reduced, and impermeable cement.

4. Water sealing treatment

Surkhi is utilized as the primary constituent in waterproofing treatment alongside lime. Now and again, concrete and surkhi are utilized in waterproofing rather than lime.

Surkhi is added so that the pozzolanic activity can be expanded which can make the waterproofing treatment impermeable.

Also read: Low Heat Cement

What is Surkhi Mortar?

In surkhi mortar, lime is utilized as binder material and surkhi is utilized as fine aggregate. The surkhi is finely-powdered earth which gives more strength than sand and is economically accessible on the lookout.

The mortar processed from surkhi shifts in quality since the raw components like dirt or lime present in nature broadly differ in quality.

Even from the start of the utilization of surkhi mortar for various developments; numerous sorts of examinations and studies have been done by engineers for deciding the strength, attributes and characteristics of the materials utilized for the planning of mortar

Surkhi Concrete Mix Ratio

Mix proportions generally used are 1: 1:6 (cement: lime: sand), 1:1:8 or 1:2:8. Generally, fat lime is used. (iv) Pointing: Pointing is done with the following mortar mixes: 1. Lime mortar 1: 2 mix (1 lime: 2 sand or surkhi)

How is Surkhi manufactured?

In the processing plant; clays are burnt equivalent to blocks however at a high temperature of around 600° C to 1000° C in a blast furnace. Then, over burnt product gains a reddish color.

It is then moved to a plant and ground into a powder with the end goal that the powder is sufficiently fine to pass IS No. 9 sieve and the residue must not be over 10% by weight. So through this process, Surkhi is obtained.

Also read: Cement vs Concrete

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