Good alternative

Natural sand is precious and mining it affects the environment. A good alternative is to use M-sand, which is of equally good quality, says K S Someswara.

In recent years, an enormous growth has been see in the construction sector, both commercial as well as residential. In any construction process, sand is an important element irrespective of the architecture or design of the building. This is an essential and basic material along with cement for mortar and concrete applications. As such, the demand for natural sand is always on the rise and its natural availability is not commensurate with the required demand. Thus, the prices have skyrocketed too.

Sand is used as a fine aggregate in mortar and concrete. Natural river sand — a product of natural weathering of rocks over millions of years — is the most preferred. However, uncontrolled extraction of natural sand from the river bed is a cause of concern for environmentalists. The need to protect river beds against erosion calls for a suitable alternative to natural sand.

A good alternative is Manufactured sand (M-Sand) which is also called artificial sand. This type of sand is produced by crushing cobble stones or other stones into sand by using a sand-making machine so that the required grain size is obtained.

M-sand contains typical rock forming materials like quartz, feldspar and mica group of minerals etc., as revealed by X-Ray diffraction (XRD). Rock forming minerals are basically inert in nature. Mica group consists of muscovite, biotite, boromuscovite, etc. These minerals do not interfere in cement hydration and strength development in mortar and concrete. In order to encourage the development of M-sand in Karnataka, the State government undertook a study of the process through the Department of Mines and Geology. The study was carried out by a group of scientists at IISc.

The sand was tested for gram size, distribution, pH and chemical composition, compression strength of mortar, flow and water retentivity, among other parameters.
The study found that M-sand is a well-graded material and falls within the specified grading limits. The shape of M-sand particles resembles that of river sand particles. Flaky and elongated coarse particles are absent in M-sand. It was also seen that mortars with M-sand exhibit better workability and water retentivity, and their compressive strength is higher than that of the mortar strength with river sand, for a given flow.

The other conclusions are as follows: Flexure bond strength of masonry using M-sand mortar is significantly higher than the mortar using river sand. This indicates better adherence of mortar to the masonry unit. Compressive strength and modulus for masonry using M-sand mortar is higher when compared with the values for masonry using river sand. Concrete with M-sand possess higher strength (compressive and flexure) when compared with river sand concrete. M-sand concrete possesses better bond strength between rebar and concrete. And, M-sand concrete and river sand concrete have similar stress-strain behaviour and characteristics.

It is a well-known fact that the increased demand for sand in our State has given rise to unhealthy practices to obtain it. The sand mafia, as it is called, has raised its ugly head and is controlling the entire industry.

Many a time, it is very difficult to get natural sand and people have to settle for inferior quality filtered sand. The production of M-sand can put an end to this problem with its good quality and competitive pricing. It can also boost the preservation of our river beds from erosion, thereby protecting the environment.

Already, in many parts of the world, M-sand or artificial sand is very much in vogue. Even in our country, the usage of M-sand has been made mandatory for all construction activities in many cities like Delhi and Mumbai. Recently, the Government of Karnataka made it mandatory to use M-Sand or such alternatives in the construction of Government buildings. The welcome trend can further extend to commercial and residential buildings for a better future.

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