M SAND

4th November, 2021 Prelims

M SAND

M Sand

M Sand is artificial sand made from crushing of rock or granite for construction purposes in cement or concrete.
It is used as a substitute for river sand.
M sand differs from natural river sand in its physical and mineralogical properties.

Manufacturing

M-Sand is manufactured in a three-stage process:

Crushing:

Quarry and Rocks stones are crushed at jaw crushers, cone crushers, and vertical shaft impact crushers, respectively leading into the formation of angular and cubical fine aggregate particles.

Screening:

Screening ensures this material is properly graded that’s similar to river sand.

Washing:

Washing removes all the micro-fine particles. Also, fine aggregates for concrete and plaster sand are also formed.

Advantages of M Sand

It is highly cohesive and compressive in strength.
It does not have the presence of impurities such as clay, dust and silt coatings. This helps in producing better quality concrete.
M-sand produced under strict industrial control and manufactured to meet BIS standards has proven to produce stronger concrete compared to river sand.
A nearly 30 %(percent) increase in masonry strength is obtained with the use of manufactured sand.
It requires a lower water-cement ratio if the mortar is mixed with manufactured sand, which also results in better characteristics in the hardened state.
It does not contain organic and soluble compound that affects the setting time and properties of cement, thus the required strength of concrete can be maintained.
Manufacturing sand also eliminates the environmental impact that occurred due to the lifting of natural sand from the river bed.

Disadvantages of M-sand

Improper crushing of manufacturing sand may lead to angular and flaky particles that are not suitable for concrete production, both technically and economically.
Also, an adequate set up of crusher may not be available in some parts of the county like West Bengal, as it costs higher than river sand.
For high-grade pumpable concrete in high-rise buildings, the requirement of cement is higher than the river sand, which may not be cost-effective

Difference Between M Sand and River Sand

Sr.No.	M-Sand	River Sand
1	M-Sand manufactured in a factory	This naturally available on river banks
2	The source of Crushed sand is a quarry. It is manufactured by quarry stones, Crushing rocks, or larger aggregate pieces into sand size particles in a factory or quarry.	This is naturally available and extracted from the riverbanks or river beds.
3	The shape of Crushed sand is angular and cubical and has a rough texture and hence, better for concrete.	The shape of natural sand is rounded and has a smooth surface.
4	No moisture content.	Moisture is generally present between the particles. Hence, it affects the assumptions of concrete mix design and quality of concrete.
5	This sand highly recommended for Reinforced concrete purposes and brick/block works.	River sand is recommended for Reinforced concrete, plastering and brick/blockwork.
6	Particle passing 75 microns: Up to 15%	Particle passing 75 microns: Up to 3%
7	M-sand specific gravity is approximate 2.73 (Depends on parent rock.)	River sand specific gravity is approximate 2.65 (Depends on rocks in the catchment area.)
8	M-sand dry density of 1.75 kg/m³	Naturally Sand dry density of 1.44 kg/m³
9	M-sand is manufactured to conform to zone II.	This sand mostly conforms to zone II and zone III
10	There is less adulteration.	There is a high probability of adulteration because of acute shortage. Natural sand adulteration with saline sea sand is common in coastal areas.
11	M-sand less damage to the environment as compared to natural sand.	This river sand is harmful to the environment. It reduces the groundwater level and rivers water gets dried up.

M-Sand and River Sand

IS Sieve	M-Sand % Age Passing	River Sand % Age Passing	% Age passing for single Normal Sand 115 383 – 19701 Zone II
4.75 mm	99.75	99.25	100 to 90
2.36 mm	78.25	93.50	100 to 75
1.18 mm	52.00	48.00	90 to 55
600 microns	38.00	21.00	59 to 35
300 microns	21.00	4.00	30 to 08
150 microns	5.00	0.05	10 to 0

Impact of Depletion of River Sand

M Sand in India

All the four southern states Andhra Pradesh, Tamil Nadu, Telangana, Karnataka have recognized it as a substitute for river sand, and have been promoting its use over the years. Gujarat also manufactures M-sand.
Karnataka has been the most pro-active of the lot. In fact, the 2011 sand policy encourages establishment of M-sand units by giving it top priority while allotting quarries. The State has 164 M-sand manufacturing units that produces 20 million tonnes of M sand per annum.

Hurdles in Using Alternative Sands

Manufactured sand is being used in India, but is still not popular due to the following reasons:

Lack of standard: In India too there are no details and specifications, especially regarding gradation, properties like void content, sand equivalent, limits of deleterious materials, and on proper mix proportions.

No government support: Besides the lack of government support, there are malpractices in every stage of construction, and lack of an appropriate policy to formulate and implement proper management of waste and use of alternatives. This is because even the government buildings are being built with river sand. Although, there are guidelines for sustainable mining, illegal sand mining continues to be prevalent.

Limited awareness: Lack of awareness of the possibilities of production and use of alternative sand in construction is a major barrier. There is a need to generate experimental data on different types of alternative sands and on their properties so that they can be recognised by the government and private construction sectors.
Absence of suitable technology: Very few commercially viable and accepted technologies for production of alternative sands are present. Knowledge to tackle feedstock storage and transportation for proper quality of the sands is still lacking. There are no proper testing equipment and lab facilities to ensure the quality of alternative sands. Also, presence of quarry dust and inspection of production units is not undertaken.
Hesitancy of people: Limited knowledge has made people reluctant towards using alternative sands. This reluctance is more amongst the government officials and builders regarding the sands’ effect on quality.

Recommendations

Generating Awareness

There is a pressing need to create awareness of the problems related to environmental degradation and use of alternative sands.
This can be brought about through the media, encouragement from different organisations, through seminars and conferences.

Government Initiative

Engagement of organizations could generate extensive experimental data.
This data in turn would help in creating guidelines and codes.
Government organizations should set an example of using alternative sand in buildings, bridges, highways, skyscrapers, etc. to bring confidence in the public at large.

Initiative by Construction Industry

The construction industry can articulate guidelines to inspire use of alternative sand in projects and create a market mandate.
An association of builders in consultation with experts and scientists can start work to promote its usage.
Likewise, contractors and builders can endorse the sands in their client buildings.

Initiative by Research institutions

Research and academic institutions can play a vital role in the development of evaluation methods and specifications for use of alternative sands in construction.

Media