Manufactured Sand/ M Sand
Manufacturing process:
- a) Crushing: Hard stones are crushed in Vertical Shaft Impact crusher where cubical and angular fine aggregate particles are produced.
- b) Screening: The process of screening helps in proper grading of the material to make it similar to river sand.
- c) Washing: The micro fine particles are removed by washing. This M Sand is vastly different from that of crusher dust. Additionally in the washing process both fine aggregates for concrete and plaster sand can be generated.
Comparison of River Sand and M Sand
Properties
|
River Sand
|
Manufactured Sand or M Sand
|
Advantages
|
Shape
|
Spherical particle
|
Cubical particle
|
Higher Cohesion and
Compressive Strength |
Gradation
|
Cannot be controlled
|
Can be controlled
|
Reduction in Voids and
Higher strength |
Marine Products
|
1-2% Like grass, clay lumps, tree barks etc.
|
0%
|
Not necessary to clean the sand before usage in the construction time.
|
Clay and Organic impurities
|
Likely to be present
(retard the setting & comp. strength) |
Absent
|
Better Concrete Quality
|
Grading zone(IS-383)
|
Likely to be present
(retard the setting & comp. strength) |
Manufactured to conform
to Zone II |
Zone II ideal
for Concrete |
M-sand of different grades is preferred for different types of work in the construction of a building-
M Sand for concreting
M Sand for plastering
PCC bottom or road work
Advantages of M Sand
- a) Consistent Supply: M Sand can be produced in areas closer to construction sites, bringing down the cost of transportation and providing an assurance of consistent supply.
- b) Lesser impurities and good working properties: M Sand is free of silt and clay particles, and has denser particle packing than natural sand.
- c) Excellent Strength: Compared to river sand, M Sand has higher compressive strength, higher flexural strength, better damage resistance, better water retentivity, higher unit weight and lower permeability as well.
- d) Better workability: The cubical shape with grounded edge and superior gradation of M Sand gives good plasticity to mortar, providing excellent workability.
- e) Eco friendly alternative: Usage of M Sand prevents dredging of river beds to get river sand which may lead to environmental disaster like ground water depletion, water scarcity, threat to the safety of bridges, dams etc. M Sands is an eco-friendly alternative to river sand.
- f) Economy:Since the usage of M Sand has increased durability, higher strength, reduction in segregation, permeability, increased workability, decreased post-concrete defects, it proves to be economical as a construction material replacing river sand.
Disadvantages of M Sand
- a) Moisture Content: Moisture is available only in water washed M Sand. Whereas, river sand has moisture which is trapped in between the particles which is good for concreting purpose.
- b) Larger proportion of micro fines: M Sand may contain larger amounts of micro fine particles than natural sand, owing to its production process. Quarry dust is one of the micro fines present in the M Sand, which is residue dust formed during the stone crushing. Chances of developing early cracks and weakening are more as it is devoid of required grades and not undergone adequate cleaning. This can affect the strength and workability of the screed or concrete.
- c) Adulteration: Due to the high demand, M-Sand is now being adulterated with quarry dust.
Solution
- a) Adulteration test
- b) Workability test
- c) Rebound test
- d) Slump cone test