ஆற்று மணல் – கட்டுரை
Typical compressive strength of concrete:
The following result show the behavior of manufactured sand and riverbed sand when used in concrete.
With using riverbed sand [all proportions are weight]
Cement- 50kg
River sand – 75kg
Agg.20mm – 75 kg
Agg.12mm – 37.5kg
Water – 19 liters
Compressive strength achieved after 7- days curing 44.1mpa with using manufactured sand [ all proportions are weight]
Cement – 50kg
Artificial sand – 70 kg
Agg. 20mm – 80kg
Agg. 12mm – 35kg
Water – 19 liters
Compressive strength achieved after 7-days curing- 46.8 mpa.
Technical specification – comparison between manufactured sand riversand.
| S.No | Property | River sand | Manufactured sand | Remarks | 
| 1 | Shape | Spherical particle | Cubical Particle | Good. | 
| 2. | Gradation | Cannot be Controlled | Can be controlled | |
| 3 | Particle passing 75 micron | Presence of silt shall be less than 3% | Presence of Dust particle shall be less than 15% | Limit 3% for unrushed and limit 15% for crushed sand. | 
| 4. | Silt and organic impurities | Present [Retard the setting compressive strength] | Absent | Limit of 5% for uncrushed & 2% for crushed sand. | 
| 5. | Specific gravity | 2.3 – 2.7 | 2.5 – 2.9 | May vary. | 
| 6. | Water absorption | 1.5-3% | 2-4% | Limit 2% | 
| 7. | Ability to hold surface moisture | Upto 7% | Upto 10% | |
| 8. | Grading zone [FM] | Zone II, III FM 2.2 – 2.8 | Zone- III FM 2.6-3.0 | Recommends zone II for mass concrete. | 
| 9. | Soundness [Sodium sulphate-ss & magnesium sulphate-ms] [5 cycles] | Relatively less sound [Ex>5] | Relatively sound [Ex>5] | Limit 10% SS and 15% ms | 
| 10. | Alkali silica relativity | 0.002-0.01 | 0.001-0.008 | Limit 0.1% expansion | 
| S.No | Property | River sand | Manufactured sand | Remarks | 
| 1 | Work ability & its retention | Good & good retention | Less & less retention | Control of fires apply water absorption correction use of plasticisers | 
| 2 | Setting | Normal | Comparativery Faster | Apply water absorption correction use retarders. | 
| 3 | Compressive Strength | Normal | Marginally higher | As shown above | 
| 4 | Permeability | Poor | Very poor | |
| 5 | Cracks | May be | Send to surface crack | Early curing & protection of Fresh concrete. | 
Behavior of manufactured Sand & River sand when used in concrete.
SIEVE ANALYSIS RIVER SAND & MANUFACTURED SAND
| IS SIEVE | River sand % age passing | Manufactured sand % age passing | % age passing per single sized aggregate of normal sand [IS 383-1970] Zone II | 
| 4.75mm | 99.25 | 99.75 | 90 to 100 | 
| 2.36mm | 93.50 | 78.25 | 75 to 100 | 
| 1.18mm | 48.00 | 52.00 | 55 to 90 | 
| 600micron | 21.00 | 38.00 | 35 to 54 | 
| 300micron | 04.00 | 21.00 | 08 to 30 | 
| 150micron | 0.05 | 5.00 | 0 to 10 | 
Typical sieve Analysis: Comparison of River sand & Manufacture sand
| IS Sieve | % of passing [Riversand] | % of passing manufactured sand | Zone II (As Per IS:383) | 
| 4.75mm | 100 | 100 | 90-100 | 
| 2.36mm | 99.7 | 90.7 | 75-100 | 
| 1.18mm | 89 | 66.2 | 55-90 | 
| 600micron | 60.9 | 39.8 | 35-59 | 
| 300micron | 17.7 | 25.5 | 8-30 | 
| 150micron | 3.1 | 9.9 | 0-20 | 
| 75micron | Max 3 Zone II | Max 15 Zone II | Max 15 
 | 
Zone II Zone II: The gradation of manufactured sand can be contracted at crushing plant.



