Sub grade

sub-grade plays a prominent role in road construction,this presentation contains a brief account on it.

1. SUB-GRADE Presented by G ayan jeewantha,HND /13/009

2. Introduction to the sub-grade Characteristic of sub-grade sub-grade improvement Advantages of improved sub-grade Conclusion CONTENT

3. Introduction to the sub-grade Can referred as existing soil Consist of different types of particles such as organic and inorganic. It’s a result in a process of decaying goods since the earth’s birth. Sandy soil, gravel soil, hard lateritic soil, marshy soil, muddy soil

4. Characteristic of sub-grade Mainly there are following types of deposit in the sub-grade. Rock Sedimentary Metamorphic Igneous

5. Soil boulders cobbles G ravels Sands Silts C lay Organic Clay silt or sand Peats

6. Sedimentary rocks Metamorphic Igneous B o ul ders cobbles Silts

7. Peats G ravels C lay

8. Sub-grade improvement can done in following ways 1. Dispose the existing soil and refill with imported soil.

9. 2. Cut and fill method amount of material from cuts roughly matches the amount of fill needed to make 

10. 3. Soil stabilization Mixing with cement (to improve compaction strength)

11. Mixing with lime. (increasing the density of the soil)

12. Mixing with Tar-bitumen

13. Applying a tar coat on the surface of sub-grade

14. Advantages of sub-grade improvement to maintain a high level of bearing capacity in a road to avoid initial cost in reconstruction In road to enhance the quality of road to avoid diffential settlements in the ground.

15. It's always advisable to go for a feasibility study on sub grade before constructing a road. conclusion

16. THANK YOU!