1. Lecture 4 – BackfillingLecture 4 – Backfilling
Objectives:-
1.To learn the backfill to existing structures.
2.To relate the backfilling as per clauses in
SMM2
3.To determine the various clauses applied to
the backfilling
Outcomes:-
1.Able to differentiate the different clauses
used for backfilling
2.Able to write down the dimensions clearly.

2. BackfillingBackfilling
 It is an activity immediately afterIt is an activity immediately after
excavation work.excavation work.
 This activity needs a lot of thinkingThis activity needs a lot of thinking
and imagination.and imagination.

3. Once we have excavated the soilOnce we have excavated the soil
what next?what next?
Fig. 1 Excavated pit Fig 2. Excavated pit with
footing and stump

4. Then what ?Then what ?
Fig.1 Plan of a
footing
Fig.2 Section of a footing
We need to backfill

5. After backfill what next?After backfill what next?
A
B
Total excavated material( A + B = C) so A is the backfill
quantity while C – A = B ( Qty. to be removed)

6. Lets look at a simple structureLets look at a simple structure
F1
(1.00m x
1.00m )
Ground beam 150mm x 450mm
Stump 150mm
x 150mm
Plan of a Guard house

7. Testing your eye sightTesting your eye sight
View A
View B
View A
View B
GB1
GB2 GB3
GB4
GB1
GB4GB3

8. Before excavation we need to knowBefore excavation we need to know
the different activities involvedthe different activities involved

9. 11stst
. Measure the oversite. Measure the oversite
excavation with average depth ofexcavation with average depth of
150mm150mm5.00m
5.00m

10. Area of oversite excavationArea of oversite excavation
5.00m
5.00m

11. Excavate for footingExcavate for footing

12. Section of excavationSection of excavation
Ground level
Base of footing level

13. Lets put in the structureLets put in the structure

14. Oversite excavation averageOversite excavation average
150mm thick150mm thick

15. Lets add in a ground floor slabLets add in a ground floor slab
Slab 100mm
thick

16. Lets look at the isometric view ofLets look at the isometric view of
the structurethe structure
Grd. Beam
Grd. Floor slab
Stump
Footing

17. Look at the sequence carefullyLook at the sequence carefully
A B C D

18. So when you measure backfill youSo when you measure backfill you
shall consider carefully the differentshall consider carefully the different
depth for the different areadepth for the different area
Area 1
Area 2
Area 3 Area 4
Plan view
of footing

19. Description for excavation, backfill andDescription for excavation, backfill and
removal.removal.
 Excavate pit for footingExcavate pit for footing
commencing from ground levelcommencing from ground level
with plan dimension less thanwith plan dimension less than
1.25m and with depth not1.25m and with depth not
exceeding 2.00m (5 nos.)exceeding 2.00m (5 nos.)
 Selected backfill to requiredSelected backfill to required
formation level, spread, levelledformation level, spread, levelled
and well rammed andand well rammed and
consolidated.consolidated.
 Removing surplus excavatedRemoving surplus excavated
material from site includingmaterial from site including
transporting to contractor’s owntransporting to contractor’s own

20. Description for oversiteDescription for oversite
excavationexcavation
 Oversite excavation average 200mmOversite excavation average 200mm
thick including transporting top soilthick including transporting top soil
to site to be determined by theto site to be determined by the
architect for re-use.architect for re-use.
 Oversite excavation commencingOversite excavation commencing
from ground level to a depth notfrom ground level to a depth not
exceeding 250mm.exceeding 250mm.

21. Exercise no. 1: measure the backfillExercise no. 1: measure the backfill
quantity using the descriptionquantity using the description
providedprovided
Footing F1 ( 12 nos.)
1000mm
1000mm
1.85m
650mm
Stump 300mm x
300mm

22. Exercise no. 2- Measure the backfillExercise no. 2- Measure the backfill
to footing F2to footing F2
900mm
900mm
F2 ( 20 nos.)
1.65m
450mm
Stump 150mm
x 150mm
Grd.
Beam
125mm x
450mm
125mm
450mm
Section of ground beam

23. Exercise no. 3 – Measure theExercise no. 3 – Measure the
following:following:
 1. Oversite excavation to footing F1.1. Oversite excavation to footing F1.
 2. Excavation to Footing F1.2. Excavation to Footing F1.
 3. Backfilling to Footing F1.3. Backfilling to Footing F1.
 4. Removing surplus earth of footing4. Removing surplus earth of footing
F1.F1.
 5. Write down your answer in the5. Write down your answer in the
correct format with correctcorrect format with correct
description.description.

24. Footing F1 ( 25 nos.)Footing F1 ( 25 nos.)
950mm
950mm
GL
Oversite excavation
150mm depth
2.00m
50mm lean concrete
Stump 250mm x
250mm
450mm
GB
250mm x
600mm
Plan
Section