final-corrected calculation (concrete)
DESCRIPTION
Sem4 Estimating-Taylor's University (BQS)TRANSCRIPT
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Estimating Seminar: Calculation (Chapter 7)
Question 5: Concrete
Note:
Strip foundation is on a solid ground thus no blinding needed
FORMWORK
Note:
Formwork needed for this strip foundation only includes 4 sides of the rectangle, front back and left
right excluding bottom and top.
Step 1 : Material cost
Item Description Calculation Unit RM
A. 1m2 of 18mm plywood m2 36.00
B. Allowance for cutting 15% waste RM 36.00 x
m2 5.40
C. 0.03m3 of struts/m2 at Rm400/m3 Rm400/m3 x 0.03m2 m2 12.00
Total cost of timber m2 53.40
D. Allow 4 uses for timber formwork
m
2 13.35
E. 10% wastage on each use RM 13.35 x
m2 1.34
F. Allow for nail, bolts, mould oil m2 1.50
Total cost for formwork per usage m2 16.19
1.00m
0.30m
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Step 2 : Labour Cost
I. Total quantity of formwork
= [(1.0m x 2) + (30.0m x 2)] x 0.30m x 4 nos
= 74.40m2
To erect and strike 1m2 of formwork takes 1 hour
Item Description Calculation Unit RM
A. 1 Joiner RM8.00/hr x 1 hr/m2 m2 8.00
B. 1 Labourer RM5.00/hr x 1 hr/m2 m2 5.00
Total cost of labour m2 13.00
Step 3 : Total Unit Rate
Item Description Unit RM
A. Material m2 16.19
B. Labour m2 13.00
Total unit rate m2 29.19
Step 4 : Total Cost
Total quantity of formwork x total unit rate = 74.40m2 x RM 29.19/m2
= RM 2171.74
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REINFORCEMENT BARS
Step 1 : Material Cost (Tonnes)
Item Description Calculation Unit RM
A. High yield steel rebar deliver to site ton 1480.00
B. Allow labour for stacking and loading ton 5.00
C. Allow wastage 7% on rebar RM 1480 x
ton 103.60
D. Tie wire 0.66kg/100kg @ RM 4.80/kg
x 1000 x RM4.80/kg
ton 31.68
E. Spacer ton 4.00
F. Rolling Margin ton 22.00
Total Material Cost ton 1646.28
Step 2 : Labour Cost (per Tonne)
Item Description Calculation Unit RM
A. 1 skilled labour hr 6.00
B. 1 unskilled labour hr 4.80
Total hr 10.80
C. Allow 10% idling time
x 1000
hr 1.08
Total Cost of Labour hr 11.88
Time required for 100kg
= (28 + 32 + 35 + 23 + 7) mins/60 mins
= 2.08 hours / 100kg
= 0.0208 hour/kg
= 20.8 hour/tonne
Hence, labour cost per tonne = 20.80 hour/tonne x RM11.88
= RM 247.10
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Step 3 : Total Unit Rate
Item Description Unit RM
A. Material ton 1646.28
B. Labour ton 247.10
Total unit rate per tonne ton 1893.38
Step 4 : Total Cost
Total Volume of Concrete used for Strip Foundation
= 0.30m x 1.0m x 30.0m
= 9m3
Since given allowance for rebar = 80kg/m3,
Hence, for 1m3 the allowance for rebar will be
= 9 m3 x
= 720kg / 1000
= 0.72 tonne
Thus, total cost
= RM 1893.38 x 0.72 tonne x 4 nos
= RM 5452.93
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CONCRETE
Ratio 1 : 2 : 3
Cement : Fine Aggregate : Coarse Aggregate
Step 1 : Material Cost
Item Description Calculation Unit RM
A. OPC of 1420kg/m3 at RM 10.00/50kg
x RM10.00 m3 284.00
B. Fine aggregate 2m3 at 1600kg/m3 at
RM30/tonne
x RM30.00 x
2m3
m3
96.00
C. Coarse aggregate 3m3 at 1400kg/m3 at
RM40/tonne
x RM40.00 x
3m3
m3
168.00
m3 548.00
D. Allow 20% placing wastage Rm548x0.12 m3 109.60
Total m3 657.60
E. Allow 50% shrinkage, consolidation,
wastage
Rm657.60x0.50 m3 328.80
Total Cost for 6m3 of Concrete Mix 6m3 986.40
Total Cost for 1m3 of Concrete Mix RM986.40/6m3 m3 164.40
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Step 2 : Labour and Mix Plant
Item Description Calculation Unit RM
A. One mixer at 1.2m3/hr
x RM5.00/hr m3 4.17
B. Cost of labour
x RM3.50
x 5 people
m3
14.58
C. Cost of labour placing concrete into
foundation
RM 5.00 x 0.66hr m3 3.00
D. Cost of labour working around rebar RM 5.00 x 0.55hr m3 2.75
E. Cost of vibrator RM 6.30/ 1.50m3 m3 4.20
Total Cost m3 28.70
Step 3 : Total unit rate
Item Description Unit RM
A. Material m3 164.40
B. Labour m3 28.70
Total unit rate m3 193.10
Step 4 : Total Cost
Total quantity of concrete = 0.30m x 1.0m x 30.0m x 4 nos
= 36 m3
Hence, total cost
= 36 m3 x RM 193.10
= RM 6951.60
FINAL ANSWER
Total Estimated cost for strip foundation = RM 2171.74 + RM 5452.93 + RM 6951.60
= RM 14576.27