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Design of CC Road

This document summarizes the design of a cement concrete pavement for a road project from NH234 to Motlur via Chikkanahally & nallakadirenahally chainage: 0.00 to 4.10km. Key details include a concrete grade of M-30, CBR of 5%, design wheel load of 50kN, and trial thickness of 150mm over 150mm cementitious subbase. Based on the analysis, it is recommended to provide a 150mm thick cement concrete pavement (M-30) over 150mm granular sub-base and 100mm dense lime concrete (M-15) to safely support the expected traffic loads.

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pallavi
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491 views3 pages

Design of CC Road

This document summarizes the design of a cement concrete pavement for a road project from NH234 to Motlur via Chikkanahally & nallakadirenahally chainage: 0.00 to 4.10km. Key details include a concrete grade of M-30, CBR of 5%, design wheel load of 50kN, and trial thickness of 150mm over 150mm cementitious subbase. Based on the analysis, it is recommended to provide a 150mm thick cement concrete pavement (M-30) over 150mm granular sub-base and 100mm dense lime concrete (M-15) to safely support the expected traffic loads.

Uploaded by

pallavi
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Design of Cement Concrete Pavement

Name of the work: Improvements to road from NH234 to Motlur via Chikkanahally
& nallakadirenahally chainage: 0.00 to 4.10km

Design Data
Grade of concrete = M-30
CBR = 5%
Pd = 50 kN = 50 x103 N
p = 0.80 MPa
µ = 0.15
E = 30,000 MPa
α = 10x10-6 per oC
k = 42 MPa/m or 42x10-3 MPa/m, for granular sub-base (as per table 4,
IRC:SP–049)

Design
Design wheel load = 50 kN
Tyre pressure = 0.80 MPa
CBR Value = 5%
From Table 1, IRC:SP–049 the k value corresponding to a CBR value of 5 = 42
MPa/m

Sub-base
75 mm thick WBM over 100 mm GSB/150 mm/200 mm cementitious subbase

Effective k Value
The k value over granular bases can be increased by 20 percent (IRC:SP–049,
para 2.5)
Effective k value = 1 .20 x 42 = 50.4 MPa/m
Effective k over 150 mm/200 mm cementitious subbase = 2 x 42 = 84 MPa/m
Minor variation in k value is little effect on stresses

Concrete Strength
Adopt a 28 day compressive strength of 30 MPa.
28 day flexural strength = ff = 0.7√fc = 3.834 MPa
90 day flexural strength = 1.10 x 3.834 MPa = 4.22 MPa

Design Thickness for Traffic of 50 CVPD


Trial thickness = 150 mm, joint spacing = 3.75 m
Since the volume of traffic = 45 CVPD, temperature stresses need not be
considered since occurrence of heavy vehicles and maximum temperature
gradient at the same time is least likely

Edge Load Stress


k = 50.4 MPa/m for granular subbase
From the excel sheet, edge load stress for a dual wheel load = 4.20 MPa < MR =
4.22 MPa,
If the same load is applied by a single wheel of a tractor trailer whose tyre
pressure is only 0.5 MPa, the stress is 4.37 MPa > MR (4.22 MPa)

Hence the design is unsafe for k = 50.4 MPa/m


The pavement is unsafe even for a tractor trailer carrying the same load at a
lower tyre pressure.
K = 70 MPa (Cementitious subbase)
Stress for a dual wheel load of 50 kN = 3.985 MPa < 4.22 MPa hence safe for a
thickness of 150 mm over 150 mm cementitious subbase.
Consider a trial thickness of 150 mm and joint spacing of 2.50 m

Result: It is therefore, recommended to provide 150 mm thick cement concrete


pavement (M-30) over 150 mm GSB and 100 mm DLC(M-15). Since, the
thickness of concrete pavement is lesser than 200 mm it is not desirable to
provide dowel bars at contraction joints.

150 mm PQC (M-30)

100 mm DLC (M-15)

150 mm Drainage Layer / GSB

200 mm Prepared Subgrade

Proposed Pavement Thickness

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