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# Highway Engineering (101-120)

Updated: Apr 26, 2020

101. The group index for a soil, whose liquid limit is 40 percent, plasticity index is 10

percent and percentage passing 75 micron IS sieve is 35, is 0

102. Bottom most layer of pavement is known as subgrade

103. Flexible pavement distribute the wheel load through a set of layers to the subgrade

104. The number of repetitions, which the pavement thickness designed for a given wheel load should be able to support during the life of pavement is

1000000

105. Group index method of design of flexible pavement is an empirical method based on physical properties of subgrade soil

106 Minimum and maximum values of group index can be 0 and 20 respectively

107. If the group index value of subgrade is between 5 and 9, then the subgrade is

treated as poor

108. Tyre pressure influences the quality of surface course

109. Rigidity factor for a tyre pressure greater than 7 kg/cm² is less than 1

110. In a dual wheel assembly if P is equal to each wheel load, S is centre to centre

distance of dual wheels and d is the distance between walls of wheels, then

total stress due to the dual wheels at any depth greater than 2 S is equiva

lent to a single wheel load of magnitude 2 P

111.Main drawback of CBR method is that it gives the total thickness which

remains the same irrespective of the quality of materials used in the' component layers

112.Radius of relative stiffness in cm is given by where.E = modulus of elasticity of cement

concrete, kg/cm²

μ = Poisson's ratio for concrete

h = slab thickness, cm

113.Critical load position in a rigid pavement design is taken as

114. If the radius of wheel load distribution is 30 cm and slab thickness is 15 cm, then the equivalent radius of resisting section is 30 cm

115. The critical combination of stresses for corner region in cement concrete roads is load stress + warping stress

116. Tie bars in cement concrete pavements are at longitudinal joints

117. The maximum spacing of contraction joints in rigid pavements is 4.5 m

118. The maximum thickness of expansion joint in rigid pavements is 25 mm

119. The function of an expansion joint in rigid pavements is to allow free expansion

120. A traffic survey revealed the present average daily traffic of commercial vehicles as 1000. The annual rate of growth of traffic is found to be 8 percent. The

pavement construction is to be completed in three years after the last traffic count.Then the number of vehicles for design of rigid pavements will be taken as

1000 (1.08)²³