1. In Marshall method of mix design, the coarse aggregate, fine aggregate, fines and bitumen having respective values of specific gravity 2.60, 2.70, 2.65 and 1.01, are mixed in the relative proportions (% by weight) of 55.0, 35.8, 3.7 and 5.5 respectively. The theoretical specific gravity of the mix and the effective specific gravity of the aggregates in the mix respectively are:

1. 1. 2.42 and 2.63

   
   
   

   2. 2.42 and 2.78

   
   
   

   3. 2.42 and 2.93

   
   
   

   4. 2.64 and 2.78

   
   
   

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1. View Hint View Answer Discuss in Forum

   Theoretical specific gravity of mix, G_T
   G_T = w₁ + w₂ + w₃ – w₄
   

   	w1	+	w2	+	w3	+	w4
   	G1		G2		G3		G4

   
   

   =	100
   	55	+	35.8	+	3.7	+	5.5
   	2.6		2.7		2.65		1.01

   
   = 2.424
   Effective specific gravity of aggregates in mix, G_E
   

   GE =	(w1G1) + (w2G2)	(only fine + coarse)
   	w1 + w2

   
   

   =	(55 × 236) + (35.8 × 2.7)	= 2.64
   	55

   Correct Option: A

   Theoretical specific gravity of mix, G_T
   G_T = w₁ + w₂ + w₃ – w₄
   

   	w1	+	w2	+	w3	+	w4
   	G1		G2		G3		G4

   
   

   =	100
   	55	+	35.8	+	3.7	+	5.5
   	2.6		2.7		2.65		1.01

   
   = 2.424
   Effective specific gravity of aggregates in mix, G_E
   

   GE =	(w1G1) + (w2G2)	(only fine + coarse)
   	w1 + w2

   
   

   =	(55 × 236) + (35.8 × 2.7)	= 2.64
   	55

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2. The design speed for a two-lane road is 80 kmph. When a design vehicle with a wheel base of 6.6 m is negotiating a horizontal curve on that road, the off-tracking is measured as 0.096 m.The required widening of carriageway of the two-lane road on the curve is approximately

1. 1. 0.55 m

   
   
   

   2. 0.65 m

   
   
   

   3. 0.75 m

   
   
   

   4. 0.85 m

   
   
   

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1. View Hint View Answer Discuss in Forum

   Off tracking means mechanical widening, i.e.	nL²
   	2R

   
   

   0.096 =	nlL²	=	6.6²
   	2R		2R

   
   ∴ R = 226.87 m
   

   Psychological widening =	V	=	80	= 0.56 m
   	9.5√R		9.5√226.87

   
   Total widening = 0.56 + 2 × 0.096 = 0.75 m

   Correct Option: C

   Off tracking means mechanical widening, i.e.	nL²
   	2R

   
   

   0.096 =	nlL²	=	6.6²
   	2R		2R

   
   ∴ R = 226.87 m
   

   Psychological widening =	V	=	80	= 0.56 m
   	9.5√R		9.5√226.87

   
   Total widening = 0.56 + 2 × 0.096 = 0.75 m

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3. The value of lateral friction or side friction used in the design of horizontal curve as per India Roads Congress guidelines is

1. 1. 0.40

   
   
   

   2. 0.35

   
   
   

   3. 0.24

   
   
   

   4. 0.15

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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4. The following data pertains to the number of commercial vehicles per day for the design of a flexible pavement for a national highway as per IRC:37–1984
   
   Assuming a traffic growth factor of 7.5% per annum for both the types of vehicles, the cumulative number of standard axle load repetitions (in million) for a design life of ten years is

1. 1. 44.6

   
   
   

   2. 57.8

   
   
   

   3. 62.4

   
   
   

   4. 78.7

   
   
   

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1. View Hint View Answer Discuss in Forum

   Cumulative standard axle:
   (1) 2 axle truck :
   
   = 51.6 msa
   (2) Tandem axle truck:
   
   = 6.2 msa
   Total CSA = 51.6 + 6.2 = 57.8 msa

   Correct Option: B

   Cumulative standard axle:
   (1) 2 axle truck :
   
   = 51.6 msa
   (2) Tandem axle truck:
   
   = 6.2 msa
   Total CSA = 51.6 + 6.2 = 57.8 msa

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5. The design speed on a road is 60 kmph. Assuming the driver reaction time of 2.5 seconds and coefficient of friction of pavement surface as 0.35, the required slopping distance for two-way traffic on a single lane road is

1. 1. 82.1 m

   
   
   

   2. 102.4 m

   
   
   

   3. 164.2 m

   
   
   

   4. 186.4 m

   
   
   

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1. View Hint View Answer Discuss in Forum

   SSD = vt +	v²
   	2g

   
   

   v = 60 ×	5	= 16.67 m/s
   	18

   
   

   SSD = 16.67 × 2.5	16.67²	= 82.134 m
   	2 × 9.81 × 0.35

   
   For 2 way traffic, SSD' = 2 × SSD = 164.27 m

   Correct Option: C

   SSD = vt +	v²
   	2g

   
   

   v = 60 ×	5	= 16.67 m/s
   	18

   
   

   SSD = 16.67 × 2.5	16.67²	= 82.134 m
   	2 × 9.81 × 0.35

   
   For 2 way traffic, SSD' = 2 × SSD = 164.27 m

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