Civil engineering interview questions in Roadway/Highway /Expressway department

 

Welcome friends,

We shall learn about the various questions which are frequently ask by an  interviewer In the field of infrastructure. 

So let's get start.......

EMBANKMENT/SUBGRADE/BORROW AREA

•Liquid Limit  <50%

•Plastic Limit  < 25%

•Proctor Density(Min. Value)
For Embankment =1.52 to 1.60 gram/cubic centimeter

For Subgrade= 1.75 gram/ cubic centimeter

Sub-grade top

• Field Dry Density (FDD)
For Embankment= min. 95%
For Sub grade = min. 97%

•Number of test
For Embankment = 1set/3000 sq.meter(1set=10pits)

For subgrade= 1set/2000 sq.meter
(1 set=10 pits)

GRANULAR SUB- BASE

•Maximum thickness of single compacted layer = 200 mm

• Minimum thickness of single compacted layer( only when GSB is laying in two layers) = 150 mm


•Max. Allowable size of aggregate =75mm

•Number of grading of GSB = 6

•Liquid limit  should not be  more than 25% ( test procedure as per IS 2720 (part 5)).

•Plasticity index should  not be more than 6%( test procedure as per IS 2720 (part 5)).

•Aggregate impact value should not be more than 40%.

•CBR value should be less than 30%.

•FDD(Field Dry Density) should not be less than 98% of MDD(Max. Dry Density).

•1 test/ 1000 sq. Met. should be done during checking of FDD.

•Moisture content  = 1-2% below OMC

For more updates about GSB please click on

https://gyanofengineering.blogspot.com/2019/02/full-details-about-gsb-including.html

WET MIX MACADAM (WMM)


 •Maximum thickness of single compacted layer = 200 mm


Minimum thickness of single compacted layer= 75 mm

•Plasticity index should  not be more than 6%(Test procedure as per IS 2720 (part 5)).

•Aggregate impact value should not be more than 30%.

• Los Angles Abrasion(LAV) should be more than 40%.

•Combined FI ( flakiness index ) & EI (elongation index) should not be more than 35%.

•FDD(Field Dry Density) should not be less than 98% of MDD (Max. Dry Density).

•1 set / 1000 sq. Met. ( 1 set = 3 pits) should be done during checking of FDD.

•Max. Allowable size of aggregate =53 mm

•After final compaction of WMM course, the bed of WMM shall be allowed to dry for 24 hours.

For more  about WMM kindly click on 

https://gyanofengineering.blogspot.com/2019/02/wet-mix-macadam-wmm-sub-base-base.html

DENSE BITUMINOUS MACADAM (DBM)

•  The thickness of a single layer shall be 50 mm to 100 mm.

•Combined flakiness and elongation index should not be more than 35%.

                            DBM(Grade-1)

•Los Angles Abrasion value(LAV) should not be more than 35%.

•Aggregate impact value(AIV) should not be more than 27%.

•Coating and stripping of bituminous aggregate mix should not be less than 95%.

•Grades of DBM

 # GRADING -1

Nominal size of aggregate - 37.5 mm

Layer thickness= 75-100 mm

Bitumen content % by mass of total mix should not be less than 4%.

# GRADING - 2

Nominal size of aggregate - 26.5 mm

Layer thickness= 50-75 mm

Bitumen content % by mass of total mix should not be less than 4.5%.

• DBM should be measured either in cubic meter,tonnes or square meter (only for specified thickness as indicated in contract drawing).

Temperature ranges of bituminous material for various grades of bitumen

•

For more updates about DBM please click on
https://gyanofengineering.blogspot.com/2019/08/bituminous-macadam-technical.html

OR
https://youtu.be/T-56t2ZxEL0

PRIME COAT 

• Quantity of SS1 grade bitumen Emulsion for various types of Granular surface

TACK COAT

 It should be provided over granular surface(like WMM) treated with prime coat,bituminous surfaces and cement concrete pavement.

•Rate of application of tack coat

BITUMINOUS CONCRETE (BC)

•  The thickness of a single layer shall be 30 mm to 50 mm.

•Combined flakiness and elongation index should not be more than 35%.

•Los Angles Abrasion value(LAV) should not be more than 30%.

•Aggregate impact value(AIV) should not be more than 24%.

Bituminous concrete 

•Coating and stripping of bituminous aggregate mix should not be less than 95%.

•Grades of BC

 # GRADING -1

Nominal size of aggregate - 19 mm

Layer thickness= 50 mm

Bitumen content % by mass of total mix should not be less than 5.2%.

# GRADING - 2

Nominal size of aggregate - 13.2 mm

Layer thickness= 30-40 mm

Bitumen content % by mass of total mix should not be less than 5.4%.

•BC should be measured either in cubic meter,tonnes or square meter (only for specified thickness as indicated in contract drawing).

To get more details about BC,  Kindly click on below link

https://gyanofengineering.blogspot.com/2020/05/bituminous-concrete-bc-specifications.html

Reinforced soil earth wall (RS/RE Wall) 

 • Minimum thickness of RS/RE wall panels is 180 mm. (including facia textures, logos and embellishments)

•Minimum Concrete grade of RS/RE panels is M 35.

• Minimum width of geotextile strip to cover gaps between panels is 100 mm. 

•Height of point of impact at crash barriers above top of pavement  is 800 mm. 

•Maximum spacing of reinforcing elements shall not exceed 800 mm for RS/RE wall using panels and blocks. 

•Minimum thickness of strip footing ( levelling pad PCC) is 150 mm. 

•Minimum width of strip footing ( levelling pad PCC) is 350 mm. 

•Minimum concrete grade for levelling pad  PCC( strip footing) is M 15.

•Minimum depth of embedment below finished ground level at the foot of wall is 1000 mm. 

•Maximum compacted soil thickness of each layer is 200 mm. 

•Various types of reinforcements used in RS/RE wall

1 - Metallic elements like bars,  strips,  plates etc. 

2 - Metallic reinforcement in form of mesh

3 - Polymeric elements like strips, grids, rods mesh etc. 

•Minimum length of reinforcement shall be 0.7 H to 3 met. Whichever is greater.

Where H is design height (depth of embedment plus height above  ground level) of the RS/RE wall. 

•Crash Barrier : Horizontal impact load of 29 kN/m shall be considered in the design of crash barrier, which load shall be resisted by the upper two layers of the reinforcement over the full length. 

Thank you
Mukesh kumar(www.gyanofcivilengineering.com)