Interview Question

Updated: Jul 22, 2020

Test of concrete

All material can be bought to be room temperature preferably 27±3℃ before commencing the tests


Slump test

slump test is the most commonly used method of measuring consistency of concrete which can be e employed ida in temporary or at site work the apparatus for conducting the slump test essentially consist of a metallic mould in the form of frustum of a cone having the material dimension

bottom diameter :- 20 cm

top diameter :- 10 cm

Height :- 30 cm


Thickness of metallic sheet for the mould should not thinner than 1.6 mm

for tempering rod 16mm diameter a steel rod length = 0.6 m (600 mm)

the mould fill in four layer each layer (¼ of height)

each layer tampered 25 times.


Compacting factor = Weight of partially compacted concrete weight of fulley compacted concrete


volume of various gauge boxes

Width (cm) Height (cm) Depth (cm)Volume (liter)33.330202033.330252533.330303033.3301535


Compaction of concrete

a) hand compaction

i) rodding

ii) ramming

iii) Tampering


Compaction of vibration

i) internal vibrator ( needle vibrator)

ii) formwork vibrator ( external vibrator)

iii) table vibrator

iv) platform vibrator


Compression test

completion test is the most common test conducted on harden Concrete, parsley because it is an easy test to perform.

the cube size is 15 X 15 X 15 cm

the height of the mould and the distance between opposite face are specified size ± 0.2 mm. the angle between adjacent internal face and between Internal = 90ᵒ + 0.5ᵒ


Compaction

the the test specimen filled into three layers

approximately 5 cm deep

curing temperature 27 ± 2℃ for 48 Hour


Pile Foundation ( section 1100)

types of Pile

precast concrete piles

reinforced concrete pile

prestressed concrete pile

Steel Pile

Timber pile

concrete pile maybe derived

cast in situ

precast piles

bored cast in situ

shape of piles- circular, square, hexagonal, octagonal, ‘工’,’H’

Concrete in piles- the minimum of concrete for driven cast in situ pile shall be 100 mm to 150 mm for bored cast in situ pile 150 mm to 200 mm


minimum casing length- 2 metre length of top of bore for protecting loose soil taking in bore

bentonite suspension

density of bentonite suspension-1.05 g/cc

PH value between - 9.5 to 12

diameter of pipe 150 mm to 200mm diameter shall be used for concreting.


Tolerance-

variation in cross section dimension:- + 50mm, -10 mm

variation in the final position of head in plane:- 50 mm

variation of level of top of piles:- ±25 mm


Tolerance

PCC and raft

variation in dimension : + 50 mm,-10 mm

misplacement from specified position in plan :-15 mm

variation of level at top:- ±25 mm

Tolerance in concrete structure (Pier cap and abutment cap)

variation in cross section dimension: + 10 mm,-5 mm

Misplacement from a specified position in plan :- 10 mm

variation of level at the top: ±10 mm

variation of RL at bearing area: ±5 mm

variation from plumb overfull height:- ±10 mm

Variation in thickness of top and bottom slab for box girder: -5 mm,+10 mm

top and bottom flange for T section slabs:-5 mm,+10 mm


structural concrete (1700)

TypeSlump requiredplain cement concrete (PCC) 25 mmRCC structure with widely spaced reinforcement Eg Solid columns,Pier, abutment40-50 mm 50-75 mm 75-125 mm 150-200 mm


Foundation

type of foundation

(i) Shallow Foundation

(ii) deep Foundation


(i) Shallow Foundation:- Shallow Foundation are used when the soil has sufficient strength short depth below the ground level they need sufficient plan area to transfer the heavy loads to the base soil.

type of Shallow Foundation

plain concrete pedestal footing

isolated footing

combined footing

strip footing

Raft or mat Foundation


(ii) deep Foundation- deep Foundation are used for poor condition of soil near to the surface, the bearing capacity of soil is very low and foundation is needed in such condition is the pile Foundation


(iii) well Foundation- well Foundation is a type of deep Foundation which is generally provided below the water level of bridges. will have been inews for foundation for bridges and other structure scenes Roman and Mughals period.

it may use where the water depth more than 5 to 6 m and the velocity of water is high.



difference between abutment and Pier

abutment:- abutment is constructed in the ends of bridges to support vertical and Lateral moment.

Pier:- Pier is posted in the end of every span to support the same forces and moment



types of bearing

i) Steel bearing

ii) special bearing

iii) elastomeric bearing


Steel bearing:- it is made of mild steel, forged steel,,high tensile Steel, cart steel, stainless steel


special bearing:- spherical bearing, Pin bearing


elastomeric bearing:- made of chloroprene rubber (San field India)


checking of bore depth in pile foundation depth of pile shall be check with sounding chain and exact Death shall be recorded in pile report.


phase of cast in situ construction

The construction of bored cast in situ concrete pile consists of four primary phase.

pile boring

reinforcement cage lowering

Flushing

pile concreting

pile boring




function of PCC- PCC used for levelling and smoothing of surface for overlaying of reinforcement for foundation to transfer the load to base


purpose of shear key


purpose of approach slab:-


difference between bridge and culvert

Culvert:- Converse are used primarily to allow passage of water across physical obstacle.

Bridge:- bridges are form to provide 50 two people and vehicles over large water bodies.

technically the only difference in in the span length culverts are are up to 6 m length whereas bridges are more than 6 metre length.

Minor Bridge (6 to 60 m)

Major Bridge (>60 m)


Span is defined as the c/c the distance between two successive expansion joint

Bridges- are generally constructed at height more than 20 feet (6 m)

Culverts- are generally constructed at height below 20 feet (6 m)


difference between cloudconvert and box culvert

slab culvert- a passage for water over a natural ground having a deck slab over it as a pathway for vehicles


box culvert- box culverts are usually made up of reinforced concrete (RCC) add a box shape tunnel through which water flows and the ventricular transmission take place over the box


Haunch- haunch is provided in order to restrict the shear. The shear force is minimum at the support by providing hunch the depth is increased to the the crack can be restricted



development length of bars


the development length Ld is given by






Thickness of pile cap

as per clause number-307.2.5.2


The thickness of pile cap shall be proportional to act as stiff member.

The minimum thickness of pile cap shall be 0.5 times spacing of the pile and 1.5 times of pile diameter





Total no of pile for BridgeMinimum no of test PileUp to 50250-1503Beyond 1502% of totals Pile








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