Gujarat University 2007 B.E Civil Engineering Concrete Technology - Question Paper

3/246    2    Candidate's Seat No :_____

GUJARAT UNIVERSITY B.E. Sem V (Civil) Examination Concrete Technology

Friday, 4th January, 2008]    [Time : 3 Hours

Max. Marks : 100

Instructions : (1) Attempt all questions from each section.

(2)    Answer to the two sections must be written in separate answer books.

(3)    Figures to the right indicate full marks.

(4)    Assume suitable data if required

SECTION I

1    Attempt Any four :    (16)

(a)    Differentiate between rapid hardening and quick setting cement

(b)    What are the different methods of determining moisture content of aggregate ? Describe displacement method.

(e) What is shrinkage? Describe it briefly.

(d)    Explain Portland pozzolana cement and rapid hardening cement.

(e)    Discuss briefly Hydration of cement.

(f)    What is tire effect of finesse of cement on concrete? How can you determine in laboratory using sieve method.

2    (a) Define workability of concrete. Which are the different methods of measuring it in (05)

the laboratory? Hxplain an}' one of them.

(b)    What are the factors affecting the strength of concrete? Explain any one.    ( 05 )

(c)    Describe in detail segregation and bleeding.    (06)

(OR)

2    (a) Define admixtures and additives. Explain the effect of air entrainment on the (08)

properties of concrete.

(b) What do yon understand by grading of aggregates? Comment about suitability of (08) grading of aggregate for concrete.

4 (a) What is non-destructive testing of concrete? Discuss pulse velocity method.    U 6)

( b) Discuss the effect of H/D ratio on strength of concrete. Compare between cube and cylinder strength.

(OR)

4    (a) Discuss various method for curing concrete.    (!6)

(b) Discuss various aspects of durability of concrete. What majors are taken by IS

code to ensure durable structure ?

5    Write short notes on the following (Any three):    (18)

(1)    Hoi weather and cold weather concreting.

(2)    Under water concreting.

(3)    Factors affecting Alkali-Aggregate reaction.

(4)    Bulking of sand

(5)    Discuss test cores

6    Design a concrete mix as per IS method for following data.

(a)    Characteristic strength at 28 days    = 30 MPa

(b)    Maximum size of aggregate    = 20 mm

(c)    Degree of workability    = 0.85 (C.F.)

(d)    Quality control    = Very good

(e)    Type of expouse    = Moderate

(f)    Specific gravity of

(i)    Cement    =3.15

(ii)    Coarse aggregate = 2.80

(iii)    Fine aggregate = 2.60

It is found that sand falls in grade zone 111. Mix is designed in such a way that only one sample fails out of 20.

Table - 1 Standard deviation N/inra2

Grade t Degree of control Very good Good Fair M15 2.5 3.5 4.5 M20 3.6 4.6 5.6 M25 4.3 5.3 6.3 M30 5.0 6.0 7.0

For W/c = 0.6	Table 4 CF = 0.80	sand zone -11
Max1" size of aggregate(mm)	Water/Cubic meter of concrete (kg)	Sand as % of total aggregate
10	200	40
20	186	35
40	165	30

Table-5 Adjustment required

Change in condition Water content % Sand (a) For sand zone 111 & IV 0 - ! .5 % zone 111 (b) Increase or decrease in C.F. by 0.1 + 3.0% - (c) Each 0.05 increase or decrease in w/c ratio 1.0%

It is to be considered that amount of entrapped air is 3%. Minimum cement content for moderate condition is 290 kg/m³ and max'" permissible value of w/c is 0.55 i.e.w/c > 0.55. For max^m density grit - 30 %, kapachi - 70 %. Assume necessary data. Find proportion of water, sand, grit & kapachi for one bag of cemcnt.

Attachment: gujarat-university-2007-b-e-civil-engineering-33204-1.pdf

Earning:   Approval pending.