concrete, constituents, cement, aggregate, types of concrete, work-ability, testings, conclusion.

1. PRESENTATION ON
CONCRETE AND ITS SCENARIO IN NEPAL
PRESENTED BY:
MAHESH RAJ BHATT SUNDAR ADHIKARI RAJU KHATRI
RAM KRISHNAACHARYA SANJU SHARMA SADANA TIWARI
( 067/BCE) SCHOOL OF ENGINEERING POKHARA UNIVERSITY

2.  During two last decade rapid technological
development in concrete have taken place
in world.
 We are also in rapid developing situation
in Nepal.
 Concrete have become a major part of
construction.
 Its importance is increasing day by day.
 Western and eastern countries have beeen
making concrete of strength.
M40, M80, M100 and over too.

3.  Recently Nepal have started using concrete
-M25 , M30 and higher one too.
 I am 23 at now, during these 23 years
,specially in last 10 years, I have seen drastic
growth of use of concrete in my side
“DARCHULA”
too
Which is mountainous district of Nepal.

4.  Currently we have been also in era
of special concrete too
example:
-ferrocement concrete,
- steel fiber reinforcement concrete
-polymer concrete
-high strength concrete
-self compacting concrete
-carbon fiber reinforced polymer(CFRP)

5. In general :
An artificially build up stone
resulting from hardening of a mixture of
cement ,aggregates and water
with or without a suitable admixture
“Concrete”.
In broadest sense :
Any product or mass made by the use of cementing medium.
Here, medium is product of reaction between hydraulic
cement+water

6. Cement + aggregate + water+ admixtures
(7-16)% +(75-83)% + (16-18)% = Concrete
CEMENT:
 Adhesive & cohesive material

9.  OPC ( 33,43,53 grade):-
large scale in all general type construction
 RHC (Rapid hardening cement)-
Not used in mass Concrete
Used in road construction
 RHCE (Extra rapid hardening cement):
OPC + Cacl2 (2%)
- Road work

10.  SRC(Sulphate resisting cement)
-Marine condition
-Foundation sewage treatment plant
 QSC(Quick setting cement)
-Underground water construction
-Al204+Cacl2+OPC
 Blast furnace cement:
-Used in mass concrete
-blast slag + OPC

11.  Super sulphate cement:
-Marine works
 Low Heat Cement
-C2S is more
 Expansive cement :
-Used in grouting anchor bolts
 High strength cement
-Compressive strength higher then the OPC
 Resident cement :
-Very cold area /winter season
Patch repairs, Emergency repairs

12.  Types
i)Based on Origin
a. Natural
b. Artificial
ii. Based on size
a. Fine
b. Coarse
c. All in aggregate

13. iv) Based on shape
a. Round (void 33%)
b. Irregular( void 35-37%)
c. Angular ( void 38-45%)
d. Flaky (>0.6d)
e. Elongated (>1.8 L)
v). Based on unit weight
a. Light(1200-2300 kg/m3)
b. Normal(2300-2600 kg/m3)
c. Heavy (more than 2600 kg/m3)

15. vi) Based on surface moisture
a. Very very dry (porosity =0)
b. Dry aggregate
(pore water partly fill and surface dry)
c. Saturated surface dry
(pore fully water filled)
d. Wet or moist
(pore full water +surface water also)

16. -Pure as drinking water
-PH value (6 -8)
-vital influence in strength
-should not contain
Na,K,Mg,etc.
-in Nepal it is not given well care towards water
-water in Terai contains chemicals which are harmful to
concrete

17. -Substance other than the basic ingredients
-To improve certain properties like rate of hydration,
workability,durability,impermeablility.
Types (Commonly used in Nepal)
A. Accelerator (to gain early strength)
Example: CaCl2 ,Na2No3, Na2So4, NaoH
B. Retarders (slow down chemical process)
Example:Gypsum (CaSO42H2O)

18. C. Water proofer (to proof water)
 Example: vegetable oil , fat, tar
D. Air entraining agent
-To increase workability
-To reduce bleeding & segregation effect
E. Pigment mixture
- Mn,C,Cr203,Fe203
-for colour purpose.

19. s.
n
Gra
de
Concrete
Mix
Types of Construction
1 M10 1:3:6 Mass concrete piers, abutment , massive RCC
(currently rarely used)
2 M15 1:2:4 Normal RCC
Slab , Beam, Column, Wall ,small span arches
3 M20 1:1.5:3 Water retaining Structure
Reservoirs, column & pile
4 M25 1:1:2 Long span arches ,highly loaded column
5 M30 ----- Mass concrete foundation
6 M35 ---- Post tension pre-stressed concrete
7 M40 ------ Pre tension pre-stress concrete

20. Processes are as follow
a) Storing of cement and aggregate
b) batching ( ingridient measurement)
- volume batching ,…weight batching
c) Mixing

21. 1. Hand mixing concrete
- Can not proper mixing
- Only small amount mix
- Traditional system
- Strength can not get proper
- Commonly used in small
projects in rural areas.

22. -Proper mixing
-Large amount concrete can be formed
-Small time consume
-High strength gain
-currently use in Nepal

23. -Computerized method
-Minimum time consume
-Modern method
-Strength proper maintain
-but coastly
-also adopted in Nepal in
Some special projects

24. d) Transportation
i) pan transportation
ii) wheel barrow
iii) bucket and ropeway
iv) Belt conveyer
v) Truck mixer and damper
vi) Pump and pipeline discharge
e) Placing
layer=15-30 cm
=35-45 cm in mass work
height of pouring<1.5 m

25. F) compaction:
-5% air bubble reduces 30% strength of concrete
-10% bubble reduces 50% strength of concrete
i) hand compaction
 ramming , Tamping , Hammering
ii) Mechanical compaction(vibrator)
 internal vibrator( beam, column, slab , retain wall)
 Table vibrator( pre cast unit)
 External vibrator(through formwork)
 Surface vibrator(slab , road , bridge)
 Pan vibrator…… small repairs,concrete floor

27. g) curing:
- to make compacted concrete wet
- to gain maximum strength
 Water curing
 Membrane curing
 Heat apply (steam using)
 Chemical curing
CaCl2, NaCl …
to absorb water

29. Various test on Concrete
a. Workability Test (slum test, compaction test)
b. Bleeding & Segregation test
c. Air content test
d. Compressive strength test
-Cube test
-Cylindrical test
e. Tensile strength test

32. 1. Normal concrete
 All civil Construction
e.g residential , public , commerical buildings
 Mass construction
Example: Dams,Reservoi

33.  Mass Construction
 Example:-
Dams,Reservoirs,Bridges,Barrage,Weirs,Canal
Road ,Retaining wall

37.  Large Span bridge
 Compressive strength(1100-6700 kg/cm2)

38. - Used in Rail way steeper
- Liquid storage tank
- Heavy bridge girder
We are waiting till now to prestrength concrete

39. 1. Concrete technology M.S.Shetty
2. Concrete technology B.L.Gupta & Amit Gupta
3. Objective guides for civil engineers D. Prasad
4. http://www.slideshare.net/maheshrajbhatt
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