Bottom Ash

1. CONCRETE MIX
DESIGN WITH
BOTTOM ASH
100% Replacement of Sand by Bottom Ash in
Concrete
M15/20mm/100%

2. REQUIREM
ENT
As the natural sand sources are
decreasing and availability of raw
materials are becoming less, we
need to adopt alternate sources as
concrete making materials.
A practical study based on IS:383 –
2016 & one’s experience as
research on behavior of raw
materials
Optimize the unit rates of concrete

3. BOTTOM ASH
Bottom ash ( B.A. ) is part of the non-
combustible residue of coal
combustion in a power plant. It is
formed in a coal operated power plant
while combustion and comprises
traces of combustibles embedded in
forming clinkers and sticking to hot
side walls of a coal-burning furnace
during power plant operation. The
portion of the ash that escapes up the
chimney or stacked is referred as fly
ash. The clinkers fall by themselves
into the bottom hopper of a coal-
burning furnace and are then cooled &
portion of the ash is referred to as
bottom ash.
Most bottom ash generated at power
plants is stored in ash ponds, which
can cause serious environmental
damage.
https://www.epa.gov/coalash/coal-
combustion-residual-beneficial-use-
evaluation-fly-ash-concrete-and-fgd-
gypsum-wallboard

4. CONSIDERATIONS
While mix design of concrete following considerations are taken in
account:
- Mix could be manually placed
- Workability of mix should be +100 mm
- Precautions (includes shed, water sprinkling etc.) are required for bottom
ash to stack and feed in batching plants so still concrete mix has to
designed as non pumpable.
- Specific gravity and density of bottom ash is much less than ordinary
natural sand which will lead bottom ash lesser in weight and more in volume
in concrete mix.
- Due to 90% of Bottom ash particle size is less than 600 micron, %age of 10
mm aggregate is increased in concrete mix considering its smaller size
particles of below 10 mm & 4.75 mm could behave like sand
- As bottom ash is a waste of petroleum product its water absorption is

5. DESIGN MIX OF M-15 GRADE
CONCRETE
Grade M 15
Cement OPC 43 G Ambuja
Slump required +100 mm
Max size of aggregate 20 mm
Fine aggregate replaced 100% with
B.A.
W/C ratio adopted 0.56
S. Gravity of 20 mm 2.63
S. Gravity of 10 mm 2.64
S. Gravity of B.A. 1.868
S. Gravity of Admixture 1.11
20mm : 10 mm = 35 : 65
%age of B.A. in mix 30.8 %
20mm: 10mm : B.A.
24.22 : 44.98 : 30.8
% age of admixture 0.6%
Cement content 300 kg/cum
Admixture SIKA Viscocrete 4203
Base of Admixture PCE
Placement method Manually
Target strength of concrete 20
N/mm2

6. PROPORTION OF 20 MM : 10 MM
SIEVE ANALISIS
Taking % of 20 mm = 35%
10 mm = 65%
Sieve size (mm)
Passing of Coarse
agregate
Combined as Graded Limits
20 mm 10 mm
40.00 100.0 100.0 100.0 100
20.00 99.7 100.0 99.9 95 - 100
10.00 1.2 82.5 54.0 25 - 55
4.75 0.0 2.4 1.6 0 - 10

7. GRADING OF BOTTOM ASH DRY SIEVE
IS Sieve
Size
(mm)
WEIGHT % WEIGHT CUMULATIVE % LIMIT AS PER IS-383
RETAINED RETAINED % RETAINED PASSING ZONE I ZONE II ZONE III ZONEIV
10 0 0 0 100.0 100 100 100 100 100 100 100 100
4.75 15 1.50 1.50 98.5 90 100 90 100 90 100 95 100
2.36 12 1.20 2.70 97.3 60 95 75 100 85 100 95 100
1.18 30 3.00 5.70 94.3 30 70 55 90 75 100 90 100
0.6 39 3.90 9.60 90.4 15 34 35 59 60 79 80 100
0.3 170 17.00 26.60 73.4 5 20 8 30 12 40 15 50
0.15 619 61.90 88.50 11.5 0 10 0 10 0 10 0 15
0.075 29 2.90 91.40 8.6
Pan 86 9 100.00 0.0
TOTAL = 1000
TOTAL CUM % RETAINED = 134.6
Fineness
Modulus 1.346 %
Silt & Clay
Content 8.60 %
S. Gravity of B.A.
1.868

8. DETERMINATION OF COARSE AND
FINE AGGREGATE
Grading Zone of
sand : Bottom Ash
at 0.5 w/c ratio taking the %age of coarse
aggregate : 0.68
Present w/c
ratio : 0.56
Amount of increase of w/c ratio from 0.5 to
0.56 : 0.06
Increment of coarse aggregate @ -/+ 0.01 for every +/-
0.05 change in w/c ratio : 0.692
Method of concreting at site : Manually
For Pumpable Concrete Coarse aggregate can be reduced to
10 percent, hence taking reduction : 0%
%age of coarse aggregate : 69.2%
Therefore fine aggregate is : 30.8%
In which B.A. : 100.0%
M Sand : 0.0%

9. MIX
CALCULATI
ONS
a) Volume of concrete 1m3
b) Volume of cement 0.095m3
c) Volume of fly ash 0.000m3
d) Volume of water 0.168m3
e) Volume of admixture 0.002m3
f)
Volume of all in
aggregate 0.736m3
g)
Mass of coarse
aggregate 20 mm 468.58kg
h)
Mass of coarse
aggregate 10 mm 873.52kg
i) Mass of fine aggregate M. Sand 0.00kg
j) Mass of fine aggregate B.A. 423.23kg

10. DESIGN MIX OF M-15/20 MM
DOWN/100 % B.A.
MATERIAL in Mix WEIGHT in kg RATIO
Water 168 0.560
Cement 300 1.00
Fly Ash 0 0.00
Bottom Ash 423 1.41
Coarse Aggregate 1342 4.48
Admixture 1.80 0.006

11. OBSERVATIONS
Three no. trial mixes were observed and following points were recorded
Concrete mix behaves like no slump/tight/less fines for first 15-20 mins and after mix itself became
cohesive.
Initially workability (from water adding in mix to 15-20 mins) was nil, after mix itself became
workable.
Above observations are due to less fineness modulus of bottom ash which initially absorbs water and
then release water because of bottom ash tendency to could not retain water within its particles.
Mixing of concrete in mixer requires more (a mins x 2) times as compare to ordinary concrete mixing
time (a mins).
As observed initially mix is non workable, if water added additionally mix will bleed.
Slump observed after 30 min is 130 mm.
Compressive strength of 7 days is 13 N/mm2 & 28 days is 21.38 N/mm2
Admixture used confirming to ASTM C-494 type G, PCE admixture @ 0.6% by wt. of cement, In case of
NFB admixture it may require dosage of @1.0-1.2 % by wt. of cement
In higher grade mixes of concrete bottom ash could replace natural sand 30-50%, however practice
should involve to preserve bottom ash at site batching plants like prepare masonry bins to stack
bottom ash, sprinkling with water over bottom ash
To carryout concrete with bottom ash moisture corrections are mandatory.

12. UNIT PRICE COMPRESSION
M-15 grade ordinary mix
S.no
Ingredient Quantity Price Total Price
per cum in kg per kg per cum
1Cement 290 4.6 1334
2Water 156 0.01 1.56
3Admixture 2 72 144
420 mm 538 0.57 306.66
510 mm 657 0.57 374.49
6N.Sand 730 0.7 511
Total 2671.71
M-15 grade bottom ash mix
S.no
Ingredient Quantity Price Total Price
per cum in kg per kg per cum
1Cement 300 4.6 1380
2Water 168 0.01 1.68
3Admixture 1.8 72 129.6
420 mm 468 0.57 266.76
510 mm 873 0.57 497.61
6B.A. 423 0.2 84.6
Total 2360.25
Total Savings of Rs. 311 is achieved which is 11.6 % less than ordinary M-15 grade concrete

13. MIX DESIGN
APPROVAL