EFFECT OF REPLACEMENT OF OPC BY PAPER SLUDGE IN COMPRESSIVE

STRENGTH OF CONCRETE

By Nitin Bharadwaj H.R 1RV06CV008Harinandan. B 1RV06CV009Vijeth K.R 1RV06CV036Kishore. R 1RV06CV013

Under The Guidance OfMr. Radhakrishna

Asst ProfessorDept Of Civil Engg, RVCE

HISTORY OF CONCRETE Concrete has been in use since the Egyptian and the

roman civilizations.

During Roman empire, concrete was made from quicklime, pozzolanic ash and pumice as aggregates which posed problems while placing and provided lesser strength.

In the 1840’s Portland cement was first used in concrete.

Further evolution of concrete saw need for increasing strength and other properties which was achieved by substituting cement by additives.

Recently, the use of waste materials as concrete ingredients is gaining popularity because of increasingly stringent environmental legislation.

INTRODUCTIONNeed for Replacement

During manufacturing of 1 tones of Ordinary Portland Cement (OPC) we need about 1-1.5 tonnes of earth resources like limestone, etc and 3 to 6 GJ of fuel per tonne of clinker produced.

Further during manufacturing of 1 tonnes of Ordinary Portland Cement an equal amount of carbon-di-oxide are released into the atmosphere. The amount carbon dioxide emitted by the cement industry is nearly 900 kg of Carbon dioxide for every 1000kg of cement produced.

The cement industry produces about 5% of global man-

made carbon dioxide emissions.

In this Backdrop, the search for cheaper substitute to OPC is a needful one.

Need for Paper Sludge Utilization

From Paper manufacturing process three types of sludge are obtained namely Lime sludge, ETP sludge and De-Inking sludge. In our project we have utilized lime sludge as a replacement for cement.

Lime Sludge is a material obtained from the chemical recovery process of paper production.

Contd… Due to its low calcium(12mg/litre), Lime sludge is

used as a replacement to cement in concrete.

The silica and magnesium present in Lime sludge improves the setting of the concrete.

Lime sludge is available abundantly worldwide but

its usage to date is very limited. Each Indian mill produces an average 40 oven-dry tonnes of sludge per day.

The Lime Sludge disposed in mass level in landfill shows increase in N, P, K, B, Cl-, and organic C contents of the soil thus causing land pollution.

Study On Effect of paper sludge on soil 1. In France In 1992, crop and woodland sites

from the Lorraine region, France were treated with 186–306 tons of paper sewage sludge in order to study the effects of waste recycling.

An investigation of the blue sludge layer from 1992 to 1997 showed a decrease of calcium content, from about 23 to 10%, and of organic matter content, from about 35 to 20%. In 2000, the blue sludge layer is still clearly apparent under a fern litter layer, as shown for the woodland site on Fig.

Incresing depth shows the downward carbon transfer from the paper sludge.

Figure showing sampling of soil layers from the wood plot in August 2000.

2. Nagoan Paper Mill

This study was done in the Nagaon Pulp and Paper Mill (Assam, India) which produces 100,000 tonnes of paper annually from bamboo.

Surface soil samples (0–15 cm depth) were collected in both dry and wet seasons over a four-year period from 19 points at different distances from the mill.

Accumulation of Al2O3, Fe2O3, and MnO in soil near the mill due to the dumping of fly ash and other solid wastes in the surrounding low lying land.

Metals Ca, Mg, Na, and Pb decreased away from the mill.

The soil pH had a tendency to turn alkaline near the mill owing to the discharge of highly alkaline effluent by the mill.

The physical characteristics of the soil, viz., water holding capacity and bulk density increased with distance from the mill while the hydraulic conductivity had an opposite trend.

N, P, K, B, Cl-, and organic C contents of the soil had shown a rapid decreasing trend away from the mill

Parameters Units Average

value

pH

Moisture

Conductivity

Water holding capacity

Organic carbon

Total nitrogen

Available phosphorus

Potassium

Calcium

Magnesium

Calcium carbonate

Acid insoluble

Silica

(%)

(mS/cm)

(%)

(%)

(%)

(mg/kg)

(mg/kg)

(mg/kg)

(mg/kg)

(%)

(%)

(%)

10.88

56.8

0.765

70.9

0.14

0.03

0.08

0.05

12.00

26.41

67.43

11.1

19.0

Heavy metals Unit Average value

Zn

Mn

Cu

Pb

Ni

(mg/kg)

(mg/kg)

(mg/kg)

(mg/kg)

(mg/kg)

0.463

1.675

0.165

0.364

0.268

PROPERTIES OF TYPICAL RAW LIME SLUDGE

Comparison of Cement and typical Lime Sludge

Sl. No Constituent

Cement (in %) Lime Sludge (in %)

1. Lime(CaO) 62 46.2

2. Silica(SiO2)22 19

3. Alumina 5 3.6

4. Magnesium 1 3.33

5. Calcium sulphate 4 4.05

CHEMICAL REACTIONS INVOLVED IN PARTIALY REPLACED CONCRETE

1. Primary Hydration Cement + Water C-S-H gel + Ca(OH)2

2. Secondary Hydration Here Lime Sludge acts as a pozzolona Ca(OH)2 + Pozzolona C-S-H gel

Increase in amount of C-S-H gel increases the compressive strength but only upto a certain extent.

Setting Time for cement and typical Raw Lime Sludge

Sl. No Ingredients Initial (min)

Final(min)

1. Cement + 0% Lime sludge 30 600

2. Cement +10% Lime sludge 31 598

3. Cement +20% Lime sludge 33 597

4. Cement +30% Lime sludge 34 595

5. Cement +40% Lime sludge 36 593

6. Cement +50% Lime sludge 37 592

MATERIALS USED

Portland Cement - 43 Grade

Coarse Aggregate - 20mm downsize

Fine Aggregate - 4.75mm passing

Water - pH not less than 6

Lime Sludge - dried, powdered and cleaned

Complast Super Plasticizer -1% of cement content

EQUIPMENTS USEDSieves -IS 20mm for coarse aggregates, IS 4.75mm for fine aggregates Mortar pan and trowels

Concrete mixer

Slump cone apparatus

Cube mould-150mmx150mmx150mm

Vibrating table

Compression testing machine

TESTS ON MATERIALS1.Tests on Cement1.1 Normal Consistency Test

25

2830

32

0

5

10

15

20

25

30

35

0 1 2 3 4 5

Perc

enta

ge o

f w

ater

Penetration

% of water

The consistency of cement was found to be 32% when the penetration was 4mm from bottom.

1.2 Initial setting time

The initial setting time of cement used is 35 minutes

2. Tests on Fine aggregates

Sieve analysisSieve Size Percentage

Retained

Cumulative

Percentage

Percentage

Passing

4.75mm

2.36mm

1.18mm

600µm

300µm

150µm

00.00

00.70

17.08

32.52

31.27

16.13

00.00

00.70

17.78

50.30

81.57

97.70

100.00

99.30

82.20

49.070

18.43

2.30

The fineness modulus of sand taken is 2.48

Mix DesignMix design is done according to IS 10262-2004

The mix design is done for M30 grade concrete

The parameters known

Statistical Constant K = 1.65Exposure Conditions = ModerateSlump = 80-100mmSpecific Gravity of FA and CA = 2.6 and 2.7

respectivelySand = Zone 2Coarse Aggregate = Crushed angular 20mm

and down size

Steps:1. Characteristic Strength, fck’ = 38.25 Mpa

2. From Table 5 of IS 456 : 2000, Exposure Condition is moderate W/C=0.45

3. Water Content = 186Kg/m3 (for 20mm aggregates from Table 2, IS 10262-2004 )

4. Cement Content = 413.33 kg/m3 > 300 kg/m3 (Min Cement Content)

5. From Table 3 for 20mm aggregates and Zone 2,

Volume of coarse aggregates per unit volume of concentration=0.62

6. Absolute Volume of ingredients for 1m3 of concrete

Volume of cement = 413.33/3150 = 0.132 m3

Volume of water = 186/1000 = 0.186 m3

Volume of total aggregates = 1 - 0.132 - 0.186 = 0.6828 m3

7. Weight of all in aggregates = 0.6828 x 2.65 x 1000 = 1809.42 kg/m38. Weight of coarse aggregate = 1809.42 x 0.62 = 1121.84 kg/m39. Weight of fine aggregate = 1809.42 x 0.38 = 687.57 kg/m310. Fresh Density = Cement + FA + CA + Water = 2408.75 kg/m311. Cement : FA : CA : Water 1 : 1.664 : 2.714 : 0.45

For 12 cubesCement = 22 kgsSand = 41.77 kgsJelly = 68.15 kgsWater = 9.723 litres

Mix Proportions

 Conventional Concrete – 1: 1.664 : 2.714 10% replacement – 0.90 : 1.664 : 2.714 20% replacement – 0.80 : 1.664 : 2.714 30% replacement – 0.70 : 1.664 : 2.714 40% replacement – 0.60 : 1.664 : 2.714 50% replacement – 0.50 : 1.664 : 2.714

W/C ratio = 0.45 remains same for all the replacements.

EXPERIMENTAL STUDY1.Slump Test For a constant W/C ratio of 0.45, concrete was found to be not

workable. Hence super plasticizer was added . The amount of super plasticizer was arrived by slump test.

% of Super plasticizer added Slump Obtained ( in mm)

0.2 10

0.4 27

0.6 42

0.8 50

0.9 58

1.0 75

Therefore 1% addition of complast super plasticizer is done on partially replaced concrete and checked for slump.

Slump obtained for all replacements

% replacement Slump Obtained ( in mm)

10 70

20 70

30 66

40 62

50 55

2. Preparation of Mould Cement, course aggregate, fine aggregates, water and Super

plasticizer are calculated and weighed depending upon the volume and number of moulds to be cast.

The moulds are prepared for water content ratio of 0.45 and 1% addition of super plasticizer.

The mixer is initially cleaned then cement and course aggregate is

poured into it and required rotation is given for 1 min to mix.

The inner surface of all the moulds is greased before pouring the concrete and is then leveled.

The moulds are placed on the vibrating table and allowed to settle for 5 mins.

The cubes are kept for air drying for 24 hours and then it is demoulded.

3. Compressive strength test

After curing, the specimens were tested for compressive strength 0n 7th, 14th and 28th day using a calibrated compression testing machine of 2000kN capacity.

RESULTS Compressive Strength on Cubes at 7 Days

Partial

Replacement in %

Number of

Specimen

Ultimate

Load(kN)

Ultimate Compressive

Strength (N/mm2)

0 3 405.00 18.00

10 3 571.67 25.40

20 3 756.67 33.62

30 3 796.67 35.40

40 3 500.00 21.96

50 3 350.00 15.55

Compressive Strength on Cubes at 14 Days

Partial

Replacement in

%

Number of

Specimen

Ultimate

Load(kN)

Ultimate Compressive

Strength (N/mm2)

0 3 526.67 23.40

10 3 696.67 30.96

20 3 873.33 38.81

30 3 896.67 39.85

40 3 600.00 26.66

50 3 450.00 20.88

Compressive Strength on Cubes at 28 Days

Partial Replacement

in %

Number of

Specimen

Ultimate

Load(kN)

Ultimate Compressive

Strength (N/mm2)

0 3 951.67 42.29

10 3 1000.00 44.44

20 3 1370.00 60.88

30 3 1403.33 62.36

40 3 990.00 44.00

50 3 515.25 22.90

Analysis of graphsGraph of Compressive Strength Vs Age in Days

For 0% Replacement

For 10% Replacement

For 20% Replacement

For 30% Replacement

For 40% Replacement

For 50% Replacement

Graph of Compressive Strength Vs % Replacement

At 7 Days At 14 Days

At 28 Days

DISCUSSIONS1.Economic Feasibility

The calculations show cost values up to 50% replacement Total Cost of concrete mix for normal concrete/m3 = 3187.05 Rs Total Cost of concrete mix for 10% replacement/m3 = 2980.38 Rs

Total Cost of concrete mix for 20% replacement/m3 = 2773.70 Rs

Total Cost of concrete mix for 30% replacement/m3 = 2567.06 Rs

Total Cost of concrete mix for 40% replacement/m3 = 2360.39 Rs

Total Cost of concrete mix for 50% replacement/m3 = 2153.72 Rs

2. Comparison of strengths between conventional concrete and partially replaced concrete.

Age of Concrete

(In Days)

Compressive Strength(MPa)

Conventional

Concrete

30% replaced

Concrete

7 17.99 35.40

14 23.40 39.85

28 42.29 62.36

The difference in cost from normal concrete to partially replaced concrete at 30% was Rs.620.00/ m3

CONCLUSIONS

Compressive strength of the concrete, increases as percentage of replacement is increased up to 30%. Further increase in replacement reduces compressive strength.

Economy can be achieved with the replacement

Environmental effects from lime sludge disposal and cement manufacturing is reduced through replacement.

SCOPE FOR FUTURE WORK

Split tensile strength.

Effect of Super plasticizer on compressive strength can be studied by keeping other test parameters such as mix composition, curing period, curing time etc. constant.

Effect of curing time can be further studied by curing for 56 days.

Admixtures could be used to give better workability, higher strengths and provide ease while laying of concrete.

We as Civil Engineers must be responsible for a better environment for future generations by reducing

environmental degradation through use of wastes that are generated from

various industrial processes.

THANK YOU