USE OF MINERAL ADMIXTURE IN CONCRETE PRESENTED BY: DILIP SHAH

Ordinary Concrete CEMENT + FINE AGGREGATE COARSE AGGREGATE WATER

Modern concrete CEMENT + FINE AGGREGATE COARSE AGGREGATE WATER ADMIXTURE (Chemical and Mineral ) CEMENTITIOUS MATERIAL

Mineral Admixtures Mineral admixtures are finely divided siliceous materials which are added to concrete in relatively large amounts, generally in the range 20 to 70 percent by mass of the total cementatious material.

Types of mineral admixture 1.Natural pozzolans: clay and shales, opalinc cherts,act 2.Artificial pozzolans: fly ash, blast furnace slag, silica fume, rice husk ash, surkhi, act…

Fly Ash Fly ash is a by-product of the combustion of pulverized coal in thermal power plants. The dust collection system removes the fly ash, as a fine particulate residue, from the combustion gases before they are discharged into the atmosphere.

Fly ash

Ecological Advantage Power plants using coal as fuel and producing cast iron, silicon metal, and ferrosilicon alloys are the major sources of by-products that are being produced at the rate of millions of tonnes every year in many countries. Dumping of these by-products into landfills and streams amounts to a waste of the material and causes serious environmental pollution.

Effect on Heat of Hydration Replacement of cement by fly ash results in a reduction in the temperature rise in fresh Concrete. This is particular importance in mass concrete where cooling, following a large temperature rise, can lead to cracking.

Effect of fly ash on properties of fresh concrete Concrete using fly ash is generally reported to show Reduced segregation and bleeding and to be more satisfactory than plain concrete when placed by pumping.

Effect of fly ash on the structural properties of hardened concrete At early ages fly ash exhibits very little cementing value, at later ages cementing activity becomes apparent and a considerable Contribution to strength may results. Important variables influence strength development: -properties of fly ash -chemical composition -particle size -reactivity -the temperature and other curing conditions

Silica fume Silica fume admixtures are used to meet high strength and low permeability requirements. They have been used to produce concrete with compressive Strengths as high as about 142MPa. They are added in slurry or in dry form at the site.

Silica fume

Benefits are: Improves bonding within the concrete, Reduced permeability, Improves resistance to corrosion, Can reduce alkali-silica reactivity (ASR), Increased compressive and flexural strengths, and Increased durability.

To know the effect of fly ash on concrete perform some tests To know the effect of fly ash on concrete perform some tests. Material used for testing 1. cement 2. aggregate 3. sand 4. fly ash 5. super plasticizer 6. fibre 7. water

cement All cements which conform to IS can be used for the production of concrete. 53 grade OPC used for experimental work. Normal consistency = 30% Initial setting time = 29 min Final setting time = 580min Compressive strength 7 days 31.13 N/mm2 28 days 49.55 N/mm2

Aggregate Aggregates are the important constituents in concrete. the give body to the concrete, reduce shrinkage effect economy. The aggregates occupy 70-80 % of the volume of concrete. F.M.= 7.2 Bulk density(kg /m3) (a)Loose:--1278 (b)Compacted:1530 Specific gravity:2.85

Sand F.M.= 3.04 passing from 600µ Is sieve according to IS 383-1970 , Z Bulk density(kg /m3) (a)Loose:--1700 (b)Compacted:1949 Specific gravity: 2.65

Fly ash Fly ash is a finely divided residue resulting from the combustion of ground or powdered bituminous coal or sub bituminous coal (lignite) and transported by the flue gases of boilers fired by pulverized coal or lignite.

Super plasticizer In order to improve the workability, a high range water reducer super plasticizer added to the mixture. Poly- carboxylate ether(PCE )base, Manufactured by SIKA,FAIRMATE, ROFF and BASF tried with basic test. Mars cone Spread test Flow with tumbler

Fibre Fibre is a small piece of reinforcing material possessing certain characteristic properties. They can be circular, flat or triangular. The fibre is often described by a convenient parameter called “Aspect Ratio”

Water Portable water is used for casting of the concrete mixes. It is also used for curing.

perform following three test 1. compressive strength test, 2. slump test, 3. flow table test

Compression test This test is perform for knowing the compressive strength of concrete. First cast three cubes for each proportions mix of cement and fly ash After 24 hour cubes should be open and put for curing. After 28 days cubes are tested by testing machine.

Slump test

Slump test Test is perform to check the consistency of freshly made concrete. Slump test is done to make sure concrete mix is workable. procedure:

Flow table test mould is filled with concrete in three layer Then mould lifted vertically upward and concrete stand on its own without support. The table is then raised and dropped 12.5mm 15 times in about 15 second The diameter of the spread concrete is measured in about 6 directions. The flow of concrete is the percentage in average diameter of the mould.

Flow table test Flow per cent=

Before blow After blow

Methodology for 150mm×150mm×150 mm cubes casting It is essential to keep the mould and base plate clean and both should be oiled lightly. Dry mix should be prepare by mixing of cement, sand, aggregate, and varies percentage of fly ash then water should as add per w/c ratio. A 150 mm cube should be filled in three layers, from three different mixes. Each layer should be rammed at least 25 times with a steel bar 600 mm long and having a ramming face of 16 mm square. after 24 hour cube should be opened and put for curing

Methodology for 70×70×70mm cube casting Steel or cast iron cube of 70×70×70mm should be used for casting It is essential to keep the mould and base plate clean and both should be oiled lightly to prevent the mortar sticking to the sides. Dry mix should be prepare by mixing of cement, sand(passing from 300 µ I.S Shieve), fibre, and varies percentage of fly ash then water should as add per w/c ratio and super plasticizer should be add as per requirement. A 70 mm cube should be filled in three layers, from three different mixes. after 24 hour cube should be put for curing.

casting concrete specimens of different percentage of fly ash No. Specimen size 1. cube 150*150*150 mm3 2. 70*70*70 mm3

Mix proposition for different percentage of fly ash for M20 grade concrete as per IS:456 No. Specimen/ no of sample Size (mm3) Cement (kg) Sand Aggregate Water (lit.) % fly ash 1. Cube-3 150*150*150 4.05 6.75 13.50 2.22 2. 3.64 10 3. 3.44 15 4. 3.24 20 5. 2.83 30

Mix proposition for different percentage of fly ash & fibre-reinforcement for M20 grade concrete as per IS: 456 No. Specimen /no of sample Size (mm3) Cement (kg) Sand Water (lit.) S.P % fly ash Fibre (gram) 1. Cube-3 70*70*70 1.2429 0.6214 0.4350 0.0372 60.300 2. 1.1187 10 3. 0.9943 20 4. 0.8700 30

Compression test

compressive strength of 150mm*150mm*150mm cube after 28 days fly ash(%) KN P (N) A (mm2) Strength (N/mm2) Average 540 540000 22500 24 23.93 515 515000 22.89 560 560000 24.89 10 550 550000 24.44 24.81 565 565000 25.11 20 580 580000 25.78 25.85 575 575000 25.56 590 590000 26.22 30 570 570000 25.33

compressive strength of 70mm. 70mm compressive strength of 70mm*70mm*70mm cube after 28 days as per IS:456 fly ash (%) KN P (N) A (mm2) STRENGTH (N/mm2) AVERAGE 134.41 134407.00 4900.00 27.43 36.77 195.22 195216.00 39.84 210.90 210896.00 43.04 10 140.29 140287.00 28.63 29.56 139.31 139307.00 28.43 154.99 154987.00 31.63 20 168.76 168756.00 34.44 35.70 164.79 164787.00 33.63 191.30 191296.00 39.04 30 187.38 187376.00 38.24 208.94 208936.00 42.64 189.34 189336.00 38.64

Workability Results of Fly Ash Variation (%) Percentage Super Plasticizer Diameter d2 (d2-d0)/d0 Percentage Flowability 3 12 0.2 20 10 11.52 0.15 15.3 14.41 0.41 41 30 15.03 0.52 50.3

CONCLUSION solve the major problems of fly ash disposal and reducing use of cement. Use of fly ash improves the workability of concrete. By use of fly ash we can improve the strength of concrete up to 40N/mm2. Concrete become dens and less permeable by use of fly ash. Reduce the cost of construction. Increase the workability of concrete by use of SIKAMENT 600 HP plasticiser.  

REFERENCES 1.M.S.SHETTY, CONCREAT TECHNOLOGY THEORY AND PRACTICE, S.CHAND PUBLICATION. 2. CRISTIAN DRUTA , TENSILE STRENGTH AND BONDING CHARACTERISTICS OF SELF-COMPACTING CONCRETE, 1995. 3. LI YIJIN, ZHOU SHIQIONG, YIN JIAN, AND GAO YINGLI, THE EFFECT OF FLY ASH ON THE FLUIDITY OF CEMENT PASTE, MORTAR, AND CONCRETE. 4. Dipesh A. Gandhi, ROLE OF SAND AND FLYASH PROPORTION IN MATERIAL CHARACTERIZATION OF ECC UNDER DIFFERENT TYPES OF LOADING.

Thank you………