High Performance Concrete

HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER – 1

1. INTRODUCTION Concrete is a durable and versatile construction material. It is not only Strong, economical and takes the shape of the form in which it is placed, but it is also aesthetically satisfying. However experience has shown that concrete is vulnerable to deterioration, unless precautionary measures are taken during the design and production. For this we need to understand the influence of components on the behavior of concrete and to produce a concrete mix within closely controlled tolerances. The conventional Portland cement concrete is found deficient in respect of : 

Durability in severe environs (shorter service life and frequent maintenance)



Time of construction (slower gain of strength)



Energy absorption capacity (for earthquake resistant structures)



Repair and retrofitting jobs.

Hence it has been increasingly realized that besides strength, there are other equally important criteria such as durability, workability and toughness. And hence we talk about ‘High performance concrete’ where performance requirements can be different than high strength and can vary from application to application. High Performance Concrete can be designed to give optimized performance characteristics for a given set of load, usage and exposure conditions consistent with the requirements of cost, service life and durability. The high performance concrete does not require special ingredients or special equipments except careful design and production. High performance concrete has several advantages like improved durability characteristics and much lesser micro cracking than normal strength concrete.

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HIGH PERFORMANCE CONCRETE GRADE M50 1.1 DEFINITION Any concrete which satisfies certain criteria proposed to overcome limitations of conventional concretes may be called High Performance Concrete. It may include concrete, which provides either substantially improved resistance to environmental influences or substantially increased structural capacity while maintaining adequate durability. It may also include concrete, which significantly reduces construction time to permit rapid opening or reopening of roads to traffic, without compromising long-term servicibility. Therefore it is not possible to provide a unique definition of High Performance Concrete without considering the performance requirements of the intended use of the concrete.

American Concrete Institute defines High Performance Concrete as “A concrete which meets special performance and uniformity requirements that cannot always be achieved routinely by using only conventional materials and normal mixing, placing and curing practices”. The requirements may involve enhancements of characteristics such as placement and compaction without segregation, long-term mechanical properties, and early age strength or service life in severe environments. Concretes possessing many of these characteristics often achieve High Strength, but High Strength concrete may not necessarily be of High Performance .A classification of High Performance Concrete related to strength is shown below. Table no.1. classification of High Performance Concrete related to strength Compressive

50

75

100

125

150

I

II

III

IV

V

strength (Mpa) High Performance Class

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER – 2 2. SELECTION OF MATERIALS The production of High Performance Concrete involves the following three important interrelated steps: 

Selection of suitable ingredients for concrete having the desired rheological properties, strength etc



Determination of relative quantities of the ingredients in order to produce durability.



Careful quality control of every phase of the concrete making process.

The main ingredients of High Performance Concrete are

2.1 CEMENT (opc) Physical and chemical characteristics of cement play a vital role in developing strength and controlling rheology of fresh concrete. Fineness affects water requirements for consistency. When looking for cement to be used in High Performance Concrete one should choose cement containing as little C3A as possible because the lower amount of C3A, the easier to control the rheology and lesser the problems of cement-super plasticizer compatibility. Finally from strength point of view, this cement should be finally ground and contain a fair amount of C3S.

2.1.1 FLY ASH CEMENT Fly ash was historically known as pulverized fuel ash in the UK, it is a by-product from the burning of pulverized coal in power stations. It has both pozzolanic and physical properties that enhance the performance of cement. When Portland cement hydrates it produces alkali calcium hydroxide (lime). Pozzolanas such as fly ash can react with this lime to form stable calcium silicate and aluminate hydrates. These hydrates fill the voids within the mortar matrix, thus reducing the permeability and the potential for efflorescence. Additionally, the reduction in the quantity of lime remaining further decreases the occurance of efflorescence. This process improves the strength, durability, chloride and sulfate resistance of the concrete. SDMCET DHARWAD-02

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HIGH PERFORMANCE CONCRETE GRADE M50 Fly ash cement have improved fresh properties, in particular, cohesion and resistance to segregation and bleeding. Furthermore, they will tend to have a slower setting time which is advantageous in warmer weather conditions.

2.1.2 GGBS CEMENT Ground granulated blast furnace slag is classified as a latent hydraulic material. This means that it has inherent cementious properties, but these have to be activated. The normal means of achieving this is to combine the material with Portland cement. During the manufacture of iron, blast furnace slag is produced as a by-product. This material is rapidly cooled to form a granulate and then ground to a fine white powder (ggbs), which has many similar characteristics to Portland cement. When ggbs is blended with Portland cement further recognized cementitious materials such as Portland-slag cement and blast furnace cement are produced.

Table.2 Typical Chemical oxides of various cementitious materials Portland cement

Slag cement

Fly ash cement

CaO

65

45

25

Sio2

20

33

37

Al2O3

4

10

16

Fe2O3

3

1

7

MgO

3

6

7

2.2 FINE AGGREGATE Both river sand and crushed stones may be used. Coarser sand may be preferred as finer sand increases the water demand of concrete and very fine sand may not be essential in High Performance Concrete as it usually has larger content of fine particles in the form of cement and mineral admixtures such as fly ash, etc. The sand particles should also pack to give minimum void ratio as the test results show that higher void content leads to requirement of more mixing water.

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HIGH PERFORMANCE CONCRETE GRADE M50 2.3 COARSE AGGREGATE The coarse aggregate is the strongest and least porous component of concrete. Coarse aggregate in cement concrete contributes to the heterogeneity of the cement concrete and there is weak interface between cement matrix and aggregate surface in cement concrete. This results in lower strength of cement concrete by restricting the maximum size of aggregate and also by making the transition zone stronger. By usage of mineral admixtures, the cement concrete becomes more homogeneous and there is marked enhancement in the strength properties as well as durability characteristics of concrete. The strength of High Performance Concrete may be controlled by the strength of the coarse aggregate, which is not normally the case with the conventional cement concrete. Hence, the selection of coarse aggregate would be an important step in High Performance Concrete design mix.

2.4 WATER Water is an important ingredient of concrete as it actively participates in the chemical reactions with cement. The strength of cement concrete comes mainly from the binding action of the hydrated cement gel. The requirement of water should be reduced to that required for chemical reaction of unhydrated cement as the excess water would end up in only formation of undesirable voids in the hardened cement paste in concrete. From High Performance Concrete mix design considerations, it is important to have the compatibility between the given cement and the chemical/mineral admixtures along with the water used for mixing.

2.5 CHEMICAL ADMIXTURES Chemical admixtures are the essential ingredients in the concrete mix, as they increase the efficiency of cement paste by improving workability of the mix and there by resulting in considerable decrease of water requirement. Different types of chemical admixtures are 

Plasticizers

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HIGH PERFORMANCE CONCRETE GRADE M50 

Super plasticizers



Retarders



Air entraining agents

Placticizers and super placticizers help to disperse the cement particles in the mix and promote mobility of the concrete mix. Retarders help in reduction of initial rate of hydration of cement, so that fresh concrete retains its workability for a longer time. Air entraining agents artificially introduce air bubbles that increase workability of the mix and enhance the resistance to deterioration due to freezing and thawing actions.

2.6 MINERAL ADMIXTURES The major difference between conventional cement concrete and High Performance Concrete is essentially the use of mineral admixtures in the latter. Some of the mineral admixtures are 

Fly ash



GGBS (Ground Granulated Blast Furnace Slag)



Silica fume



Carbon black powder



Anhydrous gypsum based mineral additives

Mineral admixtures like fly ash and silica fume act as puzzolonic materials as well as fine fillers, thereby the microstructure of the hardened cement matrix becomes denser and stronger. The use of silica fume fills the space between cement particles and between aggregate and cement particles. It is worth while noting that addition of silica fume to the concrete mix does not impart any strength to it, but acts as a rapid catalyst to gain the early age strength.

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER – 3 3. BEHAVIOUR OF FRESH CONCRETE The behavior of fresh High Performance Concrete is not substantially different from conventional concretes. While many High Performance Concretes exhibits rapid stiffening and early strength gain, other’s may have long set times and low early strengths. Workability is normally better than conventional concretes produced from the same set of raw materials. Curing is not fundamentally different for High Performance Concrete than for conventional concretes although many High Performance Concretes with good early strength characteristics may be less sensitive to curing.

3.1 WORKABILITY The workability of High Performance Concrete is normally good, even at low slumps, and High Performance Concrete typically pumps very well, due to the ample volume cementitious materials and the presence if chemical admixtures. High Performance Concrete has been successfully pumped even up to 80 storeys. While pumping of concrete, one should have a contingency plan for pump breakdown. Super workable concretes have the ability to fill the heavily reinforced sections without internal or external vibration, without segregation and without developing large sized voids. These mixtures are intended to be self-leveling and the rate of flow is an important factor in determining the rate of production and placement schedule. It is also a useful tool in assessing the quality of the mixture. Flowing concrete is, of course, not required in all High Performance Concrete and adequate workability is normally not difficult to attain.

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HIGH PERFORMANCE CONCRETE GRADE M50 3.2 SETTING TIME Setting time can vary dramatically depending on the application and the presence of set modifying admixtures and percentage of the paste composed of Portland cement. Concretes for applications with early strength requirements can lead to mixtures with rapid slump loss and reduced working time. This is particularly true in warmer construction periods and when the concrete temperature has been kept high to promote rapid strength gain. The use of large quantities of water reducing admixtures can significantly extend setting time and therefore reduce very early strengths even though strengths at more than 24 hours may be relatively high. Dosage has to be monitored closely with mixtures containing substantial quantities of mineral admixtures so as to not overdose the Portland cement if adding the chemical admixture on the basis of total cementitious material.

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 4 4. BEHAVIOUR OF HARDENED CONCRETE The behavior of hardened concrete can be characterized in terms of it’s short term and long term properties. Short-term properties include strength in compression, tension and bond. The long-term properties include creep, shrinkage, behaviour under fatigue and durability characteristics such as porosity, permeability, freeze-thaw resistance and abrasion resistance.

4.1 STRENGTH The strength of concrete depends on a number of factors including the properties and proportions of the constituent materials, degree of hydration, rate of loading, method of testing and specimen geometry. The properties of

the constituent materials affect the

strength are the quality of fine and coarse aggregate, the cement paste and the bond characteristics. Hence, in order to increase the strength steps must be taken to strengthen these three sources. Testing conditions including age, rate of loading, method of testing and specimen geometry significantly influence the measured strength. The strength of saturated specimens can be 15 to 20 percent lower than that of dry specimens. Under impact loading, strength may be as much as 25 to 35 percent higher than under a normal rate of loading. Cube specimens generally exhibit 20 to 25 percent higher strengths than cylindrical specimens. Larger specimens exhibit lower average strengths.

4.1.1 STRENGTH DEVELOPMENT The strength development with time is a function of the constituent materials and curing techniques. An adequate amount of moisture is necessary to ensure that hydration is sufficient to reduce the porosity to a level necessary to attain the desired strength. Although cement paste in practice will never completely hydrate, the aim of curing is to ensure SDMCET DHARWAD-02

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HIGH PERFORMANCE CONCRETE GRADE M50 sufficient hydration. In general, a higher rate of strength gain is observed for higher strength concrete at early ages. At later ages the difference is not significant.

4.2 COMPRESSIVE STRENGTH Maximum practically achievable, compressive strengths have increased steadily over the years. Presently,28 days strength of up to 80Mpa are obtainable. However, it has been reported that concrete with 90-day cylinder strength of 130 Mpa has been used in buildings in US. The trend for the future as identified by the ACI committee is to develop concrete with compressive strength in excess of 140 Mpa and identify its appropriate applications.

4.3 TENSILE STRENGTH The tensile strength governs the cracking behavior and affects other properties such as stiffness; damping action, bond to embedded steel and durability of concrete. It is also of importance with regard to the behavior of concrete under shear loads. The tensile strength is determined either by direct tensile tests or by indirect tensile tests such as split cylinder tests.

4.4 DURABILITY CHARACTERISTICS The most important property of High Performance Concrete, distinguishing it from conventional cement concrete is it’s far higher superior durability. This is due to the refinement of pore structure of microstructure of the cement concrete to achieve a very compact material with very low permeability to ingress of water, air, oxygen, chlorides, sulphates and other deleterious agents. Thus the steel reinforcement embedded in High Performance Concrete is very effectively protected. As far as the resistance to freezing and thawing is concerned, several aspects of High Performance Concrete should be considered. First, the structure of hydrated cement paste is such that very little freezable water is present. Second, entrained air reduces the strength of high performance concrete because the SDMCET DHARWAD-02

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HIGH PERFORMANCE CONCRETE GRADE M50 improvement in workability due to the air bubbles cannot be fully compensated by a reduction in the water content in the presence of a superplasticizer. In addition, air entrainment at very low water/cement ratio is difficult. It is, therefore, desirable to establish the maximum value of the water/cement ratio below which alternating cycles of freezing and thawing do not cause damage to the concrete. The abrasion resistance of High Performance Concrete is very good, not only because of high strength of the concrete but also because of the good bond between the coarse aggregate and the matrix which prevents differential wear of the surface. On the other hand, High Performance Concrete has a poor resistance to fire because the very low permeability of High Performance Concrete does not allow the egress of steam formed from water in the hydrated cement paste. The absence of open pores in the structure zone of High Performance Concrete prevents growth of bacteria. Because of all the above- reasons, High Performance Concrete is said to have better durability characteristics when compared to conventional cement concrete.

4.5 WHEN TO USE HPC High Performance Concrete can be used in severe exposure conditions where there is a danger to concrete by chlorides or sulphates or other aggressive agents as they ensure very low permeability. High Performance Concrete is mainly used to increase the durability is not just a problem under extreme conditions of exposure but under normal circumstances also, because carbon di oxide is always present in the air .This results in carbonation of concrete which destroys the reinforcement and leads to corrosion. Aggressive salts are sometimes present in the soil, which may cause abrasion. High Performance Concrete can be used to prevent deterioration of concrete. Deterioration of concrete mostly occurs due to alternate periods of rapid wetting and prolonged drying with a frequently alternating temperatures. Since High Performance Concrete has got low permeability it ensures long life of a structure exposed to such conditions.

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 5 5. TEST CONDUCTED ON INGREDIENTS 5.1 COARSE AGGREGATE (CA) a) Water absorption test on coarse aggregate Weight of aggregate before testing (W1)

=1000gm

Weight of the coarse aggregate after surface drying (W2)

=1000gm = ((W2-W1)/W1)X100 = ((1000-1000)/1000)X100 =0%

b) Specific gravity of coarse aggregate Weight of empty pyconometer bottle (W1)

= 450 gm

Weight of pyconometer bottle+coarse aggregate (W2)

= 664 gm

Weight of pyconometer bottle+coarse aggregate+water (W3) = 1550 gm Weight of pyconometer bottle+water (W4)

= 1280 gm

= ((W2-W1)/(W2-W1)-(W3-W4)) = ((664-450)/(664-450)-(1550-1280)) G = 2.61

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HIGH PERFORMANCE CONCRETE GRADE M50 5.2 FINE AGGREGATE (FA) a) Water absorption test on fine aggregate Weight of the fine aggregate before testing (W1) =1000 gm Weight of the fine aggregate after surface drying (W2) =2979 gm So the absorption of fine aggregate

= ((W2-W1)/W1)X100 = ((3000-2979)/(3000))X100 = 0.7%

b) Specific gravity test on fine aggregate Weight of empty pyconomater bottle (W1)

= 450 gm

Weight of pyconometer bottle+fine aggregate (W2)

= 781 gm

Weight of pyconometer bottle+fine aggregate+water (W3) = 1490 gm Weight of pyconometer bottle+water (W4 )

= 1280 gm

= ((W2-W1)/(W2-W1)-(W3-W4)) = ((781-450)/(781-450)-(1490-1280) G = 2.73

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HIGH PERFORMANCE CONCRETE GRADE M50 5.3 SPECIFIC GRAVITY TEST OF CEMENT a) Cement (OPC) Weight of the empty gravity bottle (W1)

= 30 gm

Weight of empty gravity bottle +cement (W2)

= 46 gm

Weight of the gravity bottle + cement + kerosene (W3)

= 87 gm

Weight of the gravity bottle +water (W4)

= 76 gm

= ((W2-W1)/(W2-W1)-(W3-W4)) = ((46-30)/(42-30)-(87-76)) G = 3.15

b) Cement (SLAG) Weight of the empty gravity bottle (W1)

= 30 gm


= 47 gm


= 87 gm


= 76 gm

= ((W2-W1)/(W2-W1)-(W3-W4)) = ((47-30)/(47-30)-(87-76)) G = 2.9

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HIGH PERFORMANCE CONCRETE GRADE M50 c) Cement (FLYASH) Weight of the empty gravity bottle (W1)

= 30 gm


= 49 gm


= 87 gm


=76 gm

= ((W2-W1)/(W2-W1)-(W3-W4)) = ((49-30)/(49-30)-(87-76)) G = 2.37

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HIGH PERFORMANCE CONCRETE GRADE M50 5.4 SIEVE ANALYSIS FOR COMBINED 20MM & 10MM AGGREGATES Table.3 SIEVE SIZE 20 mm graded aggregate 10 mm graded aggregate Total % of passing Requirements

20 MM

10 MM

4.75 MM

PAN

49.46

8.40

0.22

-

45

40.20

0.90

-

95.45

48.60

1.12

-

95-100

25-55

0-10

0

5.5 SAND TEST: SPECIFICATIONS FOR GRADATION OF NATURAL SAND (IS 383-1970) Table.3.1 Sieve sizes

Zone ii (in %)

10 mm

100

4.75 mm

90-100

2.36 mm

75-100

1.18 mm

55-90

600 micron

35-59

300 micron

8-30

150 micron

0-10

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HIGH PERFORMANCE CONCRETE GRADE M50 5.6 AGGREGATE IMPACT VALUE TEST Table.3.2 Sieve size

Retained in gm

Passing in gm

Sample wt. In gm

Percentage

Req.

2.36

310

64

374

17.11

30%

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 6 6. CONCRETE MIX DESIGN A freshly mixed concrete for a period of two hours, from the time addition of water to the dry ingredients is called the concrete mix. The problem of designing a mix for a given purpose means obtaining a concrete of required strength, and workability at lowest cost, by as suitable choice of materials and the proportions. The following are the basic assumption made in design of concrete mix of medium strength. The compressive strength of concrete is governed by its water-cement ratio (W/c ratio). For given aggregate characteristics, the workability of concrete is governed by its water content. There are following four widely used methods of mix design. 

ACI mix design method



British mix design method.



USBR mix design



Mix design in accordance with the Indian standard recommended guide lines for concrete mix design. We have designed the mix as per the mix design in accordance with the Indian

standard recommended guide lines for concrete mix design.

a) Design Stipulations: i. Characteristic Compressive Strength of cement

: 43 N/mm2

ii. Maximum size of the aggregates

: 20 mm

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HIGH PERFORMANCE CONCRETE GRADE M50 b) Test data for Materials: i. Specific Gravity of Cement

: 3.15

ii. Specific Gravity of Coarse Aggregates(20mm)

: 2.65

Specific Gravity of Coarse Aggregates(10mm)

: 2.66

iii. Specific Gravity of Fine Aggregate

: 2.70

iv. Concrete Designation

: M50

v. Characteristic Compressive Strength (fck)

: 50 N/mm2

vi. Water Absorption a. Coarse Aggregates

: 0%

b. Fine Aggregates

: 0.7%

vii. Free (Surface) Moisture a. Coarse Aggregates

: 0%

b. Fine Aggregates

: 1.0%

6.1 STEPS IN MIX DESIGN: (IS: 10262 - 2009) A. Target Strength for Mix Proportioning: f1ck=fck+1.65S Where, f1ck = Target average compressive strength at 28 days. fck

= Characteristic compressive strength at 28 days, and.

S = Standard deviation. From Table 1, standard deviation, S= 5 N/mm2 Therefore, target strength = 50+1.65*5 =58.25 N/mm2 From Table 5 of IS 456, maximum water cement ratio = 0.35

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HIGH PERFORMANCE CONCRETE GRADE M50 B. Selection of Water Content: From Table 5 IS 10262-2009, maximum water content = 180 liter As superplasticizer is used, the water content can be reduced up 20% and above. Hence, the arrived water content =180*0.80=144 litre.

C. Calculation of Cement Content: Water content ratio

= 0.35

Cement content

= 144/0.35 = 411.42kg/m3 Say 412 kg/m3

From table 5 of IS 456 minimum cement content for severe exposure condition = 380kg/m3 412 kg/m3 > 380kg/m3 hence ok. (Assuming 67% by volume of total aggregate) Volume of course aggregate

= 0.67*1.0=0.67

Volume of fine aggregate content

=1-0.67=0.33

D. Mix Calculations: a. Volume concrete=1m3 b. Volume cement content

= mass of cement / specific gravity of cement * 1/ 1000 = 412/3.15*1/1000 = 0.1308m3

c. Volume of admixture

= mass of admixture/specific gravity of adm*1/1000 = 4.994/10145*1/1000 = = 0.0043 m3

d. Volume water

= mass of water / specific gravity of cement * 1/ 1000 = 144/1*1/1000 = 0.1440 m3

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HIGH PERFORMANCE CONCRETE GRADE M50 e. Volume of all in aggregate = [a-(b + c)] = 1-(0.1308+ 0.1440+0.0043) = 0.7209 m3 f. Mass of coarse aggregate

= e * Volume of coarse aggregate * specific gravity of coarse aggregate *1000 = 0.7209 *0.67*2.65*1000 = 1282.365kg/m3 Say 1284 kg/ m3

g. Mass of fine aggregate

= e * Volume of fine aggregate * specific gravity of fine aggregate *1000 = 0.7209 *0.33*2.61*1000 = 620.919 kg/m3 Say 621 kg/m3

Taking coarse aggregate in two fractions of – 20mm: 10mm = 0.55:0.45 coarse aggregate 20mm = 706 kg/m3. coarse aggregate 10mm = 578 kg/m3 Increasing cement, water, admixture by 2.5% for this trial Cement = 412 X 1.025 = 422 kg Water = 144 X 1.025 = 147.6 kg Admixture = 1.2 % by weight of cement = 5.064 kg

FOR 1M3 MIX PROPORTION ARE Cement

= 422 kg/ m3

Admixture

= 5.046 kg/ m3

Water

= 147.6 kg/ m3

Fine aggregate

= 621 kg/ m3

Coarse aggregate (20mm)

= 706 kg/ m3

Coarse aggregate (10mm)

= 578 kg/ m3

Water cement ratio

= 0.35

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HIGH PERFORMANCE CONCRETE GRADE M50 PROPORTION Table.4 Cement

Fine aggregate

Coarse aggregate

412

621

1284

1.00

1.472

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3.043

Water 147.6 0.35

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 7 7. CALCULATION OF REQUIRED QUANTITIES OF CEMENT, FINE AND COARSE AGGREGATE CONTENT

FOR NOMINAL MIX (6 CUBES) CEMENT

= 422 x 0.15 x 0.15 x 0.15 x 6 = 8.5455 kg

FA

= 1.472 x 8.5455 = 12.579 kg

CA

= 3.043 x 8.5455 = 26 kg

WATER

= 0.45 x 8.5455 = 3.845 liters

PLASTICIZER (BUILD PLAST) For 50 kg of cement

= 175 ml

For 8.5455 kg of cement

= 29.9 ml

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HIGH PERFORMANCE CONCRETE GRADE M50

FOR NOMINAL MIX (6 CYLINDERS) CEMENT

= 422 x 0.50 x 0.10 x 0.10 x 6 = 12.66 kg

FA

= 1.472 x 12.66 = 18.63kg

CA

= 3.043 x 12.66 = 38.52 kg

WATER

= 0.45 x 12.66 = 5.7 liters


= 175 ml


= 43.92 ml

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FOR NOMINAL MIX (6 BEAMS) CEMENT

= 422 x 0.50 x 0.10 x 0.10 x 6 = 12.66 kg

FA

= 1.472 x 12.66 = 18.63kg

CA

= 3.043 x 12.66 = 38.52 kg

WATER

= 0.45 x 12.66 = 5.7 liters


= 175 ml


= 43.92 ml

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HIGH PERFORMANCE CONCRETE GRADE M50 7.1 TABULATION OF QUANTITIES OF MATERIALS (PER 6 CUBES) Table.5 MATERIALS CEMENT(kg) FINE AGG.(kg) COARSE AGG.(kg) WATER CONTENT(ltrs) ADMIXTURE

OPC CONCRETE

SLAG CONCRETE

FLYASH CONCRETE

TOTAL QUANTITY

8.54 12.56 26 3.85 30

8.54 12.56 26 3.85 30

8.54 12.56 26 3.85 30

25.62 37.68 78 11.54 90

(PER 6 CYLINDERS) Table.5.1 MATERIALS CEMENT(kg) FINE AGG.(kg) COARSE AGG.(kg) WATER CONTENT(ltrs) ADMIXTURE

OPC CONCRETE

SLAG CONCRETE

FLYASH CONCRETE

TOTAL QUANTITY

13.42 19.75 45.66 6.04 47

13.42 19.75 45.66 6.04 47

13.42 19.75 45.66 6.04 47

40.26 59.25 136.98 18.12 141

(PER 6 BEAMS) Table.5.3 MATERIALS CEMENT(kg) FINE AGG.(kg) COARSE AGG.(kg) WATER CONTENT(ltrs) ADMIXTURE

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OPC CONCRETE

SLAG CONCRETE

FLYASH CONCRETE

TOTAL QUANTITY

12.66 18.63 38.52 5.7 43.92

12.66 18.63 38.52 5.7 43.92

12.66 18.63 38.52 5.7 43.92

38 56 115.6 17.1 131.76

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 8 8. TEST PROCEDURE 8.1.1 CUBE MOULDS Cube moulds are the standard square size blocks made of steel. They are open at top and having a base plate at bottom. Steel cube moulds are made of 6mm thick and (150*150*150) mm size.

8.1.1 A. Compressive Strength Compressive strength is the primary physical property of concrete (others are generally defined from it), and is the one most used in design. It is one of the fundamental properties. Compressive strength may be defined as the measured maximum resistance of a concrete specimen to axial loading. It is found by measuring the highest compression stress that a test cube will support.

There are three type of test that can be use to determine compressive strength; cube, cylinder, or prism test. The ‘concrete cube test' is the most familiar test and is used as the standard method of measuring compressive strength for quality control purposes (Neville, 1994). Please refer appendix 1 for details. 

Compressive strength = P/A

N/mm2

Where, P = Failure load in N. A = Cross section area of the specimen in mm2

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HIGH PERFORMANCE CONCRETE GRADE M50 8.1.1 B. Spilt Tensile Strength This test is also called “Brazilian test” test is carried out by placing cylinder specimen horizontal b/w the loading surfaces of compression testing machine and load is applied with failure of cylinder along the vertical diameter the main advantages of this test is that the same type of spaceman as are used for the compression test can employed for this test also. Spilt tensile strength=(2p/πd2)

N/mm2

Where,

P = Failure load in N. D=diameter of cylinder in mm.

8.1.1 C. Flexural Strength The Flexural strength of concrete is determined by subjecting a plain concrete beam to flexure under transfer loads. Concrete is relatively strong in compression and weak in tension. In reinforced concrete the tensile stress are resisted by the provision of reinforced steel. However tensile stressed are likely to develop in concrete due to drying, shrinkage, rousting of steel reinforcement, temperature variations and many other reasons.

A concrete road slab as to resist tensile stress from to principle sources wheel loads and volume changes in concrete. Wheel may cause high tensile stress due to bending when there is in adequate sub grade support. Volume changes from change in temperature and from the moisture may cause tensile stress due to warping and due to moment of slab along the sub grade.

Beam moulds are standard rectangular size blocks made of steel. They are open at top having a base plate at bottom. Steel cubes moulds are made up of 6mm thick and (100*100*500) mm size.

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HIGH PERFORMANCE CONCRETE GRADE M50 Machine: Universal testing machine (UTM) – 40 Tone capacities. Flexural strength = δ =P*l/b*d2 N/mm2 Where,

P = failure load in Newton and l =length of the specimen b = width of the specimen in mm d = depth of specimen in mm

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 9 9. METHODOLOGY 9.1 CUBE TEST Objective:

To determine the compressive strength of a concrete sample.

Apparatus:  Standard cube size 150mm^3  Vibrating machine General note: 

Compressive strength will be determined at the age of 7 and 28 days.



3 samples for each age will be prepare. Average result will be taken.

Procedure: 

Prepare the mould; apply lubricant oil in a thin layer to the inner surface of the mould to prevent any bonding reaction between the mould and the sample (A.M Neville, 1994).



Overfill each mould with sample in three layers (Standard Method: BS 1881:Part -3: 1970).



Fill 1/3 of the mould with sample. This would be the first layer.



Compact sample with vibrating machine. Compaction should be done continuously.



Fill 2/3 of the mould; second layer. Repeat step 4.



Continue with the third layer and repeat the same compaction step.



After compaction has been completed, smooth off by drawing the flat side of the trowel (with the leading edge slightly raised) once across the top of each cube.



Cut the mortar off flush with the top of the mould by drawing the edge of the trowel (held perpendicular to the mould) with a sawing motion over the mould.



Tag the specimen, giving party number, and specimen identification.



Store cube in moist closet (temperature; 18˚C - 24˚C) for 24 hours.

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Open mould and preserved cube in water (temperature; 19˚C - 21˚C) – BS 1881; Part 3: 1970.



Test cube for 7 days and 28 days accordingly.



Placed cube on the testing machine: cube position should be perpendicular with its pouring position ( A.M. Neville, 1994).



Without using any capping material, apply an initial load ( at any convenient rate) up to one-half of the expected maximum



load (G.E. Troxell, 1956).

Loading should be increased at a uniform increment; 15 MPa/min (2200 Psi/min) – BS 1881: Part 4: 1970. Since that certain sample are expected to have lower compressive strength, some adjustment will be made; loading will be increased with the increment

of

5%

of

the

expected

maximum

compressive strength. 

When it comes nearer to the expected maximum strength, loading increment will be lessen little by little ( A.M. Neville,1994).

9.2 CYLINDER TEST Objective:

To determine the split tensile strength of a concrete sample.

Apparatus:  Standard cylinder of 150mm diameter and 300mm height  Vibrating machine General note: 

Split tensile strength will be determined at the age of 7 and 28 days



.3 samples for each age will be prepare. Average result will be taken.

Procedure: 




Overfill each mould with sample in three layers (Standard Method: BS 1881:Part -3: 1970).

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

Compact sample with vibrating machine. Compaction should be done continuously.



Fill 2/3 of the mould; second layer. Repeat step 4.






After compaction has been completed, smooth off by drawing the flat side of the trowel (with the leading edge slightly raised) once across the top of each cube.









Store cylinder in moist closet (temperature; 18˚C - 24˚C) for 24 hours.



Open mould and preserved cube in water (temperature; 19˚C - 21˚C) – BS 1881; Part 3: 1970.



Test cylinder for 7 days and 28 days accordingly.



Placed cube on the testing machine: cylinder position should be horizontal with its pouring position ( A.M. Neville, 1994).



Without using any capping material, apply an initial load ( at any convenient rate) up to one-half of the expected maximum




Loading should be increased at a uniform increment; 15 MPa/min (2200 Psi/min) – BS 1881: Part 4: 1970. Since that certain sample are expected to have lower compressive strength, some adjustment will be made; loading will be increased with the increment

of

5%

of

the

expected

maximum

compressive strength. 


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HIGH PERFORMANCE CONCRETE GRADE M50 9.3 BEAM TEST Objective:

To determine the flexural strength of a concrete sample.

Apparatus:  Standard beam size 100mm*100mm*500mm  Vibrating machine

General note: 

Flexural strength will be determined at the age of 7 and 28 days.



3 samples for each age will be prepared. Average result will be taken.

Procedure: 




Overfill each mould with sample in three layers (Standard Method: BS 1881: Part -3: 1970).






Compact sample with vibrating machine.. Compaction should be done continuously.



Fill 2/3 of the mould; second layer. Repeat above procedure.






After compaction has been completed, smooth off by drawing the flat side of the trowel (with the leading edge slightly raised) once across the top of each beam.









Store beams in moist closet (temperature; 18˚C - 24˚C) for 24 hours.



Open mould and preserved cube in water (temperature; 19˚C - 21˚C) – BS

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HIGH PERFORMANCE CONCRETE GRADE M50 1881; Part 3: 1970 

Test beam for 7 days, 14 days and 28 days accordingly.



Placed beam on the UTM machine: cube position should be perpendicular with its pouring position (A.M. Neville, 1994).



Without using any capping material, apply an initial load (at any convenient rate) up to one-half of the expected maximum




Loading should be increased at a uniform increment; 15 MPa/min (2200 Psi/min) – BS 1881: Part 4: 1970. Since that certain sample are expected to have lower flexural strength, some adjustment will be made; loading will be increased with the increment of 5% of

the expected maximum flexural

strength. 


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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 10 10. CONDUCTING OF CONCRETE PREPARATION (PICTURE GALLERY)

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10.1 SLUMPS OBTAINED Opc concrete

= 110 mm to 120 mm

Fly ash concrete

= 90 mm to 100 mm

Ggbs concrete

= 70 mm to 80 mm

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HIGH PERFORMANCE CONCRETE GRADE M50 10.2 COMPACTION FACTOR TEST a) OPC CONCRETE Weight of the empty cylinder (W1)

= 6000 gm

Weight of the cylinder+uncompacted concrete (W2)

= 18750 gm

Weight of the cylinder+compacted concrete (W3)

= 18800 gm

CF = 0.9

b) GGBS CONCRETE Weight of the empty cylinder (W1)

= 6000 gm


= 18720 gm


= 20455 gm

CF = 0.88

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HIGH PERFORMANCE CONCRETE GRADE M50 c) FLYASH CONCRETE Weight of the empty cylinder (W1)

= 6000 gm


= 18700 gm


= 20770gm

CF = 0.86

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 11 11.TEST RESULTS 11.1.1 Compressive strength results of opc concrete cubes are listed below. Size of the cubes: 150mm x 150mm x 150mm.

For 7 days Table No.6 Sl.no

C/s area ‘A’mm

Failure load ‘P’ N

1 2 3

22500 22500 22500

810000 815000 800000

Comp. strength P/A N/mm2 36.00 36.22 35.55

Avg. comp. strength N/mm2

Comp. strength P/A N/mm2 53..33 49.11 54.22


35.92 Say 36.00

For 28 days Table No.6.1

Sl.no

C/s area ‘A’mm


1 2 3

22500 22500 22500

1200000 1105000 1220000

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52.22

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HIGH PERFORMANCE CONCRETE GRADE M50 11.1.2 Compressive strength results of GGBS concrete cubes are listed below. Size of the cubes: 150mm x 150mm x 150mm. For 7 days Table No.7 Sl.no

C/s area ‘A’mm


1 2 3

22500 22500 22500

860000 845000 840000





37.70 Say 38.00


Sl.no

C/s area ‘A’mm


1 2 3

22500 22500 22500

1395000 1300000 1310000

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59.33

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HIGH PERFORMANCE CONCRETE GRADE M50 11.1.3 Compressive strength results of fly ash concrete cubes are listed below. Size of the cubes: 150mm x 150mm x 150mm. For 7 days Table No.8 Sl.no

C/s area ‘A’mm


1 2 3

22500 22500 22500

890000 910000 895000



Comp. strength P/A N/mm2 65 65 64


39.92 Say 40.00


Sl.no

C/s area ‘A’mm


1 2 3

22500 22500 22500

1460000 1460000 1440000

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64.66

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HIGH PERFORMANCE CONCRETE GRADE M50 11.2.1 Split tensile strength of OPC concrete cylinder Size of the cylinder

: 150mm diameter and 300mm height

For 28 days Table No.9 Sr no

C/s area, ‘A’ = 2 mm2


1. 2. 3.

17671.45 17671.45 17671.45

300000 300000 310000

Tensile strength = 2p/ DL N/mm2 4.24 4.24 4.38

Average Tensile strength N/mm2 4.28

11.2.2 Split tensile strength of GGBS concrete cylinder For 28 days Table No.9.1 Sr no



1. 2. 3.

17671.45 17671.45 17671.45

360000 350000 360000

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HIGH PERFORMANCE CONCRETE GRADE M50 11.2.3 Split tensile strength of Fly ash concrete cylinder For 28 days Table No. 9.2 Sr no



1. 2. 3.

17671.45 17671.45 17671.45

339823 350424 354663

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HIGH PERFORMANCE CONCRETE GRADE M50 11.3 Flexural strength of opc, fly ash and ggbs concrete beam are listed below: Size of the beams: 100mm x 100mm x 500mm.

The following table gives the Flexural strength test results. For 7 days Table No. 10 Sr no

1.opc 2.fly ash 3.ggbs

C/s area, ‘A’ = mm2


10000 10000 10000

4905 6376.5 5346

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Flexural strength = Pl/b 2 N/mm2 2.45 3.18 2.67

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HIGH PERFORMANCE CONCRETE GRADE M50 11.4 COMPARISON BETWEEN DIFFERENT TYPES OF M50 GRADE CONCRETES Table No. 11 Properties

OPC concrete

GGBS concrete

FLYASH concrete

Slump(mm)

110 - 120

70 -80

90-100

Compaction Factor

0.9

0.88

0.86

Compressive strength at 28 days(N/mm2) Split tensile strength at 28 days(N/mm2) Flexural strength at 7 days(N/mm2)

52.22

59.33

64.66

4.28

5.04

4.93

2.45

2.67

3.18

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER – 12 CONCLUSION  From the project we can conclude that use of cements made from industrial waste materials viz fly ash and GGBS to a certain extent increases the overall performance of the particularly designed M50 grade concrete.  From the test results obtained we can say that the compressive strength of FLY ASH concrete is much higher than the target mean strength.  It is observed that compressive strength of fly ash concrete at 28 days is meeting target mean strength, and will increase upto 90 days(more than 10N/mm 2 20N/mm2).  From the slump values obtained the OPC concrete is free flowing but does not match with the target mean strength, Where as fly ash and GGBS concrete are having less free flow but matches the target mean strength.

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HIGH PERFORMANCE CONCRETE GRADE M50 CHAPTER - 13 SCOPE  For the works demanding high performance of concrete in respect of strength and workability, The designed M50 concrete using GGBS and fly ash cements can be used.  We can still improve the strength of these concretes by adding certain amount of crusher powder.  Early age heat of hydration of concrete can be reduced using GGBS concrete which will reduce water usage for curing.  workability tests can be carried out like funnel test, U tube tests etc.

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CHAPTER - 14 REFERENCES [1] A.M.Neville, “Properties of concrete”, Pearson education Asia pte ltd, England. [2] M.S. Shetty, “Concrete Technology”, 5th edition, S.Chand publications. [3] Proceedings of seventh international conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete-Vol-II Editor- V.M.Malhotra. [4] THE INDIAN CONCRETE JOURNAL (VOL.85 – NO.03 - MARCH 2011)- Published by ACC Limited. [5] The Indian concrete journal, September 2002. [6] “ASIAN JOURNAL OF CIVIL ENGINEERING (BUILDING AND HOUSING) “VOL. 10, NO.3 (2009) – V. Bhishma Kalidas Nitturkar and Y. Venkatesham. [7] IS CODE 456-2000,10262-2009,383-1970,1199-1959. [8] www.civilcampus.net ,Wikipedia. [9] Bagalkot cement factory, Bagalkot.

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High Performance Concrete

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