CONCRETE MIX DESIGN GRADE M45

A Minor Project Report

Submitted by

PAWAN CHOUHAN MD NADEEM MAYANK GEHLOT HITESH KUMAR KANARAM

In partial fulfilment for the award of the degree

Of

B.TECH IN CIVIL ENGINEERING

In

Department of Civil Engineering Engineering

At

JIET GROUP OF INSTITUTIONSJODHPUR INSTITUTE OF ENGINEERING AND TECHNOLOGY

NH-65, NEW PALI ROAD, MOGRAJODHPUR

JULY 2014

Candidate’s Declaration

I hereby declare that the work, which is being presented in the Minor Project, entitled “CONCRETE MIX DESIGN GRADE M45” in partial fulfilment for the award of Degree of “Bachelor of Technology” in Dept. Of Civil Engineering submitted to the Department of Civil Engineering, Jodhpur Institute of Engineering and Technology, Rajasthan Technical University is a record of my own WORK carried under the Guidance of Kamlesh Parihar (DY. HOD), Associate Professor, Department of Civil Engineering, Jodhpur Institute of Engineering and Technology.

I have not submitted the matter presented in this Seminar anywhere for the award of any other Degree.

Jodhpur Institute of Engineering and Technology PAWAN CHAUHAN

Counter Signed by MD NADEEM

Name of Supervisor MAYANK GEHLOT

Kamlesh Parihar HITESH NAYAK

` KANARAM

ACKNOWLEDGMENT

I have taken efforts in this report. However, it would not have been possible without the kind support and help of many individuals. I would like to extend my sincere thanks to everyone.

I am highly indebted to Prof. Kamlesh Parihar for his guidance and constant supervision for providing extensive and intensive reinforcement for the preparation of report.I would like to express my gratitude towards my parents & all member of civil engineering department (JIET) for their kind co-operation and encouragement which helped me in completion of this report.I would like to express my special gratitude and thanks to my guide Er. Kamlesh parihar & Er. Ran singh for giving me such attention and time.My thanks and appreciations also goes to my colleagues for assisting in completion of this report on due time.

DEPARTMENT OF CIVIL ENGINEERING (JIET)

1. INTRODUCTION

Concrete is by far the most widely-used man-made construction material and studies indicate that it will continue to be so in the years and decades to come’ Such versatility of concrete is due to the fact that from the common ingredients, namely, cement, aggregate and water (and sometimes admixtures), it is possible to tailor the properties of concrete so as to meet the demands of any particular situation.

The advances in concrete technology has paved the way to make the best use of locally available materials by judicious mix proportioning and proper workmanship, so as to result in a concrete satisfying the performance requirements While the properties of the constituent materials are important, the users are now interested in the concrete itself having desired materials And having desired properties of concrete & have desired strength by using mix design of concrete.The process of selecting suitable ingredients of concrete and determining their relative amounts with the objective of producing a concrete of the required, strength, durability, and workability as economically as possible, is termed the concrete mix design. The proportioning of ingredient of concrete is governed by the required performance of concrete in 2 states, namely the plastic and the hardened states. If the plastic concrete is not workable, it cannot be properly placed and compacted. The property of workability, therefore, becomes of vital importance. The compressive strength of hardened concrete which is generally considered to be an index of Its other properties, depends upon many factors, e.g. quality and quantity of cement, water and aggregates; batching and mixing; placing, compaction and curing. The cost of concrete is made up of the cost of materials, plant and labour. The variations in the cost of materials arise from the fact that the cement is several times costly than the aggregate, thus the aim is to produce as lean a depends on the quality control measures, but there is no doubt that the quality control adds to the cost of concrete. The extent of quality control is often an economic compromise, and depends on the size and type of job. The cost of labour depends on the workability of mix, e.g., a concrete mix of inadequate workability may result in a high cost of labour to obtain a degree of Compaction with available equipment. Mix as possible. From technical point of view the rich mixes may lead to high shrinkage and cracking in the structural concrete, and to evolution of high heat of hydration in mass concrete which may cause cracking.

The actual cost of concrete is related to the cost of materials required for producing a minimum Mean strength called characteristic strength that is specified by the designer of the structure. This Depends on the quality control measures, but there is no doubt that the quality control adds to the Cost of concrete. The extent of quality control is often an economic compromise, and depends on the size and type of job. The cost of labour depends on the workability of mix, e.g., a concrete Mix of inadequate workability may result in a high cost of labour to obtain a degree of Compaction with available equipment.

The basic assumption made in mix design is that the compressive strength of workable concrete is, by and large, governed by the water- cement ratio. Another most convenient

relationship applicable to normal concretes is that for a given type, shape, size and grading of aggregates, the amount of water determines its workability. However, there are various other factors which affect the properties of concrete, for example, the quality and quantity of cement, water and aggregates, batching; transportation, placing, compaction; curing; etc.

2. REQUIREMENTS OF CONCRETE MIX DESIGN

The requirements which form the basis of selection and proportioning of mix ingredient are:

a) The minimum compressive strength required from structural consideration

b) The adequate workability necessary for full compaction with the compacting

Equipment available.

c) Maximum water-cement ratio and/or maximum cement content to give adequate

Durability for the particular site conditions.

d) Maximum cement content to avoid shrinkage cracking due to temperature cycle in mass concrete.

3.Principal of Concrete Mix Design:-

Workable concrete mix. Use as little cement as possible. Use as little water as possible Gravel and sand to be proportioned to achieve a dense mix. Maximum size of aggregates should be as large as possible, to minimize the

minimize the surface area .

4.Types of Mixes

i. Nominal Mixes

In the past the specifications for concrete prescribed the proportions of cement, fine and coarse aggregates. These mixes of fixed cement-aggregate ratio which ensures adequate strength are termed nominal mixes. These offer simplicity and under normal circumstances, have a margin of strength above that specified. However, due to the variability of mix ingredients the nominal concrete for a given workability varies widelyin strength.

ii. Standard mixes

The nominal mixes of fixed cement-aggregate ratio (by volume) vary widely in strength and may result in under- or over-rich mixes. For this reason, the minimum compressive strength has been included in many specifications. These mixes are termed standard mixes.IS 456-2000 has designated the concrete mixes into a number of grades as M10, M15, M20,M25, M30, M35 and M40. In this designation the letter M refers to the mix and the number to the specified 28 day cube strength of mix in N/mm2. The mixes of grades M10, M15, M20 and M25 correspond approximately to the mix proportions (1:3:6), (1:2:4), (1:1.5:3) and (1:1:2) respectively.

iii. Designed MixesIn these mixes the performance of the concrete is specified by the designer but the mix proportions are determined by the producer of concrete, except that the minimum cement content can be laid down. This is most rational approach to the selection of mix proportions with specific materials in mind possessing more or less unique characteristics. The approach results in the production of concrete with the appropriate properties most economically. However, the designed mix does not serve as a guide since this does not guarantee the correct mix proportions for the prescribed performance.

For the concrete with undemanding performance nominal or standard mixes (prescribed in the codes by quantities of dry ingredients per cubic meter and by slump) may be used only for very small jobs, when the 28-day strength of concrete does not exceed 30 N/mm2. No control testing is necessary reliance being placed on the masses of the ingredients.

5.FACTORS AFFECTING THE CHOICE OF MIX PROPORTIONS

The various factors affecting the mix design are:

1. Compressive strength

It is one of the most important properties of concrete and influences many other describable properties of the hardened concrete. The mean compressive strength required at a specific age, usually 28 days, determines the nominal water-cement ratio of the mix. The other factor affecting the strength of concrete at a given age and cured at a prescribed temperature is the degree of compaction. According to Abraham’s law the strength of fully compacted concrete is inversely proportional to the water-cement ratio.

2. Workability

The degree of workability required depends on three factors. These are the size of the section to be concreted, the amount of reinforcement, and the method of compaction to be used. For the narrow and complicated section with numerous corners or inaccessible parts, the concrete must have a high workability so that full compaction can be achieved with a reasonable amount of effort. This also applies to the embedded steel sections. The desired workability depends on the compacting equipment available at the site.

3. Durability

The durability of concrete is its resistance to the aggressive environmental conditions. High strength concrete is generally more durable than low strength concrete. In the situations when the high strength is not necessary but the conditions of exposure are such that high durability is vital, the durability requirement will determine the water-cement ratio to be used.

4. Maximum nominal size of aggregate

In general, larger the maximum size of aggregate, smaller is the cement requirement for a particular water-cement ratio, because the workability of concrete increases with increase in maximum size of the aggregate. However, the compressive strength tends to increase with the decrease in size of aggregate.

IS 456:2000 and IS 1343:1980 recommend that the nominal size of the aggregate should be as large as possible.

5. Grading and type of aggregate. :-

The grading of aggregate influences the mix proportions for a specified workability and water-cement ratio. Coarser the grading leaner will be mix which can be used. Very lean mix is not desirable since it does not contain enough finer material to make the concrete cohesive.

The type of aggregate influences strongly the aggregate-cement ratio for the desired workability and stipulated water cement ratio. An important feature of a satisfactory aggregate is the uniformity of the grading which can be achieved by mixing different size fractions.

6. Quality Control

The degree of control can be estimated statistically by the variations in test results. The variation in strength results from the variations in the properties of the mix ingredients and lack of control of accuracy in batching, mixing, placing, curing and testing. The lower the difference between the mean and minimum strengths of the mix lower will be the cement-content required. The factor controlling this difference is termed as quality control.

6.GRADE DESIGNATION

The common method of expressing the proportions of ingredients of a concrete mix is in the terms of parts or ratios of cement, fine and coarse aggregates. For e.g., a concrete mix of proportions 1:2:4 means that cement, fine and coarse aggregate are in the ratio 1:2:4 or the mix contains one part of cement, two parts of fine aggregate and four parts of coarse aggregate. The proportions are either by volume or by mass. The water-cement ratio is usually expressed in mass.

Among the many properties of concrete, its compressive strength is considered to be the most important and has been held as an index of its overall quality. Many other engineering properties of concrete appear to be generally related to its compressive strength. Concrete is, therefore, mostly graded according to its compressive strength. The various grades of concrete is given in table where M refers to mix.

GRADE DESIGNATION SPECIFIC CHARECTERISTICS COMPRESSIVE STRENGTH 28 DAYS (N/MM^2) M 5 5M 7.5 7.5M 10 10M 15 15M 20 20

M 25 25M 30 30M 35 35M40 40M 45 45M 50 50M 55 55

NOTE:

In the designation of a concrete mix M refers to the mix and the number to the specified characteristic compressive strength of 15 cm cube at 28 days curing expressed in N/mm2.

MI5 and less grades of concrete may be used for lean concrete bases and Simple foundation for masonry walls.Grades of concrete lower than M20 shall not be used in reinforced concrete Structure as per IS 456-2000.Grades of concrete lower than M30 shall not be used in pre stressed Concrete structure.

7. INFORMATION REQUIRED FOR MIX DESIGN OF CONCRETE

In specifying a particular grade of concrete, the following information shall be included:-

1 .Type of mix, that is, design mix concrete or nominal mix concrete;2. Grade designation ( I.E RCC M20 , M 30 , M25 , M40 );3. Type of cement (PPC, OPC, RAPID HARDENING CEMENT);4. Maximum nominal size of aggregate (10mm, 12.5 mm, 20 mm);5. Minimum cement content (for design mix concrete);6. Maximum water-cement ratio;7. Workability;8. Mix proportion (for nominal mix concrete);9. Exposure conditions ( mild , moderate , severe , extreme) ;10. Maximum temperature of concrete at the time of placing;11. Method of placing; and 12. Degree of supervision. 13. Grade of cement (33 grade, 43 grade , 53 grade) ;

8.TEST WHICH ARE REQUIRED BEFORE MIX DESIGN

1.OBJECT: - To determine specific gravity and void content in a given sample of cement. (Bulk density of cement = 1.44 gm/cm³) (as per IS: 4031 (Part 11)- 1988)

APPARATUS: - Le- Chatelier flask (as per IS: 5514- 1996), beaker, weight box, empty container, kerosene free of water or naphtha having a specific gravity not less than 0.7313.

THEORY:-

Specific gravity is normally defined as the ratio between the mass of a given volume of material and mass of an equal volume of water. One of the methods of determining the specific gravity of cement is by the use of a liquid such as water- free kerosene which does not react with cement. A specific gravity bottle may be employed or a standard ‘Le- Chatelier flask’ may be used.

According to ASTM C188, the specific gravity of portland cement (without voids between particles) is about 3.15. In other words, portland cement is about 3.15 times heavier than water, but that of cement manufactured from materials other than limestone and clay, the value may vary. Specific gravity is not an indication of the quality of cement. It is used in calculation of mix proportions.

PROCEDURE (as per IS: 4031 (Part 11)- 1988):-

(1) The flask shall be filled with kerosene to a point on the stem between zero and 1 ml mark. Inside of flask above level of liquid shall be dried if necessary after pouring, the first reading i.e. weight of flask plus kerosene and level of kerosene shall be recorded.

(2) Weighed quantity of cement (about 64 gm of Portland cement) shall than be introduced in small amount into the flask. Care shall be taken to avoid splashing and to see that cement should not adhere to inside flask above the level of kerosene.

(3) After all the cement has been introduced, the stopper shall be placed in the flask and the flask rolled in an inclined position or gently whirled in horizontal circle so as to free cement from air, until no further air bubble rise to surface of liquid, if proper amount of cement has been added level of liquid will be in its final position, final reading i.e. weight of flask plus kerosene plus cement and level of kerosene shall be taken.

CALCULATIONS:

Specific Gravity of Cement = (Mass of cement)/ Volume of Solid particles in cement Vs.

= 53/17.8 = 2.97

Void content in Cement = {(V- Vs.) / V} x 100 %

=36.805-17.8/36.805*100 = 51.8%

OBSERVATION:

S No. Particular Observation

1 Mass of flask + Kerosene in gm  377

2 Level of kerosene in flask in ml.  0.6

3 Mass of flask + Kerosene + Cement in gm  430

4 Raised/ increase level of kerosene in flask in ml. 18.4

5 Mass of cement added (3) - (1) in gm  53

6Bulk volume of cement = (5) / Bulk Density (V) in cm³  36.805

7Displaced volume of solid particles in cement (4) - (2) , (Vs.) in cm³  17.8

RESULTS:-

Specific Gravity of given sample of cement = 2.97

Void content in given sample of cement = 51.8

PRECAUTIONS:-

1) Kerosene must be free from water.2) Constant temperature is to be maintained while taking observations.3) Duplicate determination of specific gravity should agree within 0.01.4) Cement should not adhere to walls of stem of the flask above the level of kerosene.5) For the first reading, after pouring kerosene, little time is to be given to maintain a stable

level of kerosene to the flask.6) Proper handling of the flask care must be taken.

2. OBJECT: - To determine the fineness modulus of Coarse aggregate and Fine aggregate. (as per IS: 2386 (Part 1)- 1963)

Apparatus: -

(1) IS sieves for grading determination For CA : 80 mm, 63 mm, 50 mm, 40 mm, 31.5 mm, 25 mm, 20 mm, 16 mm, 12.5

mm, 10 mm, 6.3 mm, 4.7 mm

For FA : 3.35 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron, 150 micron, 75 micron

(2) IS sieves for Fineness Modules Determination For CA : 150 mm, 75 mm, 40 mm, 20 mm, 10 mm, 4.75 mm, 2.36 mm, 1.18 mm,

600 micron, 300 micron, 150 micron

For FA : 4.75 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron, 150 micron

(3) Balance accurate to 0.1 percent of the weight of test sample.

Theory:-

Fineness aggregate is the sand used in mortars. Coarse aggregate that is the broken stone or gravel, and the mixed aggregate which is the combination of coarse and fine aggregates are used in concrete. The coarse aggregate, unless mixed with fine aggregate, does not produce good quality concrete for construction works. The size of the fine aggregate is limited to maximum of 4.75 mm gauge beyond which it is known as coarse aggregate.

Fineness modulus is only a numerical index of fineness giving some idea of the mean size of particles in the entire body of aggregate. Determination of fineness modulus may be considered as a method of standardization of the grading of the aggregate. If the test aggregate gives higher fineness modulus, the mix will be harsh and if on the other hand gives a lower fineness modulus, it results in an uneconomical mix. For a given workability coarse aggregate require lesser water- cement ratio.

Procedure (as per IS: 2386 (Part 1)- 1963):-

(4) The sample shall be brought to an air dry condition before weighing and sieving. This may be achieved either by drying at room temperature of by heating at a temperature of 100°C to 110°C. The air dry sample shall be weighed and sieved successively on the appropriate sieves starting with the largest; care shall be taken to ensure that the sieves are clean before use.

(5) Each sieve shall be shaken separately over a lean tray until not more than a trace passes, but in any case for a period of not less two minutes. The shaking shall be done with a varied motion, backwards and forwards, left to right, circular clockwise and anti- clockwise and with frequent jarring, so that the material is kept moving over the sieve surface in frequently changing direction. Material shall not be forced through the sieve by hand pressure, but on sieves coarser than 20 mm, placing of particles is permitted. Lumps of fine material, if present, may be broken by gently pressure with fingers against the side of the sieve. Light brushing with a soft brush on the underside of the sieve may be used to clear the sieve openings.

(6) Light brushing with a fine camel hair brush may be used on the 150- micron and 75- micron IS sieves to prevent aggregation of powder and blinding of apertures. Stiff or worn out brushes shall not be used for this purpose and pressure shall not be applied to the surface of the sieve to force particle a through the mesh.

1. On completion of sieving, the material retained on each sieve, together with any material cleaned from the mesh, shall be weighed.

(7) In order to prevent binding of the sieve apertures by overloading, the amount of aggregate placed on each sieve shall be such that the weight of the aggregate retained on the sieve at

completion of the operation is not greater than the value given for that sieve in Table III of IS: 2386 (Part I- 1963). Sample weights given in table IV of IS: 2386 (Part I- 1963) will thus normally require several operations on each sieve.

TABLE III MAXIMUM WEIGHT TO BE RETAINED AT THE COMPLETION OF SIEVING IS: 2386 (Part I)- 1963

Coarse Aggregates Fine Aggregates

IS Sieve Maximum Weight for IS Sieve Maximum Weight for

45-cm dia sieve

kg

30-cm dia sieve

kg

20-cm dia sieve kg

50-mm 10 4.5 2.36 mm 200

40-mm 8 3.5 1.18 mm 100

31.5-mm or 25-mm 6 2.5

20-mm 4 2.0

16-mm or 12.5-mm 3 1.5 600-micron 75

10-mm 2 1.5 300-micron 50

6.3-mm 1.5 0.75

4.75-mm 1.0 0.50 150-micron 40

3.35-mm - 0.30 75-micron 25

TABLE IV MINIMUM WEIGHT OF SAMPLE FOR SIEVE ANALYSIS IS: 2386 (Part I)- 1963

Maximum Size present in substantial proportions

Minimum Weight for sample to be taken for sieving

mm Kg

63 50

50 35

40 or 31.5 15

25 5

20 or 16 2

10 1

6.3 0.5

4.75 0.2

2.36 0.1

GRADING OF AGGREGATES :

1. COARSE AGGREGATES: Coarse Aggregates shall be supplied in the nominal size given in table 2 of IS: 383- 1970. For any one of the nominal sizes, the proportion of other sizes, as determined by the method described above shall also be in accordance with table 2.

2. FINE AGGREGATES: The grading of fine aggregates, when determined as described above shall be within the limits given in table 4 of IS: 383- 1970 and shall be described as fine aggregates, Grading Zones I, II, III and IV. Where the grading falls outside the limits of any particular grading zone of sieves other than 600- micron IS sieve by a total amount not exceeding 5 percent, it shall be regarded as falling within that grading zone. This tolerance shall not be applied to percentage passing the 600- micron IS sieve or to percentage passing any other sieve size on the coarse limit of Grading Zone I or the finer limit of Grading Zone IV.

TABLE 2 COARSE AGGREGATE (IS: 383- 1970)

I.S. SIEVE DESIGNATION

PERCENTAGE PASSING FOR SINGLE AGGREGATE OF NOMINAL SIZE

PERCENTAGE PASSING FOR GRADE AGGREGATE OF

NOMINAL SIZE

63mm 40mm 20mm 16mm 12.5mm 10mm 40mm 20mm 16mm 12.5mm

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)

80 mm 100 - - - - - 100 - - -

63 mm85 to 100

100 - - - - - - - -

40 mm 0 to 3085 to 100

100 - - -95 to 100

100 - -

20 mm 0 to 5 0 to 2085 to 100

100 - -30 to

7095 to 100

100 100

16 mm - - -85 to 100

100 - - -95 to 100

-

12.5 mm - - - -85 to 100

100 - - -90 to 100

10 mm 0 to 5 0 to 5 0 to 20 0 to 30 0 to 4585 to 100

10 to 35

25 to 35

30 to 70

40 to 85

4.75 mm - - 0 to 5 0 to 5 0 to 10 0 to 20 0 to 5 0 to 10 0 to 10 0 to 10

2.36 mm - - - - - 0 to 5 - - - -

TABLE 4 FINE AGGREGATE (IS: 383- 1970)

I.S. SIEVE DESIGNATION

PERCENTAGE PASSING FOR

GRADING ZONE I GRADING ZONE IIGRADING ZONE

IIIGRADING ZONE

IV

10 mm 100 100 100 100

4.75 mm 90- 100 90- 100 90- 100 95- 100

2.36 mm 60- 95 75- 100 85- 100 95- 100

1.18 mm 30- 70 55- 90 75- 100 90- 100

600 micron 15- 34 35- 59 60- 79 80- 100

300 micron 5- 20 8- 30 12- 40 15-50

150 micron 0-10 0-10 0-10 0-15

Note 1: It is recommended that fine aggregate conforming to Grading Zone IV should not be used in reinforced concrete unless tests have been made to ascertain the suitability of proposed mix proportions.

Note 2: Where concrete of high strength and good durability is required, fine aggregate conforming to any one of the four grading zones may be used, but the concrete mix should be properly designed. As the fine aggregate grading becomes progressively finer, i.e., from Grading Zone I to IV, the ratio of fine aggregate to coarse aggregate should be progressively reduced. The most suitable fine to coarse ratio to be used for any particular mix will, however, depend upon the actual grading, particle shape and surface texture of both fine and coarse aggregate

CALCULATION:

Fineness Modulus = Σ (% Cumulative Weight Retained) / 100

OBSERVATION

(1) FOR COARSE AGGREGATES (20 MM)

Weight of Coarse Aggregate = __3Kg

Sieve sizeWeight retained

(gm)

Cumulative weight retained

(gm)

Cumulative % retained

Percent pass

150 mm   - - - 100

75 mm - - - 100

40 mm  - - - 100

20 mm  422  422  14.06  85.94

10 mm  2548  2970  99  1

4.75 mm  30  3000  100  -

2.36 mm  0  3000  100  -

1.18 mm  0  3000  100  -

600 micron  0  3000  100  -

300 micron  0  3000  100  -

150 micron  0  3000  100  -

Pan  0  3000  100  -

FOR COARSE AGGREGATES (10 MM)

Weight of Coarse Aggregate = ___3 Kg

Sieve sizeWeight retained

(gm)

Cumulative weight retained

(gm)

Cumulative % retained

Percent pass

20 mm  113 113 3.76  96.24

10 mm  1490  1603  53.43  46.57

6.3mm  1316 2919 97.3 2.7

4.75 mm 70 2989 99.63 0.37

Pan 11 3000 100 -

(2) FOR FINE AGGREGATES

Weight of Fine Aggregate = ___2_Kg

Sieve sizeWeight retained

(gm)

Cumulative weight retained

(gm)

Cumulative % retained

Percent pass

4.75 mm  158 158 7.9 92.1

2.36 mm 199 357 17.85 82.15

1.18 mm 240 597 29.85 70.15

600 micron 317 914 45.7 54.3

300 micron 416 1330 66.5 33.5

150 micron 614 1944 99.7 0.3

Pan 56 2000 100 0

RESULTS:-

Fineness modulus of Coarse Aggregate (20MM) = 7.13__________

Fineness modulus of Coarse Aggregate(10MM) = _2.44_______

Fineness modulus of Fine Aggregate = ____2.675_____________

PRECAUTIONS:-

1. Sieves should be cleaned before use.2. Stiff worn out brushes should not be used.3. The sieving must be done carefully to prevent the spilling of the aggregate.4. Do not apply pressure to force the particles through the mesh.

3.OBJECT: - To determine the percentage of water required preparing a cement paste of a standard (normal) consistency for a given sample of cement. (as per IS: 4031 (Part 4)- 1988)

APPARATUS: - Vicat apparatus (conforming to IS: 5513 - 1996), plunger 10 mm diameter, balance, gauging trowel, measuring jar of 200 ml capacity, stop watch.

THEORY:-

For finding out initial setting time, final setting time and soundness of cement and strength, a parameter known as standard consistency has to be used. The object of conducting this test is to find out the amount of water to be added to the cement to get a paste of normal consistency, i.e., the paste of a certain standard solidity, which is used to fix the quantity of water to be mixed in cement before performing tests for setting time, soundness and compressive strength. The principle of this test is that standard consistency of cement is that consistency at which the Vicat plunger penetrates to a point 5-7mm from the bottom of Vicat mould.

PROCEDURE (as per IS: 4031 (Part 4)- 1988):-

a) Prepare a paste of weighed quantity of cement (400 gms) with a weighed quantity of water (start with 28% of water), taking care that the time of gauging is not less than 3 minutes, nor more than 5 min. and the gauging time shall be completed before any signs of setting occur. The gauging time shall be counted from the time of adding water to the dry cement until commencing to fill the mould.

b) Fill the Vicat mould with this paste, the mould resting upon a non- porous plate. After completely filling the mould, smooth off the surface of the paste, making it level with the top

c) of the mould. The mould may be slightly shaken to expel the air. d) Clean appliances shall be used for gauging. Temperature of cement, water and that of

test room, at the time when the above operations are being performed, shall be form 27+ 2° C in filling the mould, the operator’s hand and the blade of the gauging trowel shall alone be used. The trowel shall weight 210 + 10 g.

e) Place the test block in the mould, together with the non- porous resting plate, under the rod bearing the plunger” lower the plunger gently to touch the surface of the test block and quickly release, allowing it to sink into paste. This operation shall be carried out immediately after filling the mould.

f) Prepare trial pastes with varying percentage and test as described above until the amount of water is found. Express the amount of water as a percentage by mass of the dry cement to the first place of decimal.

OBSERVATION

Weight of cement = 400gms

S No. Weight of water addedPercentage of water

added

Penetration of plunger from the bottom of the

mould (mm)

 1.  120gm  30  10mm

 2.  124gm  31  8mm

3. 128gm 32 5mm

RESULTS:-

Water required to make a cement paste of standard consistency = 32%.

PRECAUTIONS:-

1) The experiment should be conducted at a room temperature of 27+ 2°C and at a relative humidity of 90 percent.

2) After a half minute from the instant of adding water, it should be thoroughly mixed with fingers for at least one minute. A ball of this paste is prepared and then it is pressed into the test mould, mounted on the non- porous plate.

3) The plunger should be released quickly without pressure or jerk, after the rod is brought down to touch the surface of the test block.

4) For each repetition of the experiment fresh cement is to be taken.5) Plunger should be cleaned during every repetition and make sure that it moves freely

and that there are no vibrations.

4. OBJECT: - To determine the specific gravity and voids content of a given sample of:

(a) Fine Aggregate

(b) Coarse Aggregates

APPARATUS: - Balance with an accuracy of 0.5 gm, vessel 1.00 litre capacity.

THEORY:-

The specific gravity of an aggregate is defined as the ratio of the mass of solid in a given

volume of sample to the mass of an equal volume of water at the same temperature. Since the

aggregate generally contains voids, there are different types of specific gravities.

The absolute specific gravity refers to the volume of solid material excluding the voids, and

therefore, is defined as the ratio of the mass of solid to the mass of an equal void free volume

of water at a stated temperature. If the volume of aggregate includes the voids, the resulting

specific gravity is called the apparent specific gravity.

The specific gravity of an aggregate gives valuable information on its quality and

properties. It is seen that higher the specific gravity of an aggregate harder and stronger it will

be. If the specific gravity is above or below that normally assigned to a particular type of

aggregate, it may indicate that the shape and grading of the aggregate has changed.

PROCEDURE:-

(A) For fine aggregate:

1. First weight the container empty, record it as W1.

2. Fill the container to the brim by the sample of the fine aggregate, weight it and record

as W2.

3. Now pour the water in the aggregate till it comes to brim and again weight it and

record it as W3 also while pouring water stir it well to ensure no entrapped air in the

sample.

4. Now throw the sample and clean it and then again fill it up to brim by water and

weight it and record it as W4.

(B) For Coarse aggregate:

Take the bucket instead of the small container and repeat the entire process.

OBSERVATION:

Wt. F.A. C.A.W1 66 541W2 1360 6738W3 1576 8655W4 776 4746

CALCULATIONS:-

Specific Gravity = [W2 – W1] / [{W4 – (W3 – W2)} – W1]

Void Content = [W3 – W2] / [W4 – W1]

RESULTS

F.A. C.A.Specific gravity

2.62 2.70

Void content 30.42% 45.58%

PRECAUTIONS:-

1) The strokes are to be applied uniformly throughout the entire area of the concrete

section.

2) The experiment should be completed within 2 minutes.

3) It should be ensured that the interior of the mould be clean.

4) The cone should be removed very slowly by lifting upwards without disturbing the

concrete.

5) During filling the mould must be firmly pressed against the base.

6) The base plate should be smooth and clean so that the contact is made with bottom of

the mould around its whole circumference.

9. STEPS INVOLVE IN MIX DESIGN OF M45 GRADE CONCRTE ARE

A-1 Design stipulations for proportioning

a) Grade designation : M45

b) Type of cement : OPC 53 grade confirming to IS 8112c) Maximum nominal size of aggregates: 20 mmd) Minimum cement content : 330 kg/m3e) Maximum water cement ratio : 0.45f) Workability : 160 mm (slump)g) Exposure condition : mild (for reinforced concrete)h) Method of concrete placing : Pumpingi) Degree of supervision : Goodj) Type of aggregate : Crushed angular aggregatek) Maximum cement content : 450 kg/m3l) Chemical admixture type : Superplsticiser (Conplast SP430 Specific gravity 1.18 @ 22°C + 2°C)

A-2 TEST DATA FOR MATERIALS

a) Cement used: OPC 53 grade confirming to IS 8112b) Specific gravity of cement : 2.97c) Chemical admixture : Super plasticiser conforming to IS 9103d) Specific gravity of1. Coarse aggregate : 2.702. Fine aggregate : 2.62e) Water absorption1. Coarse aggregate : 0.5 percent2. Fine aggregate : 1.0 percentf) Free (surface) moisture1. Coarse aggregate : Nil (absorbed moisture also nil)2. Fine aggregate : Nilg) Sieve analysisCoarse aggregate : Conforming to Table 2 of IS: 383Fine aggregate : Conforming to Zone I of IS: 383

A-3 TARGET STRENGTH FOR MIX PROPORTIONING

f’ck = fck + 1.65 sWheref’ ck = Target average compressive strength at 28 days,fck = Characteristic compressive strength at 28 days,s= Standard deviationSelected standard deviation, s = 6N/mm2Therefore target strength = 45 + 1.65 x 6 = 54.9 N/mm2

A-4 SELECTION OF WATER CEMENT RATIOFrom Table 5 of IS:456-2000, maximum water cement ratio = 0.45Based on experience adopt water cement ratio as 0.37

0.37 < 0.45, hence ok

A-5 SELECTION OF WATER CONTENTFrom Table-2(IS:10262-2009), maximum water content = 186 litters (for 25mm – 50mm slump range and for 20 mm aggregates, increase in w/c ratio by about 3% for every additional 25 mm slump)

Estimated water content for 100 mm slump = 186 + 10.2/100 x186 = 204.972 litersAs super plasticizer is used, the water content can be reduced up to 20 percent and aboveBased on trials with Super plasticizers water content reduction of 25 percent has been achieved.Hence the water content arrived = 19 x 0.75 =153.75 litersA-6 CALCULATION OF CEMENT CONTENTWater cement ratio = 0.37Cement content = 153.729/0.37 = 415.5 kg/m3From Table 5 of IS: 456, minimum cement content for severe exposure condition = 320 kg/m3Take cement = 420 kg/m3420 kg/m3 > 320 kg/m3, hence OK

A-7 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINEAGGREGATE CONTENTFrom Table 3, volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 =0.62

In the present case w/c= 0.37. The volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As w/c ratio is lower by 0.10, increase the coarse aggregate volume by 0.02 ( at the rate of -/+ 0.01 for every +/- 0.05 change in water cement ratio).

Therefore corrected volume of coarse aggregate for w/c of 0.37 =0.646(take 0.65)Note: In case the coarse aggregate is not angular, then also the volume of CA may be requiredto be increased suitably based on experience

For pumpable concrete these values should be reduced by 10 percentTherefore volume of coarse aggregate = 0.65 x 0.9 = 0.585Volume of fine aggregate content = 1- 0.585 = 0.415

A-8 MIX CALCULATIONS

The mix calculations per unit volume of concrete shall be as followsa) Volume of concrete = 1 m3b) Volume of cement = [420/2.97] x [1/1000] = 0.1414 m3

c) Volume of water = [153.75/1] x [1/1000] = 0.1537 m3d) Volume of chemical admixture = [8.4/1.18] x [1/1000] = 0.007 m3(SP 2%by mass of cement)e) Volume of all in aggregates (e) =a – (b + c + d) = 1 – (0.1414 + 0.1537 + 0.007) = 0.7042 m3f) Volume of coarse aggregates = e x Volume of CA x specific gravity of CA = 0.7042 x 0.585 x 2.70x 1000 = 1112.3 kg10 mm coarse aggregate (68%) =756.4kg20 mm coarse aggregate (32%) =422.7kgg) Volume of fine aggregates = e x Volume of FA x specific gravity of FA = 0.7042 x 0.415 x 2.62 x 1000 = 765.7 kg

A-9 MIX PROPORTIONS FOR TRIAL NUMBER 1

Cement = 420 kg/m3Water = 153.75kg/m3Fine aggregate = 765.7 kg/m3Coarse aggregates = 1112.3 kg/m3Chemical admixture = 8.4 kg/m3Water cement ratio = 0.37Mix proportion = 1: 1.823 : 2.648

Aggregates are assumed to be in SSD. Otherwise corrections are to be applied while calculating the water content. Necessary corrections are also required to be made in mass of aggregates.

A-10 The slump shall be measured and the water content and dosages of admixture shall be adjusted for achieving the required slump based on trials, if required. The mix proportions shall be reworked for the actual water content and checked for durability requirements.

A-11 Two more trials having variation of ± 10 percent of water cement ratio in A-10 shall be carried out keeping water content constant, and a graph between three water cement ratios and their corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However, durability requirements shall be met.

10. To determine the effect of compaction and curing on the strength of concrete.

APPARATUS: - Universal testing machine, Vibration machine, Cube moulds (15 x 15 x 15 cm), crucible for mixing cement and sand, tamping rod, measuring cylinder, trowels, balance.

THEORY:-

A thorough compaction is the basic necessity to successful concrete manufacture. The compaction eliminates most of the air pockets on the surface of concrete. The presence of even 5 percent voids in the hardened concrete due to incomplete compaction may result in a decrease in compressive strength by about 35 percent.

The concrete starts attaining strength immediately after setting is completed and the strength continues to increase with time. The development of strength is due to the hydration of cement which can take place only when the capillary pores remain saturated. In addition, additional water available from the outside is required to fill the gel- pores, which will otherwise make the capillaries empty. With the passage of time the vapour pressure in capillaries is reduced, and hence the rate of hydration and hence the rate of development of strength is reduced. To avoid this possibility the loss of water should be prevented during the process of hardening. Therefore, it is necessary to cure the freshly laid concrete to prevent the loss of moisture. The function of curing is thus two- fold: to prevent the loss of water in the concrete from evaporation as well as to supplement water consumed in hydration of cement.

PROCEDURE:-

(1) Weigh the required quantity of cement, sand and coarse aggregates.(2) Mix the ingredients dry until a uniform distribution is attained.(3) Weigh the quantity of water required according to given water- cement ratio.(4) Mix thoroughly the water with cement, sand and aggregates.(5) Give proper vibration to the mix.(6) Prepare cubes of 150 mm.(7) Fill the cubes with the mix made.(8) Give adequate compaction with tamping rod.(9) Strike off the concrete on top with a trowel so that the mould is exactly filled.(10) Repeat the above procedure with different water- cement ratio.(11) Test the cubes in compression testing machine after the given age.(12) Calculate the compressive strength.

OBSERVATION:-

Mix proportion = 1: 1.823: 2.648Volume of cube = 0.00371 m^3 (increased by 10 %)Weight of cement = 1.7 Kg

Weight of fine aggregate = 3.09 Kg

Weight of coarse aggregate = 4.5 Kg

W/C ratio = 0.37

Weight of water = 0.63 Kg

Size of cube = (15 x 15 x 15) cm

S. No. Identification MarkAge

(days)

Crushing Load (KN)

Compressive Strength (N/mm²)

1 PMN1 7 880  39.11

2 PMN2 7 890  39.55

3 PMN3 7 890  39.55

PRECAUTIONS:-

1) The strokes are to be applied uniformly throughout the entire area of the concrete section.

2) On completion of tamping any surplus concrete is carefully removed with a trowel so that the mould is exactly filled. The surplus should not be forced into the mould.

3) It should be ensured that the interior of the mould be clean.4) During filling the cube mould must be firmly pressed against the floor.