concrete Experiments

8/13/2019 concrete Experiments

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EXPERIMENT NO. 1

Fineness of Cement by Hand Sieving

INTRODUCTION

Fineness of cement is a measure of size of particle of cement . It is expressed as specific surfaceof cement. (in sq. cm /gm). Fineness of cement preferably determined by Blain Air Permeabilitymethod or it can be determined by hand sieving.

OBJECTIVE

To determine fineness of cement by sieve method to be compared with BS and ASTM

specification requirements.

For students to learn sieving and weighting.

APPARATUS AND MATERIALS

Material:

Cement sample

Apparatus

1. BS 90 and ASTM 75 micron sieves with their receiving pans and covering lid2. Weighing balance accurate up to 0.1 gm3. Trowel , brush and tray

PROCEDURE

1. Weigh accurately 100 grams of cement and place it on a B.S. 90 micron sieve let be (W)2. Breakdown any air set lumps in the sample with fingers, without rubbing them on the

sieve.

3. Continuously sieve the sample for 15 minutes by holding the sieve in both hands andgiving wrist motion.

4. Weighs the residue left on the sieve after sieving (W1).5. Repeat all the steps above using ASTM 75 micron sieve.

Data sheet

SampleNo.

Weight ofCement

(W) gm

Retained weight aftersieving (sieve 90 micron)

(W1) gm

Retained weight aftersieving (sieve 75 micron)

(W1) gm

% Retainedweight

1

2

3


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RESULTS & CALCULATIONS:

% 100Group No. ( % )Retained =

B.S and ASTM Requirements

As per B.S the residue of cement sampled on the sieve 90 micron after sieving should not exceedthe followings, % by weight for different types of cements.

Ordinary Portland cement 10%Rapid hardening cement 5%

Low heat cement 5%

Questions

1. Which method is widely used to determine the fineness of cement?2. What will happen if cement is ground beyond certain limit? Give reasons.3. What is the effect on physical properties of cement, if the residue of cement on B.S 90 m

sieve is greater than 10% for OPC? ,


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EXPERIMENT NO. 2

Specific Gravity of Cement

INTRODUCTIONSpecific Gravity is the ratio of the weight of a given volume of cement to the weight of an equalvolume of water. Water, at a temperature of (23C) has a specific gravity of 1. The specificgravity of portland cement is generally around 3.15 while the specific gravity of Portlandblast-furnace-slag and portland-pozzolan cements may have specific gravities near 2.90.

OBJECTIVE:

1. To determine the Specific gravity of cement, it is normally used in mixtureproportioning calculations

2. To convert mass of cement to volume required to calculate volume of hydrationproducts

3. Tacking specific gravity can sometimes indicate a change of material or possiblecontamination

APPARATUS & MATERIALS

Apparatus

1. Pycnometer, a flask or other suitable container into which the cement can be readilyIntroduced. Figure. 1

2.

Weighing balance accurate up to 0.01 gm3. Metal or glass funnel4. Scoop

Material

1. Cement sample2. Distilled water3. Kerosene

PROCEDURE

1. Take sample of cement approximately 25, 30 , 35 gm, Let be W12. Calibrate a specific gravity flask pycnometer by filling with Kerosene oil (23 1C) to

calibration line. Record this weight as the weight of the pycnometer filled with kerosene

to the nearest 0.01g let be W23. Place sample of cement using funnel into the pycnometer and fill with kerosene

(regulated at 23 + 1.0 ) to 90 % pycnometer capacity


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4. Manually roll, invert, and agitate the pycnometer to eliminate air bubbles , repeated forseveral times

5. Fill the pycnometer with kerosene to the calibration line ,and determine the total weightof pycnometer, specimen, and kerosene. Record the weight to the nearest 0.01g. Let be

W3.

6.

Empty ,clean and dry the pycnometer, then fill it with a water up to the specified limit.Record the weight let be W4

7. Weigh the empty Pycnometer let be W5.

RESULTS

Datasheet

Group

No.

Weight of

cement

(W1)

Weight of Pycnometer

+ Kerosene

(W2)

Weight of

Pycnometer +

Kerosene+cement

(W3)

Weight of

pycnometer

+Water

(W4)

Wt. of

empty

pycnometer

1 25

2 30

3 35

Group Gk Gc

1

2

3

CALCULATIONS

Specific Gravity of Kerosene (Gk) =

Specific Gravity of Cement (Gc) =


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6/22

EXPERIMENT NO. 3

Normal Consistency of Cement

INTRODUCTION

It means consistency which permits the Vicat's plunger of 10mm diameter to penetrate to a point

5mm to 7 mm from the bottom of Vicat's mould. It isexpressed as amount of water as apercentage by weight of dry cement.


Apparatus:

1. Vicat apparatus with plunger and mould2. Weighing balance accurate up to 0.1 gm,3. non-porous plate, tray, stopwatch, trowel and spatula

Material

Cement Sample and Water

Plunger used to determine normal consistency of cement is a special plunger used with Vicat

apparatus having 10 mm diameter and 50 mm length


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PROCEDURE

1. Weigh about 500 gm of cement accurately and place it in a pan2. Add about 25% of potable water and mix it by means of spatula. Care should be taken

that the mixing time is not less than three minutes and not more than 5 minutes.

3. Apply thin layer of oil to inner surface of mould. Fill the Vicat's mould with this paste inthe mould resting on non- porous plate.

4. Make the surface of cement paste in level with the top of mould with the trowel.5. Place the mould together with the non-porous plate under the rod bearing the plunger so

that it touches the surface of the test block.

6. Release quickly the plunger allowing it to sink in the cement paste in the mould7. If the penetration of plunger in the paste ranged from 5 to 7 mm from the bottom of

mould. Then the paste at standard consistency , if it is more than 7 mm ,repeat the test

prepare another trial paste with increase percentage of water and repeat the procedure

until the plunger penetrate to a depth 5 -7 mm from the bottom

8. Express this amount of water as a percentage by weight of dry cement.

Datasheet

GroupsWeight of dry

cement (W1)

Weight of

water

(W2)

Penetration of

Plunger from Bottom

(mm)

% Water by

Weight

W2/W1 * 100

1

2

3

RESULTS

The standard consistency of cement = ------------------ %

Questions

1. State the meaning of normal consistency of cement.2. What is the importance of this test?3. State the meaning of gauging time and its importance.4. What is the range of values of standard consistency of cement?5. What is the effect of fineness of cement on standard consistency of cement?6. How the consistency of cement paste is is measured?


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Experiment No. 4

Setting Time of Cement

INTRODUCTION

The Process of changing cement from fluid state to a solid state is called setting.

Initial setting time of cement:

It is defined as the period elapsed between the time when the water is added to the cement andthe time at which the needle of 1 mm section fails to penetrate the test block to a depth 35 + 0.5

mm and more or 5 + 0.5 mm from the bottom of mould.

Final Setting time of cement:

It is defined as the period elapsed between the time when the water is added to the cement and

the time at which the needle of area 1mm with 5mm diameter attachment, makes an impression

on the test block, while the attachment fails to make an impression on the test block.OBJECTIVE

1. To determine initial and final setting time of cement2. To interpret the results and compare with the specifications to decide the suitability of

given cement sample.


1. Vicat's apparatus with initial setting time needle and final setting time needle.2. Weighing balance accurate up to 0.1gm.3.

Non porous plate (Glass or Metal)

4. Stop watch5. Spatula.6. Trowel of about weight.7. Measuring cylinder. 250 ml capacity8. Container

Vicat Apparatus Initial setting needle Final setting needle


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PROCEDURE

1. Take 500 gm of cement .2. Prepare a neat cement paste by gauging the cement with water required to give a paste of

standard consistency.

3. Start the stop watch at the instant when water is added to the cement. The mixing timeshould be 4 + 1 minutes.

4. Fill the Vicat mould with this paste, the mould resting on non-porous plate. Level thesurface of the cement paste with the top of the mould with a trowel.

Determination of Initial Setting Time

5. Place this mould together with the non-porous plate under the rod bearing the initialsetting time needle. Adjust the needle so that it touches the surface of test block.

6. Release needle quickly allowing it to sink in the cement paste in the mould. Note downthe penetration of the needle in the paste.

7. Repeat this procedure after every 5 minutes until the needle fails to penetrate the block upto about 5 to 6 mm from the bottom of block.

8. Note the time shown by the stop watch at this instant, as Initial setting time.Determination of Final Setting time

9. Replace the needle of Vicat's apparatus by the needle with an annular attachment.10.Apply the needle gently to the surface of the test block. Repeat this procedure, until the

needle makes an impression while the attachment fails to do so .

11.Note the time shown by the stop watch at this instant , as Final setting time .RESULTS

The setting time for the given cement sample are found to be .

Initial setting =

Final setting time =

BIS REQUIREMENTS:

According to BIS269 BS112, BS 12269 , the setting time of Ordinary Portland cement tested by

Vicats apparatus method shall confirm to the following requirements

Initial setting time : Not less than 45 minutes

Final Setting time: Not more than 600 minutes

Questions:

1. Which constituent of cement affects the early setting?2. State the significance of initial setting time and final setting time of cement?3. Which concreting operations depend on initial setting time of cement


10/22

EXPERIMENT NO. 5

Soundness of Cement

INTRODUCTION

After setting of cement , it is essential that it doesnt undergo a large change in its volume or

there must be no appreciable expansion , which under restraint could result in disruptions of the

hardened cement paste.

OBJECTIVE

To detect unsoundness of cement by measuring the change in its volume which might result

after setting due to the excess amount of Free lime (CaO) in its composition

APPARATUS

1. Le-Chatlier apparatus , which includes: (cylindrical mold split longitudinally with twoindicator points are attached, Specified weight, non porous glass plates, Ruler)

2. Weighing balance accurate up to 0.1gm3. Water bath capable to be heated electrically with control for boiling the water

WaterBath

LeChatlierc lindricalmold

LeChatlierkit


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Procedure

i) Place the mould on a glass sheetii) Prepare Cement paste mixing 200 gm of cement with the water required to give a

paste of standard consistency

iii) fill the mould with the cement pasteiv) Cover the mould with another piece of glass sheet, place a small weight on this

covering glass sheet and immediately submerge the whole assembly in water at a

temperature of 23 2oC and keep it there for 24hrs.

v) Measure the distance separating the indicator points which is fixed on the cylindricalmold to the nearest 0.5mm (Let be = d1).

vi) Submerge the mould again in water at the temperature prescribed above. Bring thewater to boiling point in 25 to 30 minutes and keep it boiling for 1 hrs.

vii) Remove the mould from the water, allow it to cool and measure the distance betweenthe indicator points (Let be d2).

viii) Determine (d2 d1) which represents the expansion of cement.Data Sheet

Groups First reading

(d1)

Second Reading

(d2)

Expansion

(d1-d2)

Specification

limit

1

2

3

Results

% Expansion=

Questions

1. Which minor oxides cause unsoundness of cement2. Is this test determine the unsoundness, caused by the presence of all the minor oxides of

cement described above

3. Is there any other test to determine unsoundness of cement.4. What is the effect of boiling water and what will happen if the temperature of the water

bath raised more than boiling temperature


12/22

Experiment No. 6

Strength of Hydraulic Cement

INTRODUCTION

The compressive strength of hardened cement is the most important of all the properties ,therefore the cement is always tested for strength at the laboratory before the cement is used in

important works. Strength tests are not made on neat cement paste because of difficulties of

excessive shrinkage and subsequent cracking of neat cement. The failure loads of mortar cubes

can vary considerably according to the type of cement and the period of curing.

OBJECTIVE

1. This test method for the student to learn how to determine:1-A Compressive strength of cement mortar by casting and testing cubic specimens

1-B Tensile strength of cement mortar by casting and testing briquette specimens

2.

To Compare results of the test with the minimum value required by the specification ofthe same mix proportion

MATERIALS

Cement: Hydraulic cement

Sand : The sand for making the specimens are standard sand natural silica passing sieve 850

micron and retained on sieve 600 micron

Water: Drinking Water as a mixing water

APPARATUS:

1. The molds for making specimens for compression test made of steel , the molds arecubic with a dimension (70 X70X70) mm

2. The mold for making specimens for tension test made of brass, the molds are briquette ,the dimension of the briquette are : width at waist line is 25.4 mm , Greatest thickness at

the waist line is 25.4 mm and Total length is 76 mm.3. Weighing Balance with a capacity at least 1000 gm4. Sieves : Standard sieves square hole opening size No.20 (850 micron) and No.30 (600

micron)5. Graduated glass : Glass tubes graduated of suitable capacities to measure the amount of

mixing water

6. Standard Spatula : This is for use while casting a cement briquette.7. Compression testing Machine: Capable of applying the load continuously with a capacity

1000 KN and sensitivity 0.1 kN , Photo (3)

8. Tensile testing machine: Capable of applying the load continuously, the testing machineshall be calibrated.

9. Vibrating machine required for the compaction of cement-sand mortar


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PROCEDURE

Compressive strength test1. The proportion of the standard mortar is 1 part cement to 3 parts standard sand by weight.2. Prepare the mix , the quantity of dry materials shall be 3000 gm cement and 9000 gm

standard sand mixed at one time in a batch , the percentage of mixing water shall be 10

percent by weight of the total amount of dry material (Cement + Sand).3. Mixing the ingredients dry material with water for at least 2 minutes continuous mixing

and kneading by hands using hand gloves until to get the homogeneous mix

4. Prepare the moulds fixing the screw and cover the internal sides of the molds by a thinlayer of mineral oil

5. Place the mold and fixing in a position on a vibrating machines6. Fill the molds in 2-3 layers and operate the vibrating machine, filling and compaction

will be done in one time for each cube, it is required to get full compaction.

7. Store the cubes in the laboratory condition for 24 +1 hrs. with their upper surfacesexposed to moist air , The temperature of the Lab. shall be maintained between 20 and 25oC and Relative humidity of the mortar not less than 90%

8. Open the molds and immerse the specimens in a saturated lime water in storage tanks,keep the storage water clean and maintained at the standard temperature specified above

9. Test standard mortar specimens at the specified ages (3 , 28 ) days by a compressiontesting machine, apply the load continuously with a constant rate until the specimens will

fail , record maximum load applied.

Tensile strength test1. The proportion of the standard mortar is 1 part cement to 3 parts standard sand by

weight.

2. Prepare the mix , the quantity of dry materials shall be 500 gm cement and 1500 gmstandard sand mixed at one time in a batch , the percentage of mixing water shall be8 percent by weight of the total amount of dry material (Cement + Sand).

3. Mixing the ingredients dry material with water for at least 2 minutes continuousmixing and kneading by hands using hand gloves until to get the homogeneous mix

4. Prepare the moulds resting on a glass or metal plates and cover the internal sides ofthe molds by a thin layer of mineral oil.

5. Filling the molds and press the mortar in firmly with the thumbs applying the forcefor different times to each briquette at different points to include the entire surface,remove excess mortar on the surface of the briquette and smooth it.

6. Stroke the mortar in a briquette by standard knife for several times until to get fullcompaction.

7. Store the briquette in the laboratory condition for 24 +1 hrs. with their upper surfacesexposed to moist air , The temperature of the Lab. shall be maintained between 20

and 25 oC and Relative humidity of the mortar not less than 90% .8. Test the briquette specimens immediately after their removal from the molds and

fixing it in tensile testing machine holing by the grips and apply the load with a


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constant rate until the specimens will break , record maximum load for breaking and

measure cross section dimension at the breaking position.

RESULTS and DATASHEET

Compressive strength

Groups Specimen No. Age

days

Maximum Load

(N)

Area

(mm2)


(N/mm2)

1

2

3

Tensile strength

Groups Specimen No. Age

days

Maximum Load

(N)

Area

(mm2)


(N/mm2)

QUESTIONS

1. What is the difference in the mix proportion of the standard mortar between BS-12 andASTM C-150

2. What are the specification limits required for the compressivestrength according to BS-12 and ASTMC-150

3. Is there any other standard test method to determine tensilestrength of cement mortar, and what is the dimension of the

specimen?


15/22


16/22

Specific Gravity , Absorption and Moisture content of Aggregate

Introduction:

Apparent Specific gravity: the ratio of the mass dried in an oven at 100 to 110 oC in air for 24hours to the mass of water occupying a volume equal to that of the solid including the

impermeable pores. This is normally required in concrete Technology. According to BS EN

1097-3 use the term particle densitywhich is expressed in Kg/ m3, thus it is numerically 1000times greater than specific gravity

Absorption: The increase in mass due to water in the pores of the material, expressed as apercentage

Moisture content:

Objective:

This test for student to learn how to determine:

1. Specific gravity of Coarse aggregate2. Specific gravity of fine aggregate3. To recognize between different kinds of specific gravity4. Absorption of aggregate5. Moisture content of fine aggregate

Materials

1. Coarse aggregate test sample 5 kg2. Fine aggregate test sample 1 kg.

Apparatus

1. Balance accurate to 0.5 gm for coarse aggregate2. Accurate balance with a capacity at least 1 kg and sensitivity 0.1 gm for fine aggregate3. Pycnometer :one liter jar with a water tight metal conical screw top having a small hole at

the apex for fine aggregate

4. Wire basket has the apertures 1-3 mm in size for coarse aggregate5. Sieve of 4.75 mm


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Procedures

1. Fine aggregate1. Obtain approximately 1 kg of fine aggregate2. Cover the aggregate with water , either by immersion or by addition of at least 6%

moisture to the fine aggregate and maintain for 24 hours

3. Spread the sample on a flat non absorbent surface exposed to gently moving ofcurrent of warm air, and stir frequently to cause homogeneous drying, it is required to

achieve the saturated surface-dry condition.

4. Weigh 500 gm of SSD aggregate sample and record the weight as S.5. Partially fill the pycnometer with water and immediately introduce into the

pycnometer the SSD aggregate, fill it with water to approximately 90% of the

capacity.

6. Invert and agitate the pycnometer to eliminate all air bubbles , then fill it with waterto its calibrated capacity

7. Determine total weight of the pycnometer, specimen, and water and record it as C8. Carefully work all of the sample into drying pan , place in a 100 -110 oC for 24 hours

, record this weight as A.

2. Coarse Aggregate1. Immerse the aggregate in water at room temperature for a period of 24+ 4 hours2. Remove the test specimen from water and roll it in a large absorbent cloth until all

visible films of water are removed wipe the larger particles individually

3. Weigh the test sample which depends on maximum size (mm) in SSD condition andrecord it as B.

4. Place the specimen in the wire basket and determine its weight while it is submergedin water at a temperature of 23 +1.7 oC and record it as C

5. Dry the test sample to a constant weight , dry in oven for 24 hours at a temperature110oC and weigh it record this weight as A

Moisture content in fine aggregate

1. Weigh test sample of moist fine aggregate let be 500 gm and record it as W2. Partially fill the pycnometer with water and immediately introduce into the

pycnometer the moist aggregate, fill it with water to approximately 90% of thecapacity.

3. Invert and agitate the pycnometer to eliminate all air bubbles , then fill it with waterto its calibrated capacity

4. Determine total weight of the pycnometer, wet specimen, and water and record it as E


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Results

Fine Aggregate

Apparent Specific Gravity (G) = Bulk Specific gravity of Sand (SSD)=

Dry Bulk Specific gravity =

Absorption (%) =

100

Moisture content (m.c) = 1 1 100Coarse Aggregate

Apparent Specific gravity =

Bulk Specific gravity (SSD) =

Bulk Specific gravity (dry)=

Absorption (%) =

100

Datasheet

Groups Type ofaggregate

Weightof

aggregate

at SSD

Dryweight of

aggregate

Weight ofpycnometer

and water

Weight ofpycnometer

, water and

aggregte

Weight ofpycnometer

, water and

aggregte

Weight of

saturated

aggregate

in water

1

2


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3

Groups Type of

aggregate

Apparent

specific

gravity

Dry Bulk

specific

gravity

Bulk

specific

gravity

(SSD)

Water

Absorption

(%)

Moisture

content

(%)

1

2

3

Questions

1. Why there are different types of specific gravity2. What is the difference between specific gravity and particle density3. How you can obtain aggregate at SSD condition for both fine and coarse aggregate,

describe the procedure to test the presence of surface moisture of fine aggregate4. What is the effect of surface moisture of aggregate on concrete at mixing stage5. What is the effect of absorption of aggregate on concrete at mixing stage.


20/22

Bulk Density and voids in Aggregate

Introduction:

Bulk density or unit weight of aggregate determined according to ASTM C29 , the measuring

unit is Kg/m3. Bulk density is needed for the proportioning of portland cement concrete

mixtures. It is used to convert mass to volume according to the batching method of concrete mix.

It is affected by shape, grading, degree of packing and moisture condition of aggreghate.

Objective:

This test in a concrete done by the students to learn the determination of

1. Unit weight of dry aggregate for both fine and coarse aggregate2. Percentage of voids between aggregate particles placed in a vessel3. The effect of the degree of packing on unit weight results

Materials

Coarse Aggregate about 50 kg

Fine Aggregste: about 30 Kg,

Weight of aggregate depends on the maximum size of aggregate

Apparatus

1. A rigid metal watertight container with a known volume for coarse aggregate , for 25 mmnominal maximum aggregate size , a minimum volume of the container required is

0.0093 m3(9.3 littre)

2. Balance with a capacity at least 50 Kg.3. Standard tamping rod4. Scoop or shovel

Procedures

1. Determine the empty mass of the container, and let be M12. Fill the container with aggregate in three layers of approximately equal

volume, each layer should be compacted by standard rod . Rod each layer of

aggregate 25 strokes of the tamping rod, evenly distributed

3. Level the surface of aggregate by rolling the rod on the surface , remove theexcess aggregate


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4. Determine the mass of the container filled with the compacted aggregate ,and let be M2

5. Repeat the steps for coarse and fine aggregate in a loose state, filling theaggregate in one layer without compaction and let the mass of the container

filled with loose aggregate to be M36. Repeat all the steps for fine aggregate using rigid container of volume ( ) .

Filling the aggregate in 3 layers , each layer compacted 20 strokes by

tamping rod.

7. Calibration of the volume of the container. Fill the container with water atroom temperature and eliminate bubbles and excess water.

8. Determine the mass of the water in the container let be M4 and measure thetemperature of the water

Analysis and Results

4

2 1

3 1

% 1 100

V: Volume of the container

W: Unit weight of water use 1000 Kg/m3

: Unit weight of compacted aggregate

: Unit weight of loose aggregateG: Specific gravity of aggregate

Datasheet


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Group Aggregte M1

kg

M2

kg

M3

kg

M4

kg

Kg/m3

Kg/m3

%

Voids

1 Coarse

Fine

2 Coarse

Fine

3 Coarse

Fine

Questions1. What are the factors that influence on unit weight of aggregate2. Empirically how the percentage of voids can be determined3. What is the effect of ambient temperature on the results of the unit weight of aggregate4. Why bulk density of aggregate needs to be determined

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