DIFFERENT FORMS OF BITUMEN USED IN ROAD CONSTRUCTION

4 DIFFERENT FORMS OF BITUMEN USED IN ROAD CONSTRUCTION

DIFFERENT FORMS OF BITUMEN

1. CUTBACK BITUMEN

Normal practice is to heat bitumen to reduce its viscosity. In some situations preference is given to use liquid binders such as cutback bitumen. In cutback bitumen suitable solvent is used to lower the viscosity of the bitumen. From the environmental point of view also cutback bitumen is preferred. The solvent from the bituminous material will evaporate and the bitumen will bind the aggregate. Cutback bitumen is used for cold weather bituminous road construction and maintenance. The distillates used for preparation of cutback bitumen are naphtha, kerosene, diesel oil, and furnace oil. There are different types of cutback bitumen like rapid curing (RC), medium curing (MC), and slow curing (SC). RC is recommended for surface dressing and patchwork. MC is recommended for premix with less quantity of fine aggregates. SC is used for premix with appreciable quantity of fine aggregates.

2. BITUMEN EMULSION

Bitumen emulsion is a liquid product in which bitumen is suspended in a finely divided condition in an aqueous medium and stabilised by suitable material. Normally cationic type emulsions are used in India. The bitumen content in the emulsion is around 60% and the remaining is water. When the emulsion is applied on the road it breaks down resulting in release of water and the mix starts to set. The time of setting depends upon the grade of bitumen. The viscosity of bituminous emulsions can be measured as per IS: 8887-1995. Three types of bituminous emulsions are available, which are Rapid setting (RS), Medium setting (MS), and Slow setting (SC). Bitumen emulsions are ideal binders for hill road construction. Where heating of bitumen or aggregates are difficult. Rapid setting emulsions are used for surface dressing work. Medium setting emulsions are preferred for premix jobs and patch repairs work. Slow setting emulsions are preferred in rainy season.

3. BITUMINOUS PRIMERS

In bituminous primer the distillate is absorbed by the road surface on which it is spread. The absorption therefore depends on the porosity of the surface. Bitumen primers are useful on the stabilised surfaces and water bound macadam base courses. Bituminous primers are generally prepared on road sites by mixing penetration bitumen with petroleum distillate.

4. MODIFIED BITUMEN

Certain additives or blend of additives called as bitumen modifiers can improve properties of Bitumen and bituminous mixes. Bitumen treated with these modifiers is known as modified bitumen. Polymer modified bitumen (PMB)/ crumb rubber modified bitumen (CRMB) should be used only in wearing course depending upon the requirements of extreme climatic variations. The detailed specifications for modified bitumen have been issued by IRC: SP: 53-1999. It must be noted that the performance of PMB and CRMB is dependent on strict control on temperature during construction. The advantages of using modified bitumen are as follows

• Lower susceptibility to daily and seasonal temperature variations
• Higher resistance to deformation at high pavement temperature
• Better age resistance properties
• Higher fatigue life for mixes
• Better adhesion between aggregates and binder
• Prevention of cracking and reflective cracking

REQUIREMENTS OF BITUMEN

The desirable properties of bitumen depend on the mix type and construction. In general, Bitumen should posses following desirable properties.

• The bitumen should not be highly temperature susceptible: during the hottest weather the mix should not become too soft or unstable, and during cold weather the mix should not become too brittle causing cracks.
• The viscosity of the bitumen at the time of mixing and compaction should be adequate. This can be achieved by use of cutbacks or emulsions of suitable grades or by heating the bitumen and aggregates prior to mixing.
• There should be adequate affinity and adhesion between the bitumen and aggregates used in the mix.

SURVEY FILE

TEST TO CHECK QUALITY OF BITUMEN FOR USE IN ROAD WORK

9 TEST TO CHECK QUALITY OF BITUMEN FOR USE IN ROAD WORK

LAB TESTS ON BITUMEN TO CHECK QUALITY

Various tests are conducted on bitumen to assess its consistency, gradation, viscosity, temperature susceptibility, and safety.

There are a number of tests to assess the properties of bituminous materials. The following tests are usually conducted to evaluate different properties of bituminous materials.

1. Penetration test
2. Ductility test
3. Softening point test
4. Specific gravity test
5. Viscosity test
6. Flash and Fire point test
7. Float test
8. Water content test
9. Loss on heating test

1.PENETRATION TEST

It measures the hardness or softness of bitumen by measuring the depth in tenths of a millimeter to which a standard loaded needle will penetrate vertically in 5 seconds. BIS had standardized the equipment and test procedure.

The penetrometer consists of a needle assembly with a total weight of 100g and a device for releasing and locking in any position. The bitumen is softened to a pouring consistency, stirred thoroughly and poured into containers at a depth at least 15 mm in excess of the expected penetration. The test should be conducted at a specified temperature of 250C.

It may be noted that penetration value is largely influenced by any inaccuracy with regards to pouring temperature, size of the needle, weight placed on the needle and the test temperature.

In hot climates, a lower penetration grade is preferred. The Fig-1 shows a schematic Penetration Test setup.

Also Read: Penetration Test Procedure of Bitumen

Fig-1 Penetration Test Setup

2.DUCTILITY TEST

Ductility is the property of bitumen that permits it to undergo great deformation or elongation. Ductility is defined as the distance in cm, to which a standard sample or briquette of the material will be elongated without breaking. Dimension of the briquette thus formed is exactly 1 cm square. The bitumen sample is heated and poured in the mould assembly placed on a plate. These samples with moulds are cooled in the air and then in water bath at 270C temperature. The excess bitumen is cut and the surface is leveled using a hot knife. Then the mould with assembly containing sample is kept in water bath of the ductility machine for about 90 minutes. The sides of the moulds are removed, the clips are hooked on the machine and the machine is operated. The distance up to the point of breaking of thread is the ductility value which is reported in cm.

The ductility value gets affected by factors such as pouring temperature, test temperature, rate of pulling etc.

A minimum ductility value of 75 cm has been specified by the BIS. Fig-2 shows ductility Test Process.

Also Read: Ductility Test Procedure of Bitumen

Fig-2 Ductility Test

3.SOFTENING POINT TEST

Softening point denotes the temperature at which the bitumen attains a particular degree of softening under the specified condition of test.

The test is conducted by using Ring and Ball apparatus. A brass ring containing test sample of bitumen is suspended in liquid like water or glycerin at a given temperature. A steel ball is placed upon the bitumen sample and the liquid medium is heated at a rate of 50C per minute. Temperature is noted when the softened bitumen touches the metal plate which is at a specified distance below.

Generally, higher softening point indicates lower temperature susceptibility and is preferred in hot climates. Fig-3 shows Softening Point test setup.

Also Read: Softening Test Procedure of Bitumen

Fig-3 Softening Point Test Setup

4.SPECIFIC GRAVITY TEST

The specific gravity of bitumen is defined as the ratio of mass of given volume of bitumen of known content to the mass of equal volume of water at 270C. The specific gravity can be measured using either pycnometer or preparing a cube specimen of bitumen in semi solid or solid state.

In paving jobs, to classify a binder, density property is of great use. In most cases bitumen is weighed, but when used with aggregates, the bitumen is converted to volume using density values.

The density of bitumen is greatly influenced by its chemical composition. Increase in aromatic type mineral impurities cause an increase in specific gravity.

The specific gravity of bitumen varies from 0.97 to 1.02.

Also Read: Specific Gravity Test Procedure of Bitumen

5.VISCOSITY TEST

Fig-4 Viscosity Test

Viscosity denotes the fluid property of bituminous material and it is a measure of resistance to flow. At the application temperature, this characteristic greatly influences the strength of resulting paving mixes.

Low or high viscosity during compaction or mixing has been observed to result in lower stability values. At high viscosity, it resists the compactive effort and thereby resulting mix is heterogeneous, hence low stability values. And at low viscosity instead of providing a uniform film over aggregates, it will lubricate the aggregate particles.

Orifice type viscometers are used to indirectly find the viscosity of liquid binders like cutbacks and emulsions.

The viscosity expressed in seconds is the time taken by the 50 ml bitumen material to pass through the orifice of a cup, under standard test conditions and specified temperature. Viscosity of a cutback can be measured with either 4.0 mm orifice at 250C or 10 mm orifice at 25 or 400C.

Also Read: Viscosity Test of Bitumen Emulsion by Saybolt Furol Viscometer

6.FLASH AND FIRE POINT TEST

At high temperatures depending upon the grades of bitumen materials leave out volatiles. And these volatiles catch fire which is very hazardous and therefore it is essential to qualify this temperature for each bitumen grade. BIS defined the ash point as the temperature at which the vapour of bitumen momentarily catches fire in the form of ash under specified test conditions. The fire point is defined as the lowest temperature under specified test conditions at which the bituminous material gets ignited and burns.

7.FLOAT TEST

Normally the consistency of bituminous material can be measured either by penetration test or viscosity test. But for certain range of consistencies, these tests are not applicable and Float test is used.

The apparatus consists of an aluminum oat and a brass collar filled with bitumen to be tested. The specimen in the mould is cooled to a temperature of 50C and screwed in to oat. The total test assembly is floated in the water bath at 500C and the time required for water to pass its way through the specimen plug is noted in seconds and is expressed as the oat value.

8.WATER CONTENT TEST

It is desirable that the bitumen contains minimum water content to prevent foaming of the bitumen when it is heated above the boiling point of water.

The water in bitumen is determined by mixing known weight of specimen in a pure petroleum distillate free from water, heating and distilling of the water. The weight of the water condensed and collected is expressed as percentage by weight of the original sample.

The allowable maximum water content should not be more than 0.2% by weight.

9.LOSS ON HEATING TEST

When the bitumen is heated it loses the volatility and gets hardened. About 50gm of the sample is weighed and heated to a temperature of 1630C for 5 hours in a specified oven designed for this test. The sample specimen is weighed again after the heating period and loss in weight is expressed as percentage by weight of the original sample.

Bitumen used in pavement mixes should not indicate more than 1% loss in weight, but for bitumen having penetration values 150-200 up to 2% loss in weight is allowed.

LIST OF IS CODES RELATED TO BITUMEN TESTING

Tests for Bitumen with IS codes
Name of Test	IS code Number
Penetration Test	IS: 1203-1978
Ductility test	IS: 1208-1978
Softening Point test	IS: 1205-1978
Specific gravity test	IS: 1202-1978
Viscosity test	IS: 1206-1978
Flash and Fire Point test	IS: 1209-1978
Float Test	IS: 1210-1978
Determination of Water Content	IS: 1211-1978
Determination of Loss on Heating	IS:1212-1978

CHARACTERISTIC PROPERTIES OF BITUMEN

6 CHARACTERISTIC PROPERTIES OF BITUMEN

Bitumen is defined as “A viscous liquid, or a solid, consisting essentially of hydrocarbons and their derivatives, which is soluble in trichloro-ethyelene and is substantially nonvolatile and softens gradually when heated”. It is black or brown in colour & possesses waterproofing and adhesive properties. It is obtained by refinery processes from petroleum, and is also found as a natural deposit or as a component of naturally occurring asphalt, in which it is associated with mineral matte.

Bitumen has the following five characteristic properties.

1. Bitumen Adheres
2. Bitumen is Elastic
3. Bitumen is Plastic
4. Bitumen is Viscoelastic
5. Bitumen Ages
6. Bitumen Hardens

1. BITUMEN ADHERES

Bitumen has excellent adhesive qualities provided the conditions are favorable. However in presence of water the adhesion does create some problems. Most of the aggregates used in road construction possess a weak negative charge on the surface. The bitumen aggregate bond is because of a weak dispersion force. Water is highly polar and hence it gets strongly attached to the aggregate displacing the bituminous coating.

2. BITUMEN IS ELASTIC

When one takes a thread of bitumen from a sample and stretches or elongates it, it has the ability to return to a length close to its original length eventually. For some bitumens this process may take longer than others. This property is referred to as the elastic character of bitumen.

3. BITUMEN IS PLASTIC

When temperatures are raised, as well as when a load is applied to bitumen, the bitumen will flow, but will not return to its original position when load is removed. This condition is referred to as plastic behavior. Applying a load means that you put a weight on the bitumen in order to subject it to stress. This could be in a lab or in the bitumens final position in the road and it is done to assess the bitumens reaction to the load.

4. BITUMEN IS VISCOELASTIC

Bitumen has a Viscoelastic character. Its behavior may be either viscous or elastic depending on the temperature or the load it is carrying. At higher temperatures there is more flow or plastic behavior, while at lower temperatures and short duration loading, the bitumen tends to be stiff and elastic. At intermediate temperatures it tends to be a combination of the two.

5. BITUMEN AGES

Aging refers to changes in the properties of bitumen over time, which is caused by external condition. These changes are visible as cracks or crumbling areas. When bitumen is exposed to atmospheric conditions, the bitumen molecules react with oxygen, which results in a change of the structure and composition of the bitumen. This process of combining with oxygen, called oxidation, causes the bitumen to become brittle and hard and to change colour from dark brown or black to grey. This change is usually referred to as oxidative hardening or age hardening. This form of ageing occurs more frequently in warmer climatic or during warm seasons, causing older pavements to crack more easily. The condition can also occur where the surface films of bitumen are thin, or if there has been inadequate compaction during construction.

6. BITUMEN HARDENS

Exposure to ultraviolet (UV) rays and the evaporation of volatile compounds can cause bitumen to harden. A volatile material is a material that can change in to a gas very quickly. There are two kinds of hardening:

• Physical hardening
• Exudative hardening

Physical hardening occurs when waxy crystals form in the bitumen structures, or when asphaltenes agglomerates clump together. This condition can be reversed if the temperature is raised.

Exudative hardening is caused by the absorption of oily components in the bitumen.

RESIDUE OF BITUMEN EMULSION ON 600 MICRON SIEVE

RESIDUE OF BITUMEN EMULSION ON 600 MICRON SIEVE (IS-8887-2004)

BITUMEN EMULSION TEST – RESIDUE ON 600 MICRON SIEVEDETERMINATION OF RESIDUE OF BITUMEN EMULSION

PURPOSE

This test is done for the determination of residue of bituminous emulsion by sieving through 600-micron is sieve.

APPARATUS

• 600 Micron IS Sieve — A circular sieve approximately 100 mm in diameter and 40 mm height.
• Metal or Glass Dish — A small metal or glass dish about 110 mm in diameter (such as a clock glass).
• Oven — A well ventilated oven thermostatically controlled to 100 to 110 “C.
• Balances — One of capacity 250 g and accuracy of 0.01 g and one of capacity 10 kg and accuracy of 1 g.
• Container — A clean, weighed, 1.5-litre container.

PROCEDURE

1. Wash the 600 micron IS sieve with xylene and then acetone. Place it in the dish, dry in the oven at 1000C to 1100C for one hour, cool and weigh, together with the dish, to the nearest 0.01g (W1).
2. Remove the sieve from the dish and moisten with the solution. Remove uniformly the 4-litre sample by gentle agitation and strain immediately through the sieve into the clean, dry weighed container (W4).
3. Sieve the low and high viscosity emulsion at room temperature and 500C respectively. When whole of the emulsion has passed through the sieve, remove the sieve and weigh the container to the nearest 1 g (W2).
4. Wash the sieve repeatedly with distilled water until the washings run clear. Place the sieve in the small dish to dry for two hours in the oven at 105±50C. Cool and reweigh together to nearest 0.01 g (W3).

Calculate the Residue as follows:

Residue, percentage retained = (W3 – W1) / (W2 – W4) x 100

Where

W1 = mass in g, of sieve and small dish

W2 = mass in g, of container and emulsion

W3 = mass in g, of sieve, small dish and residue; and

W4 = mass in g, of container

Take the average of three values obtained for residue, percent.

REQUIREMENT CRITERION

Type of bituminous emulsion	Residue on 600 micron IS sieve
Rapid Setting-1     (RS-1)	0.05
Rapid Setting-2    (RS-2)	0.05
Medium Setting     (MS)	0.05
Slow Setting-1      (SS-1)	0.05
Slow Setting-2      (SS-2)	0.05

REFERENCE

IS 8887 – 2004

PENETRATION VALUE OF BITUMEN

PENETRATION VALUE OF BITUMEN (IS:1203-1978)

Penetration Test

OBJECTIVE

To determinate the penetration of bitumen.

REFERENCE STANDARD

IS : 1203-1978-Indian standard methods for testing tar and bituminious materials (Determination of penetration) 

EQUIPMENT & APPARATUS

• Container
• Needle
• Stop watch
• Water bath
• Penetration apparatus
• Thermometer                              

PROCEDURE 

1. The bitumen is softened to a paving consistency between 750 C and 1000C above the approximate temp at which bitumen softens.
2. The sample material is thoroughly stirred to make it homogeneous and free from air bubbles and water.
3. The sample containers are cooled in atmosphere of temperature not lower than 13°C for one hour. Then they are placed in temperature controlled water bath at a temperature of 25°C for a Period of one hour.
4. The weight of needle, shaft and additional weight are checked. The total weight of this assembly should be 100 g.
5. Using the adjusting screw, the needle assembly is lowered and the tip of the needle is made to just touch the top surface of the sample.
6. The needle assembly is clamped in this position. The contact of the tip of the needle is checked using the mirror placed on the rear of the needle.
7. The initial reading of the penetrometer dial is either adjusted to zero or the initial reading is noted.
8. Then the needle is released by pressing a button and a stop watch is started. The needle is released exactly for a period of 5.0 secs.
9. At least 3 measurements are made on this sample by testing at distance of not less than 100 mm apart. 

CALCULATION

The difference between the initial and final penetration readings are taken as the penetration value.

REPORT

The average penetration value of 3 tests of a given bitumen sample is reported. 

 SAFETY & PRECAUTIONS

• Use hand gloves, apron while removing containers from hot plate after switching off the hot plate.
•  No disturbance occurs at time of penetration.
• Use safety shoes & Apron at the time of test.
• Equipment should be cleaned thoroughly before testing & after testing.

SOFTENING POINT OF BITUMEN

SOFTENING POINT OF BITUMEN (IS:1205:1978)

Ring & ball aparatus

OBJECTIVE

For determination of softening point of a given bitumen. 

REFERENCE STANDARDS

IS : 1205-1978-Indian standard methods for testing tar and bituminious materials (Determination of softening point)

EQUIPMENT & APPARATUS 

•  Ring and Ball apparatus,
•  Steel balls
•  Brass rings
•  Ball guide  
•  Support
•  Thermometer
•  Bath with stirrer 

PROCEDURE

1. Sample material is heated to a temperature between 75° and 100°C above the approximate softening point until it is completely fluid and is poured in heated rings placed on the metal plate.
2. To avoid sticking of the bitumen to metal plate, coating is done to this with a solution of glycerin and dextrin.
3. After cooling the rings in air for 30 minutes, the excess bitumen is trimmed and rings are placed in the support.
4. At this time the temperature of distilled water is kept at 5°C. This temperature IS maintained for 15 minutes after which the balls are placed in position.
5. Then the temperature of water is raised at uniform rate of 5°C per minute with a controlled heating unit, until the bitumen softens and touches the bottom plate by sinking of balls. At least two observations are made. For material whose softening point is above 80°C, glycerin is used for heating medium and the starting temperature is 35°C instead of 5°C. 

RECORD /REPORTS

The temperature at the instant when each of the ball and sample touches the bottom plate of support is recorded as softening point value.An average value of two tests is reported as softening point value.

SAFETY & PRECAUTIONS

• Use hand gloves, apron while removing containers from hot plate after switching off the hotplate.
• Use glycerin for remove of bitumen from the container.
• Use distilled water in test for accuracy result.
• Use safety shoes & Apron at the time of test.
• Equipment should be cleaned thoroughly before testing & after testing.

SPECIFIC GRAVITY TEST ON BITUMEN

INTRODUCTION

Specific gravity is defined as the ratio of the mass of a given volume of the bituminous material to the mass of an equal volume of water, the temperature of both being specified as 270C.

APPARATUS

• Specific gravity bottle of 50 ml capacity, ordinary capillary type with 6 mm diameter neck or wide mouthed capillary type bottle with 25 mm diameter neck
• Balance having least count of 1g

Specific gravity bottles

PROCEDURE

1. The specific gravity bottle is cleaned, dried and weighed along with the stopper.
2. It is filled with fresh distilled water, stopper placed and the same is kept in water container for at least half an hour at temperature 270C.
3. The bottle is then removed and cleaned from outside. The specific gravity bottle containing distilled water is now weighed.
4. The bituminous material is heated to a pouring temperature and is poured in the above empty bottle taking all the precautions that it is clean and dry before filling sample materials. The material is filled up to the half taking care to prevent entry of air bubbles.
5. To permit an escape of air bubbles, the sample bottle is allowed to stand for half an hour at suitable temperature cooled to 270C and then weighed.
6. The remaining space in the specific gravity bottle is filled with distilled water at 270C , stopper placed and is placed in water container at 270C.
7. The bottle containing bituminous material and containing water is removed, cleaned from outside and is again weighed.

CALCULATION

The specific gravity of the material is calculated as follows:

Specific gravity = weight of bituminous material/weight of equal volume of water

= (c-a)/[(b-a)-(d-c)]

Where,

a = weight of specific gravity bottle, g

b = weight of specific gravity bottle filled with distilled water, g

c = weight of the specific gravity bottle about half filled with bituminous material, g

d = weight of the specific gravity bottle about half filled with material and the rest with distilled water, g

RESULTS

At least three measurements should be made for determining value of the specific gravity

PRECAUTIONS

• It is necessary that all precautions are taken in making the specific gravity bottles thoroughly cleaned and dried in the first weighting.
• The surface of the specific gravity bottle should be cleaned dry after filling with water, before weighing.
• The test temperature should be firmly adhered to.
• Inaccurate balance would never give reproducible results.

REFERENCE

IS 1202-1978-Determination of specific gravity

VISCOSITY TEST OF BITUMEN EMULSION BY SAYBOLT FUROL VISCOMETR

VISCOSITY TEST OF BITUMEN EMULSION BY SAYBOLT FUROL VISCOMETR (IS-3117-2004)

TEST FOR BITUMEN EMULSION: VISCOSITY BY SAYBOLT FUROL VISCOMETER

PURPOSE

Viscosity indicates the resistance to flow due to its internal friction. Higher the viscosity, lower the rate of flow. The test is conducted to see if it is in the specified range. The Test result is expressed in seconds for the flow of 60 cc of the emulsion sample through a 3.8 mm diameter orifice under the specified conditions of the test.

APPARATUS

• Saybolt Furol Viscometer
• Stop watch

Saybolt Furol Viscometer – used for viscosity test of bitumen emulsion

PROCEDURE

1. Clean the oil tube with a solvent, such as benzene, and remove excess solvent from the gallery. Pass the entire material through a 150 micron wire strainer before introducing into the oil tube.
2. After the tube is cleaned, pour into the tube a quantity of the material to be tested, sufficient to wet the entire surface of the tube. Allow to drain out.
3. The plunger commonly supplied with the viscometer shall never be used on instruments maintained as standards. Insert the cork stopper not less than 6.0 mm and not more than 9.5 mm into the lower end of the air chamber at the bottom of the oil tube, taking care that the cork fits tightly enough to prevent the escape of air, as tested by the absence of oil on the cork after it is withdrawn.
4. If the test temperature is above that of the room, heat the material to not more than 1.50C below the temperature of test.
5. Pour the material into the oil tube until it ceases to overflow into the gallery. Keep it well stirred with the oil tube thermometer, care being taken to avoid touching the outflow tube. Adjust the bath temperature until the temperature of the material remains constant.
6. After thermal equilibrium has been attained, no further adjustment shall be made in the bath temperature. The test results shall be discarded if the indicated bath temperature varies by more than +0.030C.
7. After the temperature of the material in the oil tube has remained constant within +0.020C of the desired temperature for one minute with constant stirring, withdraw the oil tube thermometer and remove the surplus liquid quickly from the gallery by means of the withdrawal tube so that the level of the material in the gallery is below the level in the oil tube proper. Insert the tip of the withdrawal tube at one point in the gallery.
8. The test shall be started over again if the tip of the withdrawal tube touches the overflow rim. Under no condition shall the excess liquid be removed by rotating the withdrawal tube around the gallery.
9. Place the receiving flask in position so that the stream of liquid from outlet tube strikes the neck of the flask, care being taken that the graduation mark on the receiving flask is not less than 10cm, not more than 13cm, from the bottom of the bath. Snap the cork from its position and at the same instant start the timer. Stop the timer when the bottom of the meniscus of the liquid reaches the mark on the neck of the receiving flask.
10. Time in seconds as determined by the prescribed procedure, with the proper calibration correction, is the Saybolt Furol viscosity of the material at the temperature at which the test is made.
11. Report the results to the nearest 0.1 second for viscosity values below 200 seconds and to the nearest whole second for values 200 seconds or above.

REPORTING OF RESULT

Time in seconds as determined by the above described procedure, with the proper calibration correction, is the Saybolt Furol Viscosity of the material at the temperature at which the test is made.

Report the results to the nearest 0.1 s for viscosity values below 200s and to the nearest whole second for values 200s or above.

REFERENCE

IS 3117 – 1965

REQUIREMENT CRITERION

As per IS: 8887 -2004, the acceptance limits of viscosity for different types of emulsion are as follow.

Type of Emulsion	Acceptance Limits at 500C
Rapid Setting (RS-1)	20 – 100
Rapid Setting (RS-2)	100 – 300
Medium Setting (MS)	50 – 400
Slow Setting (SS-1)	20 – 100
Slow Setting (SS-2)	30 – 150

DUCTILITY VALUE OF BITUMEN

DUCTILITY VALUE OF BITUMEN (IS:1208-1978)

Ductility test

OBJECTIVE

For determination of ductility of distillation residue a  given bitumen. 

REFERENCE STANDARD

IS : 1208-1978- Indian standard methods for testing tar and bituminous materials (Determination of ductility)

EQUIPMENT & APPARATUS

• Briquette mould,
• Ductility machine with water bath and a pulling device
• A putty knife
• Thermometer 

PROCEDURE

1. The bitumen sample is maintained to a pouring temperature (75°C to 100°C) and poured into the mould assembly and placed on a brass plate, where a solution of glycerin or soap solution is applied at all surfaces of briquette mould exposed to bitumen.
2. After the sample is poured to the mould, thirty to forty minutes the entire assembly is placed in a water bath at 27°C.
3. Then the sample is removed from the water bath maintained at 27°C and excess bitumen material is cutoff by leveling the surface using hot knife.
4. After trimming the specimen, the mould assembly containing sample is replaced in water bath maintained at 27°C for 85 to 95 minutes. Then the sides of mould are removed and the clips are carefully booked on the machine without causing any initial strain. Two or more specimens may be prepared in the moulds and clipped to the machine so as to conduct these test simultaneously.
5. The pointer is set to read zero. The machine is started and the two clips are thus pulled apart horizontally.
6. While the test is in operation, it is checked whether the sample is immersed in water at depth of at least 10 mm. 

REPORTS

The distance at which the bitumen thread of each specimen breaks is recorded (in cm) to report as ductility value.The average penetration value of 3 tests of a given bitumen sample is reported.

SAFETY & PRECAUTIONS 

• Use hand gloves while removing containers from oven after switching off the oven.
• Carefully fill the mould avoid air pocket with right arrangement.
• Use glycerin for easily remove bitumen from the container.
• Use safety shoes & Apron at the time of test.
• Equipment should be cleaned thoroughly before testing & after testing.

TEST CUBES FROM FRESH CONCRETE

HOW TO MAKE TEST CUBES FROM FRESH CONCRETE?

MAKING OF TEST CUBES FROM FRESH CONCRETE

IS-456 has laid down the acceptance criteria of quality concrete. In all the cases, the 28-days compressive strength shall alone be the criterion for acceptance or rejection of the concrete. 7 days compressive strength of concrete can be carried out in order to get a relatively quicker idea regarding the quality of concrete.

PROCEDURE OF TEST CUBE PREPARATION

EQUIPMENT

The following equipments are needed for the preparation of concrete cubes.

1. Sample tray;
2. Mould for making test cube;
3. Spanner;
4. Scoop;
5. Steel float or trowel;
6. Compacting bar;
7. Cleaning rags;
8. A bucket or barrow for transporting the samples;
9. Curing tank
10. Permanent Marker.

NO OF CUBES

6 no of Cubes of 150 x 150 x 150 mm size shall be cast, 3 for 7-days testing and 3 for 28-days testing. A sample consists of 3 cube specimens and their average compressive strength represents the test result of that sample. The individual variation of a set of 3 cubes should not be more than ± 15% of the average. If more, the test result of the sample is invalid.

SAMPLE OF CONCRETE

Sample of concrete for test specimen shall be taken at the mixer or in the case of ready mixed concrete from the transportation vehicle at the time of discharge. Such samples shall be obtained by repeatedly passing a scoop or pail through the discharge stream of the concrete. The samples thus obtained shall be mixed on a non-absorbent base with shovel until it is uniform in appearance.

Number of samples to be taken depends on the quantity of concrete. As per IS-456, the following table shall be followed during sampling.

Quantity of concrete in the work (m3)	Number of samples
1-5	1
6-15	2
16-30	3
31-50	4
51 and above	4 plus one additional sample for each additional 50 m3 or part thereof.

Note:- Frequency of sampling may be agreed upon internally by supplier and purchaser.

CASTING OF CUBES

The cube mould plates should be removed, properly cleaned assembled and all the bolts should be fully tight. A thin layer of oil then shall be applied on all the faces of the mould. It is important that cube side faces must be parallel.

After taking concrete samples and mixing them, the cubes shall be cast as soon as possible as described below.

CASTING & COMPACTION BY HAND

The concrete sample shall be filled into the cube moulds in 3 layers, each layer approximately 5 cm deep. In placing each scoopful of concrete, the scoop shall be moved around the top edge of the mould as the concrete slides from it, in order to ensure a symmetrical distribution of the concrete within the mould. Each layer shall be compacted either by hand or by the vibration. Each layer of the concrete filled in the mould shall be compacted by not less than 35 strokes by tamping bar. The strokes shall be penetrating into the underlying layer and the bottom layer shall be rodded throughout its depth. Where voids are left by the tamping bar the sides of the mould shall be tapped to close the voids.

CURING

The casted cubes shall be stored under shed at a place free from the vibration at a temperature 220C to 330C for 24 hours covered with wet straw or gunny sacking.

MARKING

Immediately after initial curing of the cubes they should be marked clearly. This can be done by writing the details of the cube in ink on a small piece of paper and placing on top of the concrete until it is demoulded.

The cube shall be removed from the moulds at the end of 24 hours and immersed in clean water at a temperature 240C to 300C till the 7 or 28-days age of testing. The cubes shall be tested in the saturated and surface dry condition.

For the true representation of actual strength of concrete in the structure, extra cubes shall be cast, stored and curded as per the identical conditions of that structure, and tested at required age.

NOTE: WHEN MOULDS ARE NOT IN USE, APPLY A THIN LAYER OF OIL OVER THE INSIDE SURFACE OF THE MOULD AND KEEP IT IN A SAFE PLACE.