What Is Softening Point | Ring-Ball Test for Softening Point of Bitumen | List of Proposed to Determine the Softening Point

Softening Point

What Is Softening Point?

The resins are noncrystalline amorphous materials that soften gradually over a range of temperatures. Therefore, the softening point is controlled by the average molecular weight of the resin.

The softening point is also related to the intrinsic viscosity, hardness, and brittleness of resins. The softening point is defined as the temperature at which the resin flows under a given load on heating.

Several standard methods have been proposed to determine the softening point of resins.

List of Proposed to Determine the Softening Point

  • Ring and Ball Method (R&B)
  • Kriimer—Sarnow Method
  • Mettler Softening Point Method
  • Plate—Plate Stress Rheonzeter Test

Ring and Ball Method (R&B)

Ring and Ball Method (R&B)

ASTM D 3461-76, DIN ISO 4625. This method is the most frequently used to determine the softening point of resins. Show above figure illustrates the experimental device used to determine the R&B softening point.

The resin is melted into a metal ring and left to cool. The ring is placed in a special metallic device, which is placed into a water or glycerol bath.

A steel ball of given diameter and mass is placed on the ring and the bath is heated at a given rate. The temperature at which the ball forces the softening resin downward is noted as the softening point.

Also, read: What Is Self Compact Concrete | What Is Slump Flow Test | Equipment for Slump Flow Test | Procedure of Slump Flow Test

Kreimer-Sarnow Method

DIN 53 180. This is the oldest method used to determine the softening point of resins and is relatively similar to the R&B method.

Instead of a ring, a small glass tube that is open at both ends is used and the load is a small mercury drop. The softening point is obtained as the temperature at which the mercury drop breaks through the softening resin and falls.

Mettler Softening Point Method

Mettler Softening Point Method

1. Heating element, 2. Platinum resistance thermometer, 3. Sample, 4. Light source, 5. Furnace, 6. Sample cup, 7. Photocell, 8. Collector sleeve.

ASTM D 3461-76. This is the most recent method. This automatic method measures the temperature at which the resin flows out of a sample cup under its own weight.

The temperature is recorded when the first drop crosses the light path of a photocell (show in the figure). This method is quite accurate and reproducible.

Also, read: Core Cutter Method | What is Compaction of Soil

Plate—Plate Stress Rheonzeter Test.

The resin is placed between the two steel plates of a stress-controlled rheometer, maintaining a gap larger than 0.5 cm. The upper plate is oscillated at a given frequency, whereas the lower plate is heated.

The variation of the storage and loss moduli as a function of the temperature is monitored. The softening temperature can be estimated from the temperature at the cross-over between the two moduli.

Ring-Ball Test for Softening Point of Bitumen

The closely defined method used for bitumen is described in BS 4692. In the ring-and-ball test, samples of bitumen are prepared by pouring the bitumen, which has been heated under specified conditions, into metal rings which serve as molds.

Preparation of the bitumen samples must be carried out in a controlled manner detailed in BS 4692. The determination is usually carried out in duplicate and the apparatus is designed to hold two discs.

Apparatus for Softening Point of Bitumen

Ring and Wall

Ring

  • A brass shouldered ring. (Show above figure)

Ball

  • A steel ball, 9.53 mm (3/8”) in diameter, weighing between 3.45 and 3.55 grams. ( Show above figure)

Ball Centering Guide

  • A guide for centering the ball and made of brass. (Show above figure)

Ring Holder

  • The rings shall be supported on a brass ring holder. (Show above figure)

Brass Pouring Plate

Brass Pouring Plate

  • A flat, smooth brass plate approximately 75 by 50 mm that has been treated to prevent the bituminous material from adhering to it.
  • Suitable treatment is to coat the plate just before use with a thin layer of a mixture of glycerin and dextrin, talc, or china clay.

Bath

Glass Vessel

  • A glass vessel, capable of being heated, not less than 85 mm in diameter and not less than 120 mm in depth from the bottom of the flare.

Thermometer

Thermometer

Thermometer having a range from -2 to +80°C.

Also, read: What Is Workability of Concrete | Factors Affecting Workability | Test |Errors

Procedure for Softening Point of Bitumen

Softening Point of Bitumen

The determination is usually carried out in duplicate and the apparatus is designed to hold two discs.

The apparatus is assembled with the rings, the appropriate thermometer, and ball guides in position, and the bath is filled to a height of 50 mm above the upper surface of the rings, as show above figure, with freshly boiled distilled water at a temperature of 5 °C when the softening point is below 80 °C, the water temperature being maintained at 5 °C for 15 min.

Using forceps, a steel ball, previously cooled to 5 °C, having a diameter of 9.53 mm and weighing 3.50 ± 0.05 g, is placed upon each sample disc contained within a tapered brass ring with a larger internal diameter of 17.5 mm.

A ball guide previously placed over the disc assists in placing the ball in position. The bath is then heated and the water stirred so that the temperature rises at a uniform rate of 5 ± 0.5 °C/min until the bitumen softens and allows the ball to pass through the ring.

The rate of temperature rise should not be averaged over the test period and any determination where the rate does not fall within the specified limits after the first 3 min must be rejected.

For each ring and ball, the temperature shown by the thermometer is taken at the instant the sample surrounding the ball touches the bottom plate. If, however, the difference between the values obtained in the duplicate determinations exceeds 1 °C the test must be repeated.

When the softening point is expected to be above 80 °C the water is replaced with glycerol, which is maintained at a temperature of 35 °C for 15 min before placing a steel ball at the same temperature on to the disc.

Observations & Results for Softening Point of Bitumen

Sr.No. Softening Point
°C
Mean
°C
1 45.2 °C 45.1 °C
2 45.0 °C

Softening Point of Bitumen Lab Report

The experiment has been performed successfully and the softening point came out to be 45.1oC. Bitumen having this softening point should not be used in DDIT Nadiyad as the city’s highest maximum temperature was 40.3 °C recorded on March 30, 1990 And 46 °C was recorded on May 26, 2013.

At the time the meteorological office recorded this official temperature in the shade, it reported a heat index in direct sunlight of 55 °C. So to avoid the problems of  Rutting and bleeding this bitumen should not be used in Lahore.


FAQ

Bitumen 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. Generally, higher softening point indicates lower temperature susceptibility and is preferred in hot climates.

Softening Point

The softening point is the temperature at which a material softens beyond some arbitrary softness. These materials have a viscoelastic property, which means they become softer and less viscose under a specific temperature.

Test on Bitumen

  • Penetration test.
  • Ductility test.
  • Softening point test.
  • Specific gravity test.
  • Viscosity test.
  • Flash and Fire point test.
  • Float test.
  • Water content test.
  • Loss on heating test

Softening Point Test

Softening point test of bitumen is done to determine the consistency of bitumen. Softening point is defined as the temperature at which bitumen softens beyond some arbitrary softness i.e. bitumen softens and sags down about 25mm below the weight of steel ball.

Asphalt Melting Point

Asphalt can also melt once outdoor temperatures reach 120 degrees Fahrenheit; while this extreme heat is rare, keep in mind that asphalt itself holds heat! For proper viscosity, the asphalt itself should remain at 250-325 degrees Fahrenheit.

Bitumen Boiling Point

Bitumen Boiling point: >300°C Melting point: 54-173°C Relative density (water = 1): 1.0-1.18 Solubility in water.

Softening Temperature

The softening point is the temperature at which a material softens beyond some arbitrary softness. It can be determined, for example, by the Vicat method (ASTM-D1525 or ISO 306).

Melting Point of Asphalt

Asphalt can also melt once outdoor temperatures reach 120 degrees Fahrenheit; while this extreme heat is rare, keep in mind that asphalt itself holds heat! For proper viscosity, the asphalt itself should remain at 250-325 degrees Fahrenheit.

Melting Point of Bitumen

Bitumen has a melting point of around 240 degrees Fahrenheit which is high enough to be safely used for roadway designs and low enough to be heated up without using a large amount of energy.

Softening Point of Bitumen

Bitumens are viscoelastic materials without sharply defined melting points; they gradually become softer and less viscous as the temperature rises. The softening point of bitumen can be determined through the use of a ring-and-ball apparatus immersed in distilled water (30 to 80°C) or USP glycerin (above 80 to 157°C).

Softening Point Apparatus

The softening point is the temperature at which the bitumen disks soften and sag downward a specified distance. Consists of 800mL beaker, 2 standard balls, shouldered rings, ball centering guides, ring holder, bottom plate and beaker cover with support rods. Order thermometer and heater separately.

Softening Point of Bitumen

Bitumens are viscoelastic materials without sharply defined melting points; they gradually become softer and less viscous as the temperature rises. The softening point of bitumen can be determined through the use of a ring-and-ball apparatus immersed in distilled water (30 to 80°C) or USP glycerin (above 80 to 157°C)

What Is Ring and Ball Softening Point?

Softening Point Ring and Ball is the second oldest test method applied to bitumen, after needle penetration. It is the temperature at which a bitumen sample in a ring has had a deformation of 25 ± 0,4 mm by a ball while heated. Definition and Terminology.

Softening Point Test Lab Report

Softening Point  °C Repeatability °C
40-60 1.0
61-80 1.5

Softening Point Test of Bitumen

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

What Is Meant by Softening Point?

The softening point of a bituminous material can be defined as the temperature at which this bituminous material further softens after its arbitrary softness point is reached. There are various methods that are helpful in determining the softening point of a bituminous material.

What Do You Mean by Softening Point?

The softening point is the temperature at which a material softens beyond some arbitrary softness. A ring and ball apparatus can also be used for the determination of softening point of bituminous materials.

What Is Softening Point of Asphalt Cement?

The softening point is defined as the temperature at which a bitumen sample can no longer support the weight of a 3.5-g steel ball.

What Is the Difference Between Softening Point and Melting Point?

The melting point is the temperature where all the crystallinity in the bags and film is destroyed. The softening point describes a temperature where the bag will begin to experience noticeable changes in physical properties.

What Is the Flashpoint of Bitumen?

The rate of stirring should be approximately 60 revolutions per minute. Observe the thermometer carefully and when the temperature is 17oC below the actual flash point (175OC) lit up the test flame.

Softening Point of Bitumen Lab Report

The softening point value of the two readings should not exceed 1.0 °C for the softening point of bitumen range 40-60 °C and 1.5 °C for the softening point between 61-80 °C. Else the test is considered invalid and it is repeated.

What Temperature Is Bitumen?

Overheating can also lead to the build-up of deposits inside the storage tank and increased emissions. For this reason, bitumen should be stored at a temperature of at least 30°C below its flash point. The bitumen industry recommends the following maximum storage and operational temperatures: Road bitumen ≤ 200 °C.

Why Is Bitumen Heated?

The bitumen is normally stored in Bitumen Tanks. This type of tank minimizes heat loss because it is properly insulated. The bitumen is actually heated by a heating tube which is W-shaped which has an automatic burner.

What Is the Softening Point of Tar?

The softening point of coal tar pitch generally falls between 60 and 68°C so it is suitable for use on flat or almost flat roofs. The softening point of residual or straight-run asphalt must usually be raised by oxidation in a blowstill before the material can be used for roofing.

Which Bitumen Does Not Need Heat?

The cutback bitumen which is the most economical type may or may not require heating, whereas the remaining required to be heated.

What Is Softening Point Test?

Softening point test of bitumen is done to determine the consistency of bitumen. Softening point is defined as the temperature at which bitumen softens beyond some arbitrary softness i.e. bitumen softens and sags down about 25mm below the weight of steel ball.

What Is the Softening Point Test of Bitumen?

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

At What Rate Is the Temperature Applied During the Softening Point Test?

Apply heat to the bath and stir the liquid so that the temperature rises at a uniform rate of 5 + 0.5 0 C per minute until the material softens and allow the balls to pass through the ring.

What Is the Purpose of Softening Point?

The softening point helps in the determination of the temperature beyond which the bitumen is softened beyond a pre-specified softness. Hence, the softening point test of bitumen helps in knowing the maximum temperature to which the given bitumen can be exposed.

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