Category Archives: aggregate

aggregate, Building materials

Los Angeles abrasion Test on Aggregates

6 Comments

Los Angeles Abrasion test is used to determine aggregates’ level of abrasion resistance and toughness. Los Angeles abrasion test of aggregate assesses the deterioration of aggregate standard gradings when subjected to abrasion and impact in a rotating steel drum containing an abrasive charge of steel balls. LA abrasion test on aggregates is the measure of aggregate toughness and abrasion resistance such as crushing, degradation and disintegration. Basically, finding the percentage wear as a result of relative rubbing between the aggregate and steel balls used as an abrasive charge is the primary objective of the Los Angeles abrasion test.

  1. Significance of Los Angeles Abrasion Test of aggregates
  2. Types of aggregate tests
  3. Los Angeles Abrasion tests on aggregates
    1. Codes and standards for Los Angeles Abrasion test of aggregates
    2. Working principle of LA Abrasion test
    3. The test procedure for the Los Angeles Abrasion test of aggregate
    4. The formula for LA Abrasion Test

Significance of Los Angeles Abrasion Test of aggregates

Aggregate is a fundamental and necessary component of concrete, flexible pavements, and other similar structures. More than 70% to 80% of the volume of concrete is aggregate. Quality matters when it comes to aggregates because they are the main component of concrete, flexible pavements, etc. Various tests are conducted to determine the following properties of Aggregates.

  • Strength
  • Toughness
  • Hardness
  • Shape
  • Water Absorption etc.

Related posts from Vincivilworld

Types of aggregate tests

The following are the various aggregate tests used to determine aggregate suitability:

This article is about Los Angeles Abrasion tests on aggregates

Los Angeles Abrasion tests on aggregates

The aggregate toughness and abrasion resistance such as crushing, degradation, and disintegration are evaluated by the Los Angeles abrasion test. Generally, this test is performed in accordance with AASHTO T 96 or ASTM C 131.

The Los Angeles Abrasion test determines the aggregate’s wearing resistance and hardness. Abrasion is indeed the wearing action on aggregate caused by vehicle movement. In order to resist abrasion, the aggregate should have an adequate abrasion value. The abrasion test value can ensure the quality and suitability of aggregates. Furthermore, aggregate with high abrasion resistance has a long life span.

Codes and standards for Los Angeles Abrasion test of aggregates

There are 3 tests commonly used to test aggregates for their abrasion resistance. (a) Deval Attrition Test (b) Dorry Abrasion Test (c) Los Angeles Abrasion Tests. However, Los Angeles abrasion test values are more realistic and correct.

Los angeles Abrasion testing apparatus
Los Angeles Abrasion Testing Apparatus

Working principle of LA Abrasion test

The principle of this test is to produce abrasive action using steel balls mixed with aggregates. Accordingly, the aggregate and steel balls are rotated in a drum for a specific number of rotations. The percentage of wear due to relative rubbing action between the aggregate and steel balls is recorded. This value is the Los Angeles Abrasion value.

Los Angeles Machine cross section
Los Angeles abrasion testing machine

The test procedure for the Los Angeles Abrasion test of aggregate

The Los Angeles abrasion testing machine consists of a hollow steel cylinder, closed at both ends, having an inside diameter of 700 mm and an inside length of 500 mm. The abrasive charge shall consist of cast iron spheres or steel spheres approximately 48 mm in. diameter and each weighing between 390 and 445 g. The number of balls to be placed shall be as per IS 2386.

Grading and number of abrasive charges
Grading and number of abrasive charges

The test sample shall consist of clean aggregate which has been dried in an oven at 105 to 110°C to substantially constant weight. They shall conform to one of the gradings shown in Table II.

GRADINGS OF TEST SAMPLES AS PER IS 2386PLES
GRADINGS OF TEST SAMPLES AS PER IS 2386
  • Firstly, place the specimen inside the horizontal drum.
  • Then, put the steel balls and rotate the cylinder for a total of 500-1000 revolutions at the speed of 30-33 rpm about its horizontal axis. For gradings A, B, C and D, the machine shall be rotated for 500 revolutions. However, for gradings E, F and G, it shall be rotated for 1000 revolutions.
  • After completing the specific rotations, collect the specimens from the cylinder.  
  • Then sieve on a 1.7 mm IS sieve and weigh the specimen.
  • Lastly, calculate the abrasion value using the formula below.

The formula for LA Abrasion Test

The original weight of aggregate sample = W1 g

Weight of aggregate sample retained = W2 g

Weight passing 1.7mm IS sieve = W1 – W2 g

Abrasion value = [(weight of sample taken – weight of sample retained on IS sieve) / weight of sample taken ] x 100

The difference between the original weight and the final weight (sieved through 1.7mm) is expressed as % of the original weight of the sample aggregate. Similarly, this value is called as Los Angeles abrasion value.

aggregate, Building materials

Specific Gravity and Water absorption test on Aggregate

1 Comment

Specific gravity and water absorption test are significant tests on aggregates. Perhaps aggregates are the fundamental and essential components of concrete and play a significant role in the design mix of concrete. More than 70 to 80 per cent of the volume of concrete is aggregate. Hence the water absorption and specific gravity test are essential and significant tests .
The specific gravity is the measure of strength of aggregates, while water absorption indicates the porosity of aggregates.

Also Read : Quality tests to be done on Concrete

Also Read : Bitumen – 9 quality tests on bitumen

Tests on Aggregates

Aggregates are the second major ingredient of concrete that contributes around 60 to 70% of its volume. One of the major contributing factors to the concrete quality is the quality of aggregates used therein. The test methods of aggregates are done as per IS 2386 part-4 assists in assessing the quality of aggregates. Following are the tests for analysing the quality of aggregate.

This article is about Specific Gravity and Water absorption test on Aggregate.

Specific gravity and water absorption test

The specific gravity is an indirect measure of the strength of aggregate. Through this test, the general identification of the aggregate becomes easier. Low specific gravity aggregates are weak. Hence, they are not suitable for construction. 

Specific gravity and water absorption test on aggregate.
Specific gravity and water absorption test on aggregate.

Water absorption of aggregate measures the weather resistance. It is the percentage of water the aggregate absorbs when immersed in water. The test method for specific gravity and water absorption test is as follows.

Relevant IS code:

  • IS:2386(Part 4)-1963

Apparatus used:

  • Weighing machine
  • Drying oven 
  • Wire mesh
  • Container
Specific gravity and water absorption testing apparatus
Specific gravity and water absorption testing apparatus

Test procedure

  • For this test, take about 2000g of aggregate and wash them thoroughly with water.
  • Remove the fine particles and dust, then drain the water and place them in the wire basket.
  • Then immerse this in distilled water with a temperature between 22 and 32 degree Celsius for 24 hours.
  • Then Weigh the basket with aggregates and record them as A1.
  • After 24 hours, remove the aggregates from the mesh and weigh them as A2.
  • Then drain the water from the aggregate and Again weigh the dried aggregate. B
  • Place the sample in the dry oven for 24 hours. after the oven drying weighs them and record as C.
  • Now calculate the specific gravity and water absorption of the aggregate using the given formula.

Specific gravity = C / (B- A)

Water absorption = {(B-C)/C} * 100

where, A= A1 – A2, ie weight of the saturated aggregate in water

B = weight of drained aggregate 

C = weight of oven-dried aggregate.

Aggregate with high specific gravity has good strength. The normal value of specific gravity is 2.5 to 3.0. The water absorption should not exceed 0.6%. Thus this test helps to determine the quality, strength and water absorption.

aggregate, Building materials

Lightweight Aggregate: Manufacturing, Properties and Types

2 Comments

Lightweight aggregate is a widely used construction material owing to its versatile properties. In this blog, I will walk you through what is a lightweight aggregate, its properties, applications and manufacturing process.

What is a lightweight aggregate?

Lightweight aggregate is a coarse aggregate used to make lightweight concrete for structural as well as non-structural applications.

  • The Compressive design strength of normal concrete for cast-in-situ, precast and prestressed concrete ranges between 20 N/mm2 to 35 N/mm2. On the other hand, the minimum compressive design strength of concrete which uses lightweight aggregate will be around 17-18 N/mm2.
  • Normal concrete has a density between 2300 and 2500 kg/m3. However, when it comes to LWC the density ranges between 500 kg/m3 to 1800 kg/m3 depending on the type of aggregate used.
  • Lightweight concrete with densities lower than 17 N/mm2 falls under the category of LWC. And, those with densities above 17 N/mm2 are referred to as structural lightweight concrete (SLWC).
  • LWC can also be designed for the minimum compressive strength as normal concrete by varying the proportions of mineral admixtures used.
  • SLWC is used for structural applications. They can be used along with reinforcement steel just like normal concrete.
Light weight aggregates -Manufacturing
Light weight aggregates -Manufacturing,

Features of Lightweight Aggregates

  • The lightweight aggregate used in concrete may have any form, including cubical, rounded, angular, and other shapes. Its workability is directly influenced by its form and texture.
  • These aggregates are known for absorbing little water and maintaining their low density. 
  • A high saturation level makes it an attractive option.
  • LWA can reduce the dead loads on the structure and make it more economical.
  • Has relatively low thermal conductivity and is preferred for roof insulations.
  • Helps in consuming industrial wastes like blast furnace slag, fly ash, clinkers etc.
  • Possess good acoustic properties.

In the next section we will see what are the desired characteristics of a lightweight aggregate.

Light weight aggregates
Light weight aggregates

Also read : Pervious Concrete- All Factors Affecting, Limitations & Methodology Explained

Lightweight Aggregate Desired Characteristics

  • The properties and composition should be consistent.
  • To ensure worthwhile structural savings, the aggregate should have a low specific weight, in compliance with the required ASTM requirements. 
  • The aggregate should have a low number of large external voids. And a high number of smaller well-distributed voids within the particles. 
  • Individual aggregate particles should be able to withstand handling and mixing. 
  • The particles should have a good bond with the cement and should not react chemically with it. 
  • The aggregate should be rated appropriately for the intended use, according to the relevant ASTM specification 

Types of Lightweight Aggregates

Lightweight Aggregates can be divided into three types by their sources:

(1)Industrial waste lightweight aggregate – This is processed by industrial wastes, such as fly as, ceramisite, expanded slag ball, cinder and light sand, etc.

(2)Natural aggregate – This is made from natural porous stone, such as pumice, volcanic cinder, and light sand, etc.

(3) Artificial lightweight aggregate – This is manufactured from local materials, such as clay ceramisite, and expanded perlite, etc.

Also read : ALC Panel – Autoclaved lightweight Concrete Panel

Lightweight Aggregates Manufacturing Process

The majority of lightweight aggregate is made from clay, shale, or slate. However, furnace slag, natural pumice, vermiculite, and perlite can all be substituted. 

The raw material (excluding pumice) is extended to about twice its original volume to create lightweight aggregate. The expanded material has properties that are similar to natural aggregate. As a result, it produces a lighter concrete product.

Let me show you the detailed procedure.

Extraction or quarrying 

Cone crushers, jaw crushers, hammer mills, and pug mills are used to crush the material, which is then screened for quality.

Sizing 

The material that passes through the screens is returned to the crushers, and the material that passes through the screens is recycled.

It is then moved to hoppers.

Reaction

  • The material is fed from the hoppers into a rotary kiln. 
  • It is heated to about 1200°C (2200°F) using coal, coke, natural gas, or fuel oil. 
  • When the raw materials are heated, carbonaceous compounds in the material liquefy, forming gas bubbles that expand the material.
  • In addition, VOCs (volatile organic compounds) are released during the process.
  • The enlarged product emerges from the kiln.

Cooling

  • The product clinker is conveyed into the clinker cooler, where it is cooled by air and shaped into a porous material. 
  • The lightweight aggregate is screened for scale, crushed if necessary, and stockpiled after cooling. 
  • Rotary kilns are used by the vast majority of plants (roughly 90%). However, travelling grates are also used to heat the raw material. 

Lightweight Aggregate Applications

  1. Screeds and thickening are made with lightweight aggregates. When the floor or roofs need thickening or smoothing, it can be used to easily achieve it.
  2. Can be applied to screeds and walls where the wood would be nailed together.
  3. Casting structural steel in lightweight aggregate concrete can protect it from fire and corrosion. Also, it can be used to cover architectural needs.
  4. Can be used on roofs as a heat insulation material.
  5. Used as insulation for water pipes.
  6. Used to construct partition walls and panel walls in frame structures.

That’s it about lightweight aggregates. Hope you found this article insightful. Let us know in the comments.

aggregate, Building materials

Shape tests on Coarse Aggregates- Flakiness index test and Elongation Index Tests.

1 Comment

Shape test on coarse aggregates constitutes flakiness Index and elongation index tests. The particle size and shape of aggregate is one of the major factors affecting the quality of the concrete.

Shape test on Coarse Aggregates

  • Flakiness index test
  • Elongation index test

Must read : Aggregate crushing test- Strength of aggregate

Must read : Bitumen – 9 lab tests on bitumen for flexible pavements.

Shape test on coarse aggregate – Flakiness index test

The particle shape of aggregates is determined by the percentages of flaky and elongated particles contained in it. for concrete and construction of bituminous works the presence of flaky and elongated particles are not suitable and cause failures and breaking during heavy loads.

The Flakiness index of aggregates is the percentage by weight of particles whose least dimension (thickness) is less than three- fifths (0.6times) of their mean dimension. This test is not applicable to sizes smaller than 6.3mm

The Elongation index of an aggregate is the percentage by weight of particles whose greatest dimension (length) is greater than nine-fifths (1.8times) their mean dimension. This test is not applicable for sizes smaller than 6.3mm.

Flake materials may cause voids in concrete and has to be kept under limit to ensure the quality of the concrete.

Relevant IS codes: 

  • IS:2386(PartI)-1963

Apparatus used

  • Weighing machine
  • Metal gauge
  • IS sieve

Test procedure

First we have to find the flakiness index.

Dimensions of thickness and length gauges
Dimensions of thickness and length gauges
  • For finding the flakiness index, we have to test at least 200 pieces of any fraction and weigh them.
  • Then sieve the sample through IS sieves according to the table below.
  • After that to determine the flakiness index separate the aggregate retained in the sieve.
  • Then pass each aggregate through the corresponding slot in the thickness gauge.
  • Finally, we calculate the flakiness index.
  • The flakiness index is the total weight of material passing through the gauge to the total weight of the sample. It is expressed in terms of percentage. Weigh the flaky material passing the gauge to an accuracy of at least 0.1 per cent of the test sample.
  • The formula for flakiness index is

F.I = (Weight of aggregate passing through the slot of the thickness gauge / Total weight of the sample) * 100

Thickness gauge
Thickness gauge

Must read : Los Angeles abrasion test on aggregates

Shape test on Coarse Aggregates- Elongation index test

The presence of elongated particles in the aggregate is undesirable for construction. Also, this shape test is made in coarse aggregate. The elongation shape test is not applicable for aggregates with a smaller size than 6.3 mm.

Relevant IS codes: 

  • IS:2386(PartI)-1963

Apparatus used

  • Weighing machine
  • Metal gauge
  • IS sieve

Test procedure

  • For finding the flakiness index, we have to test at least 200 pieces of any fraction.
  • Then sieve the sample through IS sieves according to the table below.
  • After that pass, each fraction through the gauge individually.
  • Now using a weighing machine, weigh the total amount of fraction retained.
  • Finally, we calculate the elongation index.
  • The elongation index of an aggregate is the weight of the particle whose greatest dimension is greater than 1.8 times its mean dimension.
  • The formula for elongation index is 
Shape test on aggregates
Shape test on aggregates

E.I = Weight of the aggregate retained on length gauge / Total weight of aggregate x 100

Conclusion

The shape tests give only a rough idea of the relative shapes of aggregates. Flaky and elongated particles should be avoided in pavement construction, particularly in surface course.

aggregate, Building materials

Soundness test on Aggregate | Sample selection and procedure

2 Comments

Soundness test determines the disintegration of aggregates due to weathering. This includes freezing, thawing, marine condition etc. However, the weak and porous aggregate shows a change in weight during this soundness test.

Aggregates are the significant factor that contributes adequate strength to concrete.Therefore it is important to obtain the right quality aggregate for construction. 

Must Read : Bricks – 8 tests to ensure quality

Tests on Aggregate

For ensuring the quality of aggregates the following tests are conducted.

Soundness test for aggregates (IS-2386-PART-5)

Aggregate samples are submerged in sodium sulphate or magnesium sulphate solution repeatedly. This process causes salt deposits in the aggregate pores which tends to break the aggregates. After specified number of dipping & drying process the aggregates are sieved to determine the percentage loss of material.

Soundness test of aggregate
Soundness test of aggregate

Relevant IS code

  • IS: 2386 Part V

Sample selection for fine and coarse aggregates

  • The fine aggregate passing through the 10 mm IS sieve should be held as a sample for this test.
  • Then sieve the sample again through 10mm, 4.75 mm, 2.36 mm, 1.18 mm, 600 microns, 300 microns.
  • However, the sample should be decided in such a way that, it will not yield below 100g of given sizes. 
  • For coarse aggregate, sample remove aggregates finer than 4.75 mm. 
  • Then dry the sample and again sieve through 80mm, 63mm, 40mm, 20mm, 10mm IS sieves.
  • Choose the sample in such a way that, it will not yield below the given amount for the given sizes.
  • Weigh the samples separately and store them in different containers.

Apparatus for Soundness test

  • IS Sieves (80 mm, 63 mm, 40 mm, 31.5 mm, 25 mm, 20 mm, 16 mm, 12.5 mm, 10 mm, 8.0 mm, 4.75 mm, 4.0 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron, 150 micron)
  • Container
  • Weighing machine
  • Drying oven (105 to 110 degree)

Reagents used

  • Sodium sulphate solution
  • Magnesium sulphate solution

Test procedure of soundness test

  • After the selection of aggregate samples, wash them thoroughly on a 300 micron IS sieve.
  • Then dry them at 105 to 110-degree celsius in drying oven.
  • After that immerse the sample in a solution of sodium sulphate or magnesium sulphate for 16 to 18 hours. 
  • Cover the container for reducing evaporation and accidental addition of extraneous substances. 
  • The temperature of the solution should be 27 degree Celsius. 
  • After 18 hours, take out the sample and dry them at 105 to 110-degree celsius. 
  • Allow them to cool to room temperature and repeat this process.
  • After the final cycle, wash the sample and dry them again at 105 to 100-degree celsius.
  • Weigh them and sieve them through the same sieve we used before the test.
  • The percentage of finer sieve after the test and before the test is determined.
  • The percentage loss of weight indicates the soundness of aggregate.
aggregate, Building materials

Aggregate crushing test to find Strength of aggregate

2 Comments

Aggregate crushing test is done to find out the strength of aggregate which is the fundamental and essential components of concrete, flexible pavements, etc. More than 70 to 80 per cent of the volume of concrete is aggregate. Aggregates are a very important component of concrete, so the quality really matters when it comes to aggregates. Furthermore, their uses include flexible pavements, railway ballast, etc.

Different tests are to be performed to ensure the quality requirements of aggregates for the specific uses.

Tests on aggregates

Different types of tests are done to determine their properties like

  • Strength
  • Toughness
  • Hardness
  • Shape
  • Water Absorption etc.

Must Read : Bricks – 8 reliable tests to ensure quality

Must Read : Bitumen – 9 Lab tests on bitumen for flexible pavements

Following are the types of aggregate tests conducted to ascertain the suitability of aggregates.

  • Aggregate Crushing test
  • Abrasion test
  • Impact test
  • Water absorption test
  • Flakiness index test
  • Elongation index test
  • Bulk specific gravity test
  • Polishing test

Aggregate Crushing test (IS 2386(Part 4):1963 & BS 812–110:1990)

Aggregate crushing test values indicates the strength of aggregate and hence it is very significant. Similarly we can say crushing value is the relative measure of resistance of an aggregate under gradually applied compressive loads. Higher crushing strength means lower crushing value and vice versa. If the aggregate crushing value is less than 10, means an exceptionally strong aggregate, Whereas crushing value of 35 and above means a weak aggregate.

Relevant codes for aggregate crushing test

  • IS 2386(Part 4):1963
  • BS 812–110:1990

Apparatus required

  • Compressive Testing Machine
  • Crushing Mould: A steel cylinder 15 cm diameter with plunger and base plate.
  • Weighing machine,
  • Sieve: Size of 12.5 mm, 10 mm and 2.36 mm
Aggregate crushing value test apparatus
Aggregate crushing value test apparatus

Aggregate crushing Test procedure

  • Oven dry the aggregates
  • Firstly, sieve the aggregate using Indian standard sieves.
  • Then collect the specimen passed through 12.5 mm and retained on a 10mm sieve.
  • Thus is the test sample of aggregate.
  • Then put the cylinder on the base plate and weight it (W). 
  • The aggregate sample should be filled in 3 layers , each layer is subjected to 25 strokes using tamping rod.
  • After that weigh the materials with cylinder and record as (W1)
  • Weight of aggregate will be (W1-W). ie : (Weight of cylinder with aggregates – Weight of cylinder)
  • Level the aggregate surface carefully before inserting the plunger so that it rests horizontally over the surface.
  • Place the cylinder with plunger below a compression testing machine.
  • Apply load at a uniform rate so that a total load of 40T is applied in a span of 10 minutes.
  • Then release the load and remove the material from the cylinder.
  • Following, sieve again on 2.36mm IS sieve. 
  • Then weigh the material passing through the sieve and record it as W2. 
  • Finally, calculate the specimen crushing value using the formula below. 

Aggregate crushing value = (W2 x 100) / (W1-W)

W1-W = weight of dry sample

W2 = Weight of fraction passing through the sieve after application of load.

For a good quality aggregate, the crushing strength value is low.

Recommended crushing values

Flexible pavementsCrushing value
Soling50
Water bound Macadam40
Bituminous macadam40
premix carpet30
Dense mix carpet30
Rigid pavements
Other than wearing course45
Surface or Wearing course30

The aggregates used in roads and pavement construction must be strong enough to withstand crushing under roller and traffic. If the aggregate crushing value is 30 or higher’ the result may be anomalous and in such cases the ten percent fines value should be determined instead.