CONCRETE, quality tests on concrete

Compaction factor test – Workability of concrete-Test procedure

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Compaction factor test is a practical and reliable method used to assess the workability of concrete, especially when the mix is stiff and does not show clear results in a slump test. The compaction factor test for workability of concrete evaluates how easily concrete flows under gravity. It also assesses how it compacts by comparing partially compacted concrete with fully compacted concrete. In the workability of concrete compaction factor test, engineers gain a more accurate understanding of concrete consistency for low to medium workability mixes. Following the compaction factor test procedure helps achieve consistent results during laboratory testing. The compaction factor test of concrete is commonly applied in mix design and quality control and remains one of the dependable tests for workability of concrete used in practice. Compaction factor test is a lab test and is generally conducted on concrete samples having very low workability.

This article explains the compaction factor test, covering its principle, procedure, significance, advantages, limitations, and role in accurately evaluating the workability of concrete.

  1. Significance of Quality tests on concrete
  2. Production stage quality tests on fresh concrete
  3. Significance of compaction factor test
  4. Compaction factor test for workability of concrete
    1. Compaction Factor Test – Relevant codes
    2. Apparatus used
    3. Compaction factor test procedure
  5. Key Takeaways
  6. Conclusion

Significance of Quality tests on concrete

Quality tests on concrete are essential for ensuring strength, durability, and performance in construction. These tests help engineers assess the workability of fresh concrete and the quality of hardened concrete. Common quality tests on concrete include checks during the production stage (on fresh concrete before placing), tests on hardened concrete specimens, and evaluations performed directly on finished structures. Including tests like the flow table test for concrete ensures reliable results and consistent quality throughout a project.

A construction worker wearing a hard hat and safety vest examines concrete samples on a workbench, including a concrete compression testing machine and molds.
A civil engineer in a safety helmet and reflective vest analyzing concrete test specimens in a lab, showcasing the importance of quality control in concrete workability tests.

Following are the stages of quality tests

  • Production stage quality tests ( On fresh concrete before placing)
  • Hardened stage quality tests ( hardened concrete specimens)
  • On structures ( tests done on the structures )

Production stage quality tests on fresh concrete

Production stage quality tests on fresh concrete are crucial for ensuring the right workability and consistency before placement. These tests help engineers select the best mix for construction and maintain quality control. Key tests include the slump test, compaction factor test, Vee-Bee test, Kelly ball test, and the flow table test for concrete.

This article focuses on the Compaction factor test, explaining its procedure, importance, and how it compares with other workability tests like the slump test and other tests

Significance of compaction factor test

The compaction factor test is significant because it accurately measures the workability of concrete. This is especially true for stiff and low-slump mixes. This test provides more precise results than the slump test. It supports effective mix design. It also ensures consistent concrete quality through reliable laboratory-based workability assessment.

Compaction factor test for workability of concrete

The compaction factor test is used to determine the workability of concrete. Workability refers to the ease and uniformity with which freshly mixed concrete can be mixed, placed, compacted, and finished. Workability also represents the internal effort required to achieve full compaction. The compaction factor test of concrete was developed by the Road Research Laboratory, UK. It provides more precise and accurate results than the slump test. This test is especially suitable for stiff concrete mixes that do not slump and require vibration for compaction. The compaction factor test measures the degree of compaction under controlled conditions. It offers a reliable method for assessing concrete consistency in laboratory and quality control applications.

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

Also read : Timber – Five important quality tests

Compaction Factor Test – Relevant codes

  • IS 1199 (Part 2): 2018 – Methods of Sampling and Analysis of Concrete – Workability
  • BS 1881 (Part 103) – Testing Concrete – Method for Determination of Compaction Factor
  • ASTM C1170 / C1170M – Workability of Fresh Concrete by Compaction Factor Method (Reference use)
  • DIN 1048 – Testing Methods for Fresh Concrete

These codes provide standardized procedures for conducting the Compaction Factor Test and ensure reliable evaluation of concrete workability.

The Compaction Factor Test method followed in IS 1199 (Part 2) is fundamentally the same as those in British standards. It is also similar to other international standards. All codes measure workability by comparing partially compacted concrete with fully compacted concrete.

  • Principle: Same across all standards
  • Apparatus: Same (two hoppers + cylinder)
  • Calculation: Same compaction factor ratio
  • Differences: Minor variations in dimensions, tolerances, and wording

Apparatus used

A female laboratory technician in a white lab coat and protective goggles is pouring a substance from a can into a blue funnel system, while a male colleague works in the background in a modern laboratory setting.
Laboratory setup for conducting the compaction factor test on concrete, demonstrating the apparatus used to measure workability.
  • Compacting factor apparatus
  • Cylindrical mould 
  • Hand scoop 
  • Trowel
  • Weighing machine
A blue civil engineering apparatus featuring two hoppers and a collecting bucket, designed for material testing.
Apparatus used for the Compaction Factor Test, designed to accurately measure concrete workability.

The figure shows the dimension of the hopper and the mould. The inside area of the hopper should be smooth. The apparatus is made of bronze or cast brass. At the lower ends of the hopper, there is a trap door with a 3mm thickness. A rigid frame attaches the hoppers and cylinder. After the completion of mixing, the test is conducted at a constant time interval. 

Compaction factor test procedure

  • Place the sample in the upper hopper of the apparatus using a hand scoop.
  • Fill the hopper with its brim level and open the trap door.
  • Then allow the concrete to fall into the lower hopper.
  • Immediately after the concrete rests, uncover the cylinder and open the lower trap door.
  • Cut off the excess amount of concrete above the cylinder using the trowel.
  • Then weigh the concrete in the cylinder nearest to 10g. This is the weight of partially compacted concrete.
  • Refill the cylinder with the same sample in the layers and the layer is heavily rammed or vibrated for full compaction.
  • Then weigh the fully compacted concrete and the weight of the empty cylinder.
  • Finally, Compute the compaction factor using the formula.

The compaction factor is the ratio of partially compacted concrete to fully compacted concrete.

Compaction factor = (W1 – W) / (W2 – W)

The compaction factor value varies from 0.7 to 0.95.

Key Takeaways

  • The Compaction Factor Test is used to evaluate the workability of concrete, especially stiff mixes.
  • It is more sensitive and accurate than the slump test for low-workability concrete.
  • The compaction factor test for workability of concrete measures ease of compaction under gravity.
  • It is best suited for laboratory-controlled conditions.
  • The workability of concrete compaction factor test helps compare different mix designs.
  • The test uses two hoppers and a cylindrical mould.
  • Following the compaction factor test procedure ensures consistent results.
  • The compaction factor test of concrete minimizes subjective judgment.
  • It supports quality control and mix optimization.
  • It is one of the reliable tests for workability of concrete.

Conclusion

The Compaction Factor Test remains an important method for assessing the workability of concrete. This is particularly true for mixes that show little or no slump. By measuring the ratio of partially compacted to fully compacted concrete, the compaction factor test for workability of concrete provides a clear and quantitative indication of consistency. When engineers follow the standard compaction factor test procedure, the results help in evaluating mix performance and maintaining uniform quality. The workability of concrete compaction factor test is especially useful in laboratory testing and mix design studies. As one of the established tests for workability of concrete, the compaction factor test of concrete continues to support accurate quality control and better construction outcomes.

architectural finishes, BUILDING CONSTRUCTION

Monolith- The Technology, Merits and Demerits Full Guide

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Monolith is a well-known concept in the world. The technology is used to construct high-rise buildings and skyscrapers. The monolithic structure can withstand high loads (up to 8 points) without being broken, which makes it a suitable candidate to be used in seismic zones.

Let’s look at what monolithic houses are, their benefits and drawbacks, and the construction process.

The Technology of Monolith building

Monolith
Monolith

The technology’s essence lies in pouring reinforced concrete sections of a monolithic house during erection. Since there is no load on this part of the wall, any sound (brick, block, sheet) or low-strength material (wood, PVC panel with insulation, glass) may be used to fill the gaps between slabs.

In this technology a few variants of the frame are used:

Steel rods of various diameters are used to make the reinforcement cage for a monolithic building. Many of the frame’s components are welded or bound together. However, since it takes more time and effort, the last bonding technique is rarely used.

Formwork construction

Circular or stay-in-place formwork is used for this housing. A framework structure is a large sound panel (panel formwork) or prefabricated pouring form (tunnel formwork) that prevents the concrete mixture from flowing and allows the shape to be saved during the setting time.

There are various types of formwork construction in use:

  • Horizontal
  • Vertical
  • Creeping
  • For rounded elements

In apartment buildings, monolithic houses with stay-in-place formwork are more popular. There are single-story monolithic cottages.

Concrete mixture and grouting

Concrete mixtures may be manufactured immediately on the building ground in a mixing batch or a special concrete goods plant, depending on the monolithic construction scale. In the second case, concrete is transferred to the moto mixer.

Works with setting concrete

The concrete is densified after it has been filled into a formwork. This phase is required to remove airlocks, which impede the mixture’s efficiency. The per vibrator or external vibrator is used to densify the concrete mixture. The smoothness of the surface of the walls and ceiling is influenced by the consistency of the densification of the concrete mixture, which in turn affects the fine finish budget.

Form stripping

After the concrete has reached the required strength, the formwork is removed and passed on to the next stage of grouting.

Merits and Demerits of Monolith Building

Monolith Building
Monolith Building

Monolithic houses have both benefits and drawbacks. Let’s make a distinction between them.

One of the prime benefits would be the speed of construction. Monolithic buildings, which are similar to brick houses in design, are constructed faster than the previous ones. Equality of design is also a compelling point.

The majority of houses are constructed in a specific pattern that is characterized by their constructional peculiarities. A monolithic building, on the other hand, has no bounds. Plans for such houses can be varied, multilevel, and have ceilings of varying heights, which is not typical of block or brick houses.

The complete absence of open joints in a monolithic house has a range of benefits, including:

  • Increase in sound isolation level
  • Thermal insulation improvement
  • Extension of house life
  • Increase in strength
  • Protection from cracking
  • Lowering of construction weight

You should pay attention to its disadvantages also Monolithic structures permit the easy propagation of sound and vibrations making soundproofing of the rooms a difficult task. Also, it demands a large amount of finishing work.

aggregate, Building materials

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

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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.

Building materials, timber

Timber – 5 Important Quality Tests and Procedures.

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Timber is wood suitable for construction purposes. In order to find the quality and sustainability of the Timbers, Various Quality tests are performed.

They are natural polymeric material that nearly does not age. Moreover, the structure of the wood ensures efficient strength and load capacity.
Wood can be split into two classes. They are natural and man-made. Hence some examples of man-made timber are plywood, fibreboard, impregnated wood, etc.

PROPERTIES OF GOOD QUALITY TIMBER

The timber should posses the following qualities.

  • It should have a good uniform dark colour.
  • Timber should be free from defects such as shakes, flaws, dead knots, etc.
  • It should possess regular annual rings.
  • The freshly carved surface of the wood should have a sweet smell.
  • Moreover, It should have a heavyweight.
  • The cellular tissue and fibres should be compact and hard.
  • A good timber should be durable and possess elasticity. 
  • It should be resistant to fungus, insect, etc.
  • Also, timbers with compact texture have good resistance to fire. 
  • It should be inert from mechanical, chemical and physical agencies.
  • A good quality wood should hold loads from structures.
qualities of good timber
qualities of good timber

Also Read : Bitumen – 9 lab tests on bitumen on flexible pavement

Also Read : Bricks – 8 Reliable tests to ensure quality.

TEST ON TIMBER

In order to find the quality and sustainability of the Timbers, Various Quality tests are performed. In this article, we have listed a few test procedures.

  • Moisture content test
  • Tensile strength test
  • Compressive strength test
  • Shear strength test
  • Bending test

MOISTURE CONTENT TEST OF TIMBER

This test determines the moisture content in wood. However, wood contains a small amount of moisture content. A weighing machine and a drying oven are important apparatus for the water absorption test. 

moisture content test of timber
moisture content test of timber

Relevant IS codes:

IS I 2380 ( Part VI ) – 1977

Test procedure

  • Initially, Take the specimen with a size of 5cm x 5cm x 2.4cm.
  • Then using a weighing machine weigh the specimen. Mark it as W1.
  • After that oven-dry the timber at a temperature of 103-degree celsius. 
  • Later, take out the specimen when becomes dry.
  • Again weigh and mark the weight of the dry specimen as W2.
  • Finally, calculate the percentage of moisture content by

% of moisture content = Weight of moisture in sample/ Dry weight of sample = (W1 – W2)/ W2

TENSILE STRENGTH TEST OF TIMBER

The tensile strength test defines the strength and ability to withstand breaking. Also, we can determine the load-carrying capacity of the wood.

Relevant IS codes:

IS I 2380 ( Part VI ) – 1977

Test procedure

Tensile test on timber
Tensile test on timber
  • Firstly, take a specimen with 5cm x 5cm and 20cm in length.
  • Then place the specimen on the base plate of the instrument. 
  • After that apply load either parallel or perpendicular to the grains. 
  • Mark the load at which the wood breaks.
  • Finally, calculate the tensile strength of the wood.

Tensile strength = Maximum load applied / Cross sectional area

COMPRESSIVE STRENGTH TEST

The compressive strength test defines the crushing strength of the timber. Furthermore, this test determines the load which the wood can support over a period.

Relevant IS codes:

IS I 2380 ( Part VI ) – 1977

Test procedure

Compressive test
Compressive test
  • Initially, take a specimen with a size of 5cm x 5cm x 20cm. 
  • Then place the specimen in the compressive testing machine.
  • Following this, apply load parallel to the grains.
  • The specimen should be free from defects. Gradually increase the load.
  • Then note down the load at which the timber breaks. 
  • Lastly, calculate the compressive strength from the below formula.

Compressive strength = Load at which the specimen breaks/ Total area of the specimen

SHEAR STRENGTH TEST

The shear strength is important when timber is used as slabs. The load should be applied parallel to the grains. 

Relevant IS codes:

IS I 2380 ( Part VI ) – 1977

Test procedure

Shear test apparatus
Shear test apparatus
  • The size of the specimen for shear strength is 5cm x 5cm x6.25 cm. 
  • Then cut the corner of the specimen.
  • Thus it produces failure on 5cm x 5cm surface.
  • However, this failure occurs tangentially or radially. 

BENDING STRENGTH TEST

The Bending strength test is necessary when we use timber as a beam. Through this test, we can find the modulus of rupture and modulus of elasticity.

Relevant IS codes:

IS I 2380 ( Part VI ) – 1977

Test procedure

Bending test on timber
Bending test on timber
  • For this, take a specimen of 5cm x 5cm x 7.5 cm in size
  • The specimen should be free from defects and deterioration.
  • Then drop a hammer with specific weight from a certain height.
  • Thus we get the impact bending.
  • Lastly using the load and deflection, calculate bending strength.

Also Read : Los Angeles abrasion test on aggregates

BUILDING CONSTRUCTION, prefabrication

What is Prefabrication in construction? Advantages and Disadvantages

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Prefabricated construction, or “prefab,” is a method of construction that  uses components made off-site in a factory, which are then transported put together on-site to create a structure. Prefabrication is an amazing technology that helps to reduce time and have many more benefits.Construction has always been about the speed and efficiency that can be ensured with the materials and techniques of construction.

In this blog, we will find out all the details about the same.

Let’s start from the definition.

What is prefabrication?

Prefabricated construction, or “prefab,” is a method of construction that uses components made off-site in a factory, which are then transported put together on-site to create a structure.

With different advantages to offer, there are a few different common types of prefab. You may want to consider incorporating any of these solutions, depending on your particular building project.

So, that’s the basic details. We will discuss about the benefits in next section.

Other related posts from vincivilworld

Benefits of prefabrication

Prefabrication setup
Prefabrication setup

1. Mitigating the labour shortage:

  • It is already difficult for contractors to find labour, but construction still needs to take place.
  • It decreases labour productivity much more as on-site building continues piecemeal.
  • Therefore, prefabrication helps businesses speed up timelines, make the most of their on-site labour, improve efficiency, and succeed in the marketplace.

2. Cost-effectiveness:

  • It also costs less to transport partial assemblies from a factory than to move pre-production resources to each site.
  • Plus, as labour efficiency increases, personnel-related costs decline.

3. Time savings:

  • Time is the essence of the rainy season, and prefabrication will help you manage tighter timelines.

4. Quality control:

  • Factory tools can provide added quality assurance as opposed to repetitive construction on-site.
  • In addition, consistent factory indoor environments remove much of the weather effects on manufacturing, while streamlined manufacturing and production improve job site safety on the whole.

5. Lower environmental impact:

  • Accelerated offsite production of parts results in reduced emissions and work disruption.
  • This preserves wetlands or protected areas nearby and minimises local flora and fauna disturbance.
  • The controlled, dry environment of modular construction saves water consumption and allows scrap and other materials to be recycled.
  • Plus, fossil fuel consumption plummets with less on-site traffic and streamlined transportation.

6. Better safety and security:

  • By reducing a construction site’s timeframe, you simultaneously decrease the amount of time that the site is vulnerable to vandalism or robbery.

7. Flexibility:

  • It is easy to disassemble and move modular construction to various sites.
  • This greatly decreases the demand for raw materials, minimises the resources spent and overall reduces time.
  • Modular construction also allows for versatility in the structure’s design, allowing for an infinite number of possibilities.
  • Since prefabricated building units can be used in various spaces, their neutral aesthetics can be combined with almost any form of construction.

8. Reduced Site Disruption:

  • There is much fewer truck traffic, machinery and material suppliers around the final construction site as several parts of a building are completed in the factory.
  • The disturbance of conventional workplaces suffering from noise, emissions, waste and other common irritants is therefore minimal.
  • This structured design approach offers a much more productive productivity environment and removes unwanted disruptions and interruptions typical of construction sites.

Time to know the challenges of prefabrication.

Challenges of Prefab Construction

Construction site of prefabricated building
Construction site of prefabricated building
  • The joints to be given should be well-built enough to convey all sorts of stresses, connecting the core structure and the components.
  • The strength and solidity of the whole building totally depend on the strength of the joint.
  • Therefore, rather than component-based analysis, it is important to have detailed studies on the whole system.
  • One of the key challenges in embracing prefabrication technology in construction requiring accuracy and precision is the need for skilled labour on-site and the lack of on-site automation.
  • Skill development and native automation are also mandatory for prefabricated systems to be installed.
  • It is likely to get damaged during the erection or transport of heavy machinery units, so the arrangement of the units must be performed precisely and this process in a congested area becomes sloppy.
  • Labour maintenance is another concern because prefabricated construction requires skilled labour as it differs from in-situ construction, which requires machine-oriented expertise both on-site and in the production process.

Now, let me show you the advantages of prefabrication

Advantages of Prefabrication

  • Prefabrication technology has several advantages, such as energy efficiency revision, minimal waste and inspection, efficient construction, work speed, protection, sustainability and quality.
  • As self-supporting ready-made components are used, the need for formwork, shuttering and scaffolding is substantially lowered.
  • Building time is thereby decreased, resulting in lower labour costs.
  • Reduced the quantity of waste materials relative to building on site.
  • Reduction in construction time to allow an earlier return of the invested principal.
  • Construction guarantees precise compliance with building codes and excellent quality assurance.
  • Along with quality control and factory sealing, high-energy performance.
  • It is possible to place prefabrication sites where skilled labour is more readily accessible and the costs of labour, electricity, materials, space and overhead are reduced.
  • Prefabrication permits building throughout the year, regardless of the weather (related to excessive cold, heat, rain, snow, etc.).
  • Material waste from the building is less.
  • Regardless of climatic conditions.
  • Security and worker comfort levels are higher in the off-site building.

Last, but not the least the disadvantages should be known.

Disadvantages/Limitations of prefabrication

Material assembly for prefab construction
Material assembly for prefab construction

The subsequent constraints are known to have restricted design choices, decreased reselling value, high initial expenditure, non-suitability for foundation and precast unit transport.

There are even more drawbacks. They are the following:

  • Leakage occurs in joints in prefabricated parts.
  • For huge prefabricated parts, transportation costs can be high.
  • To ensure affordability through prefabrication, increased production volume is required.
  • Initial costs for construction are higher.
  • The initial production of designs is time-consuming.
  • Large prefabricated parts require heavy-duty cranes and measurement of precision from handling to position on site.
  • Local employment can be lost, as skilled labour is needed.
  • Modular building design and construction requires high levels of cooperation between project parties, particularly architects, structural engineers and manufacturers.
  • These buildings usually depreciate more rapidly than standard site-built housing due to their shorter economic existence.

Hope the time you spent for the article was worth it. Let me know if you have any doubts in comments.

Happy learning!

aggregate, Building materials

Aggregate crushing test to find Strength of aggregate

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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.

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