Aggregate Test

1) Sieve Analysis

Sieve analysis for aggregate is a widely used test to determine the particle size distribution of coarse and fine aggregates. It provides valuable information about the grading of the aggregate, which is crucial for designing concrete and asphalt mixes, assessing material quality, and evaluating its suitability for specific applications. The sieve analysis test involves passing a sample of aggregate through a series of sieves with progressively smaller openings, stacked in order of decreasing mesh size. The sieves are usually made of wire mesh and conformed to standard specifications. The aggregate sample is placed on the top sieve, and the sieves are mechanically shaken or manually agitated to separate the particles based on size. The sieve analysis results provide information on the cumulative percentage passing through each sieve and the percentage retained on each sieve. This data helps in evaluating the aggregate’s particle size distribution, identifying any gaps or excesses in certain size ranges, and assessing its conformity to specific grading requirements for different applications.

2) Unit Weight

The unit weight test, also known as the bulk density test, is conducted to determine the weight per unit volume of aggregates. This test provides valuable information about the density and compactness of the aggregate, which is important in various engineering applications, such as concrete mix design, compaction, and volumetric calculations. The unit weight of aggregates can vary depending on factors such as particle size, shape, gradation, and moisture content. It is recommended to conduct multiple tests and average the results for more accurate values. Additionally, consider conducting the test on both dry and saturated aggregates to account for any differences in density due to moisture.

3) Specific Gravity and Water Absorption

The specific gravity and water absorption tests are commonly conducted on aggregates to assess their quality and suitability for use in construction materials. These tests provide valuable information about the density and water-holding capacity of the aggregates, which are crucial factors in various engineering applications.

The specific gravity test determines the ratio of the weight of an aggregate to the weight of equivalent volume of water. It helps in identifying the relative heaviness or lightness of the aggregate compared to water. The specific gravity value provides insights into the composition and density of the aggregate, aiding in material classification, density void analysis and mix design.

The water absorption test determines the percentage of water absorbed by the aggregate. It provides information about the porosity and permeability of the aggregate, which affects its durability, workability, and the potential for moisture-related issues in concrete or asphalt mixtures.

4) Flakiness Test

Flakiness test is a shape test for aggregate performed to determine the percentage of flat and elongated particles present in the sample. Flakiness index is the percentage by weight of aggregate whose least dimension is less than 0.6 times the mean dimension. Flat and elongated particles have a higher surface area-to-volume ratio. The flakiness index obtained from this test helps in assessing the shape characteristics of the aggregate. Higher values indicate a higher proportion of flat and elongated particles, which may affect the workability and performance of concrete or asphalt mixtures. The flakiness test is particularly important in construction projects where the presence of flat and elongated particles can cause issues such as poor compaction, reduced strength, increased water demand, and decreased resistance to wear and weathering. By evaluating the flakiness index, engineers and technicians can make informed decisions regarding the use of aggregates in specific applications and take necessary measures to optimise the mix design and overall performance of the construction materials.

5) Elongation Test

Elongation test is another shape test for aggregate performed to determine the percentage of flat and elongated particles present in the sample. Elongation index is the percentage by weight of aggregate whose largest dimension is more than 1.8 times the mean dimension. Elongated particles have a length-to-width ratio greater than a specified limit and can have negative effects on the workability, strength, and durability of concrete or asphalt mixtures. The elongation test helps in evaluating the shape characteristics of aggregates and assessing their suitability for use in construction materials. By determining the elongation index, engineers and technicians can make informed decisions regarding the use of aggregates in specific applications and take necessary measures to optimise the mix design and overall performance of the construction materials.

6) Impact Test

The impact value test, also known as the Aggregate Impact Value (AIV) test, is conducted on aggregates to determine their toughness or resistance to impact. This test provides information about the ability of the aggregate to withstand sudden loads and impacts, which is important in evaluating their suitability for road construction and other applications where they may be subjected to impact forces. The impact value represents the percentage of aggregate crushed or broken under the impact load and indicates the aggregate’s toughness or resistance to impact. Higher values suggest lower toughness, while lower values indicate higher toughness. The impact value test helps in assessing the quality and suitability of aggregates for various applications, particularly in road construction. It assists in material selection, mix design, and quality control, ensuring that aggregates can withstand impact forces and provide durable and safe infrastructure.

7) Crushing Value Test

The crushing value test, also known as the Aggregate Crushing Value (ACV) test, is conducted on aggregates to assess their strength and durability. This test provides information about the resistance of aggregates to crushing under compressive loads, which is important for evaluating their suitability for various construction applications. The crushing value represents the percentage of aggregate crushed under the applied compressive load and indicates the strength and durability of the aggregate. Lower values suggest higher strength and resistance to crushing, while higher values indicate lower strength and potential for failure under compressive loads. The crushing value test helps in evaluating the quality and performance of aggregates in various construction applications, such as road construction, pavement layers, and concrete production. It assists in material selection, mix design, and quality control, ensuring that aggregates meet the required specifications and provide durable and reliable infrastructure.

8) Los Angeles Abrasion Test

The Los Angeles Test, also known as the L.A. Abrasion Test, is conducted on aggregates to evaluate their resistance to abrasion and wear. This test provides information about the durability and quality of aggregates, especially those used in road construction and pavement applications. In this test, steel balls of 48mm diameter and weighing approx. 390-445gm are rotated in a cylinder along with aggregate sample. The Los Angeles abrasion value represents the percentage of aggregate lost during the test and serves as an indicator of the aggregate’s resistance to abrasion and wear. Lower values indicate higher resistance, while higher values suggest greater susceptibility to abrasion. The Los Angeles Abrasion Test helps in assessing the suitability of aggregates for road construction, as abrasion resistance is crucial for aggregates used in asphalt and concrete pavements. It provides valuable information for material selection, mix design, and quality control, ensuring that aggregates meet the required specifications and provide durable and long-lasting structures.