Comprehensive Guide to Fine Aggregates: Types, Classification, and Applications

What Is Fine Aggregate?

Fine aggregate (Sand) Fills voids between aggregates. It forms the bulk and makes mortar or concrete economical. It provides resistance against shrinking and cracking. It is naturally available.

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2. What Are Differences Between Shear Slump and Collapse Slump in Slump Test?
3. What Is Lap Length | Lap Length of Column | Lap Length of Slab | Lap Length of Beam
4. All About Transportation of Concrete | What Is Transportation of Concrete | Methods for Transportation of Concrete
5. What Is Limit State Method | Assumption in Limit State of Collapse | Limit State Design | What Is Working Stress Method | Assumptions in Working Stress Method | Working Stress Method of Design

Types of Fine Aggregates (Classification)

Fine aggregates are classified as follows:

1. Mode of Origin
2. Composition
3. Grain Size

1. Classification Fing Aggregates According to Mode of Origin:

Here, the fine aggregates for a mode of origin are as follows.

1. Pit Sand.
2. River Sand.
3. Sea Sand.

1.1. Pit Sand-

They are sharp and angular in outline. Translation and deposition are done by the wind. Such sand accumulation is sometimes covered by clay. It will be desirable to wash and clean this type of sand before use.

1.2. River Sand-

River sand is found in the river bed in-plane area. Grains of river sand is round in shape. This sand is clean and free from salt encrustations. No organic impurities are noticed. This sand is commonly for construction work.

1.3. Sea Sand-

This type of sand is found on beaches and along sea-shore. These sand particles are round in shape. Grains are often found covered with salts that are not easily separated.

These salts, when coming in contact with binding material of mortar or concrete, create problems. Further, these salts encrustations are hygroscopic. They absorb water from the atmosphere and delay setting. They produce dampness and efflorescence.

Hence the type of sand is not preferred. They should be thoroughly washed before use.

2. Classification of Fine Aggregates According to Composition:

Here, the fine aggregates for according to composition are as follows.

1. Clean Sand
2. Silty Sand
3. Clayey Sand

2.1. Clean Sand-

These are well-graded sand containing quartz particles in a wide range of grain sizes.

2.2. Silty Sand-

These are poorly graded, having a considerable proportion of silt and other non-plastic fines.

2.3. Clayey Sand-

There is poorly graded sand that has a prominent clay fraction and also plastic fines.

3. Classification Fine Aggregate According to Grain Size:

According to this classification sands are classified as under,

Fine Aggregate Size Requirement As Per IS 456

If you remember, I have mentioned the size of the fine aggregate as recommended by IS. Let me recall. The aggregates passing through 4.75 mm sieve and retained on 0.15 mm sieve are called fine aggregates.

Different size of sand is necessary for different works. For sand some times terms like fine sand, medium sand, and coarse sand are use.

It is difficult to distinguish one type of sand from others when such terms are used. It is advisable to express sand in terms of fineness modulus.

According to F.M. sand can be classified as under

Sand having a fineness modulus more than 3.2 will not be suitable for making satisfactory concrete. As I have stated earlier considering grain size, types of sand will be as under,

Use of Ine Aggregate for General and Specific Purpose

As per the below type of sand

1. Use of sand for general purposes
2.  Specific Uses of Sand 

Use of Sand for General Purposes

1. Preparing mortar for masonry work.
2. Preparing mortar for different types of plastering and paintings.

Preparing concrete for a slab, beams, columns, etc.

1. 1. 1. Filling in trenches
      2. Levelling ground
      3. Foundation Concrete
      4. Floorings
      5. Different types of precast units, tiles, concrete pipes, etc.

Specific Uses of Sand 

Sand can be used for many specific purposes; some important uses are mentioned below.

1. To safeguard foundations in back cotton soil.
2. Filling in breaches of canal banks.
3. Temporary cofferdam
4. Blotting excessive of bitumen from the surface of the road.
5. For playgrounds
6. Moulding works
7. Sand-blasting for cleaning
8. Counter-weights (Sand Bages)

Properties of Fine Aggregate

1. Size of Fine Aggregates.
2. Strength.
3. Shape of Fine Aggregates.
4. Specific Gravity.
5. Surface Texture of Fine Aggregates.
6. Water Absorption.
7. Surface Index of Fine Aggregates.
8. Soundness.
9. Surface Moisture.
10. Specific Surface of Fine Aggregates.

FAQs (Frequently Asked Questions) that could complement your article on fine aggregates:

What are fine aggregates?

Fine aggregates are natural sand particles or crushed stone particles smaller than ¼ inch, used in construction to fill voids between coarse aggregates and in mortar and concrete mixes.

What are the main types of fine aggregates based on origin?

Fine aggregates are classified into pit sand, river sand, and sea sand. Pit sand is angular, river sand is round and clean, while sea sand may contain salts and require washing before use due to potential issues with concrete setting.

How are fine aggregates classified according to composition?

Fine aggregates are classified as clean sand, silty sand, and clayey sand. Clean sand contains well-graded quartz particles, silty sand has a high proportion of silt, and clayey sand includes significant clay fractions.

How are fine aggregates classified based on grain size?

Fine aggregates are categorized into coarse sand (2-1 mm), medium sand (1-0.25 mm), and fine sand (0.25-0.15 mm) based on their grain size. This classification helps determine their suitability for different construction applications.

What is the role of fine aggregates in concrete and mortar?

Fine aggregates fill voids between coarse aggregates, making concrete more economical and enhancing its resistance to shrinking and cracking. In mortar, fine aggregates contribute to its workability and bonding properties.

What is the fineness modulus of fine aggregates?

The fineness modulus (FM) of fine aggregates indicates their fineness or coarseness and is determined based on the cumulative percentage retained on standard sieves. Sands with higher FM values (e.g., 2.2 – 3.2) are suitable for specific types of construction applications.

What are the properties of fine aggregates that affect concrete quality?

Properties such as particle size distribution, shape, specific gravity, surface texture, water absorption, and surface moisture content influence the workability, strength, and durability of concrete mixes containing fine aggregates.

Why is it important to classify fine aggregates before use?

Classifying fine aggregates based on origin, composition, and grain size helps ensure their suitability for specific construction purposes and minimizes potential issues such as poor concrete setting or excessive water absorption.

What are the specific uses of different types of fine aggregates?

Fine sand is typically used for preparing concrete mixes for slabs and columns, while medium and coarse sands are suitable for applications such as masonry mortar preparation, leveling ground surfaces, and filling trenches.

How can the quality of fine aggregates be ensured on-site?

On-site testing methods such as sieve analysis, specific gravity tests, and fineness modulus determination are used to assess the quality and suitability of fine aggregates for construction projects.