Aggregates are used in concrete for several reasons. First, they reduce the amount of cement and water required to make the concrete mixture. This lowers the cost and environmental impact of concrete production.

Second, they improve the strength and durability of concrete by resisting compression and preventing cracking. Third, they enhance the workability and appearance of concrete by providing a smooth and uniform texture. Fourth, they can modify the thermal and acoustic properties of concrete by influencing its heat capacity and sound absorption.

The prominent reasons behind the usage of aggregates in the concrete mixture is listed below: 

Strength and Durability

  • The bulk and structural stability of concrete are provided by the aggregates. As well as helping to withstand compressive, tensile, and shear pressures, they aid to distribute the applied stresses. 
  • Concrete is greatly strengthened by coarse aggregates in particular, and is made more durable by fine aggregates.

Volume and Economy

  • The volume of the concrete is significantly occupied by aggregates, which lowers the requirement for cement paste.
  • As aggregates are typically less expensive than cement, this lowers the overall cost of the concrete mixture. 
  • The volume of concrete can be inexpensively enhanced by the use of aggregates.
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Workability and Cohesion

  • Sand, a fine aggregate, fills the spaces between cement particles and coarse aggregates. 
  • This increases the concrete’s workability, making it simpler to mix, put, and finish. Additionally, aggregates aid in the bonding of the mixture’s constituent parts, enhancing cohesion and minimizing segregation.

There are lot of alternatives to concrete also. When the traditional approach fails and new material is available, we can use them in construction practice. One has to check for common properties and do tests to confirm for their strength, durability and other parameters.

Control of Shrinkage and Cracking

  • Concrete shrinkage and cracking are reduced with the aid of aggregates. 
  • They limit the movement of the cement paste during drying and curing by supplying a web of connected particles, reducing shrinkage and crack formation.
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Drainage and Permeability

  • Concrete’s drainage and permeability characteristics are influenced by coarse particles. 
  • They make linked gaps that let water pass through the concrete and lessen the chance of water buildup and possible freeze-thaw damage.

Thermal Insulation

  • Concrete’s thermal insulation characteristics are enhanced by the use of lightweight materials like expanded clay or shale. 
  • Due to their low thermal conductivity, these aggregates reduce heat transmission through concrete, increasing building energy efficiency.

Environmental Benefits

  • Concrete that contains recycled aggregates decreases the need for new materials and promotes building waste recycling. 
  • This lessens resource depletion, lessens the environmental impact of making concrete, and promotes sustainable construction methods.

Aesthetics and Surface Finish

  • The visual appeal and surface finish of concrete can both benefit from aggregates. 
  • Concrete surfaces can be made to look visually appealing and distinctive by using decorative aggregates, such as coloured stones or exposed aggregates.
  • They add texture, color diversity, and patterns to concrete structures, increasing their architectural and ornamental features.

Sound Insulation

  • Certain aggregate varieties, especially those that are porous or lightweight, can be useful in applications involving sound insulation.
  • They reduce noise transmission between various locations or from outside sources when used in concrete because they absorb and attenuate sound waves.

Fire Resistance

  • Concrete has built-in fire resistance when the right aggregates are used. Certain forms of expanded shale or clay aggregates, for example, have low thermal conductivity and can aid in containing the spread of fire. 
  • These aggregates are used in concrete construction to provide fire protection and improve the overall fire safety of buildings.

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