What are the Properties of Aggregates for Concrete?

The mixture of sand, stones, slag, and gravel is called the aggregates, which are used in the construction. Aggregates are widely used in building the foundation, in railroads and roads. Its usage in concrete gives economy in the cost of the concrete. They are the fillers, as they do not react with the water and cement.

Aggregates Concrete

Some of the major properties of aggregates in concrete are:

Abrasion: When the aggregate is rotated in a cylinder, the abrasion value gives a relative measure of the resistance.

Impact value: The resistance of aggregate to impact or shock gives the impact value.

Crushing value: When putting under the load of compression the measure of the aggregate gives the crushing value. This an important factor, which helps us understand the behavior under the loads.

Deleterious materials: There should not be any harmful materials, which can have adverse effects on the durability and strength of the concrete. Deleterious materials are these harmful materials in the mixture. They may have some effects on setting time, bonding, hydration, reduced strength and durability.

Specific surface: Per unit, the surface area of the material is called as a specific surface. Smaller the aggregate particles more are the specific surface. The surface area of coarse aggregate is lesser than that of the fine ones.

The fineness modulus: It indicates how coarse or fine aggregate is. Smaller the fineness modulus finer is the aggregate and the more fineness means aggregate is coarser.

Sand bulking: A thin layer of particles is formed when water is added to the dry sand. Bulking is more in fine sands than in the coarse sand.

Absorption: Pores are formed due to the solidification of the molten magma due to air bubbles. It is the difference between the weights of dry aggregates and saturated in the dry surface conditions.

There may be some conditions depending on the moisture like having some moisture, no moisture, moist, and dry.

Voids: Voids are the empty spaces between the particles of the aggregate.

Density: To fill a container of unit volume the amount aggregate required is called as the density.

Aggregates Concrete

Gravity: When the specific gravity is low, it shows porous and weak materials. On the other hand, high specific gravity shows the good quality. It also decides the suitability and considered when the concrete mixture is designed.

Surface texture: Aggregate particles and cement paste depends on the surface texture. It is the strong bond strength.

Shape and size: Shape and size are the two very important factors of aggregate particles, which have an effect on the quantity of the cement in the concrete mix.

Composition: Materials present in the aggregates reacts with the alkalis in the cement, it can cause the expansion and crack. Hence, do not use this mix.

Some of the uses and applications of the aggregates:

• Mostly, the aggregates are used in railways, road ballast, and in the construction to provide the support to the load and to maintain the load
• It is also used to resist the movement of ties and rails
• To stop the cracking and shrinkage
• To provide the strength and reduce the cracks in the concrete
• For the economy
• In many of the water and sewage filtration processes and treatments
• Many of the structures like foundations and bridges use aggregates concrete 

Though, not very commonly known, aggregate concrete plays an important role in ensuring that our building structures can stand the extreme weather and the test of time. These are the some of the important factors, which will help in selecting the best aggregate concrete.