Why is grading of coarse aggregate necessary?

Why is grading of coarse aggregate necessary?

Proper gradation of coarse aggregates is one of the most important factors in producing workable concrete. Proper gradation ensures that a sample of aggregates contains all standard fractions of aggregate in required proportion such that the sample contains minimum voids.

Which size coarse aggregate is ideal for use in a concrete mix?

– Coarse aggregates are particulates that are greater than 4.75mm. The usual range employed is between 9.5mm and 37.5mm in diameter. – Fine aggregates are usually sand or crushed stone that are less than 9.55mm in diameter. Typically the most common size of aggregate used in construction is 20mm.

What are aggregates used for?

Aggregates are used in construction to provide drainage, fill voids, protect pipes, and to provide hard surfaces. They are also used in water filtration and sewage treatment processes.

Does concrete need coarse aggregate?

The selection of good quality coarse aggregate is essential for the production of concrete that meets the desired strength and durability requirements. Ideal construction aggregate should have a rough surface texture and should be clean, strong, and free from coating and other dirt particles.

What are the advantages of grading of aggregates?

Proper grading of aggregates improves the workability, uniformity, homogeneity, and finishing qualities of concrete mix. A good grading system will help in ensuring strength, durability etc of the concrete.

Why are aggregates used in construction?

Aggregates are the most basic material used in construction. They provide the foundation for roads, bridges, and buildings, while also making up over 90\% of an asphalt pavement and up to 80\% of a concrete mix. On average, 38,000 tons of aggregates are necessary to construct one lane mile of interstate highway.

Why do we test aggregates?

Aggregate plays an important role in pavement construction. Aggregates influence, to a great extent, the load transfer capability of pavements. Hence it is essential that they should be thoroughly tested before using for construction. Aggregates are tested for strength, toughness, hardness, shape, and water absorption.

What is coarse aggregate and fine aggregate?

Coarse aggregate and fine aggregate are mixed such that the concrete becomes well graded aggregate concrete. Characteristics of aggregate such as size, shape, surface texture, grading, mineralogy affect the concrete strength. Image courtesy : civilengineersforum.com

How are aggregates graded in concrete mix design?

Aggregates are graded in a concrete mix design and the ratio of each size is determined using grading curves, charts, tables, or other methods. The shape of the aggregate is a crucial characteristic because it impacts the workability & strength of the concrete.

What is the size of an ideal aggregate?

Aggregates larger than 4.75 mm in size are termed as coarse aggregates. These aggregates are obtained from stone quarries and stone crushers, the size between 4.75 mm to 80 mm. Good qualities of an ideal aggregate: These aggregate used for the construction of concrete and mortar must meet the following requirements.

What percentage of concrete is fine aggregates?

The fine and coarse aggregates generally occupy 60\% to 75\% of the concrete volume (70\% to 85\% by mass) and strongly influ- ence the concrete’s freshly mixed and hardened proper- ties, mixture proportions, and economy.