Concrete – A Man-Made Versatile Composite

What is concrete?

Concrete is a versatile composite man-made material, widely used as building /construction material in the world. We can’t imagine any structure without the use of concrete whether it is any kind of building, high-rise structures, dams, bridges, or roads.

The use of concrete started way back in the ancient time when people used clay, gypsum, and limestone as the binding material to form a concrete-like composite. Over many years people used these materials and with every passing time, it transformed into the modern world of concrete.

But finally, in the year 1824, an English man named Joseph Aspdin patented Portland Cement. It was named by the resemblance to the Portland Stone found in England and was regarded as the most prestigious building stone at that time.

What is the composition of Concrete?

As we understand that Concrete is made from a mixture of :

Cement works as the binding agent. It hardens when combined with water.

Fine aggregates are usually sand or crushed stone that range from 0.025 to 6.5 mm or less than 9.55mm in diameter. Coarse aggregates are particularly greater than 4.75mm in size ranging from 6.5 to 38 mm or larger https://www.aimil.com/products/sieves-set-gi-frame-brass-sieves.

When all these are mixed with water form a fluid slurry which then can be molded into any shape and size, and which hardens with time. The water/cement ratio is the determining factor of the strength of concrete. 

As we understand that Concrete is made from the mixture of :

The cement works as the binding agent. It hardens when combined with water.

Fine aggregates which is usually sand or crushed stone that range from 0.025 to 6.5 mm or less than 9.55mm in diameter. Coarse aggregates are particularly greater than 4.75mm in size ranging from 6.5 to 38 mm or larger https://www.aimil.com/products/sieves-set-gi-frame-brass-sieves.

When all these are mixed with water form a fluid slurry which then can be molded into any shape and size, and which hardens with time. The water/cement ratio is the determining factor of the strength of concrete. 

What are the properties of concrete?

Concrete is well known for its specific quality like one of the strongest materials in the construction world, low in maintenance with long-lasting durability, and most important is it is economical.

Properties of Concrete can be characterized in two main categories:

  1. Properties in Fresh State/ Early age Properties (Fluid Slurry Form)
  2. Properties in Hardened State (Rock Form /Shape of the Formwork)

Properties of Concrete in Fresh state which are important to us are:

  1. Workability
  2. Air Content
  3. Temperature & Temperature rise
  4. Setting
  5. Bleeding

Properties of Concrete in Hardened Form which normally relates to its:

  1. Compressive Strength of Concrete
  2. Durability of Concrete

What are the different types of concrete grades & their uses?

Grades of Concrete:

Concrete Grade is denoted by M which is a reference to the Concrete Grade Mix Ratio. The Grade of Concrete is determined by the strength and composition of the concrete which are classified into 3 main categories depending on the Mixes Ratio:

  1. Ordinary Concrete = M5, M7.5, M10, M15, M20
  2. Standard Concrete = M25 to M55
  3. High Standard Concrete = M60 to M 80

For Example, the ratio for M10 Grade would be:

M10 = 1 : 3 : 6

Where 1 = Cement, 3 = Sand, and 6 = Coarse aggregates which are then cast for 28 days in moulds size of 150 × 150 × 150 mm (https://www.aimil.com/products/moulds)  which is then tested in the laboratory to define the strength of that particular Mix.

We need to choose the right concrete grade for the different construction jobs like C10: is for domestic & commercial use. It is used for Patio slabs, pathways, and non-structural work. C25 is for domestic & commercial use. It is used for construction in all areas. Multi-purpose concrete mix and for foundations.

Percentage Strength of Concrete at various ages

The strength of concrete increase with age as concrete don’t stop curing, but after 28 days, the strengthening process of the concrete is slow and neglected less than 1%

AgeStrength %
1 Day16%
3 Days40%
7 Days65%
14 Days90%
28 Days99%

The compressive strength of the concrete cube test provides an idea about the characteristics of concrete. The compressive strength of concrete depends on various factors such as water-cement ratio, cement strength, quality of concrete material, quality control during production of concrete etc. Test for compressive strength is carried out either on a cube or cylinder.

Conclusion:

The modern world can’t be imagined without concrete. Concrete is so versatile has been used in a wide range of applications. This versatility of the Concrete makes it suitable for applications in modern construction from basic building to larger and heavier structures.

Also Read: Importance of Construction Material Testing

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