Concrete is a construction material composed of fine and coarse aggregate bonded together with cement paste that hardens (cures) and gains certain strength over time.
Latin word “concretus” (meaning compact or condensed) is the origin of the word concrete. In this article, we’ll discuss about the concrete ingredients and grades.
Concrete Ingredients:
- Binding material: Binding material works to bind the coarse and fine aggregate together. Cement or Lime is a wonderful example of binding material.
- Fine aggregate: The main purpose of fine aggregate is to fill up the open space or gap between the coarse aggregate. we can use sand as fine aggregate to make concrete.
- Coarse aggregate: Coarse aggregate is the main load bearer component of concrete. Gravel, Crushed Stone, or such other materials work as coarse aggregate in concrete.
- Water: The main component for mixing up everything in concrete is water. Water plays an important role to process the chemical reaction of cement and aggregate.
- Admixtures: It is classed as optional ingredients. It affects the concrete setting time. We use admixtures in concrete for specific purposes only.
Concrete Grade:
The grade of concrete is the minimum strength, the concrete must possess after 28 days of construction with proper curing quality control.
The grade of concrete is denoted by prefixing M to the desired strength in MPa. If we take an example of concrete with 40 MPa strength, we’ll denote this concrete by M40, where M stands for Mix and 40 stands for concretes strength in MPa.
Concrete mix design varies with concrete grade and strength.
To know about the concrete strength, we have to perform a Compressive Test of Concrete where we can use a block (15cm x 15cm x 15 cm) or a Cylinder (15cm x 30cm). If we use the block to perform this test, we’ll denote the concrete grade using M and if we use the cylinder for this test, we’ll denote the concrete grade using C.
Following the IS 456:2000 there are Fifteen types of Concrete Grade:
Concrete Mix Ratio:
We use Cement, Sand, Aggregate, and Water for making concrete. But some standard ratios define the overall concrete strength and quality.
All kinds of works don’t need the same quality concrete. So, IS gives some code to follow.
There are two kinds of Concrete Mixes:
-Nominal Mix: This type of mixing is appropriate for small-scale construction, like residential buildings, where concrete consumption isn’t much. The nominal Mix ratio is suitable for M10, M15, M20.
-Design Mix: This type of mixing is appropriate for larger-scale construction, where the volume of concrete consumption is very high, like Bridges or any megaprojects. We obtain Mix proportions from various lab tests for design mix ratio concrete.
Classification of concrete:
According to the bulk density of the concrete:
Lightweight Concrete: We know that bulk density or unit weight of concrete is the weight of freshly mixed concrete to fill a container of a specified unit volume. It helps us to calculate the yield of concrete/cubic meters. In Lightweight concrete, bulk density should be within 1900 kg/m3. Light porous filling with quartz sand, a hydraulic binder, water, and admixtures (in particular circumstances) are the main component of the type of concrete. Though we can accept bulk density up to 2,100 kg/m3 for the improvement of mechanical characteristics
Classic (ordinary) concrete: In this type of concrete bulk density may vary from 1900 kg/m3 to 2500 kg/m3
Heavy-weight concrete: The concrete where bulk density is higher than 2500 kg/m3 can be described as Heavy-Weight Concrete. Heavy-weight aggregates, such as barite, iron ore, splinters or specially made balls of iron and steel can help to achieve this type of concrete. Boron or Lithium can be added to concrete to improve its protective characteristics. But this type of concrete doesn’t have high Compressive strength (within 40 MPa) and the tensile strength of this type of concrete ranges from 1 to 3 MPa.
According to Cementitious Materials:
Inorganic Cementitious Concrete: In this type of concrete, lime silica is used instead of cement.
Organic Cementitious Concrete: This type of concrete mainly includes asphalt concrete and polymer cement concrete, resin concrete, and so on.
According to the type of Binder:
Cement-concretes: Different types and classes of Portland cement work as the binder of this type of concrete.
Asphalt-concretes: This type of concrete is useful for constructing streets and roads where Bitumen (can be obtained by processing oil) is the main binder.
Polymer-concretes: In this type of concrete, polymers work as binder material instead of cement.
According to the consistency of concrete:
We all know that the Consistency of concrete is another factor to differentiate concrete. The degree of stiffness or mobility of fresh concrete is known as the consistency of concrete. According to the constancy, we can classify concrete in four different types: Solid, Low-plastic, Plastic, and Liquid.
According to production and construction Methods:
Different types of concrete need different types of concrete production and construction methods. We can divide concrete into various classes as per the production and construction method, such as:
1. Ready Mix Concrete
2. Pumped Concrete
3. Shotcrete
4. Stamped Concrete (Ready Mix Aggregate Concrete)
5. Roller Compacted Concrete
6. Centrifugal Concrete
7. Vacuum Concrete, etc.
According to purpose:
Concrete can be divided into various classes as per the purposes:
1. Hydro-technical concretes
2. Concretes for pavement structure
3. Prestressed concretes
4. Precast concretes
5. Decorative (visible) concretes
6. The thermal insulating concrete (lightweight concretes)
7. Concretes for fire protection,
8. Concretes for radiation protection (heavy-weight concrete)
9. The waterproofing concretes
10. The soundproofing concretes (lightweight concretes)
11. Concrete and mortar for reparation, etc.
4 thoughts on “Concrete Ingredients and Grades: A Short Study”