What is concrete?
Concrete and cement are not the same things; cement is actually just a component of concrete. Concrete is made up of three basic components: like water, aggregate (rock, sand, or gravel) and Portland cement. Cement, usually in powder form, which is acts as a binding agent when mixed with water and aggregates. This combination, or concrete mix, will be poured and harden into the durable material with which we are all familiar So lets read more about What is Concrete and Types of Concrete.
There are different types of binding material is used other than cement such as lime for lime concrete and bitumen for asphalt concrete which is used for road construction.
Various types of cement are used for concrete works which have different properties and also useful for applications. Some of the types of cement are Following:
- Portland Pozzolana Cement (PPC)
- Rapid Hardening Cement
- Sulphate Resistant Cement
How to Make Concrete?
In Civil Engineering There are two types of concrete mixes, eg: nominal mix, and design mix.
The nominal mix is used for normal construction works such as small residential buildings. Most popular nominal mix are in the proportion of 1:2:4 Ratio.
Design mixed concrete are those for which mix proportions are finalized based on various lab tests on cylinder or cube for its compressive strength. This process is also called as mix design. These tests are conducted to find a suitable mix based on locally available material to obtain strength required as per structural design. A design mixed offers economy on use of ingredients.
Once suitable mix proportions are known or completed, then its ingredients are mixed in the ratio as selected.
Generally, these two methods are used for mixing
- Hand Mixing
- Machine Mixing
Based on the quantity and quality required, the suitable method of mixing is selected. In the hand mixing, each ingredient is placed on a flat surface and water is added and mixed with hand tools as well as the machine.
While in machine mixing, different types of machines are used. In this case, the ingredients are added in the required quantity to mix and produce fresh concrete.
Once it is mixed adequately it is transported to casting location and poured in formworks. Various types of formworks are available which as selected based on usage.
Poured concrete is allowed to set in formworks for a specified time based on a type of structural member to gain sufficient strength.
After removal of formwork, curing is done by various methods to make up the moisture loss due to evaporation. Hydration reaction requires moisture which is responsible for setting and strength gain. So, curing is generally continued for a minimum 7 days after removal of formwork.
Types of Concrete In Civil Engineering
Concrete may be the following types.
- Plain concrete construction (PCC)
- Reinforced concrete Construction (RCC)
In PCC: it is poured and cast without the use of any reinforcement. This is used when the structural member is subjected only to the compressive forces and not bending.
In RCC: When a structural member is subjected to bending, reinforcements are required to withstand tension forces, structural member, as it is very weak in tension compared to compression. Generally, the strength of concrete in tension is only 10% of its strength in compression.
It is used as a construction material for almost all types of structures such as residential concrete buildings, industrial structures, dams, roads, tunnels, multi-story buildings, skyscrapers, bridges, sidewalks, and superhighways etc.
The grade of Concrete
Steps For Concrete Construction
Construction steps are Following:
- Selecting quantities of materials for selected mix proportion
- Checking of work-ability
- Pouring in formwork for casting
- Vibrating for proper compaction
- Removal of formwork after a suitable time
- Curing member with suitable methods and required time.
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