Construction materials

Concrete Proportioning and Properties are the two main fundamental things a civil engineer has to know about the construction.  Concrete possess certain Proportioning and Properties. These Concrete Proportioning and Properties are as follows

Concrete Proportioning and Properties

Proportioning

The concrete in the construction field using for construction has many classifications. There are different grades of concrete in construction. These grades design according to the strength of concrete. It bases on the calculation of time period the concrete attains full strength. The grades of concrete are

M5, M7.5, M10, M15, M20, M25, M30, M35, M40.

The letter M denotes the mix. And the number indicates the compressive strength of concrete gain at 28 days in N/mm². M5 and M7.5 concrete grade of concrete use only for a simple foundation for masonry purposes. The grade of concrete below M15 not to use for Reinforce Cement Concrete. M20, M25, and M30 are the most common grade of concrete using in the modern construction field.

Some of the nominal mixes and mixing proportions are as follows

• M5    Grade of concrete – 1:5:10
• M7.5 Grade of concrete – 1:4:8
• M10  Grade of concrete – 1:3:6
• M15  Grade of concrete – 1:2:4
• M20  Grade of concrete – 1:1½:3
• M25  Grade of concrete – 1:1:2
• M30  Grade of concrete – 1:1:3

Properties of Concrete

Some of the main and unique properties of concrete are its workability and water-cement ratios.

1. Workability

The ability of fresh mix concrete to fill the mold with proper vibration and poring method is workability. Workability depends on the water content, aggregate, binding materials, chemicals in concrete. Increasing water content and chemicals increase the strength and workability of concrete. Excessive water and chemicals lead to bleeding of the concrete/segregation. This leads to forming honeycomb in concrete structures. A good slump value to maintain in concreting for high strength.

2. Water-cement ratio

It is the weight of the mixing water divided by the weight of the cement. High-quality concrete produces by lowering the water-cement ratio without losing the workability of fresh concrete. And allowing it to properly place and cure.

A properly design mixture possesses desire workability for the fresh concrete and the long-life and strength of the concrete.

General properties of concrete

Some of the general properties of concrete are,

It possesses a high compressive strength and strength depends on the mix.

It hardens with age.

Free from corrosion and withstand chemical attacks

Bind strongly with steel as it is weak in tension

Concrete Manufacturing Process consists of many stages. The Concrete mix for delivery from a plant instead of mixing on the job site. The concrete mixes, transports and delivers to a construction site to place in formworks for construction. And to form various structures, like a column, beam, slab, etc.

Concrete Manufacturing Process

The main Concrete Manufacturing Process is as follows

• Batching
• Mixing
• Transporting
• Placing
• Compacting
• Curing

1. Batching

It is the main thing in the Concrete Manufacturing Process. The measurement of materials like aggregates, cement, water necessary for preparing different grades of concrete is Batching. It is by two processes. One is volume and other is weight batching. The volume batching is by mixing materials with its volume. And weight batching is by the self-weight ratio of materials. It has ratios according to standard codes. Some of the different grades of concrete are M10, M20, M25, M30.

2. Mixing

Mixing is to produce uniform, high-quality concrete. The mixing equipment is capable of effective concrete material. Separate paste mix shows the mixing of cement and water into a paste before combines with aggregates. This increase the compressive strength of concrete. This paste mix in high-speed, shear-type mixer at a water-cement ratio of 0.30 to 0.45 by mass. The premix paste blends with aggregates. The remaining batch water and final mix complete in a rotating concrete mixing equipment.

3. Transporting

Transporting concrete require great care. After mixing, the concrete transports to site. The mixing carries near the construction site. A bucket, ropeway, belt conveyor use to transport concrete. Readymix conveyor trucks use mostly in the modern construction times. The concrete transporting by conveyor truck has time limits. The concrete transporting by trucks reach the construction plant early.

4. Placing

Concrete to place in a good manner. It places without segregation to reach maximum efficiency. The concrete not to pour over a height of 1.5m. As the height of pouring concrete increases, it leads to separation of aggregates and cement paste. It causes segregation of concrete and causes honeycomb. Many concrete placing equipment use in modern construction times. some of the equipment are concrete pumps and boom lifts. Concrete pumps are normal pumps with joints to connect and remove according to needs.

Boom lifts are concrete pumps with movable arms. With the help of movable arm, a concrete place easily at heights and corners which is difficult with the normal pump.

5. Curing

Curing is to provide best strength and hardness to concrete. It is the next step after placing of concrete. Curing helps concrete to gain strength early. The concrete requires a moist and wet environment to gain full strength. Proper curing of concrete leads to increase the strength of concrete. And prevent cracking at surface dries. Avoid freezing and overheating of concrete to gain its full strength.

Concrete in construction Field is a mixture of paste and aggregates. It composes of fly ash, fine and coarse aggregate, water and chemicals. The fine aggregates are sand and coarse aggregates are gravel. By hydration, the paste hardens and gains strength to form the concrete.

Concrete in construction Field

Concrete is soft in newly mix, strong at hardens. Hence concrete uses to build bridges, superhighways, houses, and dams.

There are some important factors involve in the manufacturing process of concrete. They are

• Proportioning
• water-cement ratio
• Ingredients
• Hydration
• Placement
• Curing and
• Special techniques

Aggregates, water, and the cement combine, the mixture hardens. By hydration, the paste hardens and get the strength to form concrete. During this reaction, a node forms on the surface of each cement particle. The node grows and expands until it links up with nodes from other cement particles.