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.

There are many types of cement produces to fulfill the needs in construction Industry. By changing compositions and adding substances different types of cement forms.

The Types of Cement

1. Ordinary Portland Cement
2. Acid Resistance Cement
3. Rapid Hardening Cement
4. Sulpher Resisting Cement
5. White Cement
6. Colour Cement
7. High Strength Cement
8. High Alumina Cement
9. Quick Setting Cement
10. Hydrophobic Cement
11. Expansive Cement
12. Masonry Cement
13. Blast Furnace Cement
14. Low Heating Cement
15. Air-entraining Cement
16. Pozzolana Cement

1. Ordinary Portland cement

It is the most common type of cement use. It produces in different grades. The most common is Grade-53, 43 and 33. It uses for construction of residential, commercial and other constructions. It forms by burning clay and limestone at high temperature. And grinding it with Gypsum.

2. Acid Resistance Cement

It uses for acid-resistance in the chemical industry. It uses for the storage of acids and chemicals in large Tanks. And it prevents white blooming and efflorescence in storage tanks.

3. Rapid Hardening Cement

It uses in the urgent repair works, concreting in cold weather. And it attains high strength quickly.  It mainly uses in the field of Marine structures, airfield, highway pavements and in bridge decks.

4. Sulpher Resisting Cement

It uses in the structure affects by sulfate attacks. It uses mainly in the construction of water supply, sewage treatment plant, dams, and Lining of canals.

5. White Cement

It is white in color. And does not contains any coloring chemicals. It uses for architectural decorative purposes and in aerodromes. It is costly.

6. color Cement

This cement contains coloring pigments. The amount of coloring material varies from 5 to 10%. chromium gives green color. Cobalt gives a blue color. And iron oxides give a brown color. It uses in swimming pools, garden parks, tennis courts, and for finishing of floors and external surfaces.

7.  Hige Strength Cement

High Strength Cement uses in the construction of special types of work to increase the strength of the structure. It uses for multi-story complex, railway sleepers, prestressed concrete and precast constructions.

8. High Alumina Cement

It contains 32% of alumina in it. Its setting time is more than 3.5 hours. And gives more time for mixing and placing of operations. It generates a large amount of heat mixing with water. So it not affects by frost. It uses in chemical plants and furnace insulations.

9. Quick Setting Cement

It sets quickly. And consist of less amount of gypsum. The initial setting time is 5 minutes. And final setting time is 30 minutes. It mainly uses int the construction of a bridge across river and sea.

10. Hydrophobic Cement

Hydrophobic Cement mainly uses to store cement for a long time in wet climatic conditions. And at aqua constructions.

11. Expansive Cement

On curing cement shrinks normally. But in this type of cement, it expands on curing. It mainly uses for water retaining structures like sumps, dams water tanks and for repairing concrete structures.

12. Masonry Cement

It has high workability, plasticity, and water retaining properties. It uses in preparing of cement mortar and plaster.

13. Blast Furnace Cement

It produces by adding slag obtains from the blast furnace. And consists of alumina, silica, and lime. It gains strength slowly. So it not uses in RCC structures.

14. Low Heating Cement

It uses to reduce the heat produces at setting time of concrete. It has low compressive strength. And uses mainly for mass concrete works.

15. Air-entraining Cement

It is a type of Portland cement. It contains an additive that causes small air bubbles in wet concrete. The bubbles relive internal pressure on concrete by providing tiny chambers. For the expansion of water when it freezes. It gives high resistance to severe frost action.

Cement is an important material in the building construction. It is a fine powder. And use to hold the construction materials together. It is the main component of concrete. And it is an economic material using in construction.

It is an important material in the construction. And replace clay and lime uses in construction from old times. It has an ability to hold the structure together.

And occurs by burning the mixture of limestone and clay at high temperature. And it forms a  product clinker. A specific quantity of gypsum adds with it and reduce to fine particles known as Cement. The most popular type is Portland Cement. On setting and hardening, it occurs like sandstone in Portland in England and denotes as Portland Cement.

Cement uses

It uses as a basic building material in the construction of structures. Mainly structures like, dams, bridges, apartments, water tanks, cooling towers, and chimneys.

Mortar obtains by mixing it with sand, water and use for masonry works. And mainly plastering of inner faces, outer faces of wall and ceilings.

Quick setting cement prefers for underwater construction and bridges across river and sea.

Expansive cements use to repair damage concrete structures.

It uses in jointing of the concrete pipes.

Cement concrete use for laying roofs, floors, columns, beams, slab, foundation, staircase and more.

White and Rapid hardening cement use for decorative purposes and for quick construction.

To provide color finishes to floors like swimming pools, outer surfaces of building a special type of color cement employs.

It uses in the construction of precast concrete pipes, drainage sewers.

High strength cement uses to repair damage concrete structures. And in the construction of the multi-story complex.

Use in railway platforms, fencing posts and seats in the parks.

It uses to manufacture precast Elements, Pcc and Rcc.

There are many Test For Bricks. Test conduct on bricks to obtain suitability of bricks employing in the construction of various structural elements. These test conduct in site and laboratory at the time of purchasing of materials. And in the time of construction of several structures. It is necessary to conduct the test for bricks to produce a good quality and strong structure.

Test For Bricks

There are several tests for bricks they are,

• Compressive or crushing Test
• Hardness Test
• Durability
• Sound Test
• Water Absorption Test
• Structure and
• Presence of chemicals

1. Compressive or crushing Test

 

The Compressive or crushing Test performs in a compression testing machine. The load applies on the top surface of the brick. The maximum load at which the brick breaks marks. The Compressive or crushing Test calculate by

                           The compressive or crushing strength of brick =  Maximum Load / Surface Area

The Minimum crushing strength of brick is 3.50N/mm². If the Compressive or crushing strength is lesser than 3.50N/mm², the brick fails and not useful for construction.

 

2. Hardness Test

Hardness Test is a simple test. A good brick is more resistance to abrasion. Sharp object scratches the surface of bricks and if there is no impression on brick then it’s a Hard Brick.

3. Durability

 

The Durability test is by dropping the brick from a height of one meter on a flat hard surface.

4. Sound Test

Sound Test performs by striking bricks with each other or with a hammer.  A clear ringing or a metallic sound hear striking with another brick.

5. Water Absorption Test

In Water Absorption Test the brick weights and soak in water for twenty-four hours. The Difference in weight indicates the amount of water absorbs by brick. The percentage of water Absorption is lesser than twenty percent for a good quality Brick.

6. Structure

It’s a physical test for bricks for its size, shape, and color. Brick possess standard shape, uniform size, plain surfaces and sharp edges. It is rectangular in shape and copper color. The standard size of a good quality Brick is 19cm x 9cm x 9cm. And it tests for voids, cracks, and any other foreign matters present in it.

7. Presence of chemicals

 

In this test, the brick soaks in water for one day and dry in shade. If the presence of grey or white deposits spots it indicates the presence of chemicals.