UNIT 1
INTROUDC
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1.1 INTRODUCTION
Concrete is a composite material formed by the combination of (a) cement, (b) aggregate and (c) water, in a particular proportion in such a way that concrete produced meets the need of the job on hand, particularly as regards its workability, strength, durability and economy.
Hence, it is necessary to understand the details of the above materials.
1.2 HISTORIC DEVELOPMENT
1.3 COMPOSITION OF CONCRETE
1.4 ADVANTAGES OF CONCRETE OVER OTHER MATERIALS
[A] Fresh Concrete
Definition and Its Ingredients
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In the designation of a concrete mix, M refers to the mix and the number to the characteristic compressive strength of cube at 28 days, expressed in N/mm2.
The “characteristic strength” is defined as the strength of material below which not more than 5% of the test results are expected to fall.
Importance of Concrete
Concrete is the most important construction material because it is difficult to find out another material of such versatility and mouldability at such a cheap price. (i) It has got good compressive strength, durability, impermeability, fire resistance and abrasion resistance. (ii) Its weakness in tensile strength can be made-up by the use of reinforcing and prestressing techniques and this has made the use of concrete widespread and now it is almost used everywhere. (iii) In India, about 60% of plan outlay accounts for construction only. Out of this, cement and cement product would account for more than 50%. It means that 30% of the total outlay goes into cement concrete. Therefore, concrete has got a tremendous impact upon our economy and we should use this economically and judiciously.
Necessity of Supervision for Concreting
When reading of the concrete that the ancient Romans used, and learning of their unique mixture of volcanic ash and slaked lime (“pozzolana”) I find it most interesting that this concrete still proves to be standing in some places today! It is said to be less sturdy than what we use here in America (Andrews, 2012) but no doubt it gave modern civilization the ingenuity to create what we use today.
The basic principle to remember is that concrete is a sloppy God-awful mess when we first look at it but then we turn it into something wonderful. We take the sloppy mud like concoction and
Concrete can be looked at as a material made from sand, gravel and cement. According to Lambert (2002), “the first major concrete users were the Egyptians in around 2,500 BC and the Romans from around 300 BC”. Roman concrete like modern concrete was an artificial building material made up of aggregate, binding agent and water. Aggregate could be gravel, chunks of stone, chunks of rubble, broken bricks, etc. Binding agent could be mud , lime or gypsum, mixed with rubbles stone. The Roman added pozzolona, a special volcanic dust found in central Italy (Archserve, n.d). The addition of pozzolona made the bond with the aggregate far stronger than what was traditionally being used. This development drastically changed and shaped construction work in the life of Rome.
Nevertheless, this was a standard concrete technique in history, the Romans decided to strengthen their concrete mixture with another substance.
If you go to Rome today you can see many ancient ruins that are still there because Romans used a ‘secret’ ingredient to stand their buildings. An example would be the Colosseum. In Rome, you can see that most of the Colosseum are still there, that’s because the Romans used cement when they made it. This proves that cement is strong and should be used in all
First, concrete durable. Concrete is something that will outlive other products up to three times over (“What Makes…”). In addition to durability, concrete is efficient. Concrete can be made with byproducts from power plants, and other aspects of manufacturing. Concrete is primarily made up limestone, the most abundant material on Earth. Above all of this concrete can be recycled. Concrete can be crushed and recycled into another structure or product, reducing the need to mine the limestone for production. Concrete also allows water to pass through which reduces the chance of flash flooding, erosion, and water table depletion as compared to other materials. This is a major check in the sustainability of concrete; the conservation of soil, landscape and ecosystems. Concrete is a very green option when it comes to building
What is concrete. According to Concrete Network (1999) “Concrete is made up of three basic components: water, aggregate (rock, sand, or gravel) and cement. Cement, usually in powder form, 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”. The Roman's did it a little
Concrete is a tough and reliable material, and it can be used for a wide range of projects. Eventually though, a structure made from this versatile material will need to be replaced. At the very least, it may require repairs.
Both the use of the arch and the invention and use of cement are ubiquitous features of Roman buildings which have survived to the modern era. The Roman arch style has been widely copied and adapted, and both this style and the use of cement have been fundamental elements of buildings everywhere ever since.
Concrete is the ultimate building block of society; there are a plethora of ways that it has been used. Romans were some of the first, in recorded history, to use it; they used it to build their aqueducts and even the Colosseum. If anything, the Romans were some of the first to make huge developments in concrete, and they were some of the first to actually use concrete on a large scale. America has also used concrete on a large scale, using concrete to build the Hoover Dam and the Grand Coulee Dam. Those examples show how concrete is an incredibly strong and durable building material that has remained standing after all these years and will continue to be the primary
Concrete is used for many different things in daily life, although is often taken for granted. Concrete has a very deep history that leads us up to the modern day concrete and variations of. Most people will turn a blind eye, but at one point in history concrete was a stellar invention that had many different purposes and uses and still does today.
Most people think concrete is an impenetrable solid. But in actually, concrete is a porous material with many capillaries and voids throughout the surface. Although concrete is strong in compressive strength, it is weak in tensile stength and elasticity. Concrete can tolerate heavy loads, but it is susceptible to damage which causes it to break apart over time.
In order to discuss concrete; one must first mention cement. Cement is a water-based binder used to bind other building materials together. It is used in the production of mortar and concrete during the construction process. Concrete is a material used in construction, made by mixing aggregate, cement, small stones and water. Cement is important because it hold structures together. Many sources states concrete was invented 1756 by a British Engineer named John Smeaton. He did so by mixing pebbles as a coarse aggregate into a powdered brick into the cement. Years layer in 1824, a English inventor named Mr Joseph Aspdin created the first true artificial cement by burning ground limestone and clay together. He is also noted for creating today’s popular concrete; Portland cement. Many buildings use concrete because of its strong element. It solidifies then hardens after mixing with water and placement due to the chemical process known as hydration. Water reacts with the cement, which bonds the other components together, eventually creating a stone-like material. Concrete is used to make pavements, pipe, various structures, foundations, roads, bridges, brick walls and so on. It is either produced site-cast or pre-cast. Site-cast Concrete is standard concrete that is poured into site-specific forms and cured on site; the concrete is created on the actually construction site. Precast concrete is a construction
One of the biggest advantages that concrete has over the other driveway paving options is that the concrete can be customized. For example, if you want to get away from the standard black or gray driveway that your neighbors most likely have, you can choose to have your driveway constructed from concrete and then have the contractor stain the concrete into a completely
The definition of high strength changes over the years as concrete strength used in the field increases. Any construction activity requires several materials such as concrete, steel, brick, stone, glass, clay, mud, wood, and so on. However, the cement concrete remains the main construction material used in construction industries. For its suitability and adaptability with respect to the changing environment, the concrete must be such that it can conserve resources, protect the environment, economize and lead to proper utilization of energy. To achieve this, major emphasis must be laid on the use of wastes and byproducts in cement and concrete used for new constructions. The utilization of recycled aggregate