The strength of concrete varies according to the proportions of its constituents. Concrete gains its strength over time as it hardens by means of setting, where by cement undergoes a chemical reaction known as hydration. It can set and harden underwater hence it can be used as foundation material. Its hardening process can be enhanced by curing. Due to its workability it can be formed into different
Concrete materials are still a dominant material for construction due to its advantages suchas workability, low cost and fire resistance as well as its low maintenance cost. It is formed from a hardened mixture of cement, fine aggregate, coarse aggregate, water and some admixture. Massive exploration of the natural resources for producing concrete affect to the environment condition and global warning. We have responsibility to reduce the effect of the application of concrete materials to environmental impact. The concrete should be used as efficient as possible.
temperature, humidity and wind play a vital role in the quality and strength of hardened concrete. The following points must be ensured at site to produce the concrete of required strength: 1. In order to achieve full compaction and maximum density, it is necessary to use a mix with adequate workability. 2. To obtain maximum strength of the concrete a driest possible concrete should be produced and shall be compacted 100 %.
These materials have been used for both structural and appearance purposes. That is to say, they work to bear load and give the building a facade. Dry walls and wooden panelling have also been used inside. Steel beams are also easily identifiable supporting the stair cases made of concrete. The building itself is constructed with a wide array of structural elements.
Look around, and try to find an everyday object that is not made out of plastic. You should find only a few. Plastic takes up more than 75% of our everyday items… And humans are facing the pollution that plastic is causing to the earth. There isn 't a realistic solution to this, because plastic is used in automobile tires, and also is used in electronic devices, silicon etc. The reason plastic is used in many products is because it can withstand up to tons of pressure per cm3, is cheap, is durable, and finally, there is no worry for discoloring.
Steel is strong enough to be used for building structures and big projects. Although steel was used with big tasks it is also used in small items that people use in their everyday life. Many appliances are made out of steel such as fridges, dishwashers, ovens etc. Steel is also used in cars, shower trays in bathrooms, pots and pans, and
Why use composites? Advantages of Composites The greatest preferred standpoint of present day composite materials is that they are light and also solid. By picking a suitable mix of network and fortification material, another material can be made that precisely meets the necessities of a specific application. Composites likewise give plan adaptability in light of the fact that a large number of them can be formed into complex shapes. The drawback is frequently the cost.
Chapter 1 1. INTRODUCTION 1.1 General The various materials used in modern construction are concrete, bricks, timber, steel, etc. Each material has its own advantages and disadvantages. Advantages of structural steel include strength, speed of construction, prefabrication, high strength to weight ratio, sustainability, good fire resistance, and demount ability and good scrap value among others. It is used in load bearing frames in buildings and as members in trusses, bridges and space frames.
Concrete is weak in tension, and for normal strength concrete, tensile strength is only 10% of its compressive strength and for High strength concrete tensile strength ratio is further reduced. Thus, tensile strength of concrete is often neglected in strength calculations. However, it is an important property, because cracking in concrete is generally due to tensile stresses and the structural damage of the member in tension is often generated by progression in microcracking in thermal expansion coefficients between the aggregate and cement paste and decomposition of calcium hydroxide. At temperatures above 450˚C concrete compressive strength drops significantly due to loss of bond between the aggregate and cement paste. Under fire conditions tensile strength of concrete can be even more crucial in cases where fire induced spalling occurs in a concrete structural member.
This reaction makes the cement solid and binds other particles. Currently , The demand for cement is very high because it is very important uses. In this case the particles that will be used to make cement are reduced or exhausted, in another side, the cost to buy cement is very expensive. For this problem needed materials to replace the cement and also the material effect on the quality of concrete