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.
Portland cement mixed with sand, gravel and water, a process called hydration, is how concrete is created. Crushed stone aggregate fine and coarse aggregates make up the bulk of a concrete mixture. Durability of concrete may be defined as the ability of concrete to resist weathering action, chemical attack, and abrasion while maintaining its desired engi-neering properties. Different concretes require different degrees of durability de-pending on the exposure environment and properties desired. For example, concrete exposed to tidal seawater will have different requirements than an indoor concrete floor.
• Prestressed concrete is a modern material in which the stresses resulting from external loads are counteracted to a desired degree by introducing internal stresses of a suitable magnitude. • In reinforced concrete members, the prestress is commonly introduced by tensioning the steel reinforcement. • The apparent tensile strength of a material like concrete, which is strong in compression but weak in tension, is increased by application of permanent compressive stresses. • ¬¬¬¬Once the initial compression has been applied, the resulting material has the features of ductile high-strength steel when subject to tension forces and high-strength concrete when subjected to any compression forces. The tensile strength of the material increases because the subsequent application of tensile stress must nullify the compressive prestress.
Concrete: cellular concrete of clay- gypsum and invention of light weight concrete Ferro concrete: this concrete is made up of a layer of fine mesh wire saturated with cement. Gunite: or commonly referred as a shot crete. This type or form of concrete is most commonly used in areas where formwork is limited or hard to use. Shoring up exposed vertical excavations, banks or surfaces susceptible to collapse. For example, vertical soil or rock surfaces.
For this the mold should be made from high strength preferably of hardened steel. Secondly, for better mechanical properties it is advised that the molded items be annealed. Thirdly, mold release agents if required should only be made from fluorine based compounds to avoid stress cracks. Applications Poly (ether sulphone) has a variety of applications in a vast array of fields. The most successful applications are mentioned below.
The material would then be pulverized, with which you would get a powder. When this powder was mixed with water, it would become as hard as rock. Concrete Concrete made it possible to use bricks and concrete to build massive permanent structures. Concrete took the place of rubble for the filling between the bricks of a wall. Stones that were irregularly shaped could now easily be used to build a wall because they had concrete to
In and around Pittsburgh, various pillars and materials are used to support structures. The type of pillar to be used depends on a number of issues, such as the structure to be put up and the period such a structure is to exist. For houses, for instance, engineers tend to use thick round pillars, filled with concrete to give the structure in question the support it needs. The cross-section depends on the width and height of the building, plus its intended purpose. Materials used in such pillars include cement and sand.
Properties of Roller Compacted Concrete with Pozzolan as Cement Replacement Material Introduction: Roller compacted concrete (RCC) gets its name from the heavy vibratory steel drum and rubber-tired rollers used to compact it into its final form. RCC has similar strength properties and consists of the same basic ingredients as conventional concrete_ well graded aggregates, cementitious materials, and water_ but different mixture proportions. The largest difference between RCC mixtures and conventional concrete mixtures is that RCC has a higher percentage of fine aggregates, which allows for tight packing and consolidation . RCC may be considered for applications where no-slump concrete can be transported, placed, and compacted