Concrete

﻿ ﻿Concrete is a building material made out of cement and water, that is also mixed with sand and stone. It has many advantages, it is waterproof, fireproof and since it can be poured into forms while liquid to produce a grat variety of structural elements. Also, it is a economical substitute for traditional materials, it fuses with other materials and it has the absence of joints. On the other hand, concrete can break with sudden changes in temperature and its weight is also a disadvantages. Reinforced concrete was developed to add the tensile strength of steel to the compressive strength of mass concrete. It serves not only for constructing rigid frames but also for foundations and columns. Over the years building techniques with concrete have developed and allowed concrete to be used more easily for more complicated structures. For example, concrete-shell construction allows the erection of vast vaults and domes.Precast-concrete construction is less time consuming but costs in erection and Prestressed concrete can resist particular load.

|| concrete-shell construction permits the erection of vast vaults and domes with a concrete and steel content so reduced that the thickness is comparatively less than that of an eggshell. || precast-concrete construction , employs bricks, slabs, and supports made under optimal factory conditions to increase waterproofing and solidity, to decrease time and cost in erection, and to reduce expansion and contractions || prestressed concrete provides bearing members into which reinforcement is set under tension to produce a live force to resist a particular load. Since the member acts like a **spring**, it can carry a greater load than an unstressed member of the same size. || || || || precast concrete:
 * • Definitions (concepts found in the text)|| Concrete is a manufactured mixture of cement and water, with aggregates of sand and stones, which hardens <span style="font-family: Times New Roman,Times New Roman;">rapidly by chemical combination to a  stonelike<span style="font-family: Times New Roman,Times New Roman;"><span style="font-family: Times New Roman,Times New Roman;">,  water-and-fire-resisting <span style="font-family: Times New Roman,Times New Roman;"><span style="font-family: Times New Roman,Times New Roman;">solid of great  compressive <span style="font-family: Times New Roman,Times New Roman;"><span style="font-family: Times New Roman,Times New Roman;">but low  tensile strength<span style="font-family: Times New Roman,Times New Roman;"><span style="font-family: Times New Roman,Times New Roman;">.



Concrete shell:



• What is the difference between tiltwall construction, tilt-up panel construction and pre-cast concrete construction?

tilt-up and tiltwall are two terms used to describe the same process. For a tilt-up concrete building, the walls are created by assembling forms and pouring large slabs of concrete called panels directly at the job site. The panels are then tilted up into position around the building's slab. On the other hand, Tiltwall panels can sometimes be extremely wide and/or tall

The precast concrete building process is similar to tilt-up construction, but it addresses the challenges presented by weather. For precast concrete buildings, work crews do not set up forms at the job site to create the panels. Instead, workers pre cast concrete panels at a large manufacturing facility. The fact that precast concrete walls are formed at a manufacturing facility resolves the weather issue, but presents a different limitation not found in tilt-up construction. Because the panels must be transported - sometimes over long distances - places a substantial limitation on how wide or tall each panel can be.For a precast construction project, the panels must be smaller and more manageable to allow trucks to haul them over the road to their final destination. This places greater design restrictions on architects and limits the applications where precast construction can be used.

Clearly, tilt-up or tiltwall construction and precast concrete are similar processes. Because tilt-up affords more flexibility, it is the method of choice in locations where the weather allows it. Precast concrete is a suitable choice in circumstances where environmental factors and the construction schedule preclude tiltwall as a viable option