Concrete

**Concrete** is a manufactured mixture of cement and water, with aggregates of sand and stones, which hardens rapidly by chemical combination to a stonelike, water-and-fire-resisting solid
of great compressive but low tensile strength.

**Pros-and cons**
of continuity (absence of joints) and of fusing with other materials.
 * Strengths:** Cheap, fireproof and weatherprof. Molds to any shape, strong in compression. It provides an economical substitute for traditional materials, and it has the advantages


 * Weakness:** Cracks with temperature changes, weak in tension.

**Reinforced concrete:**
Reinforced concrete was developed to add the tensile strength of steel to the compressive strength of mass concrete. It was invented (1849) by Joseph Monier. The typical form of using reinforced concrete is to embedded the metal by being set as a mesh into the forms before pouring, and in the hardened material the two act uniformly. The combination is much more versatile than either product; it serves not only for constructing rigid frames but also for foundations, columns, walls,floors, and a limitless variety of coverings.

The school of Plastic Arts by Arq. Mauricio Rocha Iturbide

Pre-cast concrete means the employment of 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.
 * Pre-cast concrete**

Casa pentimento by J.M. Sáez and D. Barragán.

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.
 * Prestressed concrete**



Concrete shell produces a radical effect on architecture. It 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.
 * Concrete-shell**

The Palace of Justice (the formal reception rooms of the Ministry of Justice) by Oscar Niemeyer


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

Several terms - tilt-up panel construction, tiltwall construction, precast concrete building construction - are used to reference new or nontraditional cement building processes.

"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 cement called panels directly at the job site. The cement panels are then tilted up into position around the building's slab to form the walls. Because the concrete tiltwall forms are assembled and poured directly at the job site, no transportation of panels is required. One major benefit of this is that the size of the panels is limited only by the needs of the building and the strength of the concrete panels themselves. Tilt-up construction panels can sometimes be extremely wide and/or tall. Tilt-up concrete panels have been measured at just over 69 feet across and almost 93 feet from top to bottom. Thus, architects and tilt-up concrete contractors have a great deal of flexibility in planning and creating their buildings. Because concrete tilt-up walls are poured outdoors, contractors are at the mercy of climatic conditions. When temperatures drop below freezing, curing the concrete panels becomes more difficult and expensive. This is why tilt-up concrete construction is particularly popular in southern parts of the United States, where cold weather occurs less frequently. Certainly, tilt-up concrete buildings are built in northern areas, but the window of time for temperate weather is much smaller and less predictable, which can make construction schedules more difficult to meet. 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. Because the precast concrete forms are poured indoors, this activity can take place regardless the weather conditions. After curing, the precast concrete panels are trucked to the job site. From this point, precast concrete buildings are assembled in much the same manner as tiltwall buildings. 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. It would be impossible to load precast panels that were 60 feet wide or 90 feet long onto trucks and transport them any distance. 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 concrete 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 tilt-up as a viable option."1

1 _ http://www.tiltup.com/commercial-construction-articles/precast-concrete-tiltwall-tilt-up/