The first concrete structures were built by Nabatean or Bedouin merchants who occupied and controlled a series of oases and developed a small empire. A bricklayer from Andernach, Germany, tried to mix volcanic ash called trass with lime mortar. The resulting material was water resistant and strong, and the chain reaction initiated by the discovery would lead to the creation of modern cement. Egyptians used early concrete forms more than 5000 years ago to build pyramids.
They mixed mud and straw to form bricks and used gypsum and lime to make mortars. The invention of reinforced concrete gave the material a new life. It was pioneered in France in the mid-19th century, but was popularized by California-based engineer Ernest Ransome, who poured iron (and later steel) bars to improve its tensile strength. Take part in the history of concrete today with PC Concreting in Canberra services and equipment.
While modern concrete is a mixture of cement based on lime, water, sand and an aggregate such as gravel, the recipe for concrete established by architect Vitruvius in the first century BC included pozzolana and pieces of volcanic rock, known as tuff. Modern concrete is generally prepared as a viscous fluid, so that it can be poured into molds, which are containers erected in the field to give the concrete the desired shape. Around 200 BC, the Romans successfully implemented the use of concrete in most of their construction. A concrete plant consists of large storage hoppers for various reactive ingredients such as cement, storage of bulk ingredients such as aggregates and water, mechanisms for adding various additives and amendments, machinery for accurately weighing, moving and mixing some or all of those ingredients, and facilities for dispense mixed concrete, often to a concrete mixer truck.
Examples of improved appearance include patterned concrete in which the wet concrete has a pattern printed on the surface, to give a paved, cobbled or brick effect, and may be accompanied by coloring. Residents could sit in cast concrete furniture designed by Edison, keep food fresh in their concrete fridge, and entertain themselves with their concrete phonograph cabinet. Ransome patents a system that uses twisted square rods to improve the bond between steel and concrete and starts building with steel-reinforced concrete. Similar systems continue to be used; depending on the volume of the pour, the concrete mix used, and the ambient air temperature, the cooling process can take many months after placing the concrete.
Concrete production is the process of mixing the various ingredients: water, aggregate, cement and any additive to produce concrete. Most concrete is poured with reinforcing materials (such as rebar) embedded to provide tensile strength, resulting in reinforced concrete. For example, lower floor columns of high-rise concrete buildings can use concrete of 80 MPa (11,600 psi) or greater, to keep column sizes small. Additives are materials in powder or fluid form that are added to concrete to give it certain characteristics that cannot be obtained with simple concrete mixes.
To ensure complete hydration during curing, concrete slabs are often sprayed with curing compounds that create a film that retains water on the concrete. Fiber reinforcement, in which glass, carbon, steel, nylon, or other synthetic fibers are mixed into wet concrete prior to pouring, was introduced as a way to reinforce concrete. Modern paving methods and design practices have changed the economics of concrete pavement, so that a well-designed and laid concrete pavement will be less costly in upfront costs and significantly more economical over the lifecycle. .
