What is Concrete?
Concrete is a construction material composed of cement (commonly Portland cement) as well as other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate such as gravel limestone or granite, plus a fine aggregate such as sand and water) and chemical admixtures. The word concrete comes from the Latin word "concretus", which means "hardened" or "hard".
Concrete solidifies and hardens after mixing with water and placement due to a chemical process known as hydration. The water reacts with the cement, which bonds the other components together, eventually creating a stone-like material. The reactions are highly exothermic and care must be taken that the build-up in heat does not affect the integrity of the structure.
Concrete is used to make pavements, architectural structures, foundations, motorways, roads, bridges, overpasses, parking structures, brick or block walls and footings for gates, fences and poles.
What is a Concrete Mixer?
A concrete mixer (the more appropriate name for a cement mixer) performs the function of mixing concrete, water and either gravel or sand to make concrete. A revolving drum is used in the concrete mixer to properly mix these components. A portable concrete mixer gives the needed time for the construction workers to use it, before it becomes hard. An alternative to a machine is mixing concrete or cement by hand. This is usually done in a wheelbarrow; however, several companies have recently begun to sell modified tarps for this purpose.
Today’s Concrete Mixer
Today’s market increasingly requires consistent homogeneity and short mixing times for the industrial production of ready-mix concrete, and more so for pre-cast/pre-stressed concrete. The increasing demand for ready-mix concrete with short mixing times meant for industrial production eventually resulted in many new technologies in concrete production.
Using concrete mixers, batch mixing with twin-shafts with only thirty- seconds of mixing time per batch are possible now. Worldwide, twin-shaft batch mixers are becoming more important for high-quality concrete production. They introduce very high turbulence into the mix and achieve about 95% homogeneity at only around 30 seconds mixing time per batch.
Delivery of ready-mix concrete from the factory or plant to the construction yard is made by a concrete mixer, which is part of special transport trucks with a spiral blade fitted to overcome the tipping of large drums attached to the concrete truck. Continuous rotating concrete mixers totally mix the concrete and, using its own hydraulic link cylinder, it also completely empties the concrete without leaving any residue in the drum.
From there, the cement truck may go onto chutes to guide the viscous concrete directly to the job site. If the truck cannot get close enough to the site to use the chutes, the concrete may be discharged into a concrete pump connected to a flexible hose or onto with a conveyor belt which can be extended some distance (typically ten meters). Meanwhile, the pump provides the means to move the material to precise locations, multi-floor buildings and other distance-prohibitive locations.