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Self-leveling concrete was invented in 1952 by Axel Karlsson from Sweden. The first product was a combination of wood glue, fine sand and cement with additives. [1] It was called flytspackel, which directly translates to "floating putty". The term self-leveling can be traced back to a patent applied by the company Lafarge in 1997. [2]
The mixer already exhibited the still common basic construction with a tiltable conical drum (as double cone at that time) with blades. On February 9, 1904, the first portable concrete mixer was patented by Richard Bodlaender, an inventor from Breslau, Germany. [2] This concrete mixer was horse-drawn and called 'Mortar Mixer'.
In civil engineering, concrete leveling is a procedure that attempts to correct an uneven concrete surface by altering the foundation that the surface sits upon. It is a cheaper alternative to having replacement concrete poured and is commonly performed at small businesses and private homes as well as at factories, warehouses, airports and on roads, highways and other infrastructure.
Self-consolidating concrete or self-compacting concrete (SCC) [1] is a concrete mix which has a low yield stress, high deformability, good segregation resistance (prevents separation of particles in the mix), and moderate viscosity (necessary to ensure uniform suspension of solid particles during transportation, placement (without external compaction), and thereafter until the concrete sets).
The volumetric mixer varies in capacity size up to 12 m 3 and has a production rate of around 60m 3 an hour depending on the mix design. Many volumetric concrete mixer manufacturers have innovated the mixer in capacity and design, as well as added features including color, multiple admixes, fiber systems, and the ability to do gunite or shotcrete.
The cone is placed in the center of the flow table and filled with fresh concrete in two equal layers. Each layer is tamped 10 times with a tamping rod. Wait 30 seconds before lifting the cone. The cone is lifted, allowing the concrete to flow. The flow table is then lifted up 40mm and then dropped 15 times, causing the concrete to flow.
They spread the concrete using shovels and rakes, sometimes using a straightedge back and forth across the top of the forms to screed or level the freshly placed concrete. After levelling the concrete, they smooth the surface using either a hand trowel, a long handed bull float o r by using powered floats.
Smoothing concrete with a large concrete float, or bull float. A concrete float is a tool used to finish a concrete surface by making it smooth. A float is used after the surface has been made level using a screed. In addition to removing surface imperfections, floating will compact the concrete as preparation for further steps.