Self-consolidating concrete or self-compacting concrete (commonly abbreviated as SCC ) is a concrete mixture that has low yield stress, high deformability, segregation resistance (preventing the separation of particles in the mixture), and moderate viscosity (necessary to ensure uniform solid particle suspension during transport, placement (without external compaction), and subsequently until the concrete set).
In everyday terms, when poured, SCC is a very liquid mixture with the following special practical features - it flows very easily inside and around the formwork, can flow through the barrier and around the corner ("graduation capability"), close to self-leveling (though not really self-leveling), does not require vibration or tamping after pouring, and follows the shape and texture of the mold surface (or shape) very closely arranged. As a result, pouring SCC is also much more labor intensive than the standard concrete mix. Once poured, SCC is usually similar to standard concrete in terms of regulation and time of preservation (gain strength), and strength. SCC does not use high water proportions to become liquids - in fact SCC may contain less water than standard concrete. In contrast, SCC obtains its fluid properties from an unusually high proportion of fine aggregates, such as sand (typically 50%), combined with superplasticizers (additives that make sure particles are dispersed and not settled in fluid mixtures) and admixtures that increase viscosity (VEA). ).
Typically, concrete is solid, viscous when mixed, and when used in construction, requires the use of vibration or other techniques (known as compaction) to remove air bubbles (cavitation), and hole-like hives, especially on surfaces, where air trapped during pouring. This type of air content (unlike the one in aerated concrete) is undesirable and weakens the concrete if left. However it is tiring and takes time to eliminate vibration, and improper or inadequate vibration can lead to undetected problems later on. In addition some complex shapes can not be easily vibrated. Self-consolidating concrete is designed to avoid this problem, and does not require compaction, thereby reducing labor, time, and possible sources of technical problems and quality control.
SCC was conceptualized in 1986 by Prof. Okamura at Ouchi University, Japan, when skilled labor was in limited supply, causing difficulties in concrete-related industries. The first generation SCC used in North America is characterized by the use of relatively high binding content and high doses of chemical mixtures, usually superplasticizers to improve flowability and stability. Such high-performance concrete has been widely used in repair applications and for casting concrete in forbidden areas. The first generation of SCC is therefore characterized and determined for specific applications.
SCC can be used for casting of reinforced parts, where no access to the vibrator for compaction and in the form of complex formworks that may not be cast, provides a much superior surface than conventional concrete. The relatively high cost of materials used in the concrete continues to hamper its widespread use in various segments of the construction industry, including commercial construction, but productivity economies take over in achieving profitable performance benefits and working to become economical in the pre-cast industry. Merging powders, including additional cement and fillers, can increase the volume of the paste, thereby increasing deformability, and can also increase the compactness of the paste and the stability of the concrete. Reduction of cement content and increased density of packing material smoother than 80 Ã,Âμm, such as fly ash etc. can reduce the water-cement ratio, and demand for high water dampers (HRWR). Reduction of free water can reduce the viscosity-visible viscosity (VEA) concentration required to ensure proper stability during casting and afterwards until early hardening. It has been shown that the total fine aggregate content ("fine", usually sand) is about 50% of the total aggregate corresponding in the SCC mixture.
Video Self-consolidating concrete
Overview
- The SCC is measured using a slump-flow (or "flow table") test rather than a regular slump test, because it is too fluid to keep the shape when the cone is removed. A typical SCC blend will have a slump of about 500 - 700mm.
- SCC is attenuated, not amplified, by vibration. Since vibration is not required to solidify the mixture, all it achieves is to separate and separate it.
Maps Self-consolidating concrete
References
See also
- Concrete deterioration test
- Test flow table
External links
- Proportion of self-contained concrete - UCL method - a paper summarizing the general mixture, usage, additive options, property, and extensive information about SCC.
- Working With SCC No Need to Be Hit or Miss - the experience of precast concrete makers is SCC/what to do and not do.
- * Self Compacting Concrete - The Flow Moment by Unibeton Ready Mix
Source of the article : Wikipedia
0 Comments