Self Compacting Concrete.ppt __LINK__

Self-compacting concrete is able to flow and consolidate under its own weight and is deaerated almost completely while flowing in the formwork. It is cohesive enough to fill the spaces of almost any size and shape without segregation or bleeding. This makes SCC particularly useful wherever placing is difficult, such as in heavily-reinforced concrete members or in complicated workforms. Self-compacting concrete, also referred to as self-consolidating concrete, is an alternative to conventional concrete mixtures and allows concrete to be placed without vibration. With the use of SCC, the placement of concrete in the confined spaces is easy. The advantages of self-compacting concrete include: uniformity, high strength, higher fracture toughness, low permeability, high durability, fire-resistant concrete, and no segregation.

The objective of the research work was to evaluate the compressive and splitting tensile strength of self-compacting and normal concrete by using cylindrical specimens, in order to find out if the self-compacting concrete is able to show an increase in these strengths and a better bonding between aggregate and cement paste, compared to normal concrete. The tests were carried out in accordance with the standard guidelines and procedures as specified by the American Concrete Institute (ACI), which include the test methods for concrete. The data obtained from the tests were analyzed using different statistical methods to determine the trends. The water-cement ratios varied from 0.3 to 0.6 while the rest of the components were kept the same, except the chemical admixtures, which were adjusted for obtaining the self-compactability of the concrete. All SCC mixtures exhibited greater values in both splitting tensile and compressive strength after being tested, compared to normal concrete. The splitting tensile strength increased by approximately 30%, whilst the compressive strength was around 60% greater.

The Scanning Electron Microscopy images have shown that the width of the microcracks was greater for normal concrete than for self-compacting concrete, which implies that the aggregate-cement bonds were better for SCC than for normal concrete.

In conclusion, the strength of the SCC specimens was shown to be higher than that of the normal concrete, because of the chemical admixtures used in the concrete mixtures. The strength of concrete may improve over time as the cement paste bonds well with the aggregate, particularly in fresh concrete.

Self-compacting concrete is characterized by its high fluidity. Thanks to this property, it spreads into concrete formwork with no need for vibration equipment. This non-segregating concrete is distributed by its own weight, while maintaining the properties of regular concrete, such as durability and strength.

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