Self-compacting concrete (SCC), also known as self-consolidating concrete, is a specialized high performance concrete that does not need to be compacted by vibration as it compacts into every corner and space of a formwork as a result of its own weight. The most laudable property of SCC is that it leaves no void in the formwork, and that too, without the need of mechanical vibration (De Schutter, 2007; Okamura & Ouchi, 2003; Hurd, 2002). SCC, therefore, has superior engineering properties that make it a highly versatile and immensely useful material for construction. It was first developed in Japan in 1988 as a result of research on durability of concrete structures. Since then, research on SCC has progressed to a large extent, leading to its increased applicability in the construction industry.
Evolution of Self-Compacting Concrete – From Necessity to Invention
‘Necessity is the mother of invention’, goes the adage. Such is the story of Self-Compacting Concrete, whose invention materialized out of an urgent need. Increasing the durability of concrete structures was Japan’s major concern in the 1980s (Okamura & Ouchi, 2003). Japan faced a severe shortage of skilled workers in its construction industry, and compaction of concrete had to be performed by skilled workers to ensure durability of the concrete structures. Therefore, the development of self-compacting concrete that could fill every space of the formwork by virtue of its own weight without the need of mechanical vibration seemed a very promising alternative. This would also eliminate noise sensitivity, white finger syndrome and other environmental and biological inconveniences that resulted from the vibrations on site (De Schutter, 2007). The concept of SCC was first pr...
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...07). Report 38: Durability of Self-Compacting Concrete - State-of-the-Art Report of RILEM Technical Committee. Bagneux: RILEM Publications.
Hurd, M. K. (2002). Self-Compacting Concrete— Can you fill your forms without vibrating. Washington, DC: Hanley-Wood, LLC. Retrieved 28 November, 2011 from http://www.concreteconstruction.net/Images/Self-Compacting%20Concrete_tcm45-589881.pdf
Okamura, H., and Ouchi, M. (2003). Self-compacting concrete. Journal of Advanced Concrete Technology, 1 (1), 5-15. Retrieved 28 November, 2011 from http://www.eng-forum.com/articles/articles/selfconcrete.pdf
Shah, D. L., and Modhere, C. D. (2009). Parameter-Study on the Influence of Steel and Polyester Fibers in the Self Compacting Concrete. The Pacific Journal of Science and Technology, 10 (2), 178-186. Retrieved 28 November, 2011 from http://www.akamaiuniversity.us/PJST10_2_178.pdf
• Compaction is done in a rectangular or triangular pattern in a number of phases, each phase has a number of passes, it could be a primary pass, or secondary pass, …etc.
Many people go through tough struggles in their lives, but no one really sees it, and most of the time no one really cares. The Rose That Grew From Concrete was written by Tupac Shakur. In this poem the author uses conflict, the characters, and mood to illustrate that just because something shouldn’t happen doesn’t mean that it won’t happen.
Suddenly the brick occurs to mind when the story starts by talking about lightness. A brick itself is small and light enough to be handled by hand, but a brick house is hefty. The brick is made from dried mud; that makes clearer the meaning of lightness of brick. However, the land that holds the mud means a full deadweight. Heaviness from lightness and lightness from heaviness, there are various possible ways to look into the relationship between heaviness and lightness through the brick; that’s why we should talk about heaviness while keeping lightness in mind and vice versa.
Metal foam in the future will be an integral part of our society, however, in order to prevent abuse from this technology ethical principles will be applied and anticipated. Metal foam will be heavily used in the medical field, specifically orthotics. It potentially could replace and enhance the human bone structure. Consequentially, there is a great potential that people will misuse the technology, prevent others from benefiting from the technology, and falsely misrepresent the technology. The principles used to anticipate ethical problems are justice, rights, and consequentialism.
The objective of this lab experiment was to determine the density of a set of plastic beads by using two different methods and decide which method was better. Density is a physical property that is defined as the ratio of an object’s mass to an object’s volume. Also, density can be described as the measurement of how compact a substance is in a given space. To find an object’s density, it is necessary to measure the object’s mass, the amount of matter present, and volume, the space it takes up. Also when studying density, it is key to note how objects with varying densities behave. The density of water, at room temperature, is 1.00 g/mL and is often used to determine the density of a substance based on if it sinks or floats in water. The measurement
For centuries slavery had been a problem in many countries but especially in the United States of America since it was known as “the land of the free”. Slavery mostly targeted people of color, African Americans. These African Americans were being sold to white males and were forced to work and do whatever they say. Slaves did not have their own home, they did not have a voice. Slaves were not allowed education so they were mostly illiterate. After many, many years and presidents later, slavery was abolished in the south and in the north. Although African Americans were now considered “free” it was still the opposite of that. Two African American men, Booker T. Washington and W.E.B Du Bois wrote autobiographies explaining their views and their
Concrete poetry presents its readers with a unique and often confounding situation. In addition to using language or parts of language in non-traditional ways, concrete poetry also uses elements that are more commonly associated with visual art. However, concrete poetry is not visual art. It is still concerned, primarily, with the use of language, generally to communicate some meaning to the reader in a way that is undeniably linguistic in nature. Concrete poetry is therefore an especially unique genre that draws upon and incorporates many different concepts from a variety of disciplines in order to fill in the gaps left when traditional grammar and syntax are eschewed.
According to major supplies, “Use of synthetic fibers for reinforcing concrete is continuously, increasing. The increase has been considerable since 1980, but slowed somewhat in 1990, a year of substantial construction cutbacks. Apparently the construction community believes there are advantages in the use of synthetic fibers in concrete.” (Schupack) Synthetic fibers are used to improve crack control in concrete. Some reports say that synthetic fiber reinforced concrete (SFRC) would replace welded wire fabric in many slab-on-grade applications. But in reality if the welded wire fabric is placed properly it controls crack width better than the synthetic fiber reinforced concrete. In a case study of the use of synthetic fibers in reinforced concrete, the following conclusions were obtained. No matter what concrete placing job is being done, there is no substitute for good concrete practices. The use of a low fiber volume mix will help control plastic shrinkage cracks and bleeding, but not give good cracking control once the crack forms. The synthetic fibers running through a crack have a poor bond providing no shear friction. Impact and toughness tests on synthetic fiber reinforced concrete imply less edge spalling will occur. The American Concrete Institute (ACI) conducted two studies on polypropylene fiber reinforced concrete, one dealing with plastic shrinkage cracking and the other on permeability characteristics. Plastic shrinkage cracking occurs when the surface water on the concrete evaporates faster than the bleed water reaches the surface of the concrete. It was determined by the plastic shrinking cracking study that polypropylene fibers helped reduce the total plastic shrinkage crack area on test panels. Also determined is that the screeding rate affects the total crack area in polypropylene reinforced concrete, while finishing operations showed no significant effects. This study also suggests the use of longer fibers (about 0.75in.) will produce less crack area. “Permeability plays an important role in long-term durability of concrete materials. Permeability of concrete generally refers to the rate at which particular aggressive substances (water, sulfates, chloride ions, etc.) can flow through the concrete.” (Soroushian) As discussed in the plastic shrinkage study that polypropylene fibers reduce cracking. Less cracking in the concrete surface that surface would be less permeable. In the permeability study, they concentrated on the effects of chloride and the permeability of the concrete. The results of this study concluded polypropylene fibers had little effects on chloride permeability of concrete. The polypropylene fibers only help reduce plastic shrinkage cracks.
Whether you are responsible for a major thoroughfare, commercial parking lot or residential driveway featuring asphalt pavement, you have probably heard that timely crack repairs can extend the life of your pavement. Cracks that are left open to the elements allow water to penetrate to the pavement's supporting foundation. The foundation becomes unstable and incapable of bearing the weight of the pavement, frequently leading to widespread damage that can only be remedied by replacing the pavement. However, you may not know whether to choose a hot-pour or cold-pour sealant when you ask a contractor to repair the cracks in your pavement. An overview of the differences between the two types of sealants can help you make the best choice for your
In this report, we will introduce and illustrate on precast concrete, pre-stressed concrete, ready-mix concrete, reinforced concrete, terrazzo and Urbanite in details.
Three types of compression test specimens are used: cubes, cylinders and prisms. In our country, usually cube and cylinder are used. The concrete grade is based on the 150 mm size cube strength and if the cylinder is tested, the strength should be modified into equivalent cube strength.
In this paper we have studied compressive strength of concrete by replacing natural aggregate with recycled aggregate by 25%, 50% and 75%.This mixture formed in the sample of cubes of dimension 150x150x150mm3.
As concrete is plastic material in Green State it has to kept in enclosure till its harden. This enclosure is known as ‘ Formwork or Shuttering’.
Concrete is a composite material composed of water, coarse granular material embedded in hard matrix of material (the cement or binder) that fills the space among the particles and glues them together. Concrete is known by Romans as old as 12 million years. It was a revolutionary material laid in the shape of arches, vaults and domes. Concrete is widely used for making architectural structures, foundations, brick/block walls, pavements, bridges/overpasses, highways, runways, parking structures, dams, pools/reservoirs, pipes, footings for gates, fences and poles and even boats. From roman to now Concrete has taken many designs. Present researchers have experimented with addition of materials to create improved properties such as strength or electrical conductivity.
Sustainable concrete materials and sustainable steel reinforcement have been introduced to civil engineers to get closer to the sustainable development. Sustainable buildings constructed with use of these materials have shown an increased service life and the final cost has been reduced due to them.