International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017
p-ISSN: 2395-0072
www.irjet.net
REHABILITATION OF REINFORCED GEOPOLYMER CONCRETE BEAM K.Santhosekumar1 1Student
Department of civil engineering KLN College of information technology. ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - The aim and scope of this project is to prepare
eco-friendly geopolymer RC beam with 100% replacement of cement along with wrapping of oven dried fibre mat with number of layers and achieving the required target mean flexural strength of conventional concrete. This project comprises material testing of ingredients for geopolymer concrete such as Low Calcium Fly Ash, Metakaolin, Lime, Alkaline liquids (sodium silicate+sodium hydroxide), Fine Aggregate (natural sand) and coarse aggregates.At first, The conventional Reinforced Concrete beam of grade M20 is casted and testing of conventional RC beam for finding the load carrying capacity and flexural strength was done after 28 days curing period. The report represents the comprehensive summary of extensive studies conducted on fly ash based geopolymer concrete. Test data are used to identify the effects of salient factors that influence the properties of geopolymer concrete in the fresh and hardened states. These results are utilized to propose sample for the design of geopolymer concrete mixtures.
Key Words: Low Calcium Fly Ash, Metakaolin, Lime, Alkaline liquids (sodium silicate+sodium hydroxide)
1. INTRODUCTION Concrete is the most abundant manmade material in the world. One of the main ingredients in a normal concrete mixture is Portland cement. However, the production of cement is responsible for approximately 5% of the world’s carbon dioxide emissions. Among the Green house gases Carbon dioxide is the one which contributes about 65% for climatic change in the environment. In order to create a more sustainable world, engineers and scientists must develop and put into use a greener building material. This is unacceptable in a world where sustainable and green building has become a major issue. This brings up a very good question: Is there a cleaner, more efficient, more reliable, and even stronger substitute to the concrete that is currently used? The answer is geopolymer concrete.
1.1 GEOPOLYMER CONCRETE Geopolymer concrete does not use Portland cement; it uses a highly abundant material called fly ash. Fly ash is a waste by product of thermal power plant with high fineness (> OPC) which produces an impermeable geopolymer concrete. Geopolymer concrete is also much more durable that Š 2017, IRJET
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ordinary concrete due to its resistance to corrosion. It is also much stronger than ordinary concrete.There are two main constituents of geopolymers, namely the source materials and the alkaline liquids. The source materials for geopolymers based on alumina-silicate should be rich in silicon (Si) and aluminium (Al). These could be natural minerals such as kaolinite, clays, etc. Alternatively, byproduct materials such as fly ash, silica fume, slag, rice-husk ash, red mud, etc could be used as source materials. The choice of the source materials for making geopolymers depends on factors such as availability, cost, type of application, and specific demand of the end users. The alkaline liquids are from soluble alkali metals that are usually sodium or potassium based. The most common alkaline liquid used in geopolymerisation is a combination of sodium hydroxide (NaOH) or potassium hydroxide (KOH) and sodium silicate or potassium silicate. Low-calcium (ASTM Class F) fly ash is preferred as a source material than high-calcium (ASTM Class C) fly ash. Since class F fly ash is preferred over class C due to a lower percentage of calcium. Presence of calcium in elevated levels could hinder the polymerization reaction and leads to flash set due to the formation of calcium hydrate products.
1.2 COMPOSITION AND CREATION Geopolymer concrete is made of up multiple ingredients. Like normal concrete, about 75%-80% of the mass is made of coarse and fine aggregates. An example of coarse aggregate is crushed stone or gravel and an example of fine aggregate is sand. Chemical admixtures such as air entrainers or super plasticizers can be added to the concrete mixture so that its qualities can be adjusted to meet the needs of the project. Air entrainers add air bubbles into the mixture and super plasticizers reduce the amount of water in the mixture and allow it to be much more workable. However, while ordinary concrete uses cement to bind the aggregates together, geopolymer concrete mixtures use a geopolymer paste. Geopolymer paste is created by combining fly ash, which contains silicon and aluminum, with a sodium hydroxide and sodium silicate solution. This is also known as water glass. The resulting reaction starts the process of geopolymerization which leads to the creation of a geopolymer. ISO 9001:2008 Certified Journal
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