Technology Effects and Benefits of Using High Content of Fly Ash in Concrete (original) (raw)
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Effects and benefits of using high content of fly ash in concrete
2016
The usage of fly ash products by the South African cement and construction industries has saved the country over 6 million tons of harmful greenhouse gas emissions. The recycling of it as cement extenders provides an immediate benefit for the environment while still improving the quality of concrete, and increasing the amount used in concrete can promote sustainable development. This study evaluated properties of 35MPa/9,5mm concrete with fly ash substituted at 30%, 40%, 50% and 60%. Increasing the fly ash content can result in more workable and less permeable concrete. The compressive strength and durability index results showed that the fly ash content can be increased beyond 50% and still achieve the required strength and produce durable concrete. Substituting high volumes of cement with fly ash in concrete can provide good quality concrete and a relief to the environment without compromising the quality and cost of concrete.
Influence of high content fly ash on concrete durability
2014
The use of fly ash products by the South African cement and construction industries has saved the country over 6 million tons of harmful greenhouse gas emissions. Fly ash is an industrial by-product that is normally consigned to landfills and the re-use of it as cement extenders provides an immediate benefit for the environment while still improving the quality of concrete. Fly ash blended cements in concrete perform better than pure cement in providing better concrete properties. Current specifications limit the use of fly ash in concrete to 30%, although an increase of this amount can be very beneficial in concrete structures, economically and environmentally. In South Africa the durability index of concrete is commonly determined by performing the Oxygen Permeability test, Water Sorptivity test and Chloride Conductivity test, developed by the Universities of Cape Town and the Witwatersrand. Performing these tests in this study, the results obtained showed that concrete mixes with fly ash content that is higher than the specification limit can result in concrete with acceptable good durability qualities, and with age, the durability qualities are improved due to pozzolanic reactions. Substituting high volumes of cement with fly ash in concrete can provide high quality concrete and a relief in the environment without compromising the quality of concrete. Index terms-Concrete, durability, environment, fly ash.
TECHNOLOGY Utilization of Fly ash in Improving Concrete Properties
2014
The following paper is related with finding out the utilization of fly ash in improving concrete prope rties and its several environmental benefits. Fly ash is pozzolon ic material & it improves the properties of concret e like compressive strength & Durability. Here the method used for determining this is experimental. Here cub es casted with different amounts of fly ash proportions rangi ng from 10%-30% are used and their 7 and 28 days strength are found out. The strength of cubes was found out by t he use of compressive testing machine. Their degree of economy has also been found out. In the present study the r esults obtained are discussed and compared with the available literature.
Challenge Journal of Concrete Research Letters
Researchers and decision makers are continuously looking out to determine the potential and effectiveness of fly-ash as a partial replacement of cement in concrete. The current study is carried out to check the optimum or nearly optimum quantity of fly-ash with which cement should be replaced to get most of the properties of concrete enhanced and to give the idea about the quantities of fly-ash that can be used in a better way and better cause so that a proper management scheme of its usage and disposal can be implied. Further, a comparison is given between normal concrete and fly-ash concrete to show the properties which can be enhanced by proper utilization of fly-ash as a partial replacement of cement. After carrying out the lab experiments, it has been seen that the replacement of fly-ash in concrete has resulted in general increase in compressive strength, flexural strength and splitting tensile strength up to 15% replacement and after then the strength is decreased considerabl...
Researchers and decision makers are continuously looking out to determine the potential and effectiveness of fly-ash as a partial replacement of cement in concrete. The current study is carried out to check the optimum or nearly optimum quantity of fly-ash with which cement should be replaced to get most of the properties of concrete enhanced and to give the idea about the quantities of fly-ash that can be used in a better way and better cause so that a proper management scheme of its usage and disposal can be implied. Further, a comparison is given between normal concrete and fly-ash concrete to show the properties which can be enhanced by proper utilization of fly-ash as a partial replacement of cement. After carrying out the lab experiments, it has been seen that the replacement of fly-ash in concrete has resulted in general increase in compressive strength, flexural strength and splitting tensile strength up to 15% replacement and after then the strength is decreased considerably than that of normal concrete. Addition of fly-ash in concrete has resulted in decrease in the water absorption of concrete and hence decreases in permeability of concrete. There is a progressive increase in workability with increase in percentage of fly-ash in concrete. The current study has led to a conclusion that in order to achieve best results in use of fly-ash concrete, the fly-ash used for replacing cement in concrete should have the required properties as specified by the standards and proper techniques of processing fly-ash as well as mixing of fly-ash with cement must be employed.
Indonesian journal of urban and environmental technology, 2024
Innovations in material technology are expected to reduce the use of commercial cement and replace it with other environmentally friendly materials with the same performance as normal concrete. Aim: This study aim to analyze the mechanical property of High-Volume Fly Ash Concrete (HVFAC) using F class fly ash with different mix percentages. Methodology and Results: The experiment was conducted in laboratory scale. Four variations of test specimens consisted of: 1 variation (F0), which is conventional concrete with 100% Portland cement as control specimen, and three variations of HVFC (F70, F80, and F90), which were made with fly ash content (%) 70, 80, and 90 of total cementitious. Fresh concrete testing to determine workability, while hard concrete testing is done by density and compressive strength tests at the age of 3, 7, and 28 days on specimens that have been treated with the water submerged curing method. Conclusion, significance, and impact of study: All HVFAC specimens fulfill the Self Compacting Concrete (SCC) category. The compressive strength test results at 28 days showed that the addition of fly ash percentage caused a decrease in compressive strength values in all HVFAC variants, but still exceeded the minimum requirements of high and medium quality concrete. All HVFAC variations meet the requirements of ASTM C618-23 based on the evaluation of Strength Activity Index (SAI) values at 7 and 28 days of age. The utilization of 90% fly ash as a cement substitute resulted in an environmentally friendly concrete product based on the concept of cleaner production.
Utilization of Fly ash in Improving Concrete Properties
The following paper is related with finding out the utilization of fly ash in improving concrete properties and its several environmental benefits. Fly ash is pozzolonic material & it improves the properties of concrete like compressive strength & Durability. Here the method used for determining this is experimental. Here cubes casted with different amounts of fly ash proportions ranging from 10%-30% are used and their 7 and 28 days strength are found out. The strength of cubes was found out by the use of compressive testing machine. Their degree of economy has also been found out. In the present study the results obtained are discussed and compared with the available literature.
An Experimental Study on Strength and Durability for Utilization of Fly Ash in Concrete Mix
Advances in Materials Science and Engineering, 2014
The intention of this study is to discuss the variation of concrete exposed to high sulfate environment of a specific region with respect to strength and durability. Secondly, it is aimed to discuss the possibility of reducing the cement amount in construction of concrete structures. For this purpose, laboratory tests were conducted to investigate compressive strength and sulfate resisting capacity of concrete by using 20% fly ash as mineral additives, waste materials, instead of cement. As a case study the soil samples, received from Siirt Province areas which contain high sulfate rate, have been compared with respect to sulfate standard parameters of TS 12457-4. In such regions contact of underground water seep into hardened concrete substructures poses a risk of concrete deterioration. In order to determine the variation of strength and durability for concrete exposed to such aggressive environment, the samples were rested in a solution of Na 2 SO 4 (150 g/lt) in accordance with ASTM C 1012 for the tests. As a result of this experimental study, it is noted that the use of 20% fly ash, replacement material instead of cement, has no significant effect on compressive strength of concrete over time.
Evaluating the performance of high-volume fly ash (HVFA) concrete, for South African fly ash
2016
Due to the benefits provided by the usage of FA in concrete, the usage of HVFA concrete is increasing within the concrete industry. This study looked at the effects of increasing the content of FA in concrete, beyond the conventional 30% amount, to find an optimum amount suitable for use in concrete structures, without compromising the quality of concrete. Concrete mixes of 25MPa, 35MPa and 50MPa with FA partially substituting the cement at 30%, 40%, 50% and 60%, were produced and numerous concrete properties were evaluated in a laboratory environment, to determine an optimum amount of HVFA that can be used and still obtain better or comparable concrete to ordinary concrete. Concrete testing for compressive strength, durability, slump, setting time and drying shrinkage was performed at laboratories over a period of one year. Also a cost comparison between the ordinary concrete and FA concrete was done. Test results showed that HVFA concrete can perform well in structures with good c...
Concrete is the most common construction material in the world because it combines very good mechanical and durability properties, workability and relative low cost. However, cement production emits greenhouse gases, mainly CO2, being responsible for about 5% of global anthropogenic CO2 emissions in the world. The use of pozzolans as cement replacement is a problem that would have local solutions since transport is one of the main cost components for cementitious materials. The application of fly ash in concrete production brings positive effects of the environment; hence it reduces the problems associated to their disposal. Several benefits will be attained regarding green house gas emissions resulting from the use of mineral admixtures as cement additive, since their use allows reducing cement production. Regarding their use as cement additive, mineral admixtures affect the performances of paste, mortar and concrete owing to both physical and chemical effects. Therefore it is possible to use fly ash as cement additive and replacement material to improve quality and reduce cost of pozzolonic construction material The cement has been replaced by fly ash accordingly in the range of 0%, 5%, 10%, 15%, 20% & 25% by weight of cement for mix. Concrete mixtures were produced, tested and compared in terms of compressive strengths with the Conventional concrete. These tests were carried out to evaluate the compressive strength properties for the test results of 28, 56 days compressive strengths which were exposed to elevated temperatures of 4000C, 5000 C &6000C for time duration of 30 minutes and 60 minutes respectively.