Evaluating the performance of high-volume fly ash (HVFA) concrete, for South African fly ash (original) (raw)
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.
Technology 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.
Experimental Study on Performance of High Volume Fly Ash Concrete
More than 88 million tons of fly ash is generated in India each year. Most of the fly ash is of Class F type. The percentage utilization is around 10 to 15%. To increase its percentage utilization, an extensive investigation was carried out to use it in concrete. This article presents the results of an experimental investigation dealing with concrete incorporating high volumes of Class F fly ash. Portland cement was replaced with three percentages (40%, 45%, and 50%) of Class F fly ash. Tests were performed for fresh concrete properties: slump, air content, unit weight, and temperature. Compressive, splitting tensile and flexural strengths were determined up to 28 days of testing. Test results indicated that the use of high volumes of Class F fly ash as a partial replacement of cement in concrete decreased its 28-day compressive, splitting tensile strength and flexural strengths of the concrete. Based on the test results, it was concluded that Class F fly ash can be suitably used up to 50% level of cement replacement in concrete for use in precast elements and reinforced cement concrete construction. Keywords: HVFA, Fly ash is a pozzolan, HSC _______________________________________________________________________________________________________
Development and Evaluation of High-Volume Fly Ash (HVFA) Concrete Mixes
Concrete is the world’s most consumed man-made material. Unfortunately, the production of portland cement, the active ingredient in concrete, generates a significant amount of carbon dioxide. For each pound of cement produced, approximately one pound of carbon dioxide is released into the atmosphere. With cement production reaching nearly 6 billion tons per year worldwide, the sustainability of concrete is a very real concern. Since the 1930’s, fly ash – a pozzolanic material – has been used as a partial replacement of portland cement in concrete to improve the material’s strength and durability, while also limiting the amount of early heat generation. From an environmental perspective, replacing cement with fly ash reduces concrete’s overall carbon footprint and diverts an industrial by-product from the solid waste stream (currently, about 40 percent of fly ash is reclaimed for beneficial reuse and 60 percent is disposed of in landfills). Traditional specifications limit the amount...
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.
Study of Strength and Workability of High Volume Fly Ash Concrete
2020
1Associate Professor in Department of Civil Engineering, SRPCE, Nagpur, Maharashtra, India.-441203 2-6Student of Department of Civil Engineering, SRPCE, Nagpur, Maharashtra, India.-441203 ---------------------------------------------------------------------***---------------------------------------------------------------------Abstract The utilization of High Volume of Fly Ash in concrete is gaining significance and is considered as a sustainable option for many concrete constructions. According to various test conducted the results show that, HVFA concrete has lower strength at early ages but at later age HVFA concrete shows continuous increase in strength properties. HVFA Concrete exhibits comparable costs, increased strengths and enhanced workability. Thus, the HVFA concrete is more suitable for warm weather sand where early strength is not essential. This project shows workability and strength properties of High Volume Fly Ash Concrete.
The Use of Fly Ash as Additive Material to High Strength Concrete
Jurnal Teknik Sipil dan Perencanaan, 2018
The use of coal waste (Fly Ash) is currently being developed in building materials technology, as a highstrength concrete mix material. This study aims to determine the strength of concrete by adding fly ash as a substitute for cement in high-strength concrete mixtures. This research was conducted using an experimental method to obtain results and data that would confirm the variables studied. The total numbers of specimens used in this study were 36 pieces with different sizes of cube tests which were 15 cm x 15 cm x 15 cm. A total of 36 concrete samples were used to test the compressive strength of concrete with a percentage of Fly Ash in 0% (normal concrete), 20%, 25% and 30% with a concrete treatment age of 7 days, 21 days and 28 days. A total of 12 more samples were used to test water absorption in concrete at 28 days of maintenance. Each percentage of Fly Ash uses 3 concrete test samples. The increase in compressive strength occurs at 7, 21 and 28 days in concrete. However, the compressive strength of concrete produced by concrete using the percentage of Fly Ash is always lower than the value of normal concrete compressive strength. From testing the compressive strength of concrete at 28 days of treatment with
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.
RECENT INNOVATIONS IN HIGH VOLUME FLY ASH CONCRETE: A REVIEW
In this study, an extensive literature review has been conducted to understand the increased potential of HVFA concrete in recent years. HVFA concrete performance depends on material ingredients and mixture proportioning, which leads to denser and relatively more homogenous particle packing. However, sustained research studies in producing HVFA using various mineral admixture such as ultra-fine fly ash, class C and F fly ash, line stone powder, GGBS, Silica fume, Alccofine under various curing conditions are studies here and a database was compiled from various research and field studies on the fresh and hardened properties of high volume fly ash concrete using mineral admixture. The literature review revealed that the curing time, fly ash content, choice of mineral admixtures and its content are the main factors that control the mechanical and durability properties. Although various research have been conducted on HVFA concrete still there are challenges regarding the selection of mineral admixture and its content in HVFAC. This study helps to better understand the potential and capabilities of HVFA using various mineral admixture in concrete, which will minimize the drawback of HVFA and provide sustainable construction material to the construction industry.