scholarly journals Fly Ash-Based Eco-Efficient Concretes: A Comprehensive Review of the Short-Term Properties

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4264
Author(s):  
Mugahed Amran ◽  
Roman Fediuk ◽  
Gunasekaran Murali ◽  
Siva Avudaiappan ◽  
Togay Ozbakkaloglu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Silica Content ◽  
Structural Elements ◽  
Short Term ◽  
Conventional Concrete ◽  
Sustainable Concrete ◽  
Pozzolanic Material ◽  
Curing Regimes ◽  
Alkali Activated

Development of sustainable concrete as an alternative to conventional concrete helps in reducing carbon dioxide footprint associated with the use of cement and disposal of waste materials in landfill. One way to achieve that is the use of fly ash (FA) as an alternative to ordinary Portland cement (OPC) because FA is a pozzolanic material and has a high amount of alumina and silica content. Because of its excellent mechanical properties, several studies have been conducted to investigate the use of alkali-activated FA-based concrete as an alternative to conventional concrete. FA, as an industrial by-product, occupies land, thereby causing environmental pollution and health problems. FA-based concrete has numerous advantages, such as it has early strength gaining, it uses low natural resources, and it can be configurated into different structural elements. This study initially presents a review of the classifications, sources, chemical composition, curing regimes and clean production of FA. Then, physical, fresh, and mechanical properties of FA-based concretes are studied. This review helps in better understanding of the behavior of FA-based concrete as a sustainable and eco-friendly material used in construction and building industries.

scholarly journals CONCRETOS AUTOADENSÁVEIS E CONVENCIONAIS: ANÁLISE DAS PROPRIEDADES EM ESTADO FRESCO E ENDURECIDO

2020 ◽  
Vol 15 (2) ◽  
pp. 167-178
Author(s):  
Ana Claudia Bergmann ◽  
Gustavo Savaris ◽  
Carlos Eduardo Tino Balestra ◽  
Lucia Bressiani
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Fresh Concrete ◽  
The Self ◽  
Structural Elements ◽  
Negative Effects ◽  
Conventional Concrete ◽  
Self Consolidating Concrete ◽  
Passing Ability ◽  
Main Factor

RESUMO: Os concretos autoadensáveis destacam-se por suas características essenciais: capacidade de preenchimento de fôrmas, habilidade passante e resistência à segregação, permitindo assim o aumento da qualidade de peças estruturais de concreto, assim como a otimização de sua execução. Contudo, para obtenção de suas características essenciais, um fator é imprescindível trata da utilização de materiais finos, com o objetivo de controlar os efeitos negativos de segregação e exsudação à que o concreto fresco é suscetível a apresentar. Neste contexto, o presente trabalho tem por objetivo comparar as propriedades no estado fresco e endurecido de um concreto autoadensável, utilizando cinza volante como material fino, com um concreto convencional, produzidos com materiais disponíveis na região de Toledo-PR. Os resultados demonstraram que o concreto autoadensável apresentou melhor desempenho quanto às propriedades mecânicas em relação ao concreto convencional. As imagens obtidas por meio da microscopia eletrônica de varredura corroboraram para sustentar as afirmativas acerca da melhora nas propriedades mecânicas do concreto autoadensável, uma vez que foi evidenciada uma menor quantidade de vazios graças à atividade pozolânica da cinza volante. Neste sentido, este trabalho contribui para a difusão do concreto autoadensável e seu uso em construções usuais, resultando em estruturas de concreto duráveis e confiáveis, reduzindo a necessidade de manutenções. ABSTRACT: The self-consolidating concretes stand out for their essential characteristics: flowability, passing ability and segregation resistance, allowing the increase of the structural elements quality, as well as the optimization of their production. However, in order to obtain its essential characteristics, the main factor is the use of fines, in order to control the negative effects of segregation and bleeding to which fresh concrete is susceptible. In this context, the aim of this paper is to compare the properties, in the fresh and hardened states, of self-consolidating concretes, using fly ash as fine material with the properties of a conventional concrete, produced with materials available in the Toledo-PR, Brazil. The results showed that the self-consolidating concrete presented better performance in relation to the mechanical properties compared to conventional concrete. Using scanning electronic microscopy the affirmations about the improvement in the mechanical properties of self-consolidating concrete were proven, since a smaller amount of voids was evidenced due to the pozzolanic activity of fly ash. In this sense, this work contributes to the diffusion of self-consolidating concrete in the literature and its use in usual constructions, resulting in durable and reliable concrete structures, reducing the maintenance works.

Mechanical Properties of Alkali Activated Fly Ash Geopolymer Stabilized Expansive Clay

2019 ◽  
Vol 23 (9) ◽  
pp. 3875-3888 ◽  
Author(s):  
Anant Lal Murmu ◽  
Anamika Jain ◽  
Anjan Patel
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Expansive Clay ◽  
Alkali Activated

Influence of Different Mineral Precursors on the Properties of Fly Ash Based Alkali-Activated Mortars

2018 ◽  
Vol 761 ◽  
pp. 73-78 ◽  
Author(s):  
Matej Špak ◽  
Pavel Raschman
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Chemical Composition ◽  
Coal Combustion ◽  
Pure Aluminum ◽  
Partial Replacement ◽  
Black Coal ◽  
Fly Ashes ◽  
Final Composition ◽  
Alkali Activated

Alkali-activated materials based on fly ash are widely developed and also produced on the present. Some of fly ashes are not suitable for production of alkali-activated materials because of their inconvenient chemical composition. Alumina-silicates are the most important components that are needed to accomplish the successful reaction. The proper content of amorphous phase of alumina-silicates and its proportion as well should be provided for the final composition of alkali-activated materials. The influence of pure aluminum oxide powder as well as raw milled natural perlite on mechanical properties and durability of alkali-activated mortars was investigated. These minerals were used as partial replacement of fly ash coming from black coal combustion. In addition, the mortars were prepared by using different alkali activators.

Alternative Concrete – Geopolymer Concrete

2021 ◽  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Construction Industry ◽  
Building Material ◽  
Construction Materials ◽  
Raw Material ◽  
Geopolymer Concrete ◽  
Sustainable Solutions ◽  
New Construction ◽  
Alkali Activated

Concrete is the most versatile, durable and reliable material and is the most used building material. It requires large amounts of Portland cement which has environmental problems associated with its production. Hence, an alternative concrete – geopolymer concrete is needed. The general aim of this book is to make significant contributions in understanding and deciphering the mechanisms of the realization of the alkali-activated fly ash-based geopolymer concrete and, at the same time, to present the main characteristics of the materials, components, as well as the influence that they have on the performance of the mechanical properties of the concrete. The book deals with in-depth research of the potential recovery of fly ash and using it as a raw material for the development of new construction materials, offering sustainable solutions to the construction industry.

Mechanical Properties of Mortars Prepared by Alkali Activated Fly Ash Coming from Different Production Batches

2015 ◽  
Vol 244 ◽  
pp. 140-145 ◽  
Author(s):  
Matej Špak ◽  
Pavel Raschman
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Construction Materials ◽  
Chemical Properties ◽  
Raw Material ◽  
Fly Ashes ◽  
Coal Burning ◽  
Alkali Solutions ◽  
One Year ◽  
Alkali Activated

Fly ash is a well utilizable secondary raw material for the production of alkali activated construction materials. It is a significant alumina-silicates source suitable for the chemical reaction resulting in hardened composites. Physical and chemical properties of fly ashes as a co-product of coal burning mainly depend on characteristics of coal, burning temperature and combustion conditions. High variability of the properties of fly ash causes an uncertainty in the properties of alkali activated mortars. Time behaviour of the composition of the fly ash produced in a heating plant located in Košice, Slovakia as well as leaching behaviour of both alumina and silica from particular batches during one-year period was documented. Leaching tests were carried out using the distilled water and alkali solutions with three different concentrations. Both compressive and tensile strengths of alkali activated mortars were measured, and the correlation between the mechanical properties of hardened mortars and the chemical composition of fly ashes as well as their leaching characteristics was investigated.

EFFECT OF MIXING PROPORTION ON COMPRESSIVE STRENGTH OF FLY-ASH BASED GEOPOLYMER PASTE AND MORTAR USING TAGUCHI’S METHOD

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Sajid Khan Afridi ◽  
Vanissorn Vimonsatit
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Elevated Temperatures ◽  
Three Dimensional ◽  
Silica Content ◽  
Polymeric Chain ◽  
Low Carbon ◽  
Solid Ratio ◽  
Mix Proportion ◽  
Alkali Activated

Alkali activated pozzolan are known low carbon cementitious binders which can be used to replace cement. The material is also known as geopolymer because of its three dimensional polymeric chain and ring like structure consisting silica and alumina. A common type of pozzolan used is fly ash because of its rich silica content; therefore the term alkali activated fly-ash based binders is adopted. Despite much research and development of this material, there is no specific standard for design mix proportion. This research used the Taguchi’s design of experiment method to determine the optimum mix proportion of alkali activated fly ash based cement paste and mortar. Four factors were considered in the tests, silica fume, sand to cementitious ratio, liquid to solid ratio, and percentage of superplasticiser. Tests were conducted on the 9 batches of alkali activated fly-ash based paste and mortar samples to determine the compressive strength under ambient condition. Tests were also conducted to determine the residual strength of the samples after exposed to elevated temperatures. ANOVA analysis of the test results revealed the main factors contribution on the tested properties and led to the determination of the optimum design proportion of the factors considered in these tests.

MECHANICAL PROPERTIES OF FLY ASH-BASED ALKALI-ACTIVATED CEMENT USING A STATISTICAL ANALYSIS TECHNIQUE

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Hyuk Lee ◽  
Vanissorn Vimonsatit
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Statistical Analysis ◽  
Fly Ash ◽  
Silica Fume ◽  
Dry Density ◽  
Analysis Method ◽  
Solid Ratio ◽  
Alkali Activated ◽  
Alkali Activated Cement

This paper presents the mechanical properties of fly ash-based alkali-activated cement (AAC). A statistical analysis method was used to determine the effect of mix proportion parameters on the dry density and compressive strength of fly ash-based AAC pastes and mortars. For that purpose, sample mixtures were designed according to Taguchi’s experimental design method, i.e., in a L9 orthogonal array. Four factors were selected: “silica fume content” (SF), “sand to solid ratio” (s/c), “liquid to solid ratio” (l/s), and “superplasticiser content” (SP). The experimental results were analysed by using signal to noise for quality control of each mixture, and analysis of variance (ANOVA) was used to determine the significant effect on the compressive strength of fly ash-based AAC. Furthermore, a regression-analysis method was used to predict the compressive strength according to the variation of the four factors. Results indicated that silica fume is the most influencing parameter on compressive strength, which could be decreased by superplasticiser and l/s ratio. There is no significant effect of sand-to-cementitious ratio on compressive strength of fly ash-based AAC. The dry density decreases as the sand-to-cementitious ratio is decreased. The increasing l/s ratio and superplasticiser dosage could further decrease the dry density of fly ash-based AAC.

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