Fundamentals of Geopolymers and Related Alkali Activated Materials

The sustainability of resources is becoming a worldwide concern, including construction and building materials, especially with the alarming increase rate in global population. Alternative solutions to ordinary Portland cement (OPC) as a concrete binder are being studied, namely the so-called alkali-activated cements (AAC). These are less harmful to the environment, as lower CO2 emissions are associated with their fabrication, and their mechanical properties can be similar to those of the OPC. The aim of developing alkali-activated materials (AAM) is the maximization of the incorporated recycled materials, which minimises the CO2 emissions and cost, while also achieving acceptable properties for construction applications. Therefore, various efforts are being made to produce sustainable construction materials based on different sources and raw materials. Recently, significant attention has been raised from the by-products of the steelmaking industry, mostly due to their widespread availability. In this paper, ladle slag (LS) resulting from steelmaking operations was studied as the main precursor to produce AAC, combined with phosphating bath sludge—or phosphate sludge (PS)—and aluminium anodising sludge (AS), two by-products of the surface treatment of metals, in replacement rates of 10 and 20 wt.%. The precursors were activated by two different alkaline solutions: a combination of commercial sodium hydroxide and sodium silicate (COM), and a disposed solution from the cleaning of aluminium extrusion steel dies (CLE). This study assesses the influence of these by-products from the steelmaking industry (PS, AS and CLE) on the performance of the alkali-activated LS, and specifically on its fresh and hardened state properties, including rheology, heat of hydration, compressive strength and microstructure and mineralogy (X-ray diffraction, scanning electron microscopy coupled with energy dispersive spectroscopy and Fourier transform infra-red. The results showed that the CLE had no negative impact on the strength of the AAM incorporating PS or/and AS, while increasing the strength of the LS alone by 2×. Additionally, regardless of the precursor combination, the use of a commercial activator (COM) led to more fluid pastes, compared with the CLE.

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Radiological and physico-chemical characterization of red mud as an Al-containing precursor in inorganic binders for the building industry

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp2102182k ◽

2021 ◽

Vol 36 (2) ◽

pp. 182-191

Author(s):

Ljiljana Kljajevic ◽

Miljana Mirkovic ◽

Sabina Dolenec ◽

Katarina Ster ◽

Mustafa Hadzalic ◽

...

Keyword(s):

Construction Industry ◽

Natural Radioactivity ◽

Red Mud ◽

Building Materials ◽

Raw Materials ◽

Construction Materials ◽

Polymerization Process ◽

Alkali Activation ◽

Silica Alumina ◽

Alkali Activated

The potential re-use of red mud in the building and construction industry has been the subject of research of many scientists. The presented research is a contribution to the potential solution of this environmental issue through the synthesis of potential construction materials based on red mud. A promising way of recycling these secondary raw materials is the synthesis of alkali-activated binders or alkali activated materials. Alkali-activated materials or inorganic binders based on red mud are a new class of materials obtained by activation of inorganic precursors mainly constituted by silica, alumina and low content of calcium oxide. Since red mud contains radioactive elements like 226Ra and 232Th, this may be a problem for its further utilization. The content of naturally occurring radionuclides in manufactured material products with potential application in the building and construction industry is important from the standpoint of radiation protection. Gamma radiation of the primordial radionuclides, 40K and members of the uranium and thorium series, increases the external gamma dose rate. However, more and more precedence is being given to limiting the radiological dose originating from building materials on the population these days. The aim of this research was to investigate the possible influence of alkali activation-polymerization processes on the natural radioactivity of alkali activated materials synthesized by red mud (BOKSIT a. d. Milici, Zvornik, Bosnia and Herzegovina) and their structural properties. This research confirmed that during the polymerization process the natural radioactivity was reduced, and that the process of alkali activation of raw materials has an influence on natural radioactivity of synthesized materials.

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Parametric Studies Regarding the Development of Alkali-Activated Fly Ash-Based Geopolymer Concrete Using Romanian Local Raw Materials

Proceedings ◽

10.3390/proceedings2020063011 ◽

2020 ◽

Vol 63 (1) ◽

pp. 11

Author(s):

Adrian-Victor Lăzărescu ◽

Henriette Szilagyi ◽

Cornelia Baeră ◽

Andreea Hegyi

Keyword(s):

Fly Ash ◽

Building Materials ◽

Negative Impact ◽

Raw Materials ◽

Geopolymer Concrete ◽

Human Needs ◽

Alternative Material ◽

Parametric Studies ◽

And Performance ◽

Alkali Activated

Current research and development policies in the field of building materials, in the context of sustainable development, have the main objectives of increasing the safety and performance of the built environment at the same time as reducing pollution and its negative impact. Today, the idea that the sustainable city of the future should meet human needs and maintain a higher quality of life is worldwide unanimously accepted. The aim of this paper is to present results regarding the production of alkali-activated fly ash-based geopolymer concrete, a new, alternative material, produced using local available raw materials from Romania.

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Radiological and physico-chemical characterization of red mud as an Al-containing precursor in inorganic binders for the building industry

Nuclear Technology and Radiation Protection ◽

10.2298/ntrp2002182k ◽

2021 ◽

Vol 36 (2) ◽

pp. 182-191

Author(s):

Ljiljana Kljajevic ◽

Miljana Mirkovic ◽

Sabina Dolenec ◽

Katarina Ster ◽

Mustafa Hadzalic ◽

...

Keyword(s):

Construction Industry ◽

Natural Radioactivity ◽

Red Mud ◽

Building Materials ◽

Raw Materials ◽

Construction Materials ◽

Polymerization Process ◽

Alkali Activation ◽

Silica Alumina ◽

Alkali Activated

The potential re-use of red mud in the building and construction industry has been the subject of research of many scientists. The presented research is a contribution to the potential solution of this environmental issue through the synthesis of potential construction materials based on red mud. A promising way of recycling these secondary raw materials is the synthesis of alkali-activated binders or alkali activated materials. Alkali-activated materials or inorganic binders based on red mud are a new class of materials obtained by activation of inorganic precursors mainly constituted by silica, alumina and low content of calcium oxide. Since red mud contains radioactive elements like 226Ra and 232Th, this may be a problem for its further utilization. The content of naturally occurring radionuclides in manufactured material products with potential application in the building and construction industry is important from the standpoint of radiation protection. Gamma radiation of the primordial radionuclides, 40K and members of the uranium and thorium series, increases the external gamma dose rate. However, more and more precedence is being given to limiting the radiological dose originating from building materials on the population these days. The aim of this research was to investigate the possible influence of alkali activation-polymerization processes on the natural radioactivity of alkali activated materials synthesized by red mud (BOKSIT a. d. Milici, Zvornik, Bosnia and Herzegovina) and their structural properties. This research confirmed that during the polymerization process the natural radioactivity was reduced, and that the process of alkali activation of raw materials has an influence on natural radioactivity of synthesized materials.

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Concrete with Fluidized Bed Combustion Fly Ash Based Light Weight Aggregate

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.249.8 ◽

2016 ◽

Vol 249 ◽

pp. 8-13

Author(s):

Rudolf Hela ◽

Martin Ťažký ◽

Václav Vachuška ◽

Tomáš Ťažký

Keyword(s):

Fly Ash ◽

Fluidized Bed ◽

Building Materials ◽

Lightweight Concrete ◽

Raw Materials ◽

Construction Materials ◽

Lightweight Aggregate ◽

Fluidized Bed Combustion ◽

Freezing And Thawing ◽

Long Time

Conventional high temperature fly ash has been used for manufacturing of construction materials, concrete in particular, for quite a long time. Fluidized bed combustion fly ash, however, has little use in this area, mainly for its chemical composition and morphology. Current efforts are directed towards the development of new technological processes and building materials that would allow the use of this industrial waste and its qualities. One possible way of fluidized bed combustion fly ash’s utilizing in construction industry is the production of cold balled lightweight aggregate. Production of this material is economically advantageous and enables processing of large volumes of raw materials. This paper describes possibilities of using this aggregate for production of lightweight concrete of lower compressive strength classes and consequent testing of durability and resistance to various types of aggressive environment and cyclical freezing and thawing. Physico-mechanical properties and microscopic defects were also studied

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Mix Design and Mechanical Properties of Fly Ash and GGBFS-Synthesized Alkali-Activated Concrete (AAC)

Infrastructures ◽

10.3390/infrastructures4020020 ◽

2019 ◽

Vol 4 (2) ◽

pp. 20 ◽

Cited By ~ 3

Author(s):

Ramamohana Reddy Bellum ◽

Ruben Nerella ◽

Sri Rama Chand Madduru ◽

Chandra Sekhar Reddy Indukuri

Keyword(s):

Mechanical Properties ◽

Fly Ash ◽

Raw Materials ◽

Construction Materials ◽

Xrd Analysis ◽

Mix Design ◽

Geopolymer Concrete ◽

Curing Conditions ◽

Factors Affecting ◽

Alkali Activated

Cement is one of the construction materials widely used around the world in order to develop infrastructure and it is also one of the factors affecting economies. The production of cement consumes a lot of raw materials like limestone, which releases CO2 into the atmosphere and thus leads to global warming. Many investigations are underway in this area, essentially focusing on the eco-accommodating environment. In the research, an alternative material to cement binder is geopolymer binder, with the same efficiency. This paper presents scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis of factory byproducts (i.e., fly ash and ground granulated blast furnace slag (GGBFS)). The mix design process for the manufacture of alkali-activated geopolymer binders synthesized by fly ash and GGBFS is presented. The mechanical properties (compression, split tensile and flexural strength, bond strength) of geopolymer concrete at different mix proportions and at dissimilar curing conditions were also investigated. Geopolymer concrete synthesized with 30% fly ash and 70% GGBFS has better properties at 14 M of NaOH and cured in an oven for 24 h at 70 °C.

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Mortars with Recycled Aggregates from Building-Related Processes: A ‘Four-Step’ Methodological Proposal for a Review

Sustainability ◽

10.3390/su13052756 ◽

2021 ◽

Vol 13 (5) ◽

pp. 2756

Author(s):

Federica Vitale ◽

Maurizio Nicolella

Keyword(s):

Building Materials ◽

Thermal Analyses ◽

Construction Materials ◽

Physical And Mechanical Properties ◽

Research Trends ◽

Mix Design ◽

Recycled Aggregates ◽

Design Parameters ◽

Natural Aggregates ◽

By Products

Because the production of aggregates for mortar and concrete is no longer sustainable, many attempts have been made to replace natural aggregates (NA) with recycled aggregates (RA) sourced from factories, recycling centers, and human activities such as construction and demolition works (C&D). This article reviews papers concerning mortars with fine RA from C&D debris, and from the by-products of the manufacturing and recycling processes of building materials. A four-step methodology based on searching, screening, clustering, and summarizing was proposed. The clustering variables were the type of aggregate, mix design parameters, tested properties, patents, and availability on the market. The number and the type of the clustering variables of each paper were analysed and compared. The results showed that the mortars were mainly characterized through their physical and mechanical properties, whereas few durability and thermal analyses were carried out. Moreover, few fine RA were sourced from the production waste of construction materials. Finally, there were no patents or products available on the market. The outcomes presented in this paper underlined the research trends that are useful to improve the knowledge on the suitability of fine RA from building-related processes in mortars.

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The Influence of Cement Substitution by Biomass Fly Ash on the Polymer–Cement Composites Properties

Materials ◽

10.3390/ma14113079 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3079

Author(s):

Beata Jaworska ◽

Dominika Stańczak ◽

Joanna Tarańska ◽

Jerzy Jaworski

Keyword(s):

Fly Ash ◽

Building Materials ◽

Raw Materials ◽

Combustion Process ◽

Biomass Combustion ◽

Cement Composites ◽

Cement Mortars ◽

Mineral Additive ◽

Biomass Fly Ash

The generation of energy for the needs of the population is currently a problem. In consideration of that, the biomass combustion process has started to be implemented as a new source of energy. The dynamic increase in the use of biomass for energy generation also resulted in the formation of waste in the form of fly ash. This paper presents an efficient way to manage this troublesome material in the polymer–cement composites (PCC), which have investigated to a lesser extent. The research outlined in this article consists of the characterization of biomass fly ash (BFA) as well as PCC containing this waste. The characteristics of PCC with BFA after 3, 7, 14, and 28 days of curing were analyzed. Our main findings are that biomass fly ash is suitable as a mineral additive in polymer–cement composites. The most interesting result is that the addition of biomass fly ash did not affect the rheological properties of the polymer–cement mortars, but it especially influenced its compressive strength. Most importantly, our findings can help prevent this byproduct from being placed in landfills, prevent the mining of new raw materials, and promote the manufacture of durable building materials.

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Alternative Concrete – Geopolymer Concrete

10.21741/9781644901533 ◽

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.

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Bio-based construction materials for a sustainable future

IABSE Congress, New York, New York 2019: The Evolving Metropolis ◽

10.2749/newyork.2019.0859 ◽

2019 ◽

Author(s):

Rijk Block ◽

Barbara Kuit ◽

Torsten Schröder ◽

Patrick Teuffel

Keyword(s):

Construction Industry ◽

Structural Engineering ◽

Building Materials ◽

Raw Materials ◽

Construction Materials ◽

Flax Fibres ◽

The Past ◽

Natural Building ◽

Paris Climate Agreement ◽

Primary Materials

<p>The structural engineering community has a strong responsibility to contribute to a more efficient use of natural resources. Nowadays the construction industry is by far the most resource intense industry sector, approximately 40-50% of all primary raw materials are used, which raises the question about the architects and engineer’s accountability. In this context and as a result of the Paris Climate agreement the Dutch government defined the program “Nederland Circulair in 2050”, which states the ambition to use 50% less primary materials in 2030 and to have a full circular economy in 2050.</p><p>One possible approach to achieve these ambitious goals is the application of renewable, bio-based materials in the built environment and to replace traditional, typically cement-based, materials. Already in the past natural building materials, such as timber and bamboo have been used widely, but in recent years new materials came up and provide new opportunities to be used in the construction industry. The authors explored various alternatives, such as hemp and flax fibres, mycelium and lignin-based fibres for composite materials, which will be described with various experimental and realised case studies.</p>

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