Effect of AlF3 production waste on the processes of hydration and hardening of the alkali-activated Portland cement with sodium silicate hydrate

An efficient solution to increase the sustainability of building materials is to replace Portland cement with alkali-activated materials (AAM). Precursors for those systems are often based on water-cooled ground granulated blast furnace slags (GGBFS). Quenching of blast furnace slag can be done also by air but in that case, the final product is crystalline and with a very low reactivity. The present study aimed to evaluate the cementitious properties of a mechanically activated (MCA) air-cooled blast furnace slag (ACBFS) used as a precursor in sodium silicate alkali-activated systems. The unreactive ACBFS was processed in a planetary ball mill and its cementing performances were compared with an alkali-activated water-cooled GGBFS. Mixes based on mechanically activated ACBFS reached the 7-days compressive strength of 35 MPa and the 28-days compressive strength 45 MPa. The GGBFS-based samples showed generally higher compressive strength values.

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The contribution of life-cycle assessment to environmentally preferable concrete mix selection for breakwater applications

Ambiente Construído ◽

10.1590/s1678-86212018000200262 ◽

2018 ◽

Vol 18 (2) ◽

pp. 413-429 ◽

Cited By ~ 2

Author(s):

Maristela Gomes da Silva ◽

Vanessa Gomes ◽

Marcella Ruschi Mendes Saade

Keyword(s):

Life Cycle Assessment ◽

Life Cycle ◽

Portland Cement ◽

Sodium Silicate ◽

Impact Category ◽

Cradle To Gate ◽

Natural Aggregates ◽

Comprehensive Framework ◽

Regulation Compliance ◽

Alkali Activated

Abstract Life cycle assessment (LCA) provides a comprehensive framework for positioning low energy and global warming potential alternatives regarding Portland cement and concrete. Published LCA work on alkali-activated cements is, however, relatively limited. In this paper, we illustrate how LCA critically supports concrete technological studies in the search for low impact concrete mixes. Previous research on breakwater applications explored replacing a low-clinker Portland cement and natural aggregates with seven different alkali-activated blast furnace slag (bfs) binder systems and with coarse and granulated bfs aggregates. Its outcome suggested a sodium silicate-activated bfs formulation as the best match between concrete properties and environmental regulation compliance. To validate this outcome through LCA, our cradle to gate assessments followed ISO 14044 (INTERNATIONAL…, 2006b) and used Ecoinvent v.2.2 and CML baseline 2001 v.2.05. We adopted the ‘net avoided burden approach’ to handle multifunctionality intrinsic to by-product-based AAC. Whilst sodium silicate-activated mixes rivaled the reference regarding GWP, impacts in several categories were increased. LCA highlighted the implications of driving mix selection by focusing on a single environmental impact category.

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Effect of sodium hydroxide and sodium silicate solutions on strengths of alkali activated high calcium fly ash containing Portland cement

KSCE Journal of Civil Engineering ◽

10.1007/s12205-016-0327-6 ◽

2016 ◽

Vol 21 (6) ◽

pp. 2202-2210 ◽

Cited By ~ 16

Author(s):

Tanakorn Phoo-ngernkham ◽

Sakonwan Hanjitsuwan ◽

Nattapong Damrongwiriyanupap ◽

Prinya Chindaprasirt

Keyword(s):

Fly Ash ◽

Portland Cement ◽

Sodium Hydroxide ◽

Sodium Silicate ◽

High Calcium ◽

High Calcium Fly Ash ◽

Alkali Activated

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A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

Materials ◽

10.3390/ma13163467 ◽

2020 ◽

Vol 13 (16) ◽

pp. 3467

Author(s):

Ankit Kothari ◽

Karin Habermehl-Cwirzen ◽

Hans Hedlund ◽

Andrzej Cwirzen

Keyword(s):

Carbon Dioxide ◽

Portland Cement ◽

Ordinary Portland Cement ◽

Cementitious Materials ◽

Cold Climate ◽

Supplementary Cementitious Materials ◽

Short Exposure ◽

Chemical Admixtures ◽

Composite Cements ◽

Alkali Activated

Most of the currently used concretes are based on ordinary Portland cement (OPC) which results in a high carbon dioxide footprint and thus has a negative environmental impact. Replacing OPCs, partially or fully by ecological binders, i.e., supplementary cementitious materials (SCMs) or alternative binders, aims to decrease the carbon dioxide footprint. Both solutions introduced a number of technological problems, including their performance, when exposed to low, subfreezing temperatures during casting operations and the hardening stage. This review indicates that the present knowledge enables the production of OPC-based concretes at temperatures as low as −10 °C, without the need of any additional measures such as, e.g., heating. Conversely, composite cements containing SCMs or alkali-activated binders (AACs) showed mixed performances, ranging from inferior to superior in comparison with OPC. Most concretes based on composite cements require pre/post heat curing or only a short exposure to sub-zero temperatures. At the same time, certain alkali-activated systems performed very well even at −20 °C without the need for additional curing. Chemical admixtures developed for OPC do not always perform well in other binder systems. This review showed that there is only a limited knowledge on how chemical admixtures work in ecological concretes at low temperatures and how to accelerate the hydration rate of composite cements containing high amounts of SCMs or AACs, when these are cured at subfreezing temperatures.

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Corrosion behaviour of low-carbon steel reinforcement in alkali-activated slag-steel slag and Portland cement-based mortars under simulated marine environment

Corrosion Science ◽

10.1016/j.corsci.2020.108874 ◽

2020 ◽

Vol 175 ◽

pp. 108874 ◽

Cited By ~ 1

Author(s):

Nanqiao You ◽

Jinjie Shi ◽

Yamei Zhang

Keyword(s):

Carbon Steel ◽

Portland Cement ◽

Marine Environment ◽

Corrosion Behaviour ◽

Steel Slag ◽

Low Carbon Steel ◽

Steel Reinforcement ◽

Low Carbon ◽

Activated Slag ◽

Alkali Activated

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Complex multifunctional additive for anchoring grout based on alkali-activated portland cement

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/907/1/012055 ◽

2020 ◽

Vol 907 ◽

pp. 012055

Author(s):

P V Krivenko ◽

O M Petropavlovskyi ◽

I I Rudenko ◽

O P Konstantynovskyi ◽

A V Kovalchuk

Keyword(s):

Portland Cement ◽

Multifunctional Additive ◽

Alkali Activated

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Positive Influence of Liquid Sodium Silicate on the Setting Time, Polymerization, and Strength Development Mechanism of MSWI Bottom Ash Alkali-Activated Mortars

Materials ◽

10.3390/ma14081927 ◽

2021 ◽

Vol 14 (8) ◽

pp. 1927

Author(s):

Lei Jin ◽

Guodong Huang ◽

Yongyu Li ◽

Xingyu Zhang ◽

Yongsheng Ji ◽

...

Keyword(s):

Sodium Silicate ◽

Setting Time ◽

Bottom Ash ◽

Free Water ◽

Polymerization Reaction ◽

Liquid Sodium ◽

Strength Development ◽

Mswi Bottom Ash ◽

Alkali Activated ◽

Development Mechanism

Setting time and mechanical properties are key metrics needed to assess the properties of municipal solid waste incineration (MSWI) bottom ash alkali-activated samples. This study investigated the solidification law, polymerization, and strength development mechanism in response to NaOH and liquid sodium silicate addition. Scanning electron microscopy and X-ray diffraction were used to identify the formation rules of polymerization products and the mechanism of the underlying polymerization reaction under different excitation conditions. The results identify a strongly alkaline environment as the key factor for the dissolution of active substances as well as for the formation of polymerization products. The self-condensation reaction of liquid sodium silicate in the supersaturated state (caused by the loss of free water) is the major reason for the rapid coagulation of alkali-activated samples. The combination of both NaOH and liquid sodium silicate achieves the optimal effect, because they play a compatible coupling role.

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Volcanic Ash as a Sustainable Binder Material: An Extensive Review

Materials ◽

10.3390/ma14051302 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1302

Author(s):

Andrés Játiva ◽

Evelyn Ruales ◽

Miren Etxeberria

Keyword(s):

Chemical Composition ◽

Portland Cement ◽

Urban Areas ◽

Volcanic Ash ◽

Mechanical Performance ◽

Cement Clinker ◽

Alkali Activation ◽

Cement Production ◽

Sustainable Solutions ◽

Alkali Activated

The construction industry is affected by the constant growth in the populations of urban areas. The demand for cement production has an increasing environmental impact, and there are urgent demands for alternative sustainable solutions. Volcanic ash (VA) is an abundant low-cost material that, because of its chemical composition and amorphous atomic structure, has been considered as a suitable material to replace Portland cement clinker for use as a binder in cement production. In the last decade, there has been interest in using alkali-activated VA material as an alternative material to replace ordinary Portland cement. In this way, a valuable product may be derived from a currently under-utilized material. Additionally, alkali-activated VA-based materials may be suitable for building applications because of their good densification behaviour, mechanical properties and low porosity. This article describes the most relevant findings from researchers around the world on the role of the chemical composition and mineral contents of VA on reactivity during the alkali-activation reaction; the effect of synthesis factors, which include the concentration of the alkaline activator, the solution-to-binder ratio and the curing conditions, on the properties of alkali-activated VA-based materials; and the mechanical performance and durability properties of these materials.

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