scholarly journals Alkali-Activation of Synthetic Aluminosilicate Glass With Basaltic Composition

2021 ◽  
Vol 9 ◽  
Author(s):  
Mohammad I. M. Alzeer ◽  
Hoang Nguyen ◽  
Christopher Cheeseman ◽  
Paivo Kinnunen
Keyword(s):  
Mechanical Performance ◽  
High Strength ◽  
Aluminosilicate Glass ◽  
Alkali Activation ◽  
Basalt Glass ◽  
Sodium Aluminosilicate ◽  
Granulated Blast Furnace Slag ◽  
Basaltic Composition ◽  
Sodium Aluminosilicate Hydrate ◽  
Alkali Activated

Alkali-activated materials (AAMs) are a potential alternative to Portland cement because they can have high strength, good durability and low environmental impact. This paper reports on the structural and mechanical characteristics of aluminosilicate glass with basalt-like compositions, as a feedstock for AAMs. The alkali-activation kinetics, microstructure, and mechanical performance of the alkali activated glass were investigated. The results show that AAMs prepared from basalt glass have high compressive strength (reaching up to 90 MPa after 7 days of hydration) compared to those made using granulated blast furnace slag (GBFS). In addition, calorimetry data show that the hydrolysis of the developed glass and subsequent polymerization of the reaction product occur at a faster rate compared to GBFS. Furthermore, the obtained results show that the alkali activation of the developed glass formed sodium aluminosilicate hydrate (N-A-S-H) intermixed with Ca aluminosilicate hydrate gel (C-A-S-H), while the alkali activation of GBFS resulted in predominantly C-A-S-H gel. The developed glass can be formed from carbonate-free and abundant natural resources such as basalt rocks or mixtures of silicate minerals. Therefore, the glass reported herein has high potential as a new feedstock of AAMs.

scholarly journals Volcanic Ash as a Sustainable Binder Material: An Extensive Review

Materials ◽  
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.

scholarly journals Influence of Na2O Content and Ms (SiO2/Na2O) of Alkaline Activator on Workability and Setting of Alkali-Activated Slag Paste

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2072 ◽  
Author(s):  
Sung Choi ◽  
Kwang-Myong Lee
Keyword(s):  
Setting Time ◽  
High Strength ◽  
Abrupt Decrease ◽  
Na2o Content ◽  
Alkali Activated Slag ◽  
Granulated Blast Furnace Slag ◽  
Type Composition ◽  
Activated Slag ◽  
Binary Alkaline ◽  
Alkali Activated

The performance of alkali-activated slag (AAS) paste using activators of strong alkali components is affected by the type, composition, and dosage of the alkaline activators. Promoting the reaction of ground granulated blast furnace slag (GGBFS) by alkaline activators can produce high-strength AAS concrete, but the workability might be drastically reduced. This study is aimed to experimentally investigate the heat release, workability, and setting time of AAS pastes and the compressive strength of AAS mortars considering the Na2O content and the ratio of Na2O to SiO2 (Ms) of binary alkaline activators blended with sodium hydroxide and sodium silicate. The test results indicated that the AAS mortars exhibited a high strength of 25 MPa at 24 h, even at ambient temperature, even though the pastes with an Na2O content of ≥6% and an Ms of ≥1.0 exhibited an abrupt decrease in flowability and rapid setting.

Comparison of Selected Properties of Portland Cement Based Materials and Alkali Activated Materials Based on Granulated Blast Furnace Slag

2016 ◽  
Vol 865 ◽  
pp. 107-113 ◽  
Author(s):  
Pavel Mec ◽  
Jana Boháčová ◽  
Josef Koňařík
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Water Glass ◽  
Sodium Metasilicate ◽  
Alkali Activation ◽  
Granulated Blast Furnace Slag ◽  
Cement Based Materials ◽  
One Year ◽  
Furnace Slag ◽  
Alkali Activated

Alkali activated systems are materials formed by alkali-activation of latent hydraulic or pozzolanic materials. The outcome is a polymeric structure with properties comparable to materials based on cement.The principle of the experiment is to compare selected properties of alkali-activated materials based on blast furnace slag and using various types of activator (sodium water glass, potassium water glass, DESIL AL and sodium metasilicate) to binders based on white and Portland cements of the highest quality. The samples were left for one year in environments simulating the conditions in the interior and exterior. Selected physical-mechanical properties were evaluated and compared.

Alkali-Activation Reactivity and Al Environment of Chemosynthetic Al2O3–2SiO2 Powders

2009 ◽  
Vol 79-82 ◽  
pp. 2079-2082 ◽  
Author(s):  
Guang Jian Zheng ◽  
Xue Min Cui ◽  
Wei Peng Zhang ◽  
Zhang Fa Tong
Keyword(s):  
Sol Gel ◽  
High Strength ◽  
Alkali Activation ◽  
Gel Method ◽  
Fine Grained ◽  
Heat Treated ◽  
27Al Mas Nmr ◽  
Alkali Activated ◽  
Heat Treated Temperature ◽  
Pure Al2o3

In this study, pure Al2O3-2SiO2 powders for a geopolymer were prepared by a sol-gel method, alkali-activation tests and alkali-dissolvability of the powders were carried out, and structure of the powders and alkali-activated products was investigated by 29Si and 27Al MAS NMR and SEM. Results showed that higher alkali-activation reactivity (higher compressive strengths of alkali-activated products) appeared in the powders heat-treated between 600-800 °C and alkali-dissolvability trend was different from that of alkali-activation tests. There were clear correlations between microstructure of alkali-activated products and alkali-activation reactivity and Al environment of the powders. It was found that high strength was related to a dense, fine grained microstructure. Such a structure was found in the alkali-activated products synthesized with the powders with high 5-coordinated Al contents. In addition, the peaks attributed to 5-coordinated Al were strengthened with the rise of heat-treated temperature of the powders.

Experimental Study on Compound Binding Material of Alkali Activated Metakaolin and Ground Granulated Blast Furnace Slag

2011 ◽  
Vol 287-290 ◽  
pp. 1275-1279
Author(s):  
Yong Jia He ◽  
Lin Nu Lu ◽  
Shu Guang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Hydration Product ◽  
Alkali Activation ◽  
Granulated Blast Furnace Slag ◽  
Binding Material ◽  
Measurement Results ◽  
Furnace Slag ◽  
Alkali Activated

Compound binding material was prepared by the alkali activation of metakaolin and ground granulated blast furnace slag. Hydration product components, microstructure and mechanical properties of the hardened paste were investigated by IR, XRD, SEM, MIP, and compressive strength measurement. Results indicated that hydration products included C-S-H and geopolymer, and both of them were amorphous although there were differences in their structure and morphology. When the dosage of slag was less than 50%, the compressive strength of hardened paste increased as the dosage increased, which was mainly because C-S-H produced by the reaction of GGBFS and alkali filled void in geopolymer phase, and part of unreacted slag particles acting as microaggregate to prevent from extension of microcrack in the hardened paste, so the porosity of hardened paste decreased and compressive strength increased.

scholarly journals A Review of Durability and Strength Characteristics of Alkali-Activated Slag Concrete

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1198 ◽  
Author(s):  
Osama Ahmed Mohamed
Keyword(s):  
Rapid Development ◽  
Setting Time ◽  
High Rate ◽  
Alkali Activation ◽  
Promising Alternative ◽  
Alkali Activated Slag ◽  
Granulated Blast Furnace Slag ◽  
High Alkalinity ◽  
Activated Slag ◽  
Alkali Activated

Alkali-activated slag (AAS) is a promising alternative to ordinary Portland cement (OPC) as sole binder for reinforced concrete structures. OPC is reportedly responsible for over 5% of the global CO2 emission. In addition, slag is an industrial by-product that must be land-filled if not re-used. Therefore, it has been studied by many investigators as environmentally friendly replacement of OPC. In addition to recycling, AAS offers favorable properties to concrete such as rapid development of compressive strength and high resistance to sulfate attack. Some of the potential shortcomings of AAS include high shrinkage, short setting time, and high rate of carbonation. Using ground granulated blast furnace slag (GGBS) as an alternative to OPC requires its activation with high alkalinity compounds such as sodium hydroxide (NaOH), sodium sulfate (Na2SO3), sodium carbonate (Na2CO3), or combination of these compounds such as NaOH and Na2SO3. The mechanism of alkali-activation is still not fully understood and further research is required. This paper overviews the properties, advantages, and potential shortcomings of AAS concrete.

Preliminary Studies on the use of Sugar Cane Bagasse Ash (SCBA) in the Manufacture of Alkali Activated Binders

2014 ◽  
Vol 600 ◽  
pp. 689-698 ◽  
Author(s):  
Vinicius N. Castaldelli ◽  
Mauro M. Tashima ◽  
José Luiz P. Melges ◽  
Jorge L. Akasaki ◽  
J.M. Monzó ◽  
...  
Keyword(s):  
Sugar Cane ◽  
Binary Systems ◽  
Mechanical Performance ◽  
Sugar Cane Bagasse ◽  
Mineral Admixtures ◽  
Alkali Activation ◽  
Sugar Cane Bagasse Ash ◽  
Alkali Activated Binders ◽  
Mechanical Strengths ◽  
Alkali Activated

Alkali activated binders require the addition of a mineral-rich amorphous silica and alumina. This paper proposes the use of a mineral residue from the burning of sugar cane bagasse. The alkali activated mixtures were prepared containing binary mixtures of sugar cane bagasse ash (SCBA) and other mineral admixtures: fly ash (FA) or blast furnace slag (BFS). As alkaline activators, mixtures of alkali (Na+ or K+) hydroxide and alkali (Na+ or K+) silicate were used. Alkali-activated pastes and mortars containing binary systems SCBA/FA or SCBA/BFS were prepared and cured at 65 oC. Microstructural properties of these alternative binders were assessed by means of TGA, SEM, XRD and pH measurements. Mechanical strength of mortars was performed after 3 and 7 days at 65 oC. Compressive mechanical strengths of these mortars were in the range 30-55 MPa, showing the good mechanical performance achieved by the alkali activation. Microstructural studies suggested the development of stable matrices and the formation of typical gel.

scholarly journals A study of alkali-activated concrete mixes with ground granulated blast furnace slag

2018 ◽  
Vol 20 (2) ◽  
pp. 208-215
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Statistical Significance ◽  
Alkali Activation ◽  
Curing Conditions ◽  
Granulated Blast Furnace Slag ◽  
Number Of Factors ◽  
Furnace Slag ◽  
Alkali Activated Concrete ◽  
Alkali Activated

The paper presents a laboratory study of concrete mixes based on the alkali-activation of an industrial by-product, ground granulated blast furnace slag (GGBS). A number of factors potentially affecting the resulting concrete quality in terms of workability and strengths were investigated (namely activator type, molarity, curing conditions and times). The statistical significance of the effect of these factors was supported by ANOVA. Higher workability and strengths (with lower activator concentrations) were obtained for KOH containing mixes. Curing at constant moisture and ambient temperature was successful for most alkaline activators and mixes, which showed good concrete strengths at all curing times; when Na2SiO3 was used in addition to NaOH or KOH activators of moderate to high molarity, strengths exceeded those of Ordinary Portland Cement (CEM-I) concrete of a similar water/cement ratio.

scholarly journals Method for experimentally determining N-A-S-(H) solubility

2019 ◽  
Vol 3 ◽  
pp. 104-113 ◽  
Author(s):  
Trevor Williamson ◽  
Joonkyoung Han ◽  
Lynn Katz ◽  
Gaurav Sant ◽  
Maria Juenger
Keyword(s):  
Cementitious Materials ◽  
Primary Phase ◽  
Inorganic Polymer ◽  
Engineering Properties ◽  
Solution Composition ◽  
Sodium Aluminosilicate ◽  
Polymer Binders ◽  
Phase Development ◽  
Sodium Aluminosilicate Hydrate ◽  
Alkali Activated

Inorganic polymer binders, also sometimes called geopolymers or alkali-activated cements, can serve as an alternative to ordinary portland cement (OPC) in concrete.  The development of thermodynamic models to predict phase development and, ultimately, engineering properties, of inorganic polymer binders is an important step toward enabling their widespread use. However, such models require self-consistent solubility data of the primary phase in inorganic polymer binders, sodium aluminosilicate hydrate(s). To date, there is very little solubility information available for this phase. Here, a rigorous method for synthesizing sodium aluminosilicate hydrate(s) of controlled composition, and for measuring its solubility is presented. This approach allows complete stoichiometric control over the (initial) solution composition to elucidate directly the development of N-A-S-H composition as it relates to a given solution composition. A review of previous literature related to the solubility of other cementitious materials is presented, and the need for thermodynamic data is discussed. Finally, a sample calculation is presented for determining the solubility product (Ksp) of a laboratory synthesized sodium aluminosilicate hydrate.

scholarly journals Alkali Activation of Copper and Nickel Slag Composite Cementitious Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1155 ◽  
Author(s):  
Tingting Zhang ◽  
Shiwei Zhi ◽  
Tong Li ◽  
Ziyu Zhou ◽  
Min Li ◽  
...  
Keyword(s):  
Glass Phase ◽  
Chemical Activation ◽  
Cementitious Materials ◽  
Mineral Admixture ◽  
Alkali Activation ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Ft Ir ◽  
Furnace Slag ◽  
Alkali Activated

Alkali-activated copper and nickel slag cementitious materials (ACNCMs) are composite cementitious materials with CNS (copper and nickel slag) as the main materials and GGBFS (ground-granulated blast-furnace slag) as a mineral admixture. In this paper, the activity indexes of CNS with different grinding times were studied using CNS to replace a portion of cement. NaOH, Na2SO4, and Na2SiO3 activators were used to study the alkaline solution of the CNS glass phase. The effects of the fineness of CNS and the type of activator on the hydration of ACNCMs were investigated via physical/mechanical grinding and chemical activation. The hydration products of ACNCMs were analyzed via XRD, SEM, FT-IR, TG, and MIP. The results of the study revealed that the activity indexes of CNS ground with different grinding times (10, 30 and 50 min) were 0.662, 0.689, and 0.703, respectively. When Na2SiO3 was used as the activator, the glass phase dissolved the most Si4+, Al3+, and Ca2+, and the respective concentrations in the solution were found to be 2419, 39.55, and 3.38 mg/L. Additionally, the hydration products of ACNCMs were found to have a 28-day compressive strength of up to 84 MPa.

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