Experimental Study on Mechanical Properties and Micro-Mechanism of All-Solid-Waste Alkali Activated Binders Solidified Marine Soft Soil

2021 ◽  
Vol 1036 ◽  
pp. 327-336
Author(s):  
Ya Lei Wu ◽  
Jun Jie Yang ◽  
Si Chen Li ◽  
Man Wang
Keyword(s):  
Mechanical Properties ◽  
Solid Waste ◽  
Coal Fly Ash ◽  
Soft Soil ◽  
Deformation Modulus ◽  
Alkali Activation ◽  
Activation Process ◽  
Pozzolanic Materials ◽  
Alkali Activated Binders ◽  
Alkali Activated

Utilizing granulated blast furnace slag (GBFS), coal fly ash (FA), and furfural residue incineration ash (FRIA) as pozzolanic materials, then activated with calcium carbide residue (CCR) respectively to prepare all-solid-waste alkali activated binders (ASW binders). The laboratory tests were performed to research the effects of pozzolanic materials with different reactivity on the macro- and micro- characteristics of solidified marine soft soil. Results show that the mechanical properties and alkali-activation process of ASW binders solidified soil was determined mainly by the reactivity of pozzolanic materials, the higher reactivity of the pozzolanic materials in ASW binders couldn’t change the main hydration products, however, it would accelerate the hydrate reaction. The degree of hydrate reaction increased, the microstructure became denser with the increase of the reactivity of the pozzolanic materials in ASW binders solidified soil, on the macro- side, the strength and deformation modulus of the solidified soil increased, meanwhile, the brittleness of the solidified soil will be more obvious during the deformation resistance process. ASW binders (CCR:GBFS=1:1) solidified soil could reach the strength of cemented soil under the same conditions.

scholarly journals Effects of EAF-Slag on alkali-activation of tungsten mining waste: mechanical properties

2019 ◽  
Vol 274 ◽  
pp. 01003 ◽  
Author(s):  
Naim Sedira ◽  
João Castro-Gomes
Keyword(s):  
Mechanical Properties ◽  
Sodium Silicate ◽  
Mining Waste ◽  
Alkali Activation ◽  
X Ray Diffraction ◽  
Eaf Slag ◽  
Electric Arc Furnace Slag ◽  
Solid Liquid ◽  
Alkali Activated Binders ◽  
Alkali Activated

The mechanical properties of alkali-activated binders based on blends of tungsten mining waste mud (TMWM) and electric arc furnace slag (EAF-S) were investigated. The synthesis of alkali-activated binders was conducted at 60°C for 24 h with different TMWM/EAF-Slag ratios (90:10, 80:20, 70:30, 60:40, and 50:50 vt.%). Using sodium hydroxide (SH) and sodium silicate (SS) solutions as alkaline activators with ratio solid/liquid 4 by unit of volume, and the sodium silicate to NaOH (SS:SH) ratio of 2:1. The X-ray Diffraction (XRD), mercury intrusion porosimetry (MIP) were determined. The different percentages of the precursors and the alkaline activators were optimised to produce paste samples. The compressive strength of samples with 10 vt.% EAF-Slag was close to 20.7 MPa after 90 curing days. The mechanical properties were further increased up to 30 MPa by increasing the percentage of EAF-Slag to 50 vt.%. This demonstrates a new potential for re-using waste material for various constructional applications.

scholarly journals Fayalite Slag as Binder and Aggregate in Alkali-Activated Materials—Interfacial Transition Zone Study

Proceedings ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 1 ◽  
Author(s):  
Adediran ◽  
Yliniemi ◽  
Illikainen
Keyword(s):  
Transition Zone ◽  
Sodium Hydroxide Solution ◽  
Coal Fly Ash ◽  
Construction Materials ◽  
Fine Powder ◽  
Silicate Solution ◽  
Interfacial Transition Zone ◽  
Alkali Activation ◽  
Fayalite Slag ◽  
Alkali Activated

Alkali-activated materials (AAMs) are an environmentally friendly option for Portland cement mortars and concretes. Many industrial residues such as blast furnace slag and coal fly ash have been extensively studied and applied as AAM precursors but much less focus has been on the use of fayalite slags. Water-cooled fayalite slag comes in granular form, which is then milled into fine powder (d50 ~10 microns) prior to its alkali activation. In addition, the un-milled granular fayalite slag can be used as an aggregate to replace sand in mortar. The alkaline solution utilized for the study was a mix of 10 M sodium hydroxide solution and commercial potassium silicate solution. A liquid to solid ratio of 0.15 was held constant for all the mixes. The particle size distributions of the binder and the aggregates were optimized, and the microstructure and chemical composition of the interfacial transition zone (ITZ) was studied using scanning electron microscope coupled with energy dispersive X-ray spectroscopy. ITZ is a region that exists between the aggregate and the binder and this can influence the mechanical and transport properties of the construction materials. The results showed that the mechanical properties of mortar having fayalite slag as aggregate and binder was significantly higher than one with standard sand as aggregate. No distinct ITZ was found in the samples with fayalite slag as aggregate. The outer rim of the fayalite slag aggregate participated in the hardening reaction and this significantly contributed to the bonding and microstructural properties of the mortar samples. In contrast, an ITZ was observed in mortar samples with standard sand aggregates, which contributed to its lower strength.

scholarly journals Evaluation of Physical Properties of a Metakaolin-Based Alkali-Activated Binder Containing Waste Foam Glass

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5458
Author(s):  
Petra Mácová ◽  
Konstantinos Sotiriadis ◽  
Zuzana Slížková ◽  
Petr Šašek ◽  
Michal Řehoř ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Physical Properties ◽  
Foam Glass ◽  
Glass Production ◽  
Alkali Activation ◽  
Activation Process ◽  
X Ray ◽  
Thermal Insulating ◽  
The Matrix ◽  
Alkali Activated

Foam glass production process redounds to large quantities of waste that, if not recycled, are stockpiled in the environment. In this work, increasing amounts of waste foam glass were used to produce metakaolin-based alkali-activated composites. Phase composition and morphology were investigated by means of X-ray powder diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy. Subsequently, the physical properties of the materials (density, porosity, thermal conductivity and mechanical strength) were determined. The analysis showed that waste foam glass functioned as an aggregate, introducing irregular voids in the matrix. The obtained composites were largely porous (>45%), with a thermal conductivity coefficient similar to that of timber (<0.2 W/m∙K). Optimum compressive strength was achieved for 10% incorporation of the waste by weight in the binder. The resulting mechanical properties suggest the suitability of the produced materials for use in thermal insulating applications where high load-bearing capacities are not required. Mechanical or chemical treatment of the waste is recommended for further exploitation of its potential in participating in the alkali activation process.

scholarly journals An overview of the utilisation of Fe-rich residues in alkali-activated binders: Mechanical properties and state of iron

2021 ◽  
pp. 129900
Author(s):  
Vitalii Ponomar ◽  
Juho Yliniemi ◽  
Elijah Adesanya ◽  
Katja Ohenoja ◽  
Mirja Illikainen
Keyword(s):  
Mechanical Properties ◽  
Alkali Activated Binders ◽  
Alkali Activated

scholarly journals Mechanical properties of alkali activated geopolymer paste using different Romanian fly ash sources – experimental results

2019 ◽  
Vol 289 ◽  
pp. 11001 ◽  
Author(s):  
Adrian Lăzărescu ◽  
Călin Mircea ◽  
Henriette Szilagyi ◽  
Cornelia Baeră
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Production Control ◽  
Experimental Results ◽  
Activation Process ◽  
Geopolymer Concrete ◽  
Alkaline Activation ◽  
Concrete Production ◽  
Specific Reactions ◽  
Alkali Activated

As concrete demand is constantly increasing in recent years and also considering that cement production is both a consumer of natural resources and a source of carbon dioxide release into the atmosphere, there have been worldwide investigations into green alternatives for making concrete environmentally friendlier and simultaneously to satisfy the development of infrastructure facilities. The use of fly ash as a component of cementitious binders is not new but when considering the specific case of alkaline activation and fly ash representing the only source for the binder formation, it necessitates a more complete understanding of its specific reactions during the alkaline activation process. Since the fly ash varies dramatically, not only from one source to another, but also from one batch to another even when provided by the same power plant, its chemistry in obtaining alkali-activated materials during the geopolymerisation process and the final mechanical properties are considered crucial for the performance of geopolymer concrete. This paper will provide a review of the experimental results concerning the physical and mechanical evaluation of the alkali-activated fly ash-based geopolymer materials, developed with different types of fly ash, for a better understanding of geopolymer concrete production control.

scholarly journals The Potential of Ladle Slag and Electric Arc Furnace Slag use in Synthesizing Alkali Activated Materials; the Influence of Curing on Mechanical Properties

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1173 ◽  
Author(s):  
Češnovar ◽  
Traven ◽  
Horvat ◽  
Ducman
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Room Temperature ◽  
Electric Arc Furnace ◽  
Electric Arc ◽  
Alkali Activation ◽  
Arc Furnace ◽  
Curing Time ◽  
Promising Alternative ◽  
Alkali Activated

Alkali activation is studied as a potential technology to produce a group of high performance building materials from industrial residues such as metallurgical slag. Namely, slags containing aluminate and silicate form a useful solid material when activated by an alkaline solution. The alkali-activated (AA) slag-based materials are promising alternative products for civil engineering sector and industrial purposes. In the present study the locally available electric arc furnace steel slag (Slag A) and the ladle furnace basic slag (Slag R) from different metallurgical industries in Slovenia were selected for alkali activation because of promising amorphous Al/Si rich content. Different mixtures of selected precursors were prepared in the Slag A/Slag R ratios 1/0, 3/1, 1/1, 1/3 and 0/1 and further activated with potassium silicate using an activator to slag ratio of 1:2 in order to select the optimal composition with respect to their mechanical properties. Bending strength of investigated samples ranged between 4 and 18 MPa, whereas compressive strength varied between 30 and 60 MPa. The optimal mixture (Slag A/Slag R = 1/1) was further used to study strength development under the influence of different curing temperatures at room temperature (R. T.), and in a heat-chamber at 50, 70 and 90 °C, and the effects of curing time for 1, 3, 7 and 28 days was furthermore studied. The influence of curing time at room temperature on the mechanical strength at an early age was found to be nearly linear. Further, it was shown that specimens cured at 70 °C for 3 days attained almost identical (bending/compressive) strength to those cured at room temperature for 28 days. Additionally, microstructure evaluation of input materials and samples cured under different conditions was performed by means of XRD, FTIR, SEM and mercury intrusion porosimetry (MIP).

scholarly journals Incorporation of Alkali-Activated Municipal Solid Waste Incinerator Bottom Ash in Mortar and Concrete: A Critical Review

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3428 ◽  
Author(s):  
Rawaz Kurda ◽  
Rui Vasco Silva ◽  
Jorge de Brito
Keyword(s):  
Literature Review ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Bottom Ash ◽  
Curing Temperature ◽  
Partial Replacement ◽  
Alkali Activation ◽  
Waste Incinerator ◽  
Alkaline Activator ◽  
Alkali Activated

In the light of one of the most common waste management issues in urban areas, namely the elimination of municipal solid waste (MSW; about 486 kg of the waste per capita were generated in the EU in 2017), this study discusses one technique as an outlet in the construction industry for the by-product of the waste’s incineration in energy recovery facilities (i.e., MSW incinerator bottom ash—MIBA). There have been some investigations on the use of MIBA as partial replacement of cement to be used in cementitious composites, such as concrete and mortars. However, the waste’s incorporation ratio is limited since further products of hydration may not be produced after a given replacement level and can lead to an unsustainable decline in performance. In order to maximize the incorporation of MIBA, some research studies have been conducted on the alkali activation of the waste as precursor. Thus, this study presents an extensive literature review of the most relevant investigations on the matter to understand the material’s applicability in construction. It analyses the performance of the alkali-activated MIBA as paste, mortar, and concrete from different perspectives. This literature review was made using search engines of several databases. In each database, the same search options were repeated using combinations of various representative keywords. Furthermore, several boundaries were made to find the most relevant studies for further inspection. The main findings of this review have shown that the chemical composition and reactivity of MIBA vary considerably, which may compromise performance comparison, standardization and commercialization. There are several factors that affect the performance of the material that need to be considered, e.g., type and content of precursor, alkaline activator, curing temperature and time, liquid to solid ratio, among others. MIBA-based alkali-activated materials (AAM) can be produced with a very wide range of compressive strength (0.3–160 MPa). The main factor affecting the performance of this precursor is the existence of metallic aluminum (Al), which leads to damaging expansive reactions and an increase in porosity due to hydrogen gas generation stemming from the reaction with the alkaline activator. Several approaches have been proposed to eliminate this issue. The most effective solution was found to be the removal of Al by means of eddy current electromagnetic separation.

The Leachability of Heavy Metals from Alkali-Activated Fly Ash and Blast Furnace Slag Matrices

2016 ◽  
Vol 851 ◽  
pp. 141-146
Author(s):  
Jan Koplík ◽  
Miroslava Smolková ◽  
Jakub Tkacz
Keyword(s):  
Mechanical Properties ◽  
Heavy Metals ◽  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Inductively Coupled Plasma ◽  
Emission Spectrometry ◽  
Alkali Activation ◽  
Furnace Slag ◽  
Alkali Activated

The ability of alkali-activated materials (AAMs) to fix and immobilize heavy metals was investigated. Two raw materials were used to prepare alkali-activated matrices – high-temperature fly ash and blast furnace slag (BFS). NaOH served as an alkaline activator. Two heavy metals (Mn, Ni) were added in different amounts to find out the influence of dosage of heavy metal on the mechanical properties of the matrices and the leachability. Leachability was measured as concentration of heavy metals in leachates (ČSN EN 12457-4) by inductively coupled plasma/optical emission spectrometry (ICP/OES). Structure of prepared matrices was characterized by scanning electron microscopy (SEM). Increasing of addition of heavy metals led to decrease of mechanical properties of matrices. The leaching tests showed, that both matrices can immobilize Mn and Ni in dosages of 0.1 – 2,5%. Higher dosages caused deterioration of the matrices and increased the leachability. After alkali activation both heavy metals were transformed into the form of insoluble salts.

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.

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