scholarly journals Mine Tailings Geopolymers as a Waste Management Solution for A More Sustainable Habitat

2019 ◽  
Vol 11 (4) ◽  
pp. 995 ◽  
Author(s):  
Helena Paiva ◽  
Juho Yliniemi ◽  
Mirja Illikainen ◽  
Fernando Rocha ◽  
Victor Ferreira
Keyword(s):  
Waste Management ◽  
Mine Tailing ◽  
Effect Of Temperature ◽  
Alkali Activation ◽  
Activation Process ◽  
Fine Aggregate ◽  
Curing Conditions ◽  
Waste Valorisation ◽  
Binder Type ◽  
Hardened State

The demand for low environmental impact of materials in our habitat is one of the current societal challenges. Along with other solutions of waste valorisation, alkali activation as geopolymers can be one possible solution of waste valorisation because they may allow, for instance, an alternative solution for cement-based materials in some applications and it is one contribution for circular economy. This work has focused on the development and processing of geopolymers that incorporates as a fine aggregate a high-sulfidic mining waste (mine tailing), a difficult waste to process. Rheology analysis was applied as an important step to understand not only the geopolymers behaviour but also its transition from the fresh to the hardened state. The effect of precursor binder type (metakaolin or blast furnace slag), of mine tailing content and also the effect of temperature and curing conditions of different formulations were studied in this solution. It was possible to conclude that although this particular mine tailing is not a geopolymer binder precursor, it may be incorporated as an alternative fine aggregate in construction products. Furthermore, rheology could be used to follow up the geopolymer alkali-activation process and even to setup proper curing conditions and components contents in order to optimize the final mechanical strength of this material as a waste management solution. The final properties of these geopolymers compositions were adequate and after 28 days of curing, these geopolymers exhibit significant chemical resistance under severe test conditions.

scholarly journals Role of Natural Stone Wastes and Minerals in the Alkali Activation Process: A Review

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2284
Author(s):  
Bartolomeo Coppola ◽  
Jean-Marc Tulliani ◽  
Paola Antonaci ◽  
Paola Palmero
Keyword(s):  
Raw Materials ◽  
Natural Stone ◽  
Partial Substitution ◽  
Alkali Activation ◽  
Activation Process ◽  
Active Components ◽  
Curing Conditions ◽  
Mineral Additions ◽  
Alumino Silicate

This review aims to provide a comprehensive assessment concerning alkali activation of natural stone wastes and minerals. In particular, the structure of the review is divided into two main sections in which the works dealing with alumino-silicate and carbonatic stones are discussed, respectively. Alumino-silicate stones are generally composed of quartz and feldspars, while carbonatic stones are mainly made of calcite and dolomite. The role of these minerals in the alkali activation process is discussed, attesting their influence in the development of the final product properties. In most of the works, authors use mineral additions only as fillers or aggregates and, in some cases, as a partial substitution of more traditional raw powders, such as metakaolin, fly ash, and granulated blast furnace slag. However, a few works in which alumino-silicate and carbonatic stone wastes are used as the main active components are discussed as well. Not only the raw materials, but also the entire alkali activation process and the curing conditions adopted in the literature studies here reviewed are systematically analyzed to improve the understanding of their effect on the physical, mechanical, and durability properties of the final products and to eventually foster the reuse of natural stone wastes for the purposes of sustainability in different applications.

Performance of Lime-Metakaolin Pastes and Mortars in Two Curing Conditions Containing Kaolin Wastes

2015 ◽  
Vol 668 ◽  
pp. 419-432 ◽  
Author(s):  
Aline Figueirêdo Nóbrega de Azerêdo ◽  
Givanildo Azeredo ◽  
Arnaldo Manoel Pereira Carneiro
Keyword(s):  
Hydrated Lime ◽  
Microstructural Characteristics ◽  
Curing Conditions ◽  
Pozzolanic Material ◽  
Cement Mortars ◽  
Lime Mortars ◽  
Moist Environment ◽  
Hardened State ◽  
Hydrated Products ◽  
Hardened Properties

Many works have shown that metakaolin is very good pozzolanic material for using in lime mortars and Portland cement mortars. Alternatively, many studies also have shown that kaolin wastes, after some treatment, can become a high quality pozzolans. Most of these studies have discussed about the microstructural characteristics and hardened properties of pastes, mortars or concretes mixes containing metakaolin or kaolin wastes cured in moist environment. In this work pastes and mortars made of metakaolin and hydrated lime (L-MK), which the metakaolin was obtained from the kaolin production waste, were assessed in their hardened state. Two curing conditions were considered: dry and moist environment; and three ages of curing (28, 90 and 180 days) were studied. Pastes were assessed by XRD and TG/DTG. In pastes according to the XRD and TG/DTG results, the main hydrated products found were strätlingite, in moist curing, and monocarboaluminate, in dry curing. Properties like flexural and compressive strengths, water absorbed capillarity and loss mass variation were studied in mortars. The results showed that mortars in dry curing presented lower strengths than one in moist curing. In moist curing mortars presented compressive strength values around 12 MPa and in dry curing this value reached 6 MPa. This fact indicate that the strätlingite maybe is responsible for the high strengths in mortars in moist curing when compares with the strengths of mortars cured in dry environment. Further the results showed that mortars in dry curing presented higher water absorbed and mass loss variation than mortars in moist curing.

scholarly journals PROPERTIES OF MORTARS CONTAINING TIRE RUBBER WASTE AND EXPANDED POLYSTYRENE (EPS)

2018 ◽  
pp. 219-225 ◽  
Author(s):  
Adriane Pczieczek ◽  
Adilson Schackow ◽  
Carmeane Effting ◽  
Itamar Ribeiro Gomes ◽  
Talita Flores Dias
Keyword(s):  
Compressive Strength ◽  
Specific Gravity ◽  
Water Absorption ◽  
Expanded Polystyrene ◽  
Fine Aggregate ◽  
Tire Rubber ◽  
Air Content ◽  
Rubber Waste ◽  
Hardened State ◽  
Entrained Air

This study aims to evaluate the application of discarded tire rubber waste and Expanded Polystyrene (EPS) in mortar. For mortars fine aggregate was replaced by 10%, 20% and 30% of rubber and, 7.5% and 15% of EPS. We have verified the consistency, density, amount of air and water retentitivity in fresh state. The compressive strength, water absorption, voids ratio and specific gravity have been also tested in hardened state. The application of rubber powder contributed to the increase in entrained air content and in reducing specific gravity, as well as reducing compressive strength at 28 days. The addition of EPS also contributed to the increase of workability, water absorption and voids ratio, and decreased density and compressive strength when compared to the reference mortar. The use of rubber waste and EPS in mortar made the material more lightweight and workable. The mortars mixtures containing 10% rubber and 7.5% EPS showed better results.

Waste management and value extraction in Italy: Where is the citizen? Waste to worth

2020 ◽  
pp. 159-180
Author(s):  
Dario Minervini
Keyword(s):  
Waste Management ◽  
Waste Recycling ◽  
Public Utility ◽  
The Political ◽  
Documentary Analysis ◽  
Identity And Agency ◽  
Waste Valorisation ◽  
Urban Welfare

The chapter focuses on the role of citizens and how this role is framed in official reports about waste. The hypothesis advanced is that the “objectivity” of the win-win game of waste recycling, accounted for by the official national reports, neutralizes the political overlapping of the neoliberal logic of waste commodification with the logics of public utility and urban welfare. A documentary analysis of official reports released by three of the most important actors performing Italian governance of waste management and recycling, is presented. The findings show how different logics adopted in the institutional accounting strategy contribute towards enacting a particular identity and agency of citizens in the process of waste valorisation.

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.

Alkali activation of fly ash. Part III: Effect of curing conditions on reaction and its graphical description

Fuel ◽  
2010 ◽  
Vol 89 (11) ◽  
pp. 3185-3192 ◽  
Author(s):  
M. Criado ◽  
A. Fernández-Jiménez ◽  
A. Palomo
Keyword(s):  
Fly Ash ◽  
Alkali Activation ◽  
Curing Conditions

Strength Development Characteristic of Cementless Mortar for Repair of Concrete

2018 ◽  
Vol 774 ◽  
pp. 277-282
Author(s):  
Gum Sung Ryu ◽  
Kyung Taek Koh ◽  
Gi Hong An ◽  
Hyeong Yeol Kim ◽  
Sung Choi
Keyword(s):  
Concrete Structures ◽  
Strength Development ◽  
Alkali Activation ◽  
Curing Conditions ◽  
Granulated Blast Furnace Slag ◽  
Repair Materials ◽  
Binder Ratio ◽  
Development Characteristic ◽  
High Bond ◽  
High Bond Strength

Repair materials for concrete structures are often required to exhibit high bond strength at a concrete substrate, and it typically consists of ordinary Portland cement (OPC) incorporating expensive admixtures at a low water-to-binder ratio. Meanwhile, cementless mortar employs alkali-activation of cementless and pozzolanic precursors such as ground granulated blast-furnace slag (GGBFS) and fly ash (FA). The final product develops strength relatively faster than OPC, and its strength can be flexibly talyored by controlling the type and dosage of the activator. The present study investigates the strength development characteristic of cementles mortar for use in repair of concrete structures. Independent variables include mix proportions and curing conditions, which were chosen to optimize the performance of the cementless mortar.

Manufacture of High-Performance Concrete Made with Powdered Polyester Resin Waste and Carboxylic-Ester Based Superplasticizer

2015 ◽  
Vol 1129 ◽  
pp. 523-529 ◽  
Author(s):  
A. Rodríguez ◽  
Pablo Luis Campos ◽  
J. Garabito ◽  
Juan García ◽  
Isabel Santamaría
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
Polyester Resin ◽  
High Performance Concrete ◽  
The Other ◽  
Partial Substitution ◽  
Fine Aggregate ◽  
Hardened State ◽  
Aggregate Material ◽  
Research Show

A high-performance concrete design is presented that incorporates powdered polyester resin waste as a fine aggregate material in partial substitution of sand, with additions of both a superplasticizer based on carboxylic ethers and silica fume. The potential application of the powdered polyester resin and its properties as an aggregate are both analysed as well as the mechanical behaviour, in both the fresh and the hardened states, of the concrete. Both the flexural and the compressive strength of the concrete were shown to depend on the amount of waste used in substitution of the sand. The results of the research show that the designed concrete reaches the resistances of a high performance concrete with values ​​above 50 MPa. On the other hand, the rest of its properties are equivalents, both in the fresh and hardened state, proportional to the amount of powdered polyester resin that is added. However, to achieve this, the use of superplasticizers additives and admixtures of silica fume is necessary.

Fly Ash Based Lightweight Geopolymer Concrete Using Foaming Agent Technology

2014 ◽  
Vol 679 ◽  
pp. 20-24 ◽  
Author(s):  
Mohd Mustafa Al Bakri Abdullah ◽  
Zarina Yahya ◽  
Muhammad Faheem Mohd Tahir ◽  
Kamarudin Hussin ◽  
Mohammed Binhussain ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Room Temperature ◽  
Lightweight Concrete ◽  
Agent Technology ◽  
Alkali Activation ◽  
Geopolymer Concrete ◽  
Foaming Agent ◽  
Curing Conditions ◽  
Foam Generator

This paper presents the mechanical properties of a lightweight geopolymer concrete synthesized by the alkali-activation of a fly ash source (FA) produced by mixing a paste of geopolymer with foam produced by using NCT Foam Generator. Two curing conditions are used, curing at room temperature and curing in an oven with a constant temperature which is 60 oC. Bulk density showed that fly ash-based geopolymer lightweight concrete is light with the density of 1225 kg/m3 - 1667 kg/m3 with an acceptable compressive strength of 17.60 MPa for the density of 1667 kg/m3.

scholarly journals Rice Hull-Derived Carbon for Supercapacitors: Towards Sustainable Silicon-Carbon Supercapacitors

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4463
Author(s):  
Changwei Li ◽  
Honglei Chen ◽  
Liqiong Zhang ◽  
Shenghui Jiao ◽  
Huixin Zhang ◽  
...  
Keyword(s):  
High Energy ◽  
High Energy Density ◽  
Rice Hull ◽  
Alkali Activation ◽  
Activation Process ◽  
Biomass Waste ◽  
Thin Walls ◽  
Silicon Carbon ◽  
Potential Applicability ◽  
Optimal Material

A simple and effective mixing carbonization-activation process was developed to prepare rice hull-derived porous Si–carbon materials. The morphologies and pore structures of the materials were controlled effectively without any loading or additions at various carbonization temperatures. The structures of the samples changed from large pores and thick walls after 800 ∘C carbonization to small pores and thin walls after 1000 ∘C carbonization. An additional alkali activation–carbonization process led to coral reef-like structures surrounded by squama in the sample that underwent 900 ∘C carbonization (Act-RH-900). This optimal material (Act-RH-900) had a large specific surface area (768 m2 g−1), relatively stable specific capacitance (150.8 F g−1), high energy density (31.9 Wh kg−1), and high-power density (309.2 w kg−1) at a current density of 0.5 A g−1 in 1 M KOH electrolyte, as well as a good rate performance and high stability (capacitance retention > 87.88% after 5000 cycles). The results indicated that Act-RH-900 is a promising candidate for capacitive applications. This work overcomes the restrictions imposed by the complex internal structure of biomass, implements a simple reaction environment, and broadens the potential applicability of biomass waste in the field of supercapacitors.

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