Cristina Leonelli

Università degli Studi di Modena e Reggio Emilia | UNIMO · Department of Engineering "Enzo Ferrari"

This work aims to synthesize new foaming laterite geopolymer foam using laterite, sodium silicate solution, sand, and aluminium powder. The porosity rapidly increased with the addition of the foaming agent. The foam matrix had thermal conductivity values of 0.10 W/m K with 0.7% of Al powder and 0.64 W/m K with 0% of Al powder. For fire resistance,...

A systematic study on the dissolution in concentrated alkali of two volcanic ashes from Cameroon, denoted as DAR and VN, is presented here. One volcanic ash, DAR, was 2 wt% richer in Fe and Ca and 4 wt% lower in Si than the other, designated as VN. Such natural raw materials are complex mixtures of aluminosilicate minerals (kaersutite, plagioclase,...

A number of synthesis parameters directly influence the degree of reticulation/geopolymerisation of metakaolin exposed to alkaline solutions of sodium hydroxide and/or sodium silicate. In the latter case, a sodium silicate solution can be depolymerised by the introduction of an appropriate amount of NaOH. The effects of the ageing of the activator...

In the present study, alkali-activated materials were assessed as adsorbents for mine water treatment. The composition of alkali-activated materials, involving mixtures of metakaolin, blast-furnace slag, mine tailings, and zeolite, was optimized based on their leaching behavior and adsorption performance. The most effective adsorbent contained sole...

Nanocomposites of sodium alginate (SA) and TiO 2 nanoparticles have gained attention in the last decade for their versatile uses in several applications. Indeed, TiO 2 is particularly appealing for its photocatalytic and antimicrobial activity and inherent safety. In this paper, TiO 2 nanoparticles are successfully embedded, synthesized by a microw...

This study demonstrates the preparation of porous geopolymers using different foaming agents for dye removal in water using methylene blue as the model solution. The porous membranes were prepared by combining alkaline activation solution, aluminosilicate source (either clay-rich laterite or iron-rich laterite), amorphous silica (rice husk ash) wit...

Water-intensive industries face challenges due to water scarcity and pollution. In the management of these challenges, membrane processes play an important role. However, they produce significant amounts of reject waters, in which the separated salts and pollutants are concentrated. This study aims to develop a novel management concept for reject w...

Geopolymers are amorphous aluminosilicate inorganic polymers synthesized by alkaline activation characterized by a lower carbon footprint, greater durability, and excellent mechanical properties compared to traditional concrete, making them promising building materials for sustainable construction. To develop sustainable lightweight geopolymer-base...

Processing conditions applied during microwave-assisted processes severely affects the final result, be it the yield of a reaction product or the microstructure of a determined heat treatment. Numerical simulation can help gather a deeper insight into microwave assisted processes, and by developing processing map, it can help selecting the optimum...

High early-strength concrete and geopolymer offer advantages of faster construction and require less curing time than traditional concrete. Bagasse ash (BA), an inert pozzolan with low reactivity in alkaline media, was activated with 10M NaOH to enhance its porosity and surface area. It was then incorporated into an 80:20 wt% mixture of metakaolin...

This perspective article delves into the transformative potential of alkali‐activated materials, acid‐activated materials, and geopolymers in mitigating climate change and market challenges. To harness the benefits of these materials, a comprehensive strategy is proposed. This strategy aims to integrate these materials into existing construction re...

This study provides experimental insights into the optimization of alkali-activated materials (AAMs) carried out in situ at the restoration site of Monreale Cathedral, Italy. Volcanic ash from Mt. Etna volcano (Italy) was used asa precursor to obtain AAMs. Standard and modified pastes with a small amount of slaked lime paste werecompared in terms...

Geopolymerization, a sustainable route to advanced binders, has traditionally been explored using common activators and single precursors such as metakaolin. Although previous investigations have explored the potential of feldspathic minerals, particularly with metakaolin as a partial replacement, there remains a gap in understanding the nuances of...

In this work, we focused on the possibility of using clay sediments found in Sicily as precursors to produce alkali activated materials (AAMs) with properties comparable to those of traditional materials used in construction. Two different clays were selected: Plio-Pleistocenic marly clay (PP) and Numidian Flysh clay (NU) to test the use of sedimen...

In this work, a rapid microwave-assisted hydrothermal method under mild conditions is investigated for the preparation of the Eu3+:YPO4 (5 mol % Eu) luminescent material, which belongs to a large family of phosphates that, when doped with lanthanide ions, acquire specific luminescence properties used primarily as phosphors for modern light sources...

The focus of this research is to investigate of the possibility of reusing mineral wastes and by-products from mining processes to produce more sustainable binders in large amounts. A mining by-product consisting of halloysite (approximately 48 wt%) was used to produce dense alkali activated solids. Attention was paid to the influence of temperatur...

In this investigation, mechanical activation (MA) of pegmatite quarry wastes was perform via an eccentric vibratory mill to improve the geopolymeric reactivity. The MA at miscellaneous times (0 to 90 min) resulted in different activation degrees of samples with improved the fineness of particle size and specific surface area from 2.974 to 5.311 m 2...

This work aims to synthesize new cementitious materials (binders) using marble powder, rice husk ash, activated laterite and NaOH solution by applying low energy process. The binder was used to stabilize solid precursors (laterite and pozzolan). To achieve this objective, calcium–silicate–hydrate (CSH) was first synthesized at different temperature...

This research reports the investigations of threshold reactivity limit of blends of pegmatite with different calcined clays as well as the influence of calcined clay source on the geopolymerization kinetic, microstructural, and physico‐mechanical properties of feldspathic mineral‐based inorganic polymer composites. These composites were designed fr...

In the recent century, geopolymer materials have grown significantly due to their unique properties applicable in many different fields. In the present work, the heat evolution, thermal and mechanical behavior of inorganic geopolymer composites (IPCs), based on solid solution of feldspathic minerals (pegmatite and granite) or sand quartz that were...

The objective of this study was to investigate the impact of the geographic and climatic conditions on laterites properties and on geopolymerization based-laterite. Four different laterite deposits in the four geographical zones of Cameroon were studied. This included the center, north, south and west corners of Cameroon, having chemical compositio...

In this work, geopolymer binders obtained from a mixture of Cameroonian pegmatite and type 1/1 calcined clays (metakaolin and metahalloysite) at different proportions (10-30 wt%) were used for the formulation of mortars. The kinetic parameters of the reactivity of the pegmatite mixed with different calcined clays in alkaline medium were evaluated v...

In this study we report on the addition of a waste, a real spent corundum abrasive powder collected after testing, to a metakaolin-based alkali activated binder. The waste has been chosen as representative of spent grits produced by industrial blasting processes. In this model system based on metakaolin, the effect of corundum powder in the environ...

The application of microwave technology for efficient and environmentally friendly synthesis of ceramic pigments is a successful and rapidly evolving area of research. However, a clear understanding of the reactions and their relationship with the material absorbance has not been fully achieved. The present study introduces an in situ permittivity...

Cork powdery waste (CW) from agglomerated cork caps manufacturing is commonly transported to waste-to-energy plants, although it could be locally exploited for lightweight building materials. The transformation of CW into a geopolymer formulation to obtain a novel composite formulation suitable for insulating panels is presented in this contributio...

Few studies have explored the immobilization of organic macromolecules within the geopolymer matrix, and some have found their chemical instability in the highly alkaline geopolymerization media. The present work reports on the feasibility of encapsulating the potentially toxic acridine orange (AO) dye in a metakaolin based geopolymer while maintai...

Italian volcanic quarry scraps, with fine particle size and of little market interest, have been considered for the manufacturing of lightweight geopolymers and highly porous foams. Both powders have been alkali activated with NaOH solution at 8M and 3M, respectively. Geopolymers were characterized in terms of density, porosity, humidity absorption...

In the present study, the performances of the end products prepared using calcined iron-rich laterite at 600 °C (LAT600) with different alkaline solution (AS) to calcined laterite (AS/LAT600) mass ratio (0.45-0.65) were investigated. The effect of AS/LAT600 mass ratio on microstructural and mechanical properties of consolidated geopolymer samples,...

Alkali activated binders, based on an aluminosilicate powder that is activated by an alkaline solution, have been proven to encapsulate a wide number of different wastes, both in the form of liquids and solids. In this study, we investigated the effect that the addition of a spent abrasive powder, mainly composed of corundum grains (RC), had on the...

A new approach for the synthesis of Y3Al2Ga3O12 (YAGG) nanophosphors allowing the preparation of crystallites with sizes starting from 45 nm is presented. The controllability of the energy and trap density of the resulting material samples by annealing temperature was confirmed by thermoluminescence (TL) measurements. It has been shown that the ann...

Weathered bottom ash (WBA) from municipal solid waste incineration is a calcium alu-minosilicate-rich material mainly used in construction and civil engineering as a secondary aggregate. However, its use is also being considered as a precursor in the manufacture of alkali-activated binders (AA-WBA). This preliminary research aimed to deepen underst...

Over the years, many materials have been used to restore buildings, paintings, ceramics, and mosaic pieces exhibiting different types of dyes and colour hues. Recently, geopolymers have been used for restoration purposes owing to their high chemical and mechanical resistance. In this work, white metakaolin was used to obtain white geopolymers, cure...

Glass recycling reduces the amount of waste to be treated or disposed in landfills, allowing both to limit environmental damage and to save on the costs of transportation and disposal of waste. In this paper, an advantageous method for recycling glass containers (bottles, jars, jars for food, glasses, and cans for drinks, etc.) is presented. The gl...

The high amount of organic and inorganic wastes has increased the attention to new strategies aiming to reduce the waste disposals. Organic wastes, such as tomato wastes (TWs), are a good source from which the red color can be obtained. Among the different technologies, the geopolymers had been proposed as a powerful technology able to incorporate...

A microstructural approach to the prediction of heat flux transport in porous geopolymers is used experimentally to under- stand the effects of the pore size distribution and pores connectivity to the transfer of the thermal flux across the porous network of geopolymers. Controlling the mix design and the concentration of porogen agent, capillary p...

This article highlights recent experimental advances in the use of inorganic substances in the encapsulation of pollutants and, in particular, discusses the potential applicability and constraints of the geopolymerization process for the treatment of wastewater containing chromium. A great percentage of waste containing chromium salts is produced b...

Five different alkali activators were prepared by mixing sodium hydroxide with molar concentrations of 8, 10, 12, 14 and 16 M and sodium silicate, Na2SiO3 in volume ratio 1:1. The obtained alkaline activators were used for producing metakaolin/feldspathic rock-based geopolymer composites. These geopolymer composites were obtained by mixing differen...

Recycling corundum abrasive powder in metakaolin-based geopolymer formulations is proposed to reduce the amount of waste to be treated or disposed of in landfills, allowing to decrease ecological damage as well as to reduce transport costs for removal. The addition of waste corundum, as an important source of Al2O3, has proved to increase the sligh...

Novel magnetic composites consisting of a polystyrene matrix containing La0.80Sr0.20Fe0.90Cu0.10O3-w (LSFC10) and La0.80Sr0.20Fe0.80Cu0.20O3-w (LSFC20) particles, each with two weight concentrations, 0.5% and 1.0%, are prepared by extrusion technique. The LSFC10 and LSFC20 filler phases are synthetized by citrate auto-combustion technique. From the...

Biodiesel obtained through the transesterification in methanol of vegetable oils, such as soybean oil (SO) and waste cooking oil (WCO), cannot be used as a biofuel for automotive applications due to the presence of polyunsaturated fatty esters, which have a detrimental effect on oxidation stability (OS). A method of upgrading this material is the c...

Understanding the structural and meso-scale properties of alkali activated matrices subjected to high temperature treatment, provides useful information on the stability of their self-life service or, fire resistance in extreme environments. The current project focuses on the transformation of phase and structural bonds within kyanite-reinforced re...

Microwave-assisted synthesis of nanoparticles usually leads to a smaller and more uniformly distributed particle size compared to conventional heating (e.g., oil bath). Numerical simulation can help to obtain a better insight into the process in terms of temperature distribution or to evidence existing different temperature profiles and heating rat...

Alkali-activated foams (AAFs) are inorganic porous materials that can be obtained at temperatures well below 100°C with the use of inorganic wastes as aluminosilicate precursors. In this case, fly ash derived from a Slovenian power plant has been investigated. Despite the environmental benefits per se, due to saving of energy and virgin materials,...

The challenge for sustainable development is now constraining scientists, and policymakers to consider alternative materials and processes requiring low energy consumption and low emissions while prioritizing local materials and industrial waste recycling. This study investigates ways to valorize marble waste powders to design a new class of inorga...

Soluble silica content and the concentration of hydrogen peroxide were used to achieve porous geopolymers with nano, meso and milliporosity. The use of rice husk ash as a partial replacement for metakaolin allows to maintain the SiO2/Al2O3 ratio between 1.93 and 2.71 and achieve layered bulks with the desired moisture buffering capacity. Stereo Opt...

The present study deals with the use of locally prepared rice husk ash (RHA)-based sodium silicate for alkaline activation of laterites (uncalcined (LNW) and calcined (LCA)). RHA-based activator (SSR) was prepared by adding as-collected RHA to 6 M NaOH at a solid/liquid mass ratio of 0.56. The various proportions of metakaolin (MK) and basalt powde...

The development of eco- friendly environmental and sustainable building materials having low thermal conductivity and optimal physic-chemical abilities ensuring passive thermal comfort is imperative in the global quest for the minimization of greenhouse-gases (GHG) emission and energy needs in homes. To attend this objective, the present work under...

Concrete structures built in granite-based aggregate develop and proliferate contour-like cracks as they aged. Such cracks are often associated to alkali-aggregate reactions (AAR). Though, in most cases, the alkali-silica reaction (ASR) involving these aggregates has shown to be non-destructive to concretes, their contents of iron-contained mineral...

The synthesis, mechanical behaviour, and microstructure of metakaolin-based geopolymer mortar reinforced with quartz sand are presented in this investigation. Fine sand (quartz sand) aggregate were added in different proportions of 50, 60, 70 or 80 wt.% to prepare the fresh metakaolin-based geopolymer paste. The geopolymer mortar was achieved by a...

Learning about the action of alkali on aluminosilicate materials (natural ones or proceeding from industrial activities) is an old ambition of the scientific community. A few of those challenges established by scientists in this field are raw materials, manipulation of reactions, properties of the precipitated products, and fields for the applicati...

A new method for fast and simple synthesis of crystalline TiO2 nanoparticles with photocatalytic activity was developed by carrying out a classic sol–gel reaction directly under vacuum. The use of microwaves for fast heating of the reaction medium further reduces synthesis times. When the solvent is completely removed by vacuum, the product is obta...

The aim of this paper is to promote the use of mine clay washing residues for the preparation of alkali activated materials (AAMs). In particular, the influence of the calcination temperature of the clayey by-product on the geopolymerization process was investigated in terms of chemical stability and durability in water. The halloysitic clay, a min...