Proceedings of the RILEM Spring Convention and Conference 2024
Volume 1
- 2025
- Book
- Editors
- Liberato Ferrara
- Giovanni Muciaccia
- Niki Trochoutsou
- Book Series
- RILEM Bookseries
- Publisher
- Springer Nature Switzerland
About this book
This book gathers peer-reviewed contributions presented at the RILEM Spring Convention and Conference, held in Milan, Italy on April 7-12, 2024. The theme of the Conference was “Advanced construction materials and processes for a carbon neutral society”, which was aimed at discussing advanced construction/eco-friendly materials and processes, for new and existing structures, towards a carbon neutral society. The volume covers the current and emerging approaches that lead to an optimized design and maintenance of constructions and systems. It includes the development of materials and structural service life models and life cycle design, in order to maximise longevity and level of service while minimising the environmental impact of constructions and systems. It also includes the analysis and design of larger systems, such as communities, cities or regions, aiming at reducing risk andincreasing resilience. The following subtopics are included: advanced materials and structural concept to enhance the resilience and robustness of the built environment and communities at local and global scales; risk based inspection and maintenance; life cycle analysis and service models; performance based design; improved design strategies by integrating materials and structures.
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Table of Contents
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Alternative, Low Co2 Binders
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Frontmatter
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Use of Limestone Calcinated Clay in Concrete
Mahmoud M. A. Kamel, Sara Cattaneo, Luigi BiolziThe chapter delves into the use of limestone calcinated clay (LC3) as a sustainable alternative to Ordinary Portland Cement (OPC) in concrete production. It discusses the environmental benefits of LC3, including reduced carbon emissions and energy consumption. The research evaluates the mechanical properties and durability of LC3 concrete, both with and without steel fibres, through extensive testing. The study finds that while LC3 initially shows lower compressive strength, it catches up over time due to the pozzolanic activity of metakaolin. Additionally, the inclusion of steel fibres improves flexural strength and reduces shrinkage, making LC3 concrete a promising material for sustainable construction practices.AI Generated
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AbstractThe use of supplementary cementitious materials is the most common approach to reduce environmental impact of concrete production. However, the total replacement of cement is not possible because of the dramatically reduction of the mechanical properties of the concrete.The paper presents an experimental study aimed at comparing the mechanical properties (compressive, bending strength and shrinkage) of ordinary concrete with those of blended concretes (with and without steel fibres) with partial cement replacement with Limestone Calcinated Clay (LC3).The results show that the partial replacement with LC3 leads to a different development of the mechanical properties with respect to ordinary concretes. A brief discussion on the structural implications of this behaviour is also presented. -
Preliminary Assessment of Limestone Calcined Clay Cement (LC3) in Soil Stabilization for Geotechnical Applications
Joseph Mwiti Marangu, Loyford Muchui Mugambi, Julius Toeri Ratumo, Luca ValentiniThe chapter delves into the preliminary assessment of Limestone Calcined Clay Cement (LC3) as a sustainable alternative to Portland cement for soil stabilization in geotechnical applications. Highly plastic clays, characterized by high liquid limits and plasticity indices, pose significant challenges in construction, leading to structural damages and economic losses. Traditional chemical stabilization methods using Portland cement, although effective, are environmentally harmful and costly. The study introduces LC3, an eco-friendly cement with reduced CO2 emissions, and evaluates its performance in soil stabilization. Through tests such as the soaked California Bearing Ratio (CBR), Proctor test, and Atterberg limits test, the research examines the effects of LC3 dosage on the strength and geotechnical properties of stabilized soil. The results indicate that LC3 effectively reduces the plasticity index and linear shrinkage, enhances the maximum dry density, and significantly improves the California Bearing Ratio, demonstrating its potential as a viable and sustainable alternative to Portland cement in soil stabilization.AI Generated
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AbstractIn this paper, the experimental findings on the use of Limestone Calcined Clay Cement (LC3) in the stabilization of sub-grade expansive soils are reported. The effect of LC3 on mechanical properties of subgrade soil was investigated experimentally through the soaked California Bearing Ratio (CBR), Proctor and Atterberg limits tests. The difference in the performance between LC3 and Ordinary Portland Cement (OPC) treated subgrade soils was studied for comparison purposes. The LC3 and OPC stabilizers were separately mixed with the soil in the proportions of 1%, 1.5% and 2% by dry weight of the soil. The results showed that the addition of both LC3 and OPC increased plastic limit, reduced plastic index, liquid limit and linear shrinkage of the treated soils. The Maximum Dry Density (MDD) of the soil was observed to increase with a corresponding decrease in Optimum Moisture Content (OMC) upon adding varying cement dosages. Additionally, the soaked CBR of the treated soil was observed to increase significantly with increasing cement content. The maximum CBR and MDD improvement were observed at 2% cement dosage, while OMC was reduced, hence, it could be regarded as the optimum dosage for soil stabilization. The performance between LC3 and OPC treated subgrade was quite comparable. In conclusion, LC3 was found to improve the strength and stability of subgrade soil. -
Modification of Reactivated Cement Fines with Addition of Ground Blast Furnace Slag
Neshable Noel, Sadeq Alkhatib, Anne Gierth, Susanne Helmich, Tommy Mielke, Doru C. LupascuThe chapter investigates the modification of reactivated cement fines (RCFs) produced from ordinary Portland cement (OPC) through thermal treatment at 700°C. The addition of ground blast furnace slag (GBFS) at 25% and 50% weight percentages significantly alters the particle morphology and physico-mechanical properties of RCFs. The study employs analytical techniques such as particle size distribution, scanning electron microscopy, and compressive strength tests to characterize the mixtures. The results highlight the potential of GBFS to enhance the fineness and mechanical properties of RCFs, making them more suitable for cementitious applications. This research contributes to the development of sustainable cement production methods by recycling concrete waste and reducing CO2 emissions.AI Generated
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AbstractRecycling concrete waste through a thermal treatment approach is a promising eco-friendly solution against CO2 emissions related to the cement industry. Various researchers have treated laboratory-produced hydrated cement fines (HCFs) at different intermediate temperatures to produce thermally reactivated cement fines (RCFs) and highlighted the recycling possibilities by recovering the essential strength-forming clinker phases. RCFs are known for their loose and porous particle morphology, which has an adverse effect on their workability and mechanical strengths. This research intends to improve the particle morphology as well as the physico-mechanical properties of RCFs with the addition of ground blast furnace slag (GBFS). 28-day hydrated cement specimens (HCS) are crushed to particle sizes of <2 mm to produce hydrated cement fines (HCFs). HCFs are treated in an electric furnace at 700 ℃ to produce thermally reactivated cement fines (RCF-700 ℃). RCF-700 ℃ (<2 mm) are replaced with 25 wt.% and 50 wt.% of GBFS. The mixtures of RCF-700 ℃ and GBFS are milled using a planetary ball mill and sieved to achieve a particle size of <250 µm. The results indicate that RCF-700 ℃ – GBFS samples show improved particle fineness, lower water demand, lower porosity and enhanced compressive strength as compared to 100% RCF-700 ℃. -
Mechanical Activation of Various Sources of Slag in the Ordinary Portland Cement Blend for a Sustainable Binder
Jitendra Patel, Mirco Perinelli, Giulia Masi, Maria Elia Natali, Maria Chiara BignozziThe chapter delves into the global production and environmental benefits of Ground Granulated Blast Furnace Slag (GGBS) in cement blends. It highlights the impact of various factors, such as temperature, pH, and the presence of alkalis, on slag hydration. The study focuses on the mechanical activation of GGBS from Italy, India, and Turkey through ball milling, examining the effects on specific surface area, particle size distribution, and compressive strength. The research demonstrates that mechanical activation significantly enhances the reactivity of slag, leading to improved hydration and early-age strength. However, it also identifies an optimal range of specific surface area for slag reactivity, beyond which compressive strength may decrease. The chapter concludes with the potential of mechanical activation in developing sustainable binders for the construction industry.AI Generated
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AbstractSlag-blended cement is a sustainable binder for building materials. However, when slag blends are mixed with ordinary Portland cement (OPC), the initial hydration reaction takes longer time, thus limiting its use. This research focuses on the characteristics of ground-granulated blast furnace slags from various sources based on their chemical and physical properties to assess their reactivity. Furthermore, to improve its early age reactivity, a mechanical activation was performed on slags to enhance its specific surface area and particle size distribution. The hydration and crystallinity degrees were investigated with calorimetry and X-ray diffraction tests. Moreover, the slag-cement binder strength development in the initial 72 h were assessed with the help of the ultrasonic measuring device. The results showed that the mechanical treatment significantly increased the reactivity of the slag already after 24 h, leading to a higher degree of hydration and modulus of elasticity. It was observed that mechanical activation of slag was also efficient from the point of view of strength development. -
Production of Synthetic Hydraulic Binder Precursors from Steel Slags: Experimental Validation and Thermodynamic Simulation
Disconzi Filippo, Bellotto MaurizioThe chapter delves into the production of synthetic hydraulic binder precursors from steel slags, a promising alternative to traditional cement. It begins by highlighting the environmental challenges posed by the cement industry and the need for sustainable alternatives. The study focuses on the valorization of steel slags, particularly white steel slag, to create a material similar to ground granulated blast furnace slag (GGBS). Through a combination of experimental methods and thermodynamic simulations using FactSage 8.3 software, the authors explore the optimal conditions for producing this synthetic material. The research includes detailed analyses of the slag composition, heating processes, and cooling paths, providing insights into the reactivity and phase formation of the final product. The study concludes by affirming the feasibility and sustainability of this approach, emphasizing the potential for efficient waste management and resource utilization in the construction industry.AI Generated
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AbstractHydraulic binders are inorganic materials that harden when mixed with water and are widely used in the building industry. The conventional production process of portland cement results in significant greenhouse gas emissions.To address these environmental concerns, alternative hydraulic binders, including geopolymeric and alkaline-activated binders, have been developed. These binders offer reduced carbon dioxide emissions and are produced using materials like granulated blast furnace slags combined with an alkaline activator.Ground granulated blast furnace slags are obtained through the rapid cooling of blast furnace slag, a by-product of pig-iron production. A critical challenge with this material is the sustainability and supply limitations of blast furnace slag, which is directly linked to the production of cast iron.This strict dependency makes it challenging to meet the growing demand for raw materials in a cost-effective and sustainable manner.The paper introduces a potential solution to these issues by proposing a process to create a synthetic precursor for hydraulic binders that is independent of the pig-iron production process.This method relies on a reaction between steel slag in the molten state and silica: the resulting material rapidly quenched has a composition and characteristics similar to granulated blast furnace slag.The process has been verified at the laboratory scale with success, the key point for its industrialization is the energy balance that is evaluated through thermodynamic simulations using FactSage 8.3. -
Optimizing the Design of High-Volume Fly Ash (HVFA) Cementitious Materials: Enhancing the Performance with Clinoptilolite Zeolite Modification
Ilgin Sandalci, Shaghayegh Sadeghzadeh Benam, Zeynep Basaran BundurThis chapter delves into the optimization of high-volume fly ash (HVFA) cementitious materials by incorporating clinoptilolite zeolite to enhance their performance. The study addresses the environmental concerns of the cement industry by exploring sustainable alternatives. It focuses on the rheological properties, initial setting time, and compressive strength of HVFA cementitious materials modified with zeolite. The research involves detailed experiments and analyses, providing valuable insights into the potential of zeolite as a viscosity-modifying agent and its impact on the overall performance of cementitious materials. The findings suggest that zeolite can significantly improve the rheological properties and initial setting time of HVFA pastes, although it may slightly reduce compressive strength. This chapter offers a comprehensive understanding of the benefits and challenges of using zeolite in HVFA cementitious materials, making it a crucial read for professionals seeking sustainable solutions in the construction industry.AI Generated
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AbstractFulfilling the ambition for maintaining global carbon neutrality, utilizing alternative low-carbon resources is becoming more essential in the design of building materials. Recently, high-volume fly ash (HVFA) cementitious materials have been gaining attention in the industry due to their low environmental impact in terms of carbon dioxide (CO2) emissions and resource efficiency. However, applications are limited because of major material-related problems, such as increasing setting time and low early strength development. This study aims to overcome the challenges in the material system by modifying HVFA mortars with clinoptilolite zeolite. The HFVA mortar designs were established using 70%, 60%, and 50% F-type fly ash. A portion of fly ash (5 and 10%) was replaced with reactive clinoptilolite zeolite. The influence of zeolite replacement on the performance of HFVA cementitious materials was evaluated by compressive strength and initial setting time. The rheological analysis assessed the impact of zeolite addition on the yield stress and thixotropy of HVFA pastes. The results show that adding clinoptilolite zeolite reduced the delay in initial setting time in HFVA mortars and increased the yield stress and thixotropy of cementitious pastes. On the other hand, incorporating zeolite into the mix resulted in a lower compressive strength than neat HFVA mortars without any zeolite. Therefore, clinoptilolite zeolite has the potential to be used as a viscosity-modified agent in HVFA cementitious materials instead of chemical admixtures. -
Reactivity of Siderite (FeCO3) in Cementitious Systems and Its Potential Use as a Future SCM
Marjorie Pons Pineyro, Isabel Galan, Florian R. Steindl, Marlene Sakoparnig, Florian MittermayrThe chapter delves into the potential of siderite (FeCO3) as a future supplementary cementitious material (SCM) in cementitious systems. It begins by highlighting the cement industry's significant contribution to CO2 emissions and the need for sustainable alternatives. The study focuses on siderite obtained from the Styrian Erzberg mine in Austria, exploring its reactivity and influence on the early hydration of cementitious systems. The authors investigate the 'ferrolanic' reaction, where siderite consumes portlandite to form Fe-bearing AFm phases, and its impact on the activity index and durability properties of resulting mixes. The chapter also examines the effects of siderite fineness and storage time on its reactivity, as well as its potential to reduce calcium leaching and improve the sintering potential of concrete. The findings suggest that siderite could be a viable SCM, offering both environmental and performance benefits. However, further research is needed to fully understand the reaction mechanisms and optimize its use in concrete.AI Generated
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AbstractAs the supply of some traditional supplementary cementitious materials (SCMs) decreases, the necessity to study new materials to reduce the CO2 emissions of the concrete industry arises. In that context, this study investigates the new and mostly unexplored potential SCM siderite (FeCO3), an iron carbonate extracted from the Austrian Erzberg mine. For this contribution, different batches of siderite were mixed into siderite-cement binders and tested for heat of hydration, activity index, and miniature sintering potential. According to heat of hydration, siderite retards the hydration of cement, expectedly from the reaction of Fe2+ with cement. Siderite-cement mortars show a decrease in 2-day strength in the range of 37–90%, in comparison to pure cement mortars. Factors such as fineness and storage time of the siderite powder, as well as quarry differences, influence the reactivity and, consequently, the magnitude of the strength reduction. Late strength, however, can remain higher than 80%, according to past studies. Miniature sintering potential of accelerated siderite-containing binders depicts an improvement in the durability of concrete, with a 21% reduction of Ca2+ leaching. This is attributed to the consumption of portlandite by siderite to form Fe-AFm phases, preventing the Ca(OH)2 from dissolving.This investigation shows that siderite could be used as an SCM in future applications, as it can improve the durability properties of concrete while maintaining high late strengths. More evaluations need to be conducted to properly understand the hydration mechanisms. Herewith proper recommendations and optimization of cement mixtures could be estimated and implemented in the future. -
Marine Dredged Sediments as a Supplementary Cementitious Material
Prashant Devda, Salman MuhammadThe chapter delves into the utilization of marine dredged sediments as a supplementary cementitious material, focusing on their pozzolanic properties and potential to reduce CO2 emissions in the construction industry. It discusses the significant environmental and economic benefits of repurposing these sediments, which are often considered waste products. The study investigates the reactivity of these sediments through suspension studies and compares their performance with established pozzolanic materials like fly ash. The authors present a detailed analysis of the chemical and mineralogical composition of the sediments, their specific gravity, and specific surface area. The chapter also explores the mechanical performance of mortar made with calcined dredged sediments, demonstrating their potential as a viable alternative to traditional cementitious materials. The findings highlight the potential of marine dredged sediments to address both waste disposal issues and contribute to sustainable construction practices.AI Generated
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AbstractThe demand for sustainable construction materials is on the rise with global urbanization, demanding an intensified search for innovative solutions. This study investigates the utilization of marine dredged sediments (DS) as a supplementary cementitious material (SCM). The DS was calcined to improve its pozzolanic properties. An extensive examination of the physical, chemical, and mineralogical properties of raw and calcined DS was conducted. Subsequently the pozzolanic activity through suspension studies and paste studies were assessed. Comparative analyses with traditional cementitious materials offer crucial insights into the potential of calcined DS as a cement replacement. The calcination of DS affected its pozzolanic properties. Findings reveal that the material calcined to specific temperatures possesses pozzolanic potential comparable to that of fly ash. The compressive strength of mortar incorporating calcined DS was found to be comparable to that of fly ash-based mortar. These results underscore the viability of calcined DS as an effective cement substitute in construction applications, offering both sustainable and performance benefits. -
Carbonated Wollastonite as Supplementary Cementitious Material for Cement and Concrete
Frank Winnefeld, Andreas LeemannThis chapter delves into the potential of carbonated wollastonite as a supplementary cementitious material (SCM) for reducing CO2 emissions in cement and concrete production. With the limited supply of traditional SCMs like blastfurnace slag and fly ash, there is a growing need for alternative materials. Carbonated wollastonite, produced through an industrial process that emits 30% less CO2 than Portland cement clinker, offers a promising solution. The chapter presents a comprehensive study that involves the carbonation of wollastonite clinker in a wet process, followed by its blending with Portland cement at various replacement ratios. The hydration and properties of these blended cements are examined using advanced analytical methods, compressive strength measurements, and thermodynamic modeling. Key findings include the pozzolanic reaction of the silica-rich gel formed during carbonation, which contributes positively to the compressive strength of the blended cements. The chapter also highlights the environmental benefits and the potential of carbonated wollastonite in enhancing the sustainability of cement and concrete production.AI Generated
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AbstractCarbonated wollastonite is a potential novel supplementary cementitious material. Because of the limited natural reserves only industrially manufactured wollastonite, which can be produced in conventional cement kilns from limestone and a silica source, emitting 30% less CO2 than PC clinker, is of global interest. Upon carbonation, a silica-rich amorphous phase and calcite form. In blends with Portland cement, early hydration is accelerated, and the silica-rich amorphous phase shows a pozzolanic reaction. This participation in the cement hydration reactions leads to a positive contribution to compressive strength. -
Re-hydration of Thermally Treated Cement Pastes Containing Limestone and Metakaolin
Konstantinos Sotiriadis, Petra Mácová, Lucie Zárybnická, Radek ŠevčíkThe chapter delves into the re-hydration of thermally treated cement pastes containing limestone and metakaolin, a crucial aspect of sustainable concrete production. It begins by discussing the environmental concerns surrounding Portland cement production and the potential of supplementary cementitious materials like limestone and metakaolin. The study focuses on the recycling potential of waste cement paste fines, subjecting them to thermal treatment and subsequent re-hydration. The effects of thermal treatment on the phase assemblage of cement pastes are examined, with particular attention given to the formation of clinker phases and CaO. The re-hydration process is then explored, revealing the recovery of hydrated phases and the influence of limestone and metakaolin content on re-hydration characteristics. The chapter also highlights the potential of recycled concrete fines thermally treated at 800°C for cement replacement, offering comparable performance to blends with fly ash. The findings underscore the importance of understanding the re-hydration process for the effective utilization of waste cement paste fines in sustainable concrete production.AI Generated
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AbstractThe notable environmental impact of Portland cement concrete manufacture is of great concern, driving the efforts towards the design of sustainable binders with reduced cement component. Here, information about the dehydration of cement pastes containing limestone and metakaolin, and the hydration characteristics of the materials obtained after heat treatment (1 h at 800 ºC), are reported. The analytical techniques used include X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and isothermal conductive calorimetry. The results showed that the dehydration of the studied cement paste fines led to the formation of clinker phases and CaO, with C2S being dominant. The increase of limestone content in cement resulted in the formation of lower amounts of clinker phases, while less CaO formed in the thermally treated paste containing metakaolin. The re-hydration process was accelerated with the increasing limestone content in cements, but it was considerably delayed in the case of the thermally treated blend with metakaolin. Re-hydration of the thermally treated fines resulted in the recovery of the hydrated phases, and it was characterized by increased formation of Ca(OH)2 and adsorption of water, as well as by the formation of C-S-H with less polymerized silicate chains, compared to the original cement paste fines. -
Understanding the Performance Offset of Glass Powder – Cement Blends
Adrian-Alexandru Pîrvan, Salvatore Coppola, Miriam Schröder, Michael Schwendinger, Joumana Yammine-Malesys, Fabio Montagnaro, Barbara Lothenbach, Frank WinnefeldThe chapter investigates the potential of waste glass powder as a cement replacement, focusing on the early age strength deficiencies and long-term benefits. It examines the use of sodium thiosulfate as an accelerator to enhance the hydration process and improve the overall performance of cement-glass blends. Through isothermal calorimetry, phase assemblage analysis, and mortar strength tests, the study provides a comprehensive understanding of the mechanisms involved. The findings highlight the trade-offs between early age strength gains and long-term durability, offering valuable insights for optimizing the use of glass powder in sustainable concrete formulations.AI Generated
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AbstractThe demand for increasingly larger quantities of locally available waste materials has led the cement industry to move away from conventional Supplementary Cementitious Materials (SCMs) and focus on other waste materials, such as recycled soda lime glass. It does not only contribute to lowering the CO2 footprint of cement, mortar and concrete, but also improves the late performance of composite blends due to its pozzolanic activity. Concerns associated with its use include increased alkali content and slow strength development at early ages. Certain activators can compensate for this behaviour, but their role in the overall hydration of the system remains to be fully clarified. In this study, sodium thiosulfate was selected as an accelerator with the aim of understanding the performance enhancement of cement-glass mixtures. The hydration of activated and non-activated mixtures was followed using isothermal calorimetry, X-ray diffraction, and thermal analysis. The compressive strengths of standard mortars were also evaluated. It was found that the values of the activated systems after 1 day were significantly better than for the non-activated system. -
Use of Kunkur Fines from Quarrying Waste in Blended Cements: Thermodynamic Modelling and Experimental Assessment
Victor Kiptoo Mutai, Cyprian Muturia M’thiruaine, Joseph Mwiti Marangu, Filippo Disconzi, Luca ValentiniThe chapter delves into the potential of kunkur fines from quarrying waste as a supplementary cementitious material (SCM) in blended cements. Through thermodynamic modelling and experimental assessments, the study investigates the hydration products, rheological properties, and thermal durability of cement blends containing kunkur fines. The use of kunkur fines is found to affect the hydration kinetics and improve the fire resistance of cement blends, offering a promising avenue for more sustainable and durable concrete production. The chapter also highlights the importance of understanding the chemical interactions and phase transformations in cement blends to optimize their performance.AI Generated
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AbstractThe complexity surrounding the cement composition due to the presence of numerous hydrates requires a multidimensional approach to bridge the existing knowledge gaps. Thermodynamic modelling provides a fast and efficient way of predicting the cement hydrates assemblages and involved reaction mechanisms with the possibility of changing factors affecting reactions such as temperature and system composition. Thermodynamic modelling is currently being used to complement experimental data and vice versa. In the current study, we explored the role of kunkur fines, sourced as quarrying waste, in ternary blended cements. Specifically, the effect of kunkur fines addition on the physico-mechanical properties and fire resistance were assessed, in comparison with OPC and LC3 cement. The ambient temperature behaviour was modelled using the GEMS software, whereas the predicted phase assemblage at high temperature (750 ℃) was obtained by the FactSage software. The results show that kunkur fines contributed to the overall cement reactivity and influenced phase assemblage, which in turn had a role in controlling the mechanical properties and behaviour at high temperature. -
Formulation of Sustainable Cements with Kenyan Volcanic Ashes
Luca Valentini, Marco Favero, Joseph Mwiti MaranguThe chapter 'Formulation of Sustainable Cements with Kenyan Volcanic Ashes' delves into the potential of locally sourced volcanic ashes from Kenya's Rift Valley as a sustainable alternative to Portland cement. The study begins with an introduction to the high cost of cement in Sub-Saharan Africa and the need for local solutions. It then proceeds to characterize the volcanic ashes, detailing their chemical composition and the significant amorphous fraction present. The chapter explores the formulation of both binary and ternary blended cements, as well as alkali-activated cements, using these ashes. Comprehensive analyses of compressive strength and hydration kinetics are conducted, revealing the enhanced performance of ternary blends compared to binary ones. The study also employs a design of experiments approach to optimize the formulation of alkali-activated cements, highlighting the need for blending with metakaolin to achieve acceptable performance. The chapter concludes by emphasizing the value of volcanic ashes as supplementary cementitious materials, while underscoring the necessity for preliminary mineralogical and chemical assessments to ensure optimal cement formulations.AI Generated
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AbstractThe use of locally sourced raw materials has the potential to reduce the environmental impact and cost of cement, especially in those locations where the supply of conventional resources for cement production, such as limestone, is based on massive import. To this aim, this study investigates the utilisation of volcanic ashes sourced in Kenya in both blended and alkali-activated cements. Quantitative X-ray powder diffraction (XRD) phase analysis of the ashes was performed in combination with XRF with the aim of evaluating the amount and chemical composition of the amorphous fraction, as an aid to the proper formulation of the alternative cement mixes. The compressive strength and degree of hydration, and compressive strength and yield stress, were tested for the blended and alkali-activated cements respectively. The results show that the volcanic ashes are characterised by a significant amount of an amorphous glassy phase. However, the relatively low Al/Si ratio of the amorphous fraction leads to different behaviours of the volcanic ashes in blended and alkali-activated cements. The high Si content activates the pozzolanic reaction in blended cements and it is observed that the mechanical properties of ternary blends based on volcanic ashes are comparable to those of control LC3 blends. With respect to the alkali-activated cements, the limited concentration of Al in the amorphous fraction of the volcanic ashes inhibits the precipitation of N-A-S-H, therefore the addition of 37 wt.% metakaolin, based on a Design-of-Experiments (DoE) approach, was found to be suitable for optimising both the mechanical performance and workability. -
A Chemometric Approach for the Optimization of Low Carbon Concrete Admixtures with Blended Cements
Clelia Sarta, Alexandre Agha Ghassem, Fabio Castiglioni, Giorgio Ferrari, Alexis TranchantThe chapter delves into the optimization of low carbon concrete admixtures (LCCAs) using a chemometric approach. It begins by introducing the hydration reactions of Portland cement and blended cements, highlighting the influence of various chemicals on these processes. The authors propose a new class of admixtures, LCCAs, designed to maximize cement hydration. The experimental design involves a mixture design of experiment and Principal Component Analysis (PCA) to evaluate the effectiveness of LCCAs on different cements. The results reveal that LCCAs can significantly enhance the compressive strength of binary binders but have a more complex interaction with ternary binders. The chapter concludes by emphasizing the need for further studies to fully understand the mechanisms behind these interactions and the potential of multivariate techniques in formulating complex admixtures.AI Generated
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AbstractThe roadmap to carbon neutrality of concrete provides, as one of the main actions, the partial replacement of clinker by supplementary cementitious materials (SCMs) in blended cements. Most SCMs are characterized by a much lower carbon footprint compared to clinker and therefore blended cements represent the best solution for producing concrete with low carbon content (LCC, Low Carbon Concrete). Recently, a new class of Low Carbon Concrete Admixtures (LCCAs) has been developed to compensate the loss of both early and final strength of blended cements in comparison with ordinary Portland cement (OPC). Different formulations of LCCAs have been proven to be effective in activating blended cements, some of them for improving early strength, others for enhancing final strength, or both. In the present work, a chemometric approach was used to highlight specific admixture-binder interactions aiming to identify the most effective LCCA for different blended cements. The application of Principal Component Analysis (PCA) and Design of Experiment (DoE) on datasets of compressive strength of mortars prepared with different blended cements and different LCCAs allowed to identify specific interactions related to the chemical composition of blended cements and to optimize the formulation of LCCAs for specific applications.
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- Title
- Proceedings of the RILEM Spring Convention and Conference 2024
- Editors
-
Liberato Ferrara
Giovanni Muciaccia
Niki Trochoutsou
- Copyright Year
- 2025
- Publisher
- Springer Nature Switzerland
- Electronic ISBN
- 978-3-031-70277-8
- Print ISBN
- 978-3-031-70276-1
- DOI
- https://doi.org/10.1007/978-3-031-70277-8
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