scholarly journals Prospective Life Cycle Assessment at Early Stage of Product Development: Application to Nickel Slag Valorization Into Cement for the Construction Sector

2021 ◽  
Vol 7 ◽  
Author(s):  
Eva Quéheille ◽  
Michel Dauvergne ◽  
Anne Ventura
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Product Development ◽  
New Caledonia ◽  
Cementitious Materials ◽  
Cement Industry ◽  
Supplementary Cementitious Materials ◽  
Construction Sector ◽  
Mineralization Process ◽  
Electricity Grid

Pyrometallurgical nickel industry in New Caledonia produces several tons of slag per year, which is stocked on site. There is no valorization today, except for a small transformation into sand. Pyrometallurgy highly consumes fossil-fuel energy and electricity for ore pre-treatment and nickel extraction inside electrical furnaces, which produces significant CO2 emissions. A new valorization approach is suggested to use these two local productions (slag and CO2) to mineralize slag and produce silico-magnesian cement for the construction sector. In order to ensure suitable environmental performances, many questions arise about the target valorized product: where and how to capture CO2 and produce cement, what constraints should be targeted for the mineralization process, can products be exported and where? Moreover, New Caledonia aims to develop renewable energies for electricity grid, which would mitigate local industries impacts in the future. A prospective Life Cycle Assessment (LCA) is used to define constraints on future product development. Two hundred scenarios are defined and compared as well as electricity grid evolution, using Brightway software. Thirteen scenarios can compete with traditional Portland cement for 12 of the 16 impacts of the ILCD midpoint method. The evolution of electricity grid slightly affects the performance of the scenarios by a mean of less than+/−25%, bringing a small difference on the number of acceptable scenarios. The main constraint requires improving the mineralization process by considerably reducing electricity consumption of the attrition-leaching operation. To be in line with scenarios concerning carbon neutrality of the cement industry by 2050, a sensitivity analysis provides the maximum energy consumption target for the mineralization process that is 0.9100 kWh/kg of carbonated slag, representing a 70% reduction of the current energy measured at lab scale. Valorization of nickel slag and CO2 should turn to carbon capture and utilization technology, which allows for the production of supplementary cementitious materials, another product for the construction sector. It will be the topic of a next prospective study.

scholarly journals Effects after 1500 Hardening Days on the Microstructure and Durability-Related Parameters of Mortars Produced by the Incorporation of Waste Glass Powder as a Clinker Replacement

2021 ◽  
Vol 13 (7) ◽  
pp. 3979
Author(s):  
Rosa María Tremiño ◽  
Teresa Real-Herraiz ◽  
Viviana Letelier ◽  
Fernando G. Branco ◽  
José Marcos Ortega
Keyword(s):  
Diffusion Coefficient ◽  
Water Absorption ◽  
Glass Powder ◽  
Cementitious Materials ◽  
Cement Industry ◽  
Waste Glass ◽  
Supplementary Cementitious Materials ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Waste Glass Powder

One of the ways of lessening the CO2 emissions of cement industry consists of replacing clinkers with supplementary cementitious materials. The required service life of real construction elements is long, so it is useful to characterize the performance of these materials in the very long term. Here, the influence of incorporating waste glass powder as a supplementary cementitious material, regarding the microstructure and durability of mortars after 1500 hardening days (approximately 4 years), compared with reference mortars without additions, was studied. The percentages of clinker replacement by glass powder were 10% and 20%. The microstructure was studied using impedance spectroscopy and mercury intrusion porosimetry. Differential thermal and X-ray diffraction analyses were performed for assessing the pozzolanic activity of glass powder at the end of the time period studied. Water absorption after immersion, the steady-state diffusion coefficient, and length change were also determined. In view of the results obtained, the microstructure of mortars that incorporated waste glass powder was more refined compared with the reference specimens. The global solid fraction and pores volume were very similar for all of the studied series. The addition of waste glass powder reduced the chloride diffusion coefficient of the mortars, without worsening their behaviour regarding water absorption after immersion.

scholarly journals Life-Cycle Assessment of a Rural Terraced House: A Struggle with Sustainability of Building Renovations

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2472
Author(s):  
Karel Struhala ◽  
Milan Ostrý
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Environmental Impacts ◽  
Energy Sources ◽  
Construction Sector ◽  
Building Stock ◽  
Existing Building ◽  
New Construction ◽  
Consumption Energy

Contemporary research stresses the need to reduce mankind’s environmental impacts and achieve sustainability. One of the keys to this is the construction sector. New buildings have to comply with strict limits regarding resource consumption (energy, water use, etc.). However, they make up only a fraction of the existing building stock. Renovations of existing buildings are therefore essential for the reduction of the environmental impacts in the construction sector. This paper illustrates the situation using a case study of a rural terraced house in a village near Brno, Czech Republic. It compares the life-cycle assessment (LCA) of the original house and its proposed renovation as well as demolition followed by new construction. The LCA covers both the initial embodied environmental impacts (EEIs) and the 60-year operation of the house with several variants of energy sources. The results show that the proposed renovation would reduce overall environmental impacts (OEIs) of the house by up to 90% and the demolition and new construction by up to 93% depending on the selected energy sources. As such, the results confirm the importance of renovations and the installation of environmentally-friendly energy sources for achieving sustainability in the construction sector. They also show the desirability of the replacement of inefficient old buildings by new construction in specific cases.

Use of Algerian Natural Mineral Deposit as Supplementary Cementitious Materials

2018 ◽  
Vol 34 ◽  
pp. 48-58 ◽  
Author(s):  
Karima Arroudj ◽  
Saida Dorbani ◽  
Mohamed Nadjib Oudjit ◽  
Arezki Tagnit-Hamou
Keyword(s):  
Mechanical Strength ◽  
Calcium Hydroxide ◽  
Cement Paste ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Heat Of Hydration ◽  
Cement Industry ◽  
Supplementary Cementitious Materials ◽  
Natural Mineral ◽  
Different Ages

Much of the current research on concrete engineering has been focused on including siliceous additions as supplementary cementitious materials (SCMs). Silica reacts with Calcium hydroxide release during cement hydration, and produces more C-S-H. The latter contributes to increase compactness, mechanical strengths and sustainability of concrete. This paper explores the hydration characteristics of cement paste based on various natural mineral additions, that are very abundant in Algeria and present a high silica content (ground natural pozzolana “PZ” and ground dune sand “DS”). For this purpose, several analyses were carried out on modified cement pastes and mortars. TheseSCMswere introduced by replacement levels of 15, 20 and 25 by weight of cement. We first, studied the effect of these SCMs on the heat of hydration and mechanical strength of mortars at different ages. The evolution of hydration of modified paste was studied, by using Thermal analysis (TG/TDA) at different ages, to analyze the Calcium Hydroxide (CH) content of the modified pastes. It is shown that the CH content of the mixes including SCMs is lower than that of the plain cement paste, indicating that silica reacts with the cement paste through a pozzolanic reaction. Increased pozzolanic activity results in higher amounts of Calcium Silicate Hydrate in the paste, which in turn results in higher compressive strength for modified cement mortars. Due to its crystalline morphology, the ground DS particles present a partial pozzolanic effect, compared to PZ which is semi-crystalline. Modified mortars by 20% DS can be the optimal composition. It presents satisfactory results: good mechanical strength and low heat of hydration. It can lead to an economic and sustainable concrete. Ground DS is very abounded in Africa and free of any impurities and can be a good alternativeSCMsin cement industry.

scholarly journals Ontology based social life cycle assessment for product development

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881227 ◽  
Author(s):  
Zhen Shang ◽  
Meidan Wang ◽  
Daizhong Su ◽  
Qinhui Liu ◽  
Shifan Zhu
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Product Development ◽  
Social Life ◽  
Design Method ◽  
Data Access ◽  
Life Cycles ◽  
Assessment Process ◽  
Social Life Cycle Assessment ◽  
Aided Design

Social life cycle assessment is an important method to assess products’ social impacts throughout their life cycles. There are already some indicators and software to assist conducting social life cycle assessment. However, it is hard for users to share or reuse assessment results because of different application data structures. To resolve this problem, a knowledge-based social life cycle assessment–aided design method is developed in this research. With this method, all elements in the social life cycle assessment process are analyzed and represented as classes, their relationships are described as object properties, and the data structure is represented as data properties to construct an ontology system for social life cycle assessment. Based on the ontology, a social life cycle assessment–aided product development web is developed. According to the data property structure, a bidirectional mapping between database and ontology is realized using JENA and ontology-based data access, which enables the result data to be automatically inputted into ontology individuals. Thus, the result data can be accumulated, shared, and reused among users. A case study with a floor product as well as a user test is carried out to prove the feasibility and usability of the web. The ontology-based social life cycle assessment–aided design method provides users with a new high-efficiency approach, setting the foundation for the intellectualization of life cycle assessment.

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