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Carbon sequestration technology in cement-based materials: a review of mechanisms and applications
No full textCarbon sequestration technology is crucial for achieving the Net Zero climate target. Regarding carbon sequestration via concrete technology, it mainly involves two approaches: reacting natural ores or industrial waste with CO2 to incorporate them into concrete and ensuring stable CO2 storage throughout the concrete lifecycle. The basic mechanism relies on the formation of calcium carbonate through reactions between CO2 and calcium/magnesium components in concrete. This technology spans from raw material carbon capture to the entire production process, enhancing concrete performance by filling pores, improving interfacial bonding, and promoting CO2 mineralization. Factors influencing sequestration efficiency include material composition, particle size, reaction conditions (time, temperature, pressure, CO2 concentration, moisture, pH), and microbial compatibility. Evaluation methods include weighing, physical, and chemical analyses. Advancements in technology, innovative materials, and structural design improvements can significantly enhance concrete\u27s CO2 absorption and storage capabilities, contributing to a sustainable construction industry and reducing greenhouse gas emissions
Materials Processing Strategies for Valorizing Industrial Residues in Construction: Mechanical Separation, CO2 Mineralization, and Metal Recovery/Stabilization
No full textBuilding a roadmap for integrating processing strategies for waste valorization with potential across multi-categories of industrial residues (metallurgical slags/residues, power-plant ashes, and mine wastes) is an emerging trend. This roadmap [1] seeks to address common industry questions regarding the most suitable valorization approaches for different industrial residues generated in plants based on specific conditions. The effective strategies involve specific technologies such as mechanical separation, CO2 mineralization, and metal recovery/stabilization—all of which extend the value of industrial residues before they can be largely incorporated into construction applications, supporting waste digestion and reducing direct disposal. This talk discusses route competition, research needs, and lab-industry disconnections in the roadmap, and presents two main cases: copper mine tailings and Waste-to-Energy (WTE) residues
Enhanced Performance of Reclaimed Concrete Slurry Waste in Cement Paste: Effect of Early-age Carbonation Curing
No full textSince early-age carbonation curing can effectively sequester CO2 while improving the properties of cementitious materials, it can be applied to solve the pore early age performance issue of cement substituted with recycled concrete slurry waste (RCSW). This paper, is therefore, aimed to investigate the feasibility of early-age carbonation curing in the cement paste replaced with different treated RCSW under different replacement ratios by testing its mechanical properties and calculating its environmental impact. The results indicated that the early compressive strength of the paste significantly improved by early-age carbonation curing. The addition of RCSW promoted the carbonation reaction in the cement paste, displaying a higher carbon sequestration capability which has been confirmed by the calculation from environmental impact
Computational Assessment of Earthquake Resistance of Natural Pozzolan-based Engineered Cementitious Composite Structures
No full textThe increasing frequency and intensity of earthquakes worldwide pose significant challenges to the structural integrity and safety of infrastructure systems. Engineered cementitious composites (ECC), known for their superior tensile ductility, strength and cracking control, provide a promising solution for enhancing earthquake resistance of structures. This study presents a computational assessment of natural pozzolan (NP)-reinforced ECC structures subjected to seismic impact through finite element analysis. The analysis investigates the dynamic performance of NP-ECC structures in terms of stress distribution and structural deformation. A three-story NP-ECC frame structure under a 6.5 magnitude earthquake on Richter scale is studied and compared with a reinforced concrete structure. The results show that the ECC structure exhibits significantly better earthquake resistance, with an average stress reduction of 64.11% and displacement reduction of 65.02%. The findings show the potential of ECC in improving structural resilience and provide insights into structural design for earthquake-prone regions
Evaluation on basic properties and surface quality of PCa members using scallop shell sand concrete with blue carbon fixation
No full textWith carbon neutrality gaining importance as one of the measures against global warming, the building industry is focusing on the development of environmentally friendly building materials to help realize a sustainable society. Japan has the second longest coastline in the world, and its fisheries industry along the coast is well developed and fisheries resources are considered important. In Hokkaido in particular, approximately 400,000 tons of scallops are landed annually, with approximately 110,000 tons of shells becoming waste. In order to make effective use of these discarded and unused resources, the development of blue carbon concrete components, in which scallop shells are partially replaced as fine aggregate, is underway. Blue Carbon certification has been initiated for algae. This technology has the potential to contribute to carbon neutrality by contributing to the reduction of the large amount of carbon dioxide emissions and the generated in the conventional cement production process and to the effective utilization of resources. In this study, it is covered exterior precast concrete members (PCa members) utilizing scallop shells. It was investigated the effects of performance and casting time between different types of concrete. This initiative is aimed at the practical application of environmentally friendly building materials for a decarbonized society, and is also expected to contribute to the construction of a resource-recycling society
An interpretable machine learning technique to predict size effect and fracture behavior of concrete
No full textThe size effect phenomenon, stemming from the inherent fracture characteristics of materials, is notably widespread in concrete. Traditional approaches to investigate this effect and concrete fracture behaviors are typically laborious. To address these issues, this study employs a machine learning (ML) methodology (e.g., light gradient boosting machine (LGBoost) and categorical boosting (CatBoost)). The findings indicate that these models deliver high accuracy in predicting the nominal flexural strength of concrete, reaching R² values of 0.933 and 0.929, respectively, for testing the models. Additionally, SHapley additive exPlanations (SHAP) analysis was used to differentiate the influence of material and geometric parameters on the predictions and determine the input parameters influences. These ML models offer a generalized framework for predicting the nominal flexural strength and fracture toughness across various materials and sizes, highlighting their utility in advancing the understanding of concrete behaviors under different mechanical stresses
Green 3D Printing Concrete Containing Biochar and Waste Wind Turbine Blade Powder
No full textThree green three-dimension printing concrete (3DPC) mixtures were made with biochar (BC), waste wind turbine blade powder (WTBP), and a pre-packaged 3DPC material (Sika-752). The mixtures were used to print small and larger beams with various fill patterns/rates. The results indicate that use of 3%BC (wetted with mixing water) and10% WTBP improved fluidity, especially slump, of the 3DPC mixture. 3%BC slightly reduced strength and ductility of the 3DPC. 10% WTBP decreased strength but increased ductility of the printed specimens. Optimized infill can improve load capacity. The use of BC and WTBP in 3DPC has promising potential in construction engineering applications
Cellulose Nanofibrils for Concrete Shrinkage Reduction
No full textCracking in concrete structures, particularly under cold-weather conditions, significantly compromises durability and long-term performance. Early-age shrinkage is a primary contributor to crack formation, leading to increased maintenance demands and reduced service life. This study investigates the incorporation of Cellulose Nanofibrils (CNF) as a sustainable additive to mitigate shrinkage and enhance mechanical properties in both cement paste and concrete. Specimens were prepared with CNF dosages of 0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% by weight of cement. In cement paste, CNF addition up to 0.3% improved compressive and flexural strength by approximately 25% and 34%, respectively, and reduced shrinkage by 21%. In concrete, CNF increased compressive strength by 16%, flexural strength by 28%, and reduced shrinkage by 17%. The highest performance was observed at 0.3% CNF, while higher dosages resulted in diminished gains, likely due to fiber agglomeration and dispersion challenges. The results highlight the potential of CNF to enhance the mechanical and durability properties of cement-based materials, offering a promising approach for developing more crack-resistant and sustainable concrete, particularly suited for cold-climate infrastructure applications
LEaPP Phoneme-Grapheme Chart
No full textThe LEaPP Phoneme-Grapheme Chart contains sounds in the English language and the corresponding orthographies to spell each sound ranging from single phonemes and complex vowels to blends and clusters. The Phoneme-Grapheme Chart also contains various spellings for vowel sounds and the approximate number of words in which these spellings occur in stressed syllables. Additional vowel spellings that are used less frequently are also included
Incorporating an Innovative Kennel in a Guide Dog Program Based on the Health and Welfare of Dogs and Humans
No full textDuring guide dog training, dogs live in kennels and lack house training. The demand for guide dogs that can live easily with their users who are visually impaired is increasing. The Kansai Guide Dogs for the Blind Association (KGBDA) in Japan built an innovative wooden kennel (Mokka Terrace) that is more similar to homes than general kennels and that efficiently controlled dogs and reviewed their operations. This study conducted a literature survey, participant observations, and semi-structured interviews with staff to clarify the background and consensus-building process involved in creating the Mokka Terrace, corresponding efforts, and its strengths, issues, and prospects. Through trial and error, expert advice and techniques from other facilities were adopted. Characteristic efforts include promoting interactions as dogs behave voluntarily, implementing house training, improving the kennel environment, and improving the quality of training. The strengths of the Mokka Terrace were that humans and dogs were in the same space; it was similar to a home environment; it was easy to share information, comfortable, and easy for volunteers to work. However, there were issues regarding communication, protection of personal information, office work environment, and difficulty in users’ independent mobility. Staff members consistently showed respect for the diverse needs and individuality of humans and dogs to realize One Health & One Welfare, which is currently the mainstream concept for simultaneously realizing the health and welfare of humans and animals. The Mokka Terrace intends to support users and guide dogs to maintain a high quality of life without placing an excessive burden on the staff. To create a comfortable symbiotic space, it is important to strengthen human–dog relationships, arrange a comfortable environment, respect diversity, and not comply with the present status. This case study can be applied to other assistance dog projects and sustainable coexistence between humans and dogs