Environmental Impact and Sustainability of Calcium Aluminate Cements

Zapata, John F.; Azevedo, Afonso Rangel Garcez de; Fontes, Carlos Augusto de Alencar; Monteiro, Sérgio Neves; Colorado, Henry A.

doi:10.3390/su14052751

Cited by 22 publications

(9 citation statements)

References 73 publications

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“…While the incessant development of global infrastructure (e.g., rapidly growing metropolises and mega-cities) ensures that demand for concrete is ever-increasing, the production of Portland cement (PC) presents considerable energy consumption (≈11 EJ/year [ 1 ]) and environmental impact- (≈9% of global CO2 emission is attributed to the production of PC [ 2 , 3 , 4 ]) related challenges. Calcium aluminate cement (CAC) has been explored as a sustainable alternative to PC [ 5 , 6 , 7 ]. The main chemical phases of CACs are calcium aluminate (CA)* and mayenite (C 12 A 7 ), whereas gehlenite (C 2 AS) and calcium di-aluminate (CA 2 ) are the minor phases [ 8 , 9 ], where C = CaO, A = Al 2 O 3 , H = H 2 O and S = SiO 2 .…”

Section: Introductionmentioning

confidence: 99%

Predicting Compressive Strength and Hydration Products of Calcium Aluminate Cement Using Data-Driven Approach

et al. 2023

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Calcium aluminate cement (CAC) has been explored as a sustainable alternative to Portland cement, the most widely used type of cement. However, the hydration reaction and mechanical properties of CAC can be influenced by various factors such as water content, Li2CO3 content, and age. Due to the complex interactions between the precursors in CAC, traditional analytical models have struggled to predict CAC binders’ compressive strength and porosity accurately. To overcome this limitation, this study utilizes machine learning (ML) to predict the properties of CAC. The study begins by using thermodynamic simulations to determine the phase assemblages of CAC at different ages. The XGBoost model is then used to predict the compressive strength, porosity, and hydration products of CAC based on the mixture design and age. The XGBoost model is also used to evaluate the influence of input parameters on the compressive strength and porosity of CAC. Based on the results of this analysis, a closed-form analytical model is developed to predict the compressive strength and porosity of CAC accurately. Overall, the study demonstrates that ML can be effectively used to predict the properties of CAC binders, providing a valuable tool for researchers and practitioners in the field of cement science.

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Section: Introductionmentioning

confidence: 99%

Predicting Compressive Strength and Hydration Products of Calcium Aluminate Cement Using Data-Driven Approach

et al. 2023

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“…In this way, the accumulated CO 2 emissions will be one of the causes of global warming at the end of the 21st century 6 . The manufacture of cement uses natural resources from mining processes, which can be considered other important environmental impacts within the process 7–9 . Thus, the construction industry decided to change its development model, focusing on the use of sustainable as well as renewable, eco‐friendly, and cheap resources, adopting a circular economy approach 10 …”

Section: Introductionmentioning

confidence: 99%

“…6 The manufacture of cement uses natural resources from mining processes, which can be considered other important environmental impacts within the process. [7][8][9] Thus, the construction industry decided to change its development model, focusing on the use of sustainable as well as renewable, eco-friendly, and cheap resources, adopting a circular economy approach. 10 These transformations have been unfolding in recent times, laying out a comprehensive roadmap for ensuring the sustainability of the built environment.…”

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confidence: 99%

Circular economy strategy for the valorization of fly ash as a substitute for cement in monoliths (resistance and reactivity evaluation)

Morales,

Herrera,

López

et al. 2023

Env Prog and Sustain Energy

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Fly ash is currently a problem in different companies, mainly in thermoelectric plants, which must follow a production and consumption model that involves reusing, renewing, and recycling, thus contributing to the circular economy. This work aims to evaluate the reactivity and compressive strength of different types of ashes in concrete monoliths. For this purpose, sugarcane bagasse (SCBA), bituminous coal (BC), and untreated hazardous waste (RUD) were evaluated as replacements for cement. Monoliths and mortars have been manufactured in different mixtures, taken to a curing room, and their compressive strength and reactivity have been determined at different times (up to 28 days for the monoliths and up to 90 for the mortars), mainly in order to check the formation of calcium silicate hydrate (CSH) gels. In the monolith tests, the best performances have been with SCBA and BC, which have been used for the manufacture of the mortars. On day 56, the behavior of the replacement of 30% fly ash (15% BC:15% SCBA) presents a type H mortar behavior, with better results than the control. By day 90, all replacements had the same resistance as M mortars and even higher resistances than the control. This demonstrates the feasibility of its use in the production of Portland cement for the manufacture of low‐performance inputs. This implies the possible reduction of impacts, both in waste disposal sites and in emissions caused by the construction industry, thus contributing to the circular economy.

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“…This concrete stands out for its manufacturing simplicity: it can be produced on-site by mixing refractory aggregate with CAC. They also offer technological advantages, including easy blending, convenient shaping, and high mixture stability [2,3]. The conventional castables, incorporating CAC with aluminum oxide not exceeding 40% and aggregates with low Al 2 O 3 content, stand out economically more attractive than medium-and low-CAC castables with expensive mixture components.…”

Section: Introductionmentioning

confidence: 99%

Bond Behavior of Stainless-Steel and Ordinary Reinforcement Bars in Refractory Castables under Elevated Temperatures

Plioplys,

Kudžma,

Sokolov

et al. 2023

J. Compos. Sci.

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Refractory castables, i.e., refractory aggregates and ultra-fine particle mixtures with calcium aluminate cement (CAC) and deflocculants, were created 40 years ago for the metallurgy and petrochemical industries. These materials demonstrate outstanding performance even over 1000 °C. Typically, they have no structural reinforcement, resisting compression stresses because of the combination of temperature and mechanical loads. This study is a part of the research project that develops high-temperature resistance composite material suitable for fire and explosion protection of building structures. However, this application is impossible without structural reinforcement, and the bond performance problem becomes essential under high temperatures. This experimental work conducts pull-out tests of austenitic stainless 304 steel bars and typical structural S500 steel bars embedded in refractory castables after high-temperature treatments. This study includes plain and ribbed bars and considers two castable materials designed with 25 wt% CAC content for 50 MPa compressive strength after drying (typical design) and 100 MPa strength (modified with 2.5 wt% microsilica). This test program includes 115 samples for pull-out tests and 88 specimens for compression. As expected, the tests demonstrated the plain bars’ inability to resist the bond stresses already at 400 °C; on the contrary, ribbed bars, even made of structural steel, could ensure a mechanical bond with cement matrix up to 1000 °C. However, only stainless steel bars formed a reliable bond with the high-performance castable, determining a promising object for high-temperature applications. Still, the scatter of the test results did not ensure a reliable bonding model. In addition, the castable strength might not be optimal to ensure maximum bond performance. Thus, the test results clarified the research objectives for further developing the reinforced composite.

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Environmental Impact and Sustainability of Calcium Aluminate Cements

Cited by 22 publications

References 73 publications

Predicting Compressive Strength and Hydration Products of Calcium Aluminate Cement Using Data-Driven Approach

Predicting Compressive Strength and Hydration Products of Calcium Aluminate Cement Using Data-Driven Approach

Circular economy strategy for the valorization of fly ash as a substitute for cement in monoliths (resistance and reactivity evaluation)

Bond Behavior of Stainless-Steel and Ordinary Reinforcement Bars in Refractory Castables under Elevated Temperatures

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