Scholarlink

<p>Carbon footprint reduction and circularity are strategic goals for the concrete sector. This study presents a concrete waste recycling process that incorporates mineral carbonation and promotes the complete reuse of concrete waste for the production of new concrete. The process is a sequence of 4 steps: (1) intensive micro-cracking of the cement paste by microwave heating to promote both (a) textural separation between the original concrete constituents, natural aggregates and hardened cement paste (HCP), and (b) carbonation of the latter, (2) non-impact crushing to physically separate them, (3) abrasive screening of the concentrated cement paste into a recycled concrete fines (RCF) fraction to further reduce residual cement paste on the surface of recycled concrete aggregates (RCA), and (4) a cement paste carbonation step for RCA and RCF. Using concrete samples of controlled formulation, the performance of the proposed process is evaluated at the laboratory scale in comparison to a conventional recycling process using crushing and screening. Microwave heating experiments were conducted using a 2.45&#xa0;GHz waveguide powered by a 2&#xa0;kW magnetron. Settings used for the micro-cracking stage of concrete samples were a 1.5&#xa0;kW incident power and a 4&#xa0;min heating time. For several performance indicators, the proposed process outperforms the reference process by a factor of 2 or more for both RCA and RCF, concentrating 75% of HCP in the RCF compared to 28% for the reference process, and averaging 5% HCP on the surface of RCA compared to 11% for the reference process. In addition, the process produces RCA that are significantly cleaner than the reference process down to a particle size of 500 microns, and RCF that have better carbonation properties than the reference process.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

A High-Performance Concrete Waste Upcycling Solution Using Microwaves and Carbonation

  • 期刊论文

  • 发表日期：

    2025年10月6日

查看全文
  • Célia Gurdjos,
  • Florent Bourgeois

摘要

Carbon footprint reduction and circularity are strategic goals for the concrete sector. This study presents a concrete waste recycling process that incorporates mineral carbonation and promotes the complete reuse of concrete waste for the production of new concrete. The process is a sequence of 4 steps: (1) intensive micro-cracking of the cement paste by microwave heating to promote both (a) textural separation between the original concrete constituents, natural aggregates and hardened cement paste (HCP), and (b) carbonation of the latter, (2) non-impact crushing to physically separate them, (3) abrasive screening of the concentrated cement paste into a recycled concrete fines (RCF) fraction to further reduce residual cement paste on the surface of recycled concrete aggregates (RCA), and (4) a cement paste carbonation step for RCA and RCF. Using concrete samples of controlled formulation, the performance of the proposed process is evaluated at the laboratory scale in comparison to a conventional recycling process using crushing and screening. Microwave heating experiments were conducted using a 2.45 GHz waveguide powered by a 2 kW magnetron. Settings used for the micro-cracking stage of concrete samples were a 1.5 kW incident power and a 4 min heating time. For several performance indicators, the proposed process outperforms the reference process by a factor of 2 or more for both RCA and RCF, concentrating 75% of HCP in the RCF compared to 28% for the reference process, and averaging 5% HCP on the surface of RCA compared to 11% for the reference process. In addition, the process produces RCA that are significantly cleaner than the reference process down to a particle size of 500 microns, and RCF that have better carbonation properties than the reference process.