Enhancing the Sustainability of CO2-based Construction Material by Utilization of Cement Kiln Dust

Abstract

The construction industry faces significant environmental challenges, driving the need for sustainable alternatives to traditional building materials. One promising approach involves nesquehonite (NQ)-based construction materials, which utilize carbon dioxide (CO₂) and rejected desalination brine, addressing two major industrial waste streams. However, previous studies indicate that NQ production still results in a carbon footprint comparable to conventional materials, necessitating further improvements in its sustainability profile. This study investigates the integration of Cement Kiln Dust (CKD) into the production of NQ-based materials to enhance their environmental performance. The research focuses on optimizing CKD leaching parameters and addition ratios to balance environmental benefits with mechanical properties. Laboratory analyses revealed that the compressive strength and material yield depend on the CKD leachate amount, with higher additions achieving a compressive strength of 9.5 MPa. A comparative life cycle assessment (LCA) was performed for three scenarios: the reference material (without CKD addition), high CKD addition (9.5 MPa), and low CKD addition (> 10 MPa). The life impact assessment results demonstrate significant reductions in environmental burdens with CKD integration. The global warming potential decreased from 0.392 kg CO₂ eq. for the reference material to 0.157 kg CO₂ eq. for the high CKD addition. Similarly, fossil fuel depletion dropped from 0.23 kg oil eq. to 0.159 kg oil eq., freshwater consumption reduced from 0.021 m³ to 0.014 m³, and metal depletion decreased from 2.8E-03 kg Cu eq. to 9.4E-04 kg Cu eq. These improvements highlight the substantial environmental advantages of incorporating CKD leachate into the production process.

Date of Award	2025
Original language	American English
Awarding Institution	HBKU College of Science and Engineering