Carbon Conscious Construction: Evaluating Compressed Stabilized Earth Blocks

The construction sector, particularly the production of materials like cement and steel, is a major contributor to global CO2 emissions, with cement alone responsible for about 8%. Conventional masonry relies heavily on cement, increasing embodied carbon and costs, but standardized data on low-carbon alternatives such as compressed stabilized earth blocks (CSEBs) remain scarce, limiting their adoption in sustainable housing. To support the United Nations Environment Program (UNEP) and the Paris Agreement goals for net-zero embodied carbon in building materials by 2050, this study aims to assess the production and performance of CSEBs as a low carbon alternative to conventional masonry. It specifically addresses the research gap on technical performance and carbon savings, providing new empirical evidence for Ethiopian soils. Soil samples from Kara (east of Addis Ababa) were analyzed for grading, plasticity, and chemical composition. Blocks were produced with Portland pozzolana cement (4–12%) under compaction pressures of 4–10 MPa and tested for compressive strength and water absorption over 56 days. Results show that 6% cement content achieved >2 MPa compressive strength, meeting the structural requirements, while higher cement content and pressure improved strength and reduced absorption. Compared to hollow concrete blocks, CSEBs cut cement use by over 50%, avoiding up to 2 tons of CO2 per 100 m2 of wall. These findings confirm CSEBs as a technically viable and climate-conscious solution for affordable housing and support their integration into sustainable construction practices.