Sustainable Concrete Production through Partial Cement Replacement Using Fly Ash and Rice Husk Ash

Meron Tesfaye — 2026-01-29

This study explores the utilization of fly ash and rice husk ash as supplementary cementitious materials to partially replace ordinary Portland cement (OPC) in concrete production. The increasing environmental impact of cement manufacturing, particularly its contribution to carbon dioxide emissions, has driven the search for alternative materials that promote sustainability without compromising performance. Fly ash and rice husk ash, both industrial and agricultural by-products, possess pozzolanic properties that enhance the mechanical and durability characteristics of concrete when properly incorporated. This paper reviews their chemical composition, particle morphology, and the effects of replacement levels on compressive strength, workability, and long-term durability. Additionally, the study discusses challenges such as variability in ash quality, optimal replacement percentages, and curing conditions that influence performance outcomes. By integrating these waste materials into concrete, significant environmental and economic benefits can be achieved, including reduced landfill disposal, conservation of natural resources, and lower greenhouse gas emissions. The findings highlight the potential of fly ash and rice husk ash as sustainable cement substitutes, supporting the development of eco-friendly construction materials aligned with green building standards and circular economy principles. This research contributes to advancing sustainable practices in the construction industry and provides insights for future studies focused on optimizing mix design, performance enhancement, and large-scale application of alternative cementitious materials.

Comparison of Piggery Wastewater Treatment after the Biogas Process by Cyperus alternifolius and Ipomoea aquatica in a Vertical Subsurface Flow Constructed Wetland System in Vietnam

Bui Thi Van Nga — 2026-02-25

Vertical subsurface flow constructed wetlands (VSF CWs) have been widely applied as an eco-friendly solution for treating livestock wastewater. This study compared the treatment performance of Cyperus alternifolius and Ipomoea aquatica planted in VSF CWs treating piggery wastewater after biogas digestion. Two laboratory-scale VSF CW systems (50 × 50 × 50 cm) with identical media configuration and operational conditions were operated in an intermittent mode with a hydraulic retention time of 3 days over 20 treatment cycles. The VSF CW planted with C. alternifolius consistently exhibited higher removal efficiencies for all monitored parameters compared with the system planted with I. aquatica (p < 0.05). The average removal efficiencies of the papyrus-based system reached 74.2 ± 3.1% for COD, 85.8 ± 3.4% for TSS, 70.9 ± 4.1% for TN, 75.1 ± 5.5% for NH₄⁺–N, and 64.7 ± 7.9% for TP, with most effluent concentrations complying with the Vietnamese discharge standard QCVN 62:2025/BTNMT (Column B). In contrast, the VSF CW planted with water spinach achieved lower treatment efficiencies, with average removal rates of 53.9 ± 2.6% for COD, 80.5 ± 5.6% for TSS, 54.6 ± 5.6% for TN, 57.0 ± 8.6% for NH₄⁺–N, and 44.5 ± 13.1% for TP, and did not consistently meet discharge limits for nitrogen and phosphorus.

Tropical Environment, Biology, and Technology

Sustainable Concrete Production through Partial Cement Replacement Using Fly Ash and Rice Husk Ash

Comparison of Piggery Wastewater Treatment after the Biogas Process by Cyperus alternifolius and Ipomoea aquatica in a Vertical Subsurface Flow Constructed Wetland System in Vietnam