Sustainable UHPC incorporating water hyacinth ash and magnetized water with enhanced mechanical and durability...

Unlike previous fragmented studies focusing on single material substitutions, this research adopts an integrated approach to understand the synergistic effects of these combined materials on ultra-High performance concrete (UHPC) behavior. Water hyacinth ash (WHA) was used as partial cement replacements at 10% and rice husk ash (RHA) was used as partial cement replacements at 10% and 20%, while glass powder (GP) and marble powder (MP) were used to partially replace sand at the same levels. Magnetized water (MW) was used as the mixing water in this study. Sixteen UHPC mixes were produced with and without MW and tested for fresh, mechanical, and durability properties. The measurement included slump flow, unit weight, compressive and tensile strengths, water absorption, apparent porosity, sulfate resistance, and residual strength after exposure to 200 °C and 400 °C. The control mix achieved 153 MPa at 90 days. Several mixes outperformed this value and reached up to 169 MPa. GP10 mix achieved the highest tensile strength of 16.5 MPa at 28 days. Most modified mixes retained higher residual strength than the control mix after exposure to high temperature. The use of MW was associated with improvements in mechanical properties and workability. The control mix's compressive strength increased to 164.7 MPa at 90 days, showing an improvement of approximately 7.7%. The highest compressive strength was recorded for the GP 10% mix with magnetized water, reaching 187.1 MPa at 90 days. In terms of workability, the slump flow values improved by 9-15% depending on the mix. In addition to mechanical and durability assessments, microstructural analysis was conducted using scanning electron microscopy (SEM). The SEM observations indicated a denser matrix and improved particle packing in mixes incorporating water hyacinth ash and/or magnetized water, which is consistent with the observed enhancements in performance. This study demonstrates that combining WHA, RHA, GP, and MP with MW not only enhances the durability and performance of UHPC but also promotes sustainable waste utilization and supports circular economy practices in construction.