Includes bibliographical references

The increasing demand for cement in the construction industry contributes greatly to the increasing global carbon dioxide emissions, producing a need for sustainable construction materials. This study aimed to evaluate the performance of Rice Husk Ash (RHA) and crystalline admixture as components of self-healing concrete while reducing the environmental impact consequent to cement production. An experimental research design was used through the preparation of four concrete mixtures consisting of a control mix and three mixes with varying percentages of RHA with 2% of crystalline admixture. The concrete samples were subjected to slump, compressive strength, density, self-healing, and environmental impact assessment tests at 14-day and 28-day curing periods. The study found that higher percentages of RHA decreased slump values due to the fine and porous particles of RHA absorbing more water. The outcome of the compressive strength test indicates that self-healing concrete with partial RHA up to 15% can be used for structural composition, while 20% is only limited to lightweight applications. Results also showed that increasing the percentage of RHA in concrete mixtures produced lower carbon dioxide emissions, with the highest reduction recorded at 91.67 kg CO/m² compared to the control mix. Crack width measurements showed no measurable crack closure within the 14-day healing period, however, small white crystalline deposits were observed on some crack surfaces, suggesting the possible initiation of self-healing activity. Density results presented slight changes in unit weight as curing progressed. The findings indicate that concrete incorporating partial RHA and crystalline admixture can contribute to sustainable construction practices while maintaining functional concrete properties.