Enhancing concrete sustainability with spent diatomaceous earth from the wine industry: Long‐term experimental and statistical analysis

Spent diatomaceous earth, a by‐product of wine filtration, holds significant promise for use in concrete mixtures due to its pozzolanic properties, which enhance concrete performance. This research explores the application of spent calcined diatomaceous earth (SCDE), heat‐treated at 700°C to remove organic content, as a partial substitute for cement or sand in concrete. The high silica content of SCDE contributes to the formation of additional calcium silicate hydrates during the hydration process, leading to improvements in mechanical strength over time. The study includes a preliminary analysis of cement replacements ranging from 5% to 10% and sand replacements from 2.5% to 15%, assessing their effects on workability, density, water absorption, and compressive strength at 7 and 28 days. The testing program focuses on three key compositions: the reference concrete and optimal mixtures with 10% cement and 5% sand replacements. Compressive strength tests are conducted at 7, 28, 90, 180, and 360 days. The results, validated through ANOVA, demonstrate the influence of SCDE on concrete strength over time, with distinctive behavior patterns identified for different mixtures. The strength of concrete with replacements correlates with the reference strength, with a multiplicative factor that varies from 7 to 90 days and then. When SCDE replaces cement, the factor is less than one before 28 days due to the slow pozzolanic reaction, whereas for sand replacement, it always exceeds one because of the initial filler effect. After 90 days, the strength multiplicative factors are 1.13 for cement replacement and 1.30 for sand replacement, demonstrating the potential of SCDE for sustainable concrete manufacturing and its positive long‐term impact on mechanical performance.