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Interaction between microbially induced calcium carbonate precipitation (MICP) and compaction procedures to stabilise raw soil materials has been studied with the aim of producing earthen engineering structures. Initial tests to optimise MICP in aqueous medium and in selected soils were performed. MICP and compaction were finally applied to assess medium-size elements. The main result was that sandy soils should be compacted before irrigation treatment to close the existing voids and prevent bacterial sweeping, whereas clayey soils should be compacted after irrigation treatment to avoid the plugging effect. MICP improved small sand soil compressive strength by up to 32% over the value reached by compaction alone. However, MICP had no positive effect on coarse soils and soils with an optimum particle size distribution: MICP treatment was not able to fill large connected voids in the first case and it caused little void generation due to bacteria sporulation in the second., Se estudió la interacción entre la precipitación de carbonato de calcio inducida por bacterias (MICP) y los procesos de compactación para estabilizar suelos naturales para producir estructuras de tierra. Se realizaron ensayos iniciales en medio acuoso para optimizar la MICP. El uso conjunto de MICP y compactación fue evaluado en elementos de tamaño medio. Los resultados indican que los suelos arenosos deben ser compactados antes de los tratamientos por irrigación para cerrar los huecos evitando el lavado de bacterias, mientras que los suelos arcillosos deben ser compactados después de las irrigaciones para evitar colmatar la superficie. La MICP mejoró la resistencia a compresión de la arena fina en un 32% en comparación con únicamente compactar. No obstante, no mejoró la resistencia de suelos granulares ni con una distribución de partículas óptima, por la interconexión de poros en el primer caso y la generación de vacíos por esporulación en el segundo.

The textile fiber made of poly(trimethylene terephthalate) came onto the market a few years ago. This fiber has certain advantages over traditional polyester, especially its greater elasticity and the fact that it can be dyed at lower temperatures. Here we study the dyeing kinetics of this “new” fiber using an azo disperse dye, C.I. Disperse Red 82, observing that the dyeing rate increases with temperature and that dyebath exhaustions only reach acceptable levels at temperatures above 80 °C. In order to quantify and compare the experimental data obtained, three kinetics models have been chosen. To fit results with models, non-linear regression methods have been applied and, to differentiate between early and final stages, two levels of exhaustion have been checked. From results obtained with the Chrastil model, apparent diffusion coefficients and the activation energy of diffusion have been calculated.