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Autogenous shrinkage in concrete is defined as the change of volume after initial setting occurs. It develops at very early ages as a result of chemical shrinkage and self-desiccation effect. These produce significant microcracks in high-strength concrete allowing the entrance of aggressive agents such as carbon dioxide, chlorides, and sulphates which cause concrete deterioration. Although considerable research of autogenous shrinkage has been done, uncertainty remains concerning the influence in concrete durability. Therefore, the purpose of this study was to quantify and analyse the effect of autogenous shrinkage on the mass transport properties of concrete using three transport tests: oxygen diffusion, oxygen permeation, and water absorption. Two methods, for three different binders, were first carried out to determine a control mixture that produces the least autogenous shrinkage: adding SRA and curing in a fog room. Subsequently, transport test results between the selected control mixture and mixtures highly affected by autogenous shrinkage were compared for different binders. Results revealed that specimens with SRA presented the least autogenous shrinkage; therefore, it is suggested to be considered as control samples. It was also found that autogenous shrinkage significantly affects the transport coefficients in concrete made with secondary cementitious materials which from a serviceability point of view could reduce the life span for any structure made with high-strength concrete. This investigation also confirmed that most of the autogenous deformation occurs during the first two weeks after casting therefore enough care should be taken when curing. Keywords: Concrete, autogenous shrinkage, transport properties. RESUMEN La retraccion autogena en el hormigon es el cambio volumetrico una vez iniciado su proceso de fraguado. Se desarrolla a edades muy tempranas debido a la retraccion quimica y a la autodesecacion. Estos causan microfisuras en hormigones de alta resistencia y permiten el ingreso de agentes nocivos como dioxido de carbono, cloruros y sulfatos que deterioran al hormigon. A pesar de haber estudios de la retraccion autogena, existe incertidumbre sobre su influencia en la durabilidad del hormigon. Por ello, el motivo del presente estudio es cuantificar y analizar el efecto de la retraccion autogena en el hormigon usando tres pruebas de transporte: difusion de oxigeno, permeabilidad de oxigeno y absorcion de agua. Dos metodos, para tres diferentes aglutinantes, fueron usados para determinar la mezcla control que produce menor retraccion: utilizando SRA y realizando el curado en un cuarto de niebla. Posteriormente, los resultados de las pruebas de transporte entre la mezcla de control seleccionada y mezclas altamente afectadas por retraccion autogena fueron comparados para diferentes aglutinantes. Resultados revelaron que muestras con SRA presentan menores retracciones autogenas y se sugiere que estas muestras sean consideradas de control. Se demostro que la retraccion autogena afecta significativamente los coeficientes de transporte los cuales en un punto de vista de servicio pueden reducir la vida util de cualquier estructura realizada con hormigon de alta resistencia. Esta investigacion ademas confirmo que la mayor deformacion autogena ocurre durante las dos primeras semanas; por lo tanto, se debe tomar cuidado suficiente en el curado. Palabras clave: Hormigon, retraccion autogena, propiedades de transporte.

Influence of autogenous shrinkage on mass transport properties of concrete