Evaluación de nanofibras de celulosa como aditivo para el curado interno y durabilidad del hormigón.
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Date
2026
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Universidad de Concepción
Abstract
El hormigón es el material de construcción más utilizado a nivel mundial, pero enfrenta importantes desafíos de durabilidad debido a la fisuración temprana y al curado interno deficiente, lo que facilita la penetración de agentes agresivos como los cloruros. Simultáneamente, la industria cementera requiere adoptar prácticas sostenibles orientadas a la economía circular. En este contexto, el presente trabajo tiene como objetivo principal evaluar el comportamiento mecánico y de durabilidad del hormigón utilizando nanofibras de celulosa (NFC) obtenidas del reciclaje de sacos de cemento posconsumo, con el fin de utilizarlas como agentes de curado interno y densificación microestructural.
Para lograr este objetivo, se confeccionaron mezclas de hormigón incorporando NFC de tamaño grande (TG) y pequeño (TP) en concentraciones restrictivas de 0,05% y 0,1% respecto a la masa del cemento, contrastándolas con una mezcla patrón. En estado fresco, la adición redujo la docilidad entre un 20% y 30% en las dosis del 0,05%. En estado endurecido, la mezcla NFC-TG al 0,05% logró incrementar la resistencia a la compresión en hasta un 16,5% a los 28 días y reducir la sorptividad capilar en un 32%. Sin embargo, el análisis termogravimétrico (Pérdida por Ignición, LOI) arrojó grados de hidratación mayoritariamente negativos en comparación al hormigón patrón (alcanzando variaciones de hasta -8,1% a los 28 días).
A partir de la discusión de estos resultados, se concluye que las NFC no mejoran la composición química de la matriz mediante curado interno, ya que su alta capacidad hidrofílica genera aglomeraciones que retienen el agua y frenan la hidratación periférica del cemento. El éxito y aumento de resistencia radican en un mecanismo de refuerzo físico-mecánico: las nanofibras dispersas actúan como un puenteo estructural tridimensional (crack bridging) que enlaza microfisuras, absorbe energía de fractura y densifica los poros capilares. Por tanto, el uso de NFC-TG al 0,05% es una innovación viable para el refuerzo físico del hormigón, condicionado a estrictos protocolos de homogeneización.
Concrete is the most widely used construction material worldwide, but it faces significant durability challenges due to early-age cracking and deficient internal curing, which facilitates the penetration of aggressive agents such as chlorides. Simultaneously, the cement industry must adopt sustainable practices oriented towards a circular economy. In this context, the main objective of this study is to evaluate the mechanical and durability behavior of concrete using cellulose nanofibers (CNF) obtained from the recycling of post-consumer cement bags, in order to use them as internal curing and microstructural densifying agents. To achieve this objective, concrete mixtures were prepared incorporating large (TG) and small (TP) size CNFs at restrictive concentrations of 0.05% and 0.1% relative to the cement mass, contrasting them with a control mixture. In the fresh state, the addition reduced workability by 20% to 30% at 0.05% dosages. In the hardened state, the optimal mixture (0.05% CNF-TG) achieved an increase in compressive strength of up to 16.5% at 28 days and a 32% reduction in capillary sorptivity. However, thermogravimetric analysis (Loss on Ignition, LOI) yielded mostly negative degrees of hydration compared to the control concrete (reaching variations of up to -8.1% at 28 days). From the discussion of these results, it is concluded that CNFs do not improve the chemical composition of the matrix through internal curing, as their high hydrophilic capacity generates agglomerations that retain water and hinder the peripheral hydration of the cement. The success and increase in strength lie in a physical-mechanical reinforcement mechanism: the dispersed nanofibers act as a three-dimensional structural reinforcement (crack bridging) that links microcracks, absorbs fracture energy, and densifies capillary pores. Therefore, the use of 0.05% CNF-TG is a viable innovation for the physical reinforcement of concrete, contingent upon strict homogenization protocols.
Concrete is the most widely used construction material worldwide, but it faces significant durability challenges due to early-age cracking and deficient internal curing, which facilitates the penetration of aggressive agents such as chlorides. Simultaneously, the cement industry must adopt sustainable practices oriented towards a circular economy. In this context, the main objective of this study is to evaluate the mechanical and durability behavior of concrete using cellulose nanofibers (CNF) obtained from the recycling of post-consumer cement bags, in order to use them as internal curing and microstructural densifying agents. To achieve this objective, concrete mixtures were prepared incorporating large (TG) and small (TP) size CNFs at restrictive concentrations of 0.05% and 0.1% relative to the cement mass, contrasting them with a control mixture. In the fresh state, the addition reduced workability by 20% to 30% at 0.05% dosages. In the hardened state, the optimal mixture (0.05% CNF-TG) achieved an increase in compressive strength of up to 16.5% at 28 days and a 32% reduction in capillary sorptivity. However, thermogravimetric analysis (Loss on Ignition, LOI) yielded mostly negative degrees of hydration compared to the control concrete (reaching variations of up to -8.1% at 28 days). From the discussion of these results, it is concluded that CNFs do not improve the chemical composition of the matrix through internal curing, as their high hydrophilic capacity generates agglomerations that retain water and hinder the peripheral hydration of the cement. The success and increase in strength lie in a physical-mechanical reinforcement mechanism: the dispersed nanofibers act as a three-dimensional structural reinforcement (crack bridging) that links microcracks, absorbs fracture energy, and densifies capillary pores. Therefore, the use of 0.05% CNF-TG is a viable innovation for the physical reinforcement of concrete, contingent upon strict homogenization protocols.
Description
Tesis presentada para optar al título de Ingeniero/a Civil.
Keywords
Hormigón, Construcción, Nanofibras, Celulosa, Resistencia de materiales