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Abstract Recycled concrete formed by crushing waste concrete in construction waste as aggregate is an environmentally friendly and sustainable material, which is of great significance for reducing resource consumption and environmental pollution. However, the aggregate surface of recycled concrete has more cracks and defects than that of natural aggregate, resulting in that the interfacial transition zone of recycled aggregate interface is the weak link of recycled concrete. In order to modify the interface between the recycled aggregate and the matrix, a method of incorporating cellulose nanofibers into the matrix was proposed from the perspective of sustainability. The effect of cellulose nanofiber content on the interfacial microstructure around the recycled aggregate was investigated by means of thermogravimetric analysis, scanning electron microscopy and energy spectrum analysis. The results show that the microstructures at the old interfaces of recycled concrete are found to be loose with many holes, and the hydration degree of cement, the density of microstructure and the distribution uniformity of element content at the new interfacial transition zones are improved after adding an appropriate amount of cellulose nanofibers. An appropriate amount of cellulose nanofibers plays a positive role in the uniform distribution and full reaction of water molecules among cement particles in the curing stage, and the cellulose nanofibers can form a relatively dense network structure with the cement hydration products and then enhance the tightness between the micro-phases.
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Published: 31 October 2024
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2024, Vol. 0 
