# Nuclear Magnetic Resonance in Tire Waste Mortars
## 1 Introduction  
In the context of sustainable development and efficient waste management, incorporating recycled materials [1, 2, 3] into cementitious compositions has gained significant attention. Among these, tire rubber waste is recognized for its potential to enhance toughness, energy absorption, and thermal properties, despite some reduction in compressive strength. The feasibility and challenges of using rubberized mortars have been demonstrated in previous studies [4, 5]. On the other hand, Nuclear Magnetic Resonance (NMR) [6] is an emerging tool in construction material analysis. Although NMR has been employed in cementitious material research for several decades, its recent applications benefit from enhanced precision and data interpretation capabilities. The capability of NMR techniques to reveal hydration dynamics, pore connectivity, and water mobility has been demonstrated in recent studies [7, 8]. Despite these advances, the combined use of NMR to evaluate mortars modified with recycled tire rubber and organic additives [9] such as casein or latex remains limited. This paper addresses this gap, applying NMR to explore microstructural evolution in eco-friendly mortars designed for animal housing applications, contributing both to sustainable construction and animal welfare. Pertaining to current European and global environmental strategies promoting sustainable development in construction materials [10], the integration of industrial waste materials as natural or synthetic polymers [11; 12] into cementitious compositions represents an innovative research direction. Among environmentally detrimental waste materials [13], end-of-life tires hold particular significance due to their substantial global annual accumulation and non-biodegradable nature [14; 15]. NMR applications in cementitious materials have been reported for tracking cement hydration by [PERSON] et al. [16] and for analyzing porosity, water distribution in fractured rocks, and predicting durability based on NMR parameters by [PERSON] et al. [8]. The current study focuses on the relatively underexplored application of NMR in rubberized mortars, especially in the context of screed layers for livestock flooring [17], where the balance between resilience and hygiene is crucial. This practical need in agricultural engineering motivated the development of durable, moderately elastic flooring [18] solutions using recycled rubber components and investigating its hydration process [19]. Recent specialized studies have extensively investigated the potential incorporation of waste tire rubber as aggregate in cementitious products such as mortars and plain concrete. A Web of Science (WOS) analysis of indexed publications reveals a marked increase in research activity focusing on rubberized mortars and concrete in recent years. As illustrated in Figure 1, the keyword search \"cement mortar with rubber granules\" demonstrates particularly heightened research interest during 2021, 2023, and 2024 (with 2024 data currently undergoing updates). For the integration of rubber tire waste into the cementitious matrix of mortars or concrete, the waste is processed into granules or flakes, which can provide benefits such as increased tensile strength through bending, superior impact resistance and improved thermal insulation [20]. However, the incorporation of these rubber granules into the cementitious matrix can also lead to negative effects on mortars or concretes, such as a reduction in compressive strength [21] and an increase in porosity, which may influence the long-term durability of construction elements. In this regard, NMR (Nuclear Magnetic Resonance) has been used as an advanced and non-destructive technique for the analysis and characterization of cementitious materials.