# Nuclear Magnetic Resonance in Tire Waste Mortars
## 3 Results and Discussion  
By analyzing the distribution of transverse relaxation times T\({}_{2}\), valuable information can be obtained about pore structure, pore size distribution, and fluid dynamics within the material. The T\({}_{2}\) relaxation time distributions for the casein-modified [35] (2%) and rubber-flake-containing (2%) screed mortar (with partial cement replacement) are presented in Figure 9.  
The distributions were measured at 3, 7, and 28 days, as shown in Figure 10. Four distinct peaks are observed, which can be associated with water bound to cement components. \begin{table}
\begin{tabular}{c c c} \hline
**MC2\%F2\%** & **MV3F5\%** & **MV5F5\%L5\%** \\ \hline Standard Mortar & Standard Mortar & Standard Mortar \\
2\% Casein & 3.5 Natural Hydraulic Lime 1 & 5 Natural Hydraulic Lime 1 \\
2\% Rubber Flakes & 5\% Rubber Flakes & 5\% Rubber Flakes \\  & & 5\% Latex \\ \hline \end{tabular} \({}^{1}\) Natural Hydraulic Lime (NHL) is the standardized European classification for hydraulic lime, as defined in EN 459-1 and it refers to a specific strength class 3.5 or 5, in our case.  
\end{table} 
Table 2: Composition of the NMR-tested materials. Figure 10: 3 NHL lime and 5% rubber flakes mortar specimen. Figure 9: 2% Casein and 2% Rubber Flakes mortar specimen. The peaks with larger integrated areas are located at T\({}_{2}\) values below 100 \(\upmu\)s. Additionally, at all three testing ages, smaller peaks appear at approximately 1 ms, 7 ms, and 30-40 ms. These correspond to: the smallest peak (\(\sim\)1 ms) representing water in very small pores, the 7-8 ms peak indicating medium-sized pores, and the 20-30 ms peak corresponding to medium-to-large pores. The T\({}_{2}\) distributions for this 2% casein/2% rubber flake mortar sample remain relatively similar across curing times, suggesting the mortar structure becomes well-established in as early as 3 days. Minor evolution is observed at 7 and 28 days, with a noticeable shift of the T\({}_{2}\) maximum: from 600-700 \(\upmu\)s at 3 days to 400-500 \(\upmu\)s at later ages. This shift indicates sample hardening. At 3 days, the bound water and small pore water peaks overlap, revealing expected sample heterogeneity at early ages. By 28 days, all peaks become well-resolved, demonstrating: hydration water incorporation into rigid components, distinct formation and separation of small and medium-to-large pores and most of the water existing as hydration water. The distributions of measured relaxation times for the lime mortar sample with 3% and 5% rubber flakes are presented in Figure 11. In this case, a dramatic evolution is observed for the samples measured at 3, 7, and 28 days. Thus, at 3 days after preparation, the appearance of two peaks is quite clearly observed: one containing the largest amount of hydrogen, which exists as hydration water but in much more mobile components than in the previous mortar sample with 2% casein and 2% rubber flakes. Additionally, there is only one type of pore that might cover the range from medium to large pores, though not very well defined. At 7 days after the preparation of the mortar sample with 3% and 5% rubber flakes, the appearance of two types of pores is observed, indicated by two peaks located at approximately 7-8 ms and around 30 ms. There is also a broader peak centered at approximately 90-100 \(\upmu\)s, which also features a shoulder at higher T\({}_{2}\) values, potentially indicating the formation of small pores in this case. Thus, the addition of lime has a dramatic effect on the mortar. At 28 days after preparation, another dramatic change in the pore distribution is observed. There is a quantity of large, medium-to-large pores in which water is present in very small amounts, as indicated by a low-amplitude peak located at approximately 70-80 ms. The distribution of medium and medium-to-large pores is no longer as well resolved or differentiated compared to medium or medium-to-large pores, and a relatively small number of small pores is also observed.