(1H NMR) relaxometry to measure water amount in cement paste. This technique allows the quantification of water in cement paste as well as water present in the crystalized form. Based on obtained relaxation rates, pore sizes can be calculated, and porosity ranging from 1 nm to 10 μm can be probed by the 1H NMR. The main advantage of the method lies in unnecessitythe optional aspect of drying, which may alter the microstructure of C-S-H gel, prior to the application of this measurement technique. On the other hand, since this technique is based on measuring of hydrogen atoms, empty pores filled with air (void pores) cannot be detected by this method. AuthorThe author compared his results with other techniques and concluded that only the desorption isotherm technique can measure gel pores properly.
The 1H NMR used to characterise cement hydration and microstructure has three principal advantages compared to other methods. The first is that the water hydrogen inherent in the sample is, itself, the probe. This immediately negates any requirement to dry or otherwise prepare the sample. This is a significant advantage, as the drying, and perhaps polishing or high pressure impregnation, required by other methods can disturb the delicate nano-scale structure of the cement hydrates.