The role of cavitation in drying cementitious materials

Using water vapour and N2 isotherms to unveil effects of SCMs on nanopores and evaluate hydration degree

“…The capillary tension in ink-bottle pores with small necks increases to a very large value, with which pressure cavitation (homogeneous nucleation of bubbles of vapour) could occur. This phenomenon is commonly observed in the N 2 [68] and water vapour desorption [45,46] curve of materials with the complex mesoscale pores. Maruyama et al [45] found no cavitation in pores smaller than 5 nm (6.4 nm including the t thickness) during the desorption of cement-based materials at 20 • C. Thommes et al [69] reported that the cavitation occurs in pores wider than 8.5 nm during N 2 desorption of mesoporous silicas, and it shows no dependence on the pore shape, pore size or the neck size (at least for necks smaller than 2.6 nm).…”

“…This model was also widely applied for the determination of PSD in cement-based materials using water vapour desorption data [10,11,41]. Although the pore shape in hcps is more complex than the assumed cylinder shape in this method, and cavitation occurs during the desorption process [45,46] (corresponding to one peak in Fig. 4), the calculated results provide meaningful information for a comparative investigation such as this study.…”

“…In general, the blending of SCMs will increase the moisture capacity in these ranges, and FA presents the largest increase. The sudden drop of moisture content from RH of 36 % to 30 % has been explained as the occurrence of cavitation during the drying process [45,46]. The cavitation-induced moisture capacity is higher in the blended pastes than in the CEM I pastes at all w/b mixtures.…”

“…Maruyama et al [45] found no cavitation in pores smaller than 5 nm (6.4 nm including the t thickness) during the desorption of cement-based materials at 20 • C. Thommes et al [69] reported that the cavitation occurs in pores wider than 8.5 nm during N 2 desorption of mesoporous silicas, and it shows no dependence on the pore shape, pore size or the neck size (at least for necks smaller than 2.6 nm). Rastogi et al [46] stated that cavitation occurred in the gel pores (in a range of 2-8 nm) of the inner product. Based on these findings, we suggest that the moisture loss from 40 % to 20 % RH is the water in SGP and the ink-bottle LGP connected with the interlayer space.…”

Comparison of the Calcium Carbide Method and Darr Drying to Quantify the Amount of Chemically Bound Water in Early Age Concrete

“…Ettringite and gypsum might already become unstable at temperatures above ca. 60 °C [ 36 , 41 , 42 ], as well as the interlayer water between the C-S-H sheets due to cavitation [ 43 ]. It must also be considered that the oven drying may lead to a significant bias in the data, because the hydration process is not stopped immediately after sample extraction.…”