Pore Structure of Calcium Silicate Hydrate in Hydrated Tricalcium Silicate

Adsorption of N 2 and water vapor was studied in completely hydrated tricalcium silicate and in fully hydrated tricalcium silicate from which Ca(OH) 2 had been extracted. Compared with results obtained using N 2 , water vapor adsorption led to increased values for small‐pore volume, peak shifts to smaller sizes, and decreased values for large‐pore volume. Marked hysteresis was observed in the case of water vapor adsorption; the resorption branch apparently represents the true pore structure. Extraction of Ca(OH) 2 from the paste increased the calculated volume of small pores strikingly, suggesting that adsorption is hindered by Ca(OH) 2 ; this tendency is more obvious in water vapor adsorption. The adsorption measurements indicate the existence of two kinds of pores, i.e. a wider intergel‐particle pore and a smaller pore existing within the gel particle. The latter pore was further classified into intercrystallite and intracrystallite pores.