Extractive Contents of Two Woods and Cork of Portuguese Origin and the Interaction of These Substrates with Cement Suspensions (Technical Note‪)‬

Abstract Data are presented on the extractive contents of blue gum, maritime pine, and cork, as an initial attempt to predict the level of compatibility of these substrates with Portland cement. In order to cover a range of polarities, several organic solvents were applied as well as water. Moreover, to simulate the chemical environment of a cement suspension, aqueous NaOH, Ca[(OH).sub.2], and the filtrate of a cement suspension were also used as extracting agents. The levels of neutral solvent extractives are discussed, but the results obtained with alkaline extracting agents suggest that, when the woods or cork are mixed with a cement suspension, cations are adsorbed onto the substrate surfaces, and are therefore, subtracted from the solution. The phenomenon is proposed as an explantion, among others, of the impairment of cement hardening when mixed with fairly compatible or incompatible wood species.