Effect of organic surface agents on properties of hydrated cement compacts

摘要

This paper reports the treatment of bottle-hydrated portland cement with organosilanes, oleic acid and octadecylamine intended to reduce the sorption of water and the corresponding dimensional changes. Compacts were made from the treated hydrated cement powder to simulate cement paste and allow measurements of sorption-dimensional change characteristics and microhardness. It was found that organochlorosilanes are not suitable for the treatment because the HCl released during the reaction produced undesirable side effects and in some cases increased the adsorption and expansion of the cement. Hexamethyldisilazane was more effective, reducing adsorption by 10 to 20%. Oleic acid was effective at concentrations as high as 25% by weight, but serious loss in mechanical property of microhardness was experienced.