Behavior of E-glass fiber in basic aqueous medium resulting from the dissolution of mineral binders containing metakaolinite

Abstract

Using the dissolution reactor precedently described and allowing to determine the dissolution rate (α) of long E-glass fiber in constantly saturated calcium hydroxide solution, it was possible to point out that in aqueous media resulting from the dissolution of “Calcium Hydroxide (CH)/Metakaolinite (MK)” or “Ordinary Portland Cement (OPC)/Metakaolinite (MK)” binders, the short-time (28 days) dissolution rate (α) of the fiber is largely decreased, compared to what occurs in solution resulting from the dissolution of CH or APC alone. The following decreasing order of α values was observed : α(CH) > α(OPC) ⪢ α(CH/MK) > α(OPC/MK), but after 28 days of “fiber-solution” contact α is never null. Scanning electron microscopy observations of the fiber surface after 28 days of contact with solutions saturated by binders con-containing metakaolinite always point out that the attack layer or deposit formation, although limited, is not at all regular and can concern some particular fibers rather than other ones, what implies either some difference in the composition of the glass from one fiber to another one, or the presence of local defects in the fiber surface. The validity of the experimental method used is discussed.