Naslov
The effect of silica fume additions on the durability of portland cement mortars exposed to magnesium sulfate attack

Autori
Zelić, Jelica ; Radovanović, Ivana ; Jozić, Dražan

Izvornik
Materiali in tehnologije (1580-2949) 41 (2007), 2; 91-94

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
blended cement ; silica fume ; sulfate attack ; durability ; elastic modulus

Sažetak
The deterioration of concrete structures due to the presence of sulfate in soils, groundwater and marine environments is a well-known phenomenon. The use of blended cements incorporating materials such as natural pozzolans, fly ash or silica fume have an important role in the long-term durability of concrete exposed to sulfate attack. In this work, the partial replacement (mass fractions 2-15 %) of commercially bended Portland cement (Type CEM IIA-S 42.5N) with silica fume (SF) was investigated in terms of the resistance of SF mortars to a magnesium sulfate (MgSO4) solution ( (SO4)2-=2.5% ; exposure time up to 6 months at 20oC). The changes in the length of the mortars due to expansion, as well as the changes in the elasticity modulus and mechanical strengths loss as a function of silica fume replacement were determined. Structural changes in the mortars due to magnesium sulfate attack were also evaluated by differential thermal analysis (DTA) and by X-ray diffraction analysis (XRD). The results show that the replacement of SF in most cases has a positive effect on the magnesium sulfate resistance. Mortars containing more than 8 % of mass fraction of SF replacement are characterized by a good sulfate resistance and show lower expansion than the control mortar on the basis of the sulfate-resisting Portland cement, due to the absence of the gypsum and ettringite, detected by the XRD analysis. It is also shown that elastic modulus is proportional to the compressive strength, but higher compressive strength does not necessary correlate with a better resistance to sulfate attack.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo

POVEZANOST RADA