Effect of the Addition of Microsilica on the Durability of Mortars Exposed To the Sodium Sulfate Attack

Abstract

This article presents a detailed experimental study on the sulfate attack of
mortars of self compacting concrete, and the effectiveness of employs microsilica and
limestone fillers in the minimization of the damage resulting from such an attack. The t est
solution used to supply the sulfate ions and the cations was the sodium sulfate solution
4.5%. The solution saturated with lime was employed as the reference solution. The main
variables investigated in the study were the type of cement and mineral addition. The
expansion measured on prisms of mortar of (40x40x160) millimeters was employed to
estimate their durability after exposure to the sodium sulfate solution attack during 91 days.
Specimens of mortars were visually examined to assess the extent of deterioration due to
the sulfate attack. The x-ray diffraction was used to evaluate the microstructural nature of
the sulfate attack. The test results proved that the use of microsilica had a beneficial effect
on the expansion due to the sodium sulfate attack. While mortars with limestone filler have
undergoes degradation even with the use of cement resistant to sulfates.
Keywords: Microsilica; Limestone filler; Sodium sulfate attack; Mortars, Expansion.