Abstract

GIRALDO, CAROLINA et al. DURABILITY OF WHITE PORTLAND CEMENT BLENDED WITH ULTRAMARINE BLUE PIGMENT. Dyna rev.fac.nac.minas [online]. 2010, vol.77, n.164, pp.45-51. ISSN 0012-7353.

The Ultramarine Blue pigment (UB) is a sodium polysulfide aluminosilicate that reacts with the tricalcium aluminate (C₃A) of the white Portland cement in presence of water, generating considerable amounts of early ettringite and a lesser proportion of tobermorite. This early ettringite is presented in the form of non-oriented fibers improving the mechanical performance of mortars, and at the same time leaving little amounts of C₃A available for the formation of delayed etringite. The durability of white Portland cement mortars substituted in 0%, 10% and 20% wt with Ultramarine Blue was evaluated in this research, through essays of capillary suction and evaluation of longitudinal change of mortars exposed to a sodium sulfate solution with a concentration of 5% (ASTM C1012). The results show a higher compressive strength and flexure, a significant reduction of expansion, and a reduction up to 800% of absorbed water in mortars with Ultramarine Blue, due to the formation of additional early ettringite and tobermorite, this phases by the electron scanning microscope (SEM) were observed.

Keywords : Ultramarine Blue; Durability; Ettringite; Capillary Suction; Mechanical strength; Blended cements.

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