DURABILITY OF BLENDED MORTARS USING FLY ASH OF HIGH UNBURNED CARBON CONTENT

Abstract

This paper presents a study of the durability properties and corrosion resistance of Blended Portland Cement Mortars using fly ash (FA) of high unburned carbon content (19%). The mortars were prepared with percentages up to 0-30% wt of FA as a partial replacement of cement. A mortar without addition was used as reference. The properties evaluated in the unreinforced mortars comprehend Compressive Strength, Absorption and Porosity, Absorptivity, Chloride – Ion Penetration and Susceptibility to Carbonation. The corrosion behavior of reinforcing steel in the mortars was evaluated using Linear Polarization Resistance test (LPR). The test was carried out in three different environment: Water, NaCl 3,5% in order to simulate a marine environment, and CO2  (1% CO2, 65 H.R. % y 25°C). The results showed that the mortars with 10% CV present a 35% increase in compressive strength at 28 days compared to the reference mortar, at the same time. This mix presented the best performance against corrosion of structural steels. Overall, all mortars showed low chloride permeability.