Influence of Environmental Aging on Properties of Polymeric Mortars

The emergence of polymeric mortars as a class of materials with applications in civil engineering requires a systematic study of their properties, including mechanical strength and durability under severe environmental conditions. This study reports results based on tests of polymeric mortars, both with epoxy and polyester resins, after exposure to (1) immersion both in distilled and in salt water, (2) salt fog spray cycles (8 h of salt fog, followed by 16 h drying, at 35°C), and (3) temperature cycles [12 h at 20 and 50°C, respectively, with relative humidity (RH) kept at 80%]. Additional tests for humidity cycles at fixed temperature and ultraviolet rays are reported elsewhere. Moisture absorption is analyzed based on mass changes for submerged specimens and Fickian type behavior evaluated. Compressive and bending strength degradation, as well as increase of brittleness, are examined for these accelerated actions and preliminary interpretation advanced. The relative severity of the effects is graphically displayed, tabulated, and analyzed. Brittleness increases more rapidly, under salt fog, for epoxy mortar and bending strength reduction at 10,000 h is also higher (50%) for epoxy mortar than for polyester mortar (32%). Thermal cycles also provoked greater deterioration of bending strength on epoxy mortars. Compressive tests led to results of similar tendency, but with smaller differences.