Abstract
This study evaluates the loss of the properties of rendering mortars with recycled fine aggregate submitted to thermal cycling tests based on the NBR 15575-4 (ABNT, 2013ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 15575-4: edificações habitacionais: desempenho: parte 4: requisitos para os sistemas de vedações verticais internas e externas: SVVIE. Rio de Janeiro, 2013.) standard. The mortars were produced at a mix-proportion of 1:1:6 in volume (cement, lime and sand) using Brazilian cement CP II F-32, CH-I lime putty, river sand and fine aggregate produced from recycled concrete, in compositions with 2, 4.5, 7 and 9.5% relatively to the mass of sand. The rendering mortars were applied on ceramic substrate and evaluated, at 28 days of age, for bond tensile strength (NBR 13528 (ABNT, 2010ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS. NBR 13528: revestimento de paredes e tetos de argamassas inorgânicas: determinação da resistência de aderência à tração. Rio de Janeiro, 2010.)), surface hardness determined by Shore durometer type D (ASTM D 2240-5 (AMERICAN..., 2005AMERICAN SOCIETY FOR TESTING AND MATERIALS. D 2240-05: standard test method for rubber property: durometer hardness. Philadelphia, 2005.)) and the velocity of ultrasound waves. The systems formed by the rendering mortars applied on the ceramic substrate were subjected to accelerated ageing by exposure to thermal cycling, which degraded the mortars. All rendering mortars presented superficial hardness decline (in the order of 10%), lowered velocity of ultrasound waves (about 25%) and lowered bond tensile strength by about 15%. The evaluation of the rupture of the rendering mortars showed that those with 2 e 4.5% fine aggregate content suffered the greater degradation.
Keywords:
Accelerated ageing; Recycled fine aggregate; Rendering mortar; Thermal cycle
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