Ataque de sulfatos externo em blocos de terra comprimidos estabilizados com cimento

Abstract

External sulfate attack is known to damage cementitious materials due to ingress of sulfate ions from external environment. This process causes loss of cohesion, increase in porosity, local expansion, spalling and cracking. The objectives of this research were to study the influence of the capillary absorption time and to study the sulfate ions concentration using compressed stabilized earth blocks (CSEB) exposed to sulfate attack. The CSEB were exposed to aqueous sodium sulfate solution by cycles of capillary absorption and drying. Two sets of procedures were used to evaluate the wear of the samples. In the first set of procedures, the wetting time was varied. In the second one, the sodium sulfate concentration was varied. The CSEB used had the same dosage of earth, cement and water and for each procedure 3 samples were tested. The masses were measured after taking the samples out of the solution and after a 2-week drying time, being that a cyclic process for each procedure. The room temperature and relative humidity allowed crystallization of thenardite and mirabilite. Granulometry, XRD, XRF and SEM tests were used to identify the materials. The results showed that capillary absorption time and sulfate concentration influences the wear of the compressed stabilized earth blocks.