Avaliação do desempenho de compósitos cimentícios com aditivo biocida

Abstract

Although cementitious composites have several applications, there are still limitations in their properties, including the difficulty of composites in relation to biodeterioration, which is deterioration caused by microorganisms. One of the ways studied to improve this property is through additions and biocidal additives. The work evaluated the properties in the fresh and hardened state of cementitious composites with incorporation of the zinc oxide biocide additive. It was also added to the gray rice husk mixture (CCA), with the intention of improving the properties of the composites generated. Five traces were developed, one as a reference, and the others with 20% addition of fixed zinc oxide and varying the CCA content from 0%, 10%, 20% and 30%. For each part of cement, 0.5 parts of fine sand were used, in the reference mix a w/c ratio of 0.45 was used and in the other mixes 0.5, also in the mixes with 10%, 20% and 30% of CCA incorporation required the use of a superplasticizer additive to generate satisfactory workability. To evaluate the performance of the mortars, in the fresh state, the consistency index test was carried out and in the hardened state the tests were carried out: compressive strength, flexural tensile strength, total water absorption, capillary water absorption and analysis were performed. visual of the bactericidal properties of cementitious composites. There was great fragility in the samples with incorporation of the biocide additive, varying the drop in compressive strength between 95.36% and 97.81% in 7 days, 91.92% and 94.37% in 28 and 60 days, 75% and 75.55% in 56 days. The decrease in flexural tensile strength varied between 99.01% and 99.46% in 7 days, 98.17% and 99.25% in 28 days and 96.79% and 97.96% in 56 days. The composites with the addition of zinc oxide showed a high capillary water absorption and total water absorption when compared to the reference. Visual analysis did not show great variation, probably due to the short time it was exposed to the weather (6 weeks). The study found that there is no feasibility in using the traits developed, requiring further studies so that this additive can be used in the civil construction market. [resumo fornecido pelo autor]