RESUMO Este trabalho tem como objetivo realizar uma análise da eficiência da tinta de base epoxídica utilizada como proteção superficial do concreto leve com argila expandida submetido ao ataque por ácido sulfúrico (H2SO4). Ataques ácidos externos podem promover reações expansivas e a degradação acelerada, comprometendo assim a durabilidade das estruturas de concreto leve. Dentre as proteções desenvolvidas, as tintas têm um importante destaque, por possuírem boa aderência à superfície do concreto, serem resistentes ao intemperismo e à fotodegradação, além de apresentar boa estabilidade química. O desempenho da tinta de base epoxídica foi avaliado por meio de inspeção visual e de ensaios de resistência à compressão, absorção de água e perda de massa do concreto antes e após ataque químico. A avaliação por inspeção visual demonstrou que os corpos de prova de concreto leve com proteção superficial epoxídica apresentaram uma diminuição da perda de coesão da pasta causada pelo ataque. Os resultados dos ensaios de absorção de água, de perda de massa e de resistência mecânica demonstraram o bom desempenho da tinta de base epoxídica, impedindo a penetração do agente agressivo nos concretos protegidos. A pesquisa permite concluir que a proteção epoxídica reduz significativamente o impacto causado pelo ácido sulfúrico ao concreto e que pode garantir a durabilidade das estruturas confeccionadas com concretos leves de argila expandida.

ABSTRACT The purpose of this study is to analyze the efficiency of epoxydic base paint used as a protective coating on expanded clay lightweight concrete under sulfuric acid (H2SO4) attack. External attacks can promote expansions and accelerated degradation, reducing the concrete durability. Developed protections, such as paints have an important performance result, because they have good adhesion to the concrete surface, weathering and photodegradation resistant, besides provide a good chemical stability. The performance of epoxydic paint was assessed through visual inspection, compressive strength test, water absorption and mass losses before and after chemical attack. The visual inspection demonstrated that the epoxy-coated lightweight concrete specimens had a clear reduction in the loss of cohesion of the paste caused by the attack. The teste results of regarding water absorption, mass loss and mechanical strength showed the good performance of the epoxydic base paint, preventing the penetration of the aggressive agent on protected concretes. This research shows that epoxydic protection reduces the impact of external acid attacks on concrete and can improve the durability of expanded clay lightweight concrete structures.

Concrete structures must be designed and constructed so as to resist the conditions established in the project design and suffer no deterioration for many years. In highly aggressive environments, in addition to the minimum layer covering the framework, the concrete must receive a protective coating. In this work, the efficiency of acrylic paint as a protective coating, while the concrete was placed in an aggressive environment, was assessed utilizing a profilometric and microstructural characterization. The concrete was dosed using the ACI - American Concrete Institute method. The specimens were prepared with 370 kg.m-3 of cement and the water-binder ratio of 0.50 corresponds to the value established in NBR6118¹ types for concrete subjected to highly aggressive environments. With the use of profilometry, 3D topographical images and surface roughness parameters were generated, which allowed for the identification of the degradation process and the minimization of the effect of this attack on concrete that had received surface protection. The topographic roughness parameters, as well as the images and chemical components identified using SEM/EDS, made it possible to identify the process of deterioration of the concrete under acid attack and to minimize such effect in the coated concrete. The methodology adopted demonstrates that the application of acrylic paint as a protective coating for concrete in an aggressive environment minimizes its surface degradation and increases its durability.