Steel reinforcement corrosion due to chloride penetration into concrete is one of the main causes of the degradation of marine structures and has been the subject of much research. Among the various factors that influence chloride penetration into concrete are environmental factors such as temperature and exposure conditions. In this context, the present study evaluated chloride penetration for three different exposure conditions (atmospheric, tidal variation and submerged) at temperatures of 15°C, 20°C, 25°C and 30°C over 18 months; samples were collected every 6 months, at depths of 1–5 mm. The environmental conditions were simulated in the laboratory. The results showed a higher concentration of chlorides in the submerged specimens. Moreover, the chloride concentration increased more intensively from 6 to 12 months and temperature was more influential above 20°C. The temperature effects were also found to be higher at advanced ages.

RESUMO A incorporação de resíduos de construção e demolição (RCD) como agregados em concretos requer bom conhecimento das propriedades dos materiais envolvidos. O objetivo da presente pesquisa foi caracterizar um produto específico de uma usina de reciclagem de RCD, a Usina de Recicláveis Sólidos Paraná (USIPAR), localizada em Almirante Tamandaré, PR, conhecido comercialmente como bica corrida. O agregado reciclado foi caracterizado quanto à sua granulometria e demais características físicas. A fração miúda do agregado reciclado foi escolhida para substituir o agregado natural. Demais características desta fração foram estudadas, como teor de material pulverulento, massa específica e absorção de água. Foram produzidos concretos com diferentes taxas de substituição (0%, 25%, 50%) de agregado natural por agregado reciclado. As propriedades do concreto foram então avaliadas e verificou-se que o aumento do teor de substituição de agregado natural por agregado reciclado reduziu a trabalhabilidade, a massa específica seca e saturada do concreto e o módulo de elasticidade, bem como aumentou a absorção e o índice de vazios. A massa específica real do concreto não foi influenciada pelo teor de substituição. Com relação às resistências à compressão e à tração, a substituição de agregado natural pelo agregado reciclado levou a um decréscimo na resistência do concreto. O concreto com 50% de teor de substituição obteve uma maior resistência à compressão axial que o concreto com teor de substituição de 25%, e mesma resistência à tração por compressão diametral que o concreto controle.

The present work presents the potential of thermographic analysis in the evaluation of pathological manifestations in facades of buildings. Its use can aid in identification and diagnosis, reducing the time and costs of these activities. For the application of this technique, the calibration of the thermal sensor was carried out and the tests were performed in two distinct periods of solar incidence. The results obtained in this work showed that the application of this technique makes it possible to identify and measuring its extension, hidden pathological manifestations in facade cladding systems, including hard to reach sites, complementing the results of visual inspections and reducing the subjectivity.

The diversity of the types of cement manufactured, driven by the extensive use of additions, has given cementitious composites properties that can directly interfere in the durability and useful life of concrete. Considering the interaction of sulfate ions with cement hydration products, in order to understand it becomes essential for the proper choice of materials in order to protect the structures from this aggressor agent. In order to verify the influence of the choice of cement type on the resistance to attack by sulfates, this article analyzes the compressive strength; sulfate content, electron microscopy and energy dispersive spectroscopy of mortars made with cements CP II-F-32, CP IV-32 and CP V-ARI submitted to calcium, sodium and magnesium sulfate solutions for 4 months. The specimens exposed to calcium and sodium sulfate solutions showed increased compressive strength at early ages due to the formation of ettringite in the pores. On the other hand, CP II-F-32 cement showed the greatest deterioration due to magnesium sulfate attack.

The main purpose of this paper was to analyze the most important properties of concrete paving blocks (CBP’s) prepared with crushed polyethylene terephthalate (PET) particles derived from soda bottles, by considering PET contents equal to 15, 25 and 35% by volume. Standardized water absorption and compressive strength tests after 21 and 28 curing days were selected. By replacing 15% of conventional aggregates by PET, a maximum increase of 25% in the characteristic compressive strength (fpk) becomes visible and the average value of 32.12 MPa is close to the minimum required value for standard traffic (35 MPa). This may be attributed to the higher interlocking level of the plastic particles within the fractured surfaces of the concrete matrix, as well as the proper amounts of plastics, natural aggregates and Portland cement in the sample and the high elastic modulus of PET. However, the fpk values decreased up to 26% and 66% for plastic contents equal to 25 and 35% by volume, respectively. Despite the general recommendation of not using the CBP’s in pavement surfaces due to the insufficient compressive strength, they may be applied on non-traffic areas such as landscapes, walkways and pedestrian plazas.