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This paper presents results from experimental studies on the residual mechanical properties of high-performance concrete reinforced with polypropylene microfibers after exposure to elevated temperatures. A conventional concrete (compressive strength of 25 MPa) and high-performance concretes (compressive strength above 78 MPa) with 1, 2, and 3 kg/m3 additions of polypropylene microfibers were developed. The mixtures were subjected to temperatures of 100, 200, and 300°C for 60 minutes. In the second part of this study, a high-performance concrete with 2 kg/m³ of microfibers was analyzed. Compressive strength, splitting tensile strength, and elastic modulus tests were also performed at 200, 400, and 600°C. Results from the experiments show that polypropylene microfibers were extremely important in minimizing the reduction of compressive strength, where the contents of 2 and 3 kg/m3 were the most effective. Through numerical simulation, it was possible to find the longitudinal elastic modulus and the Poisson’s coefficient at each temperature tested. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the influence of cement type, concrete cover, and addition of migratory corrosion inhibitor (MCI) on the corrosion resistance of reinforced concrete subjected to an aggressive environment. For this, corrosion tests were performed using CP IV RS and CP II F types of cement with two levels of concrete cover: 2.5 cm and 4 cm. In the thinner one, the migrating corrosion inhibitor was added. In the research the techniques used were the determination of concrete compressive strength, electrode potential measurements, acceleration cycles of chloride attack, and visual analysis. The results showed that both the cement type and the migratory corrosion inhibitor contributed to the inhibition of steel corrosion. In concretes with inhibitor and thinner cover the most extreme measurements were verified: in the 14th weekly cycle the concrete with CP II F cement presented a potential of -366 mV, characterizing a 90% of probability of corrosion, while the one with CP IV RS showed a potential of -119 mV, with a corrosion probability of less than 10%. However, following the cycles, it was possible to identify an increase in the value of this potential. The influence of the concrete cover thickness was also observed since the potential values found were more negative in the cases of smaller covers. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the application of discarded tire rubber waste and Expanded Polystyrene (EPS) in mortar. For mortars fine aggregate was replaced by 10%, 20% and 30% of rubber and, 7.5% and 15% of EPS. We have verified the consistency, density, amount of air and water retentitivity in fresh state. The compressive strength, water absorption, voids ratio and specific gravity have been also tested in hardened state. The application of rubber powder contributed to the increase in entrained air content and in reducing specific gravity, as well as reducing compressive strength at 28 days. The addition of EPS also contributed to the increase of workability, water absorption and voids ratio, and decreased density and compressive strength when compared to the reference mortar. The use of rubber waste and EPS in mortar made the material more lightweight and workable. The mortars mixtures containing 10% rubber and 7.5% EPS showed better results. [ABSTRACT FROM AUTHOR]