Different reasons can make certain structures need reinforcement to achieve specific levels of safety and performance. The occurrence of events of significant magnitudes, such as earthquakes, are examples of this. Retrofitting vulnerable structures becomes a practice to mitigate the destructive effects of earthquakes, and the RC Jacketing becomes an alternative. The present work studies this type of reinforcement, proposing and applying an assessment methodology under vulnerable construction built in a high seismic risk zone. The diagnostic of the current situation was determined, and the structural suitability was evaluated using RC Jacketing. With the computational software S-Model, created in this research, the effectiveness of the proposed reinforcement was verified, based on the results of the analysis carried out with commercial software. The preload was considered, and the strength of the reinforced column section was verified against all load combinations. The S-Model program was able to verify the non-simultaneous occurrence of the amplification of moments with the most critical loading. Both conditions demand more significant stresses on the element, and therefore the calculation of the steel areas of the column may be underestimated if they are not considered.

An experimental study is presented to produce Ultra High Performance Reinforced Concrete (UHPRC) with sustainable materials produced in Brazil. A complete factorial arrangement was defined and five controllable factors were selected based on the literature review. Cylindrical specimens were tested at 7, 14 and 28 days of curing, with and without heat treatment. The residual deviations of the results were determined and an analysis of variance using ANOVA was applied to know the contribution of each controllable factor on the compressive strength, which reached a maximum value of 138.12 MPa. Finally, a mix design is proposed to obtain UHPRC by applying a simple manufacturing procedure using commercial materials, with which a high performance concrete can be obtained, reaching at least 70% of its strength in seven days.

RESUMENSe presenta un estudio experimental para producir Ultra High Performance Fiber Reinforced Concrete (UHFPRC) incluyendo residuos industriales en la mezcla y determinar la resistencia a la compresión promedio. El estudio incluye arreglos factoriales para realizar análisis de varianza usando ANOVA. Los factores controlables fueron: (i) edad de la muestra; (ii) granulometría de la escoria; (iii) diseños de mezcla; (iv) porcentajes de fibras y (iv) tipo de curado. Los mayores valores de resistencia obtenidos fueron 138.12, 132.17, y 155.29 MPa, con sustituciones parciales de cemento por residuos industriales del 35, 25 y 26% respectivamente. Los diseños de mezcla fueron fabricados aplicando un procedimiento simple, usando en la mezcla materiales como cemento, humo de sílice, escoria de alto horno, polvo de cuarzo y arena fina producidos en Brasil. También se adiciona el superplastificante diluido en agua y las fibras, las cuales se incorporan cuando la mezcla se convierte en una densa masa plástica. Los resultados demostraron que todos los factores controlables tienen influencia significativa en la variable de respuesta y que la probabilidad de que las variaciones en la resistencia sean atribuidas al error experimental es menor al 1‰.Palabras-clave: UHPFRC, sustentable, resistencia a la compresión, ANOVA. ABSTRACTAn experimental study is presented to produce Ultra High Performance Fiber Reinforced Concrete (UHPFRC) including industrial waste in the mix, and determine the average compressive strength. The study includes factor arrangements to perform analysis of variance using ANOVA. The controllable factors were: (i) age of the sample; (ii) granulometry of the slag; (iii) mix designs; (iv) percentages of fibers and (iv) thermal treatment in curing. The highest resistance values obtained were 138.12, 132.17 and 155.29 MPa, with partial substitutions of cement by industrial waste of 35, 25 and 26% respectively. The mixing designs were manufactured using a simple procedure, using materials such as cement, silica fume, blast furnace slag, quartz powder and fine sand produced in Brazil. Also, the mixture includes the superplasticizer diluted in water and the fibers, which are incorporated when the mixture becomes a dense plastic mass. The results showed that all the controllable factors have significant influence on the response variable, and that the probability that the variations in resistance are attributed to the experimental error is less than 1 ‰.

RESUMOO uso de adições minerais no concreto vem se difundindo cada vez mais por meio de estudos que visam diversas características, como: aumento da durabilidade, aumento da resistência mecânica e reaproveitamento de resíduos. Esta pesquisa comparou a resistência à compressão axial obtida de concretos contendo adições minerais (escória de alto forno e sílica fume) e cinza de casca de arroz com concretos contendo adições minerais e nanotubos de carbono. Além disso as misturas eram compostas cimento Portland CPV ARI, areia fina (areia de sílica), aditivo superplastificante e água. Foram realizados ensaios de caracterização dos materiais utilizados e as comparações entre os traços foram feitas a partir do ensaio de compressão axial de corpos de prova cilíndricos. Através dos resultados encontrados constatou-se que aos 28 dias todas as misturas com CCA apresentam valores de resistência à compressão de 2,5 a 68,5% maiores que com NTC. Mesmo aos 90 dias, três das misturas apresentaram melhores resultados com CCA; em termos econômicos, a mistura contendo cinza de casca de arroz é mais viável. Pelos resultados de compressão obtidos observou-se que a melhor mistura foi a que continha 55% de cimento e 20% de CCA.