This study evaluated characteristics of mortars using recycled construction and demolition waste (CDW) from the industry as fine recycled aggregate in replacement of natural sand (NS). Mixes with replacements in volume of 20 and 100% CDW and a control mix with just NS were tested for their compressive and flexural strength and alkali–silica reactivity (ASR). For mechanical strength, experimental results showed satisfactory performance for 20% CDW content. Concerning the ASR test, mortars with CDW performed better than the control, demonstrating a general innocuous behaviour for ASR. Scanning electron microscopy and energy-dispersive X-ray analysis were performed on aggregate and mortar samples before and after the ASR test and confirmed the results, demonstrating that the attack was more severe in the samples with the greatest amount of siliceous material in the aggregate. The results demonstrate the viability of the use of CDW fine aggregate replacement in mortars, envisaging the possibility of its incorporation in concrete.

Resumo A reutilização de resíduos industriais é crucial para práticas sustentáveis na indústria da fundição. Este estudo caracteriza a areia descartada de fundição (ADF), comparando-a com a areia comum (CS) e avaliando seu comportamento temporal e variação dimensional em matrizes cimentícias. Foram realizados ensaios de granulometria, massa específica e unitária, índice de vazios, absorção de água, MEV, classificação do resíduo sólido, análise de fenóis no extrato lixiviado, perda ao fogo, TGA, FTIR, GC-MS, EDS e toxicidade aguda. A análise temporal mostrou uma redução nos valores de carbono com o tempo de armazenamento, atribuída à alteração química dos compostos orgânicos. Ensaios de perda ao fogo e TGA corroboraram as concentrações de fenol detectadas, enquanto análises por FTIR indicaram decomposição parcial da resina fenólica no processo industrial. A variação dimensional da argamassa no estado fresco foi avaliada, destacando a importância de utilizar moldes de 20 cm com discos indicadores para medição precisa. Os resultados sugerem que a ADF pode ser utilizada como matéria-prima na construção civil, conforme a legislação vigente.

The preservation of the historical heritage of a locality is of paramount importance for the identity of a society to remain alive, valuing knowledge of history, cultural and social elements, becoming a record for its successors. The Salinger house is a listed heritage site in the city of Blumenau, Santa Catarina, Brazil, a case study for the present work given the importance of knowing the materials and methods used in the construction so that its restoration can be carried out later. For this reason, the aim of this study is to characterize the materials used in the masonry of this historic building from the 20th century and to evaluate the mechanical properties of walls built with the material. With that in mind, the ceramic blocks were characterized as to their geometry, specific mass, water absorption and mechanical strength. In addition, for the mortar, a mix used at the time was defined, without the addition of Portland cement, only with lime, whose mechanical behaviour in tension and compression was measured. Finally, mechanical characterization tests were carried out on walls made with these materials, demonstrating that the system built at the time did not have a structural function, being functioning only with bearing capacity. This result was already expected since in the half-timbered constructions of the time, the blocks served only as closing masonry.