The generation of civil construction waste (CCW) and the non-rational consumption of natural aggregates (NA) are adversities faced within the scope of the Civil Construction Industry. Efforts are invested, such as non-generation, reduction, reuse, and recycling, associated with the insertion of unconventional products, such as geosynthetics. Recycling and the technical and economic feasibility of using recycled aggregates (RA) have been the object of other research that seeks to expand the range of applications of these materials to achieve acceptance and consolidation in the market. In geotechnical engineering, RA can be used in segmental retaining walls (SRW) as filling material for segmental blocks. This article presents the investigation of recycled concrete aggregates (RCA) as filling material for segmental blocks in SRW reinforced with geogrids (GG) as a replacement proposal for the NA used in this application. Therefore, the RCA and NA in the granulometric zone of 9.5/25 mm, were subjected to physical characterization and connection strength tests under normal stresses of 40 kN/m2, 50 kN/m2, 60 kN/m2, 80 kN/m2, and 100 kN/m2 to evaluate the interface elements' performance when subjected to load tensile. After carrying out the connection resistance tests on large equipment, it was verified that RCA are indicated for filler material for segmental blocks in SRW with GG with a height not exceeding 5 meters. The increase in normal tensions contributed to a more expressive reduction in the physical characteristics and performance of the connection resistance of the RCA about the test results with the use of NA.

Incorporação de resíduos de construção e demolição e pó-de-pedra em dosagens experimentais de argamassa para mitigação de impactos ambientais / Incorporation of construction and demolition residues and stone powder in experimental mortar dosages to mitigate environmental impacts

Geosynthetics are increasingly used in geotechnical engineering to replace conventional solutions due to their cost-effective and environmental benefits. For example, geotextiles can be used in sustainable waste-dewatering systems to confine solid waste for final disposal. This study is presented to analyze the durability of a geotextile regarding cyclic fatigue induced during the pumping stages in these sustainable waste-dewatering systems. A polypropylene woven geotextile was used and subjected to cyclic tensile loading levels of 10%, 30% and 50% of the ultimate average tensile strength. We also used hysteresis loops with a frequency of 0.1 Hz at different numbers of cycles (10, 20, 30, and 90 cycles). With a 95% confidence level and response surface, the results show that increasing the tensile loading levels and the number of cycles made the geotextile lose its tensile strength. Laboratory experiments simulated scenarios where the geotextile was subjected to cyclic fatigue that might directly impact its strength–strain and hysteretic stiffness performance over its design lifetime. This study contributes to a better understanding of the durability of geotextiles to subsidize decision-making involving social, environmental, and technical impacts in waste-dewatering system applications.

Degradação de Geotêxteis Expostos às Intempéries/ Degradation of Geotextiles Exposed to Weather

A pesquisa visou avaliar concretos dosados com agregados graúdos reciclados com vistas ao desenvolvimento sustentável. Foram realizadas dosagens com substituições parciais (20%) e totais (100%) do agregado graúdo natural (100%AN) de rocha gnaisse por reciclados de blocos intertravados pré-fabricados de concreto (ARCO) e de composição cimentícia (ARCI), separadamente, de granulometria comercial brita n°1. Os concretos foram dosados para resistência à compressão mínima de 25 MPa aos 28 dias e abatimento 100±20mm, com aglomerante CP II E-32, aditivo plastificante em 1% e agregado miúdo natural média. Apenas os traços de 20%ARCO (100 mm), 20%ARCI (110 mm) e 100%ARCO (80 mm) atenderam a faixa de abatimento pretendido. Todos os resultados de resistência à compressão foram superiores a 25MPa: 44,1 MPa (100%AN), 40,9 MPa (100%ARCO), 32,2 MPa (100%ARCI), 32,5 MPa (20%ARCO) e 31,4 MPa (20%ARCI). Estes resultados pontuais foram satisfatórios para as condições analisadas e visaram agregar nas discussões pautadas na redução dos impactos negativos desencadeados pela indústria da construção civil e quais são os meios possíveis de suas mitigações na busca por cidades e comunidades sustentáveis.

Sistema de confinamento de resíduos empregando geotêxteis comparados a leito de drenagem para desaguamento de lodo de estação de tratamento de água / Waste containment system using geotextiles compared to drainage bed for dewatering sludge from water treatment plant