The chemo-mechanical degradation of unreinforced concrete sewer pipes applied in domestic service locations is assessed through a systematic, integrated experimental approach, considering 18 new and 35 used sewer pipes. The characteristics and environmental conditions of the sewer pipes are reported, and data obtained from surface condition classification, residual alkalinity tests and XRD analyses are combined to identify the type and degree of chemical attack of the used sewer pipes. Concrete material properties are determined by material tests on sewer pipe samples, providing quantitative insight into the age dependency of the Young's modulus, compressive strength, tensile strength and mode I toughness. All relatively old pipes (installed in the 1920s and 1950s) show substantial chemical attack by biogenic sulphide corrosion (at the inner side of the pipe) and carbonation (at the outer side of the pipe). The time development of the corresponding corrosion depths on average follows a linear trend, whereby the corrosion rate for biogenic sulphide corrosion is about a factor of 1.3 larger than for carbonation. Due to these chemical processes, the mechanical properties of concrete may significantly depend on the age of the sewer pipe. In particular, the average compressive strength and average tensile strength decrease approximately linearly with the age of the pipe, in correspondence with relative reductions of, respectively, a factor of 1.7 and 1.5 over a period of almost 100 years. The values and time-dependent trends found for the concrete properties and corrosion depths of sewer pipes can serve as input for practical analyses and advanced numerical simulations on their bearing capacity and time-dependent degradation. The experimental results also emphasize the importance of regularly assessing the amount of chemical degradation of (especially older) in-situ sewer pipes, by determining the (decrease in) effective wall thickness via core sampling and laser profiling.

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Previous research has shown that the material properties of a three-dimensional printed strain hardening cementitious composite (3DP-SHCC) can significantly vary, depending on the printing system with which it is produced. However, limited research has been performed on the reproducibility of hardened mechanical properties under identical printing conditions. In this study, the consistency of hardened properties, including compressive strength, flexural strength and deflection, and tensile strength and strain, was tested from materials printed during three separate but identical printing sessions. The research shows that with 3DP-SHCC, significant variations in mechanical properties between printing sessions can be expected.

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Climate induced damage in decorated oak wooden panels is considered to be a high risk for the preeminent museum collections. To advise museums on the development of future sustainable preservation strategies and to define rational guidelines for indoor climate specifications, climate induced physical and mechanical damage has been analysed in a collection study, experimental testing of mock-ups and by finite element modelling. The collection study consisted of the development of a comprehensive methodology to select objects of interest from the collection and analyse their condition using a combination of visual inspection and archival searches. Mock-up samples of wooden panels with representative structural elements were exposed to varying climate conditions in climate controlled rooms and monitored with state-of-the-art experimental mechanics equipment. Further the collection study and experimental testing were used to inform the development of a finite element model of crack growth under 3-point bending. The work was performed within the Cimate4Wood project, a multidisciplinary collaboration between conservators and scientists work. The paper presents the methodology of the museum study and results from the museum study, experimental testing and modelling.@en