In a context of intense environmental pressure where the construction sector has the greatest impact on several indicators, the reuse of load-bearing elements is the most promising by avoiding the production of waste, preserving natural resources and reducing greenhouse gas emissions by decreasing embodied energy. This study proposes a methodology based on a chain of tools to enable structural engineers to anticipate future reuse. This methodology describes the design of reversible assemblies, the addition of complementary information in the building information modeling (BIM), reinforced traceability, and the development of a material bank. At the same time, controlling the environmental impacts of reuse is planned by carrying out a life cycle assessment (LCA) at all stages of the project. Two scenarios for reuse design are applied with the toolchain proposed. A. “design from a stock” scenario, which leads to 100% of elements being reused, using only elements from stock. B. “design with a stock” scenario, which seeks to integrate as many reused elements available in the stock as possible. The case study of a high-rise building deconstructed to rebuild a medium-rise building demonstrated that the developed toolchain allowed the inclusion of all reuse elements in a new structural calculation model.

This research explores the possibilities of wood composite structures with a view to designing durable lightweight composite decks. The paper examines a new wood structure technology in which an ultra-high-performance fiber-reinforced concrete (UHPFRC) slab is fastened to glulam beams. Fasteners representing most existing groups are first experimentally investigated on small beams (span one meter). The modes of functioning of each type and the various failure modes are identified. The paper proposes a method for assessing the interface shear stiffness. This method is based on analysis of flexural test results using a slip versus shear stress relation. It is shown that glued assembly of the two materials yields the best shear stiffness and highest ultimate strength. The practical aspects of surface preparation before gluing are considered. The results of a bending test carried out on a composite structure having a span of three meters, made of UHPFRC glued to two glulam beams, validate this fastening technique.

Concrete creeps, and this creep must be well characterized and modeled to properly design civil engineering infrastructures. Here, we present some results on the creep properties of cementitious materials obtained by using the indentation technique. Firstly, we show that minutes-long microindentations on cement paste yield a quantitative measurement of their long-term logarithmic creep kinetics, which can be used to predict the rate of long-term creep of concrete. Then, by performing microindentations, we study the effect of relative humidity on the long-term creep properties of hydrated C₃S samples, compacted samples made of pure C-S-H, and compacted samples made of pure CH. The last part is dedicated to a study by nanoindentation of the creep properties of C-S-H phases directly within a hydrated cement paste. We identify scaling relations independent of mix proportion and heat treatment, which we can explain by drawing a thorough analogy between the mechanical behavior of C-S-H and that of clays.