As urban development requires groundwater table isolation of various historically polluted sources, the necessity of building effective, strong, flexible, and low-permeability cutoff walls raises the question of choosing optimum construction materials. Various authors have proposed water–cement–bentonite mixtures, which are often chosen by experience or a trial-and-error approach, using classical methods for testing (Marsh funnel) and representation of results (water–cement ratio, water–bentonite ratio). The paper proposes a more precise approach for assessing the viscosity and global representation of the three components. Moreover, this approached is exemplified with a better documented recipe for the choice of materials based on laboratory results. The representation of the mixtures was undertaken on a limited domain of a ternary diagram, where the components are given in terms of mass percentage. The derived properties (viscosity, permeability, and compressive strength) are presented on a grid corresponding to the physically possible mixtures. Based on this representation, the most efficient recipes are chosen. Because the mixture contains only fine aggregates, the viscosity was determined using a laboratory viscosimeter.

In recent years, because of the continuous expansion of urban areas, an increased necessity to isolate historically polluted sites by means of artificial, flexible, low-permeability barriers has emerged. Moreover, due to cost and efficiency considerations, various combinations of materials that fulfill the previously stated requirements have been proposed. On the basis of a literature review, this paper analyses the relationships between water, cement, and bentonite, and the physical and mechanical properties of the resulting material created in combination with standard sand introduced in the mixture using a ratio of 2:1 with respect to the solid part of the mixture (cement and bentonite). The quantity of standard sand was established following previous research conducted by the authors. The relation between water, cement, and bentonite is analyzed through properties such as viscosity, permeability, and undrained cohesion, and the representation of mixtures and their corresponding parameters was carried out using a ternary diagram. This paper provides a graphical approach to finding the optimum water/bentonite/cement mixture required for barrier design, taking into account permeability, undrained cohesion, and mixture viscosity.

Timber represents a building material that aligns with the environmental demands on the impact of the construction sector on climate change. The most common engineering solution for modern timber buildings with large spans is glued laminate timber (glulam). This project proposes a tool for a topological optimized geometry generator of structural elements made of glulam that can be used for building a database of topologically optimized glulam beams. In turn, this can be further used to train machine learning models that can embed the topologically optimized geometry and structural behavior information. Topological optimization tasks usually require a large number of iterations in order to reach the design goals. Therefore, embedding this information into machine learning models for structural elements belonging to the same topological groups will result in a faster design process since certain aspects regarding structural behavior such as strength and stiffness can be quickly estimated using Artificial Intelligence techniques. Topologically optimized geometry propositions could be obtained by employing generative machine learning model techniques which can propose geometries that are closer to the topologically optimized results using FEM and as such present a starting point for the design analysis in a reduced amount of time.

This paper is based on research placed within the broader framework of the growing environmental impact requirements of building materials. Given this context, wood-based composite materials have emerged as a promising and innovative solution for structural elements. The current work aims to define a system for testing the mechanical behavior of glued laminated timber elements when exposed to high temperatures, in the neighborhood of the pyrolytic decomposition of materials. These tests monitor the transient behavior of the composite material and characterize the parameters involved in the thermo-mechanical analysis of elements constructed using this type of engineered wood product. The tests are used for the calibration of the material models involved in the numerical analysis and for the analysis of potential prototypes, considering the transient thermal load and heat propagation through the materials. By taking such tests, benchmark models and laboratory procedures are defined that can be used in the future to evaluate different materials, existing or new, and material combinations used to construct such a composite.

When studying the mechanical behavior of hydrated binders, it is necessary to prevent hydration contraction tensile failure in order to properly characterize the mechanical properties of the material. This is regulated by standards for cement testing, however for the case of water-cement-bentonite mixtures the influence of standard sand is not thoroughly studied. Since the hydration shrinkage and water suction is different for cement and bentonite, a range of eleven combinations of water-cement-bentonite were used at four sand percentages. The paper documented this influence ranging from a lower limit for which contraction cracking occurs up to an upper limit for which the presence of sand favorably interferes with the binder, the material being transformed from a binder paste into a mortar. It is documented the range of sand composition for which the variation of sand content prevents contraction, yet preserves binder properties. The laboratory testing consisted of viscosity evaluation during samples preparation, permeability and monoaxial compressive strength on samples cured in open atmosphere for 28 days.

Following the increased use of sealing structures built in order to isolate historically polluted sites or to repair infiltrations inflicted to the levee of dams, it emerged the need to choose the right materials for constructing barriers using cutoff wall technique. The objective of this paper is to assess the range of suitable material combinations (water, cement and bentonite) in order to attain proper compressive strength, permeability and ductility requirements of such a structure. This paper proposes the representation of various mixtures on a ternary diagram, where the components are used as mass percentages. Since the influence of excessive values of various components have on the physical and mechanical behavior of the samples, the study domain was limited to an area that represents feasible mixtures. The laboratory testing program aimed at studying the variation of the material ductility, expressed in terms of tangent elastic modulus at origin and maximum axial strain at failure. Other parameters previously studied (compressive strength, viscosity and permeability) are used for property correlation.