In this investigation, the Taguchi method was employed to optimize a mix based on four natural by-products for rammed earth construction. Two separate studies were conducted to enhance the dry density and the Unconfined Compressive Strength (UCS). The four materials were assessed across four different levels, with moisture content also factored in as a parameter within a statistical analysis of 16 combinations. The Taguchi method predicted the combinations in which the Particle Size Distribution optimized the dry density and UCS as well as their dry density and UCS values. From the results, Moisture Content was the parameter with the highest influence on the optimization as well as the dry density and the UCS. It was observed that there was a direct relationship between the bulk density of the different granulometric fractions and their influence on the mix’s dry density. The fines were the material constituents that showed the highest influence on the mix UCS. When using the Taguchi method in RE building, the factor that should be maximized should is the mechanical strength.

CO₂ emissions continue to rise, along with the associated environmental risks. In response, the United Nations has been promoting the adoption of sustainable practices among businesses worldwide. In parallel, an innovative technology known as additive manufacturing (AM) has emerged over the past four decades. This technology has the potential to be more sustainable than conventional manufacturing (CM) technologies. When metals are used as the material, the process is referred to as metal additive manufacturing (mAM). AM technologies have seven process categories, which include metal mAM processes, most notably powder bed fusion (PBF), directed energy deposition (DED), binder jetting (BJT), material extrusion of metal-filled feedstock, and sheet lamination. Among these, PBF and DED are by far the most widely applied metal AM technologies in both industrial practice and academic research. The use of mAM is increasing; however, is it truly more sustainable than CM? Motivated by this question, a systematic literature review (SLR) was conducted to compare the sustainability impacts of mAM and CM across the three dimensions of sustainability: environmental, economic, and social. The evidence shows mixed sustainability outcomes, which are synthesized later in the conclusions. The sustainability comparison is influenced by factors like part redesign with topological optimization (TO), the material and energy mix used, geometric complexity, production volume per batch, and the boundaries adopted. Economic viability remains critical; companies are unlikely to adopt mAM if it proves more expensive than CM as this could threaten its competitiveness. Social impacts are the least studied dimension, and it is difficult to anticipate the changes that might occur because of such a transition.

In this investigation, four distinct by-products of natural materials were used to compose a mix for rammed earth construction. The mix of these materials, which have various granulometry, affords many potential combinations, making the analysis of different combinations highly complex. The Taguchi method, a statistical approach renowned for significantly reducing the number of ex-periments in complex systems, was employed to address this challenge. Each of the four ma-terials was assessed across four different levels, with moisture content also factored in as a pa-rameter within the statistical analysis. Two separate studies were conducted to obtain two optimal com-binations of the materials to enhance the dry density and the Unconfined Compressive Strength (UCS). Taguchi method demonstrated its efficacy in predicting the optimal combination of mix-tures for enhancing both objective parameters. A natural by-product mix demonstrated its po-tential for use as a building material. The enhancement of the dry density due to a modification of the mix’s Particle Size Distribution (PSD) did not produce a direct improvement in the mix UCS. The factor to be prioritized should be the mechanical strength, rather than the dry density of the sample.

The use of foam materials in environments where they come into contact with individuals often results in deterioration, necessitating periodic replacements to maintain safety and hygiene standards. Foam, a lightweight, porous plastic formed by aggregated bubbles, possesses excellent impact-absorbing properties; however, its inherent porosity and susceptibility to wear present challenges. This project aims to develop a technological application for repurposing spent polyurethane (PU) foam from leisure facilities into effective impact absorption systems. By focusing on the reuse of deteriorated foam materials, this initiative seeks to minimize environmental impact while leveraging their beneficial technical characteristics. Addressing issues related to foam degradation, this project endeavors to create sustainable solutions by reintegrating spent foam into new systems. This innovative approach promotes sustainability while enhancing safety through the provision of high-quality, impact-resistant elements. Ultimately, this work aims to contribute to environmental conservation and the advancement of effective impact protection measures in leisure facilities.

In this investigation, different natural by-products were used to modify the Particle Size Distribution (PSD) of a soil to evaluate their potential in Stabilized Rammed Earth (SRE) building. Three different mixes were manufactured: (i) a mix composed entirely of a clayey soil, (ii) a mix consisting of mining by-products and clayey soil and (iii) a mix entirely based on mining by-products. Unstabilized and stabilized samples of the mixes were manufactured using two cement dosages (2.5% and 5%), and the samples were tested for Unconfined Compressive Strength (UCS), soaked UCS, and wetting and drying tests. Mining by-products demonstrated significant potential in SRE building, as their addition to the clayey soil resulted in higher UCS values compared to the UCS obtained from clayey soil alone. Unstabilized samples lost their integrity during exposure to water. The inclusion of mining by-products also showed potential as, although the mixes did not fully meet the requirements for soaked UCS and the wetting and drying tests, the mix containing both mining by-products and clayey soil retained its integrity in water, unlike the samples composed solely of clayey soil. M3C5 successfully met the requirements for soaked UCS and the wetting and drying tests, further highlighting the great potential of mining by-products in SRE building.

The manufacture of industrial parts using silicone molds is becoming more frequent due to their versatility, durability, and precision, particularly in the production of complex components. One specific application is the manufacture of gears, which play a fundamental role in high-performance mechanical systems, where geometric accuracy is essential. Gears produced from resins offer several advantages such as efficient tribological performance, load resistance, noise reduction, and non-magnetic properties. The main goal of this paper is to determine the main factors affecting the final quality of resin gears by analyzing two principal gear quality parameters: teeth profile (ff$\alpha$) and helix deviation (ff$\beta$). This work includes a global analysis of all contributing factors influencing the final quality of gears manufactured. One of the main conclusions obtained is that gear quality depends on a combination of factors, such as mold properties, choice of resin, the manufacturing process, and the quality of the original model. As a result, two regression equations have been developed, relating all influencing factors to the two gear quality parameters (ff$\alpha$ and ff$\beta$). Different response surfaces have been obtained, enabling the definition of the required quality level of the model to achieve reproductions with certain ff$\alpha$ and ff$\beta$ values suitable for the intended application conditions.