Borja Martínez

Eco-mortars have emerged as a sustainable alternative to conventional cement-based mortars by incorporating bio-based materials aiming to reduce the environmental impact. This study investigates the development of eco-mortars through the substitution of the cementitious binder by incorporating vegetal oils, focusing on the saponification reaction. The study analyzes the influence of oil dosage on fresh-state properties, hydration processes and physical–mechanical performance. The research comprehends the mechanical characterisation (bending, compression and ultrasound analysis) of eco-mortar conducted in samples with different 3 ratio of aggregate-binder, 2 ratio of CaO and the internal ratio of filler-sand (aggregates) and RACO (eco-binder, ricinoleic acid ”RA” and castor oil ”CO”), resulting in a total of 29 different combination of mortar mixes. Experimental results demonstrate that the optimal ratio is 85% aggregate and 15% eco-binder with a 50% of ricinoleic acid, obtaining mechanical properties of 3,9 MPa compression strength and 2,1 MPa bending strength. The findings highlight the potential of vegetable oil as a substituted for cement in eco-friendly mortar for low structural performance applications.

This study investigated the utilization of innovative green composites made from hemp shiv, a waste by-product of hemp cultivation, with the aim of promoting sustainability within the construction industry. The manufacturing method involved the application of pressure in a mold to create the samples. These materials were produced using an environmentally friendly binder consisting of colophony, arabic gum, and corn starch. Moreover, white glue and bioepoxy were also used to compare with the green resins. Three different binder compositions were used for the specimens. The samples underwent mechanical testing through tensile and bending assessments, and their performance was compared to that of non-green binders to validate the effectiveness of the manufacturing processes. The study revealed that decreasing the moisture content during the curing process was crucial for improving the mechanical properties. The best results were achieved when using arabic gum as a binder, yielding a tensile strength of 2.16 MPa and a bending strength of 5.25 MPa, with a composition of 62.5% hemp shiv and a manufacturing process involving a pressure of 5 MPa.

This study investigates the utilization of innovative green composites made from hemp shiv, a waste by-product of hemp cultivation, with the aim of promoting sustainability within the construction industry. The manufacturing method involve the application of pressure in a mold to create the samples. These materials were produced using an environmentally friendly binder consisting of colophony, arabic gum and corn starch, moreover white glue and bioepoxy are also used to compare with the green resins. Three different binder compositions for the specimens. The samples underwent mechanical testing through tensile and bending assessments, and their performance was compared to that of non-green binders to validate the effectiveness of the manufacturing processes. The study revealed that decreasing the moisture content during the curing process is crucial for improving the mechanical properties. The best results were achieved when using arabic gum as a binder, yielding a tensile strength of 2.16 MPa and a bending strength of 5.25 MPa, with a composition of 62.5% hemp shiv and a manufacturing process involving a pressure of 5 MPa.

Piezoelectric harvesters are environmentally sustainable alternative electrical production technologies aimed at supplying small autonomous devices. The particular application in roads has significant potential. However, there are discrepancies about the effectiveness of these harvesters, and their costs limit their market expansion abilities. In this context, a novel harvester approach is explored that includes low-cost membrane piezoelectric patches in modified cymbal devices. The main novelty of this approach is the inclusion of an inner contact column that punctually transmits the load of the caps of the cymbal to the centre of the membrane piezoelectric patch, maximising its deformation and energy production capabilities. Experimental tests on piezoelectric elements, harvesters and embedder harvesting units have been performed with numerical simulations to optimise the design of the harvester. The results indicate that the more punctual the inner contact column is, the more electrical energy is produced, reaching values ten times greater than those of the present cymbal configuration. Embedding the harvester into a flexible pavement and positioning it under a wheel track are beneficial aspects of the execution. Finally, the dependency on the wheel speed is confirmed with wheel-track tests on a representative pad of the system.

There has been increasing interest in green and recyclable materials to promote the circular economy. Moreover, the climate change of the last decades has led to an increase in the range of temperatures and energy consumption, which entails more energy expenditure for heating and cooling buildings. In this review, the properties of hemp stalk as an insulating material are analyzed to obtain recyclable materials with green solutions to reduce energy consumption and reduce noise to increase the comfort of buildings. Hemp stalks are a low-value by-product of hemp crops; however, they are a lightweight material with a high insulating property. This study aims to summarize the research progress in materials based on hemp stalks and to study the properties and characteristics of the different vegetable binders that could be used to produce a bio-insulating material. The material itself and its microstructural and physical aspects that affect the insulating properties are discussed, as is their influence on durability, moisture resistance, and fungi growth. Research suggests using lignin-based or recyclable cardboard fiber to develop a bio-composite material from hemp stalk, but long-term stability requires further investigation.