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In recent decades, interest in maintaining and conserving cultural assets has grown and there has been greater investment in the conservation of historical heritage. Developing a good methodology for action is key to guaranteeing adequate preservation of cultural assets. With this in mind, the Spanish Historical Heritage Institute convened a conference in 2002 to try to define basic criteria to guide the different phases of the intervention process in stone materials in all stages of stone conservation: cleaning, consolidation and protection. Carrying out efficient protection of monuments in the traditional way focuses efforts only on how it affects the property, but not on the collateral impact it may have on the environment, or how the effects of climate change may alter its functionality. Thus, a more multidisciplinary test design is needed, with a mandatory laboratory simulation phase under simulated rainfall that represents the increased environmental aggressiveness expected in the near future due to climate change. Hence, water becomes a means to simulate these future conditions, but also a way to explore the effects on rivers and groundwater near the points where the monuments will be treated. Since fresh water is one of the resources that is expected to become scarce in the short term, we intend to carry out responsible tests that take into account both aspects: saving water use and water pollution. Combining the conservation of monuments and environmental responsibility, it will be shown how it is possible to carry out research to achieve a natural product that serves as a sustainable coating for monuments of stone material that is durable but that reduces the environmental impact both in the selection of the product and in the experimental phase, as well as in its operation after application.

In the current scenario, the search for new, more economical and environmentally sustainable approaches that contribute to the circular economy are receiving special attention in all sectors. In the construction sector, the most developed approach is the use of nanotechnology. It is one of the best and most innovative options available to improve performance in this sector. The continuous growth and increasing use of natural resources leads to the search for new materials that are more efficient, sustainable and increase the useful life of materials. In this sense, the use of nanomaterials as surface treatments is one of the fields of research that is evolving the most, since it is possible to prevent deterioration and improve the durability and conservation properties of construction materials, reducing restitution. This article conducts a capillary absorption test, which determines that the graphene oxide used as a protective treatment of the concrete surface decreases capillary water absorption by 15%; this is the beginning of a more exhaustive study to determine the effectiveness of this treatment and to be considered a nano-coating.

Concern for the perpetuation of stone monuments is deeply ingrained in humans; however, despite the attempts made in this field, there is still a great deal of effort needed to bring about advancements in the conservation of ornamental stone. Erosive agents, such as rain, extreme temperatures, and chemical and biological agents, threaten our stone heritage and gradually wear away buildings, sculptures, and other monuments found all around the world. Limestone and dolostone have been widely used throughout history, given their ease of extraction and workability. Nevertheless, these properties make them particularly vulnerable to the aforementioned erosive agents, for which the main solution at present is costly and time-consuming restoration. Given the scarcity of effective and durable agents to prevent the deterioration of ornamental and heritage stones, and as graphene oxide (GO) has recently shown impressive effectiveness for this task, this work will further explore the viability of GO as a protective coating for monumental dolostone. For this purpose, GO is sprayed over dolostone surfaces by water dispersion with no adjuvants. The coating performance is assessed in terms of thermal stress, optical inspection (structured light 3D scanner), colorimetry, leachate analysis, and electron microscopy. The main results show that spray-coated GO over stone surfaces creates a highly protective and durable barrier without altering their aesthetic qualities.

The linear economy paradigm in place to date has to be seriously challenged to give way to a new school of thought known as the circular economy. In this research work, precast kerbs and paving blocks made with recycled concrete (RACC-mixture) bearing 50 wt% mixed recycled aggregate (masonry content of 33%) and an eco-efficient cementitious material as 25 wt% conventional binder replacement were evaluated to assess their intrinsic potential to replace traditional raw materials, in keeping with circular economy criteria. Therefore, precast products were subjected to mechanical strength, durability and microstructure tests and were compared to conventional concrete units (CC-mixture and commercially available precast elements). Although a class demotion was observed for water absorption and some decreases in flexural strength (26%), splitting tensile strength (12.8%) and electrical resistivity (45%) and a lower class water absorption were registered, and the recycled mixture also exhibited a greater performance in terms of compressive strength (6%), a better abrasion resistance classification and a comparable porosity and microstructure, which ensures a good concrete durability. In any case, the results showed that precast pieces were European standard-compliant, thus supporting the viability of the mixed recycled aggregates and eco-efficient cementitious replacement in footways.