Search Results (5)

The mining and steelmaking industries, while vital for economic and social development, produce and dispose of waste that contributes to environmental instability and discomfort. In this context, this study aimed to develop novel polymer composites intended for Artificial Ornamental Stone (AOS) application by incorporating iron ore tailings (IOTs), quartzite waste (QTZ), and steel slag (SS) into an epoxy (EP) matrix. The chemical, mineralogical, physical, mechanical, morphological, and thermal properties of the materials were assessed. Three waste mixtures were proposed using the Modified Andreassen Curve method, each with 35, 45, and 55 v/v% of EP. The composite properties were evaluated, showing that the composite with QTZ, SS, and 55 v/v% EP exhibited the lowest porosity (0.3%), water absorption (0.1%), and highest flexural strength (41 MPa). The composite containing the three wastes with 55 v/v% EP presented 1.0% porosity, 0.4% water absorption, and 34 MPa flexural strength. Lastly, the composite with IOTs, QTZ, and 55 v/v% EP exhibited 1.1% apparent porosity, 0.5% water absorption, and 23 MPa flexural strength. Therefore, the polymer composites developed with IOTs, QTZ, SS, and EP demonstrated suitable properties for wall cladding and countertops, presenting a potentially sustainable alternative to reduce environmental impacts from the mining and steelmaking industries. Full article

The ornamental stone industry plays a crucial role in the world economy, and thus the production process of ornamental stones generates a large volume of waste that is normally destined for landfills. Given the growing market import of artificial stones, there is a need for more sustainable practices to reduce waste and improve the use of natural resources. Thus, the present study aims to develop artificial stones with waste from the ornamental stone extraction process from the quarry, and vegetable polyurethane resin derived from castor oil, in order to analyze its viability in the production of artificial stone slabs. The wastes used in this work were three quartzites, fragmented and mixed with three grain sizes, called coarse, medium, and fine. These wastes were characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and thermal analysis (TGA/DTG/DSC). Artificial stone slabs were produced using 15 wt.% vegetable polyurethane resin derived from castor oil and 85 wt.% ornamental stone wastes (quartzite). These slabs underwent apparent density, water absorption, porosity, 3-point flexural strength, scanning electron microscopy (SEM), petrography, and X-ray diffraction (XRD) tests. According to the results obtained, it was possible to prove the technical viability of manufacturing artificial stones with ornamental stone wastes and with the use of vegetable polyurethane resin derived from castor oil. The use of these raw materials not only resulted in the manufacture of a new material but also in an environmentally conscious and sustainable approach, following precepts such as the circular economy. The creation of these eco-efficient products is a significant contribution to the search for solutions that value environmental preservation and the optimization of natural resources. Full article

The long-term endurance of building stones must be assured since their longevity has repercussions for their economic and social value. Frequently, slabs for flooring and cladding are installed with polished finishing in outdoor environments for technical and ornamental purposes in cultural heritage sites and modern civil architecture. Compared to any other finishing, glossy surfaces are rather vulnerable to wear, particularly when they interact with slightly acidic rainwater. Several hydrophobic treatments are applied to prevent this damage by preventing contact between rain and stone; such treatments are efficient but sometimes non-durable. Stakeholders and conservation scientists need better methods to anticipate the future behaviour of this building material and hydrophobic solutions. Complying with this demand, a comparison is made between outdoor natural ageing and artificial weathering, reproduced by UVA radiation, moisture and spray accelerated weathering. Artificial weathering is applied to predict the behaviour of stones over time in the real environment. Data obtained through the measurement of gloss and colour parameters, the detection of micro-textures through SEM, and the calculation of micro-roughness using a digital rugosimeter demonstrate that weakly acidic rainwater is the main cause of superficial decay of stone finishing over just six months of outdoor exposure. This period corresponds to 7–14 days of artificial weathering. Furthermore, the loss of efficiency and durability of the hydrophobic coatings is detected by measuring the static contact angle. This highlights that even if a protective treatment was proficient, it could easily deteriorate in normal weathering conditions if applied on polished, low-porosity stone. Additionally, water vapour permeability indicates variations of regular vapour transmission through the stones due to ageing. The first solution to threats is the prevention of pathologies, including aesthetic ones. A careful choice of the most suitable lithotype finish and an environmental study represent an existing solution to the problem. It must be highlighted that aesthetic requirements should not be prioritised to detriment of the technical requirements of architectural quality, performance, durability, and safety. Full article

Soluble salts are compounds found inside ornamental rocks and building stones exposed to atmospheric agents in environments rich in alkaline metal ions, such as sodium and potassium. The damage induced by their crystallization in those materials, used to build monuments and architectural structures of great importance, is an unsolved problem. Sodium sulfate is one of the most common and harmful salt found in these constructions. In this work, we studied the resistance through time to the wet-drying cycles of some natural stones (calcarenites, marbles, and sandstones) that have been utilized in the historical architecture in Italy. Samples were freshly cut and thermally aged to simulate increasing decay. Induced porosity in the thermally degraded samples was high in calcarenites, medium in marbles, and low in sandstones. Specimens subjected to artificial thermal aging lost a major percentage of mass compared to the non-weathered ones, when affected by the crystallization of soluble salts. With this study, we have observed that samples subjected to different wetting and drying cycles degrade faster due to the action of soluble salts, compared to samples that are not subjected to these cycles. Full article

Brazil is one of the world’s major ornamental stone producers. As a consequence, ornamental stone wastes are generated on a large scale and are usually open air disposed. Thus, it is important to develop novel material reusing these accumulated wastes, aiming to minimize environmental impact. The development of artificial stones made with ornamental stone wastes agglomerated by a synthetic polymer represents an excellent alternative and, therefore, is currently the subject of several works. This work seeks to develop an innovative artificial stone containing 85%wt of granite waste and 15%wt of vegetable polyurethane from castor oil, a biodegradable resin, from a renewable source. The purpose is creating a sustainable material, technically viable to be applied as a civil construction coating. To manufacture the artificial stone plates, granite and polyurethane were mixed and transferred to a metallic mold subjected to vibration, vacuum and, later, hot compression. The artificial stone presented low water absorption (0.13%) and apparent porosity (0.31%) as well as a favorable 17.31 MPa bend strength. These results were confirmed through the excellent particles/matrix adhesion displayed in the micrographs, in addition to great chemical resistance. Full article