No abstract

No abstract

a b s t r a c tA fresh green sand, spent green sand, and a weathered spent green sand (wSGS) from a foundry landfill were analyzed using diffractometry, electron microscopy, fluorometry, granulometry, spectrometry, and thermogravimetry (TG). Our objective was to understand how the physicochemical properties of the foundry green sands change from their original form after being subjected to the casting process, then after weathering at the landfill. A quantitative phase composition model was also postulated for each material based on the TG results and it was found to be the most reliable and informative quantitative data for this type of residue. The weathered sample, that remained in a landfill for two years, was found to be composed of almost pure sand. Because of the weathering process, it may be possible to use the wSGS as a virgin sand replacement in the regeneration system or in geotechnical applications where bentonite would affect the properties of the final product.Published by Elsevier B.V.

No abstract

No abstract

The importance of the preservation of water resources has resulted in the application of technologies such as nanostructured materials, which are able to minimize the impact associated with water contamination. This work evaluated the application of polyamide-66 (PA) pellets functionalized with silver nanoparticles (AgNPs) at polymer mass percentages of 0.05, 0.10 and 0.50% to disinfect of drinking water. Studies were carried out in three stages. The first stage was the synthesis of the silver nanoparticles by using silver nitrate as a metal precursor and sodium borohydrate as a reduction agent. The colloidal dispersion was characterized by UV-Vis spectrophotometry and transmission electron microscopy (MET). Afterwards, the nanostructures were incorporated into a polyamide-66 polymeric matrix. In the second stage, the silver ions leached from the polymer matrix in the water after a three-hour period were quantified in order to evaluate the limit established by Conama Resolution 357/2005, which imposes a concentration limit of 0.010 mg L-1. The best results were obtained with the application of 0.05% AgNPs in the polymeric matrix, yielding an average concentration of silver ions lixiviated of 0.008 mg L-1. The last step comprised the quantification of the antibacterial activity of the polymer matrix containing 0.05% of AgNPs against the microorganism E. coli using the Standard Test Method for Determining the Antimicrobial Agents Under Dynamic Contact Conditions. The samples containing 0.05% of AgNPs exhibited an antibacterial reduction of 97.89% after 24 h of incubation under stirring at room temperature (25°C).

Metal sinks are broadly produced with stainless steel sheets. These steel sheets are thin and may easily bend under mechanical forces. Wood or a mortar layer is used to strengthen the steel sink. In the last decade mortars have been used to replace wood. The mortar mixture is poured on the backside of the metal sink. After setting and hardening, the mortar prevents the sink metal sheet from bending.Since the concern with the cost of raw materials and with the environment, some industries are trying to use industrial waste as raw materials in mortar production. Actually, one of the biggest challenges the mankind needs to face nowadays is how to assure a continuous industrial development and improve the environment. This issue has been discussed in many global summits around the world in order to reduce the amount of industrial wastes. For the time being, political leaders have failed in find an appropriate compromise between industrial development and environmental protection. Despite all the discussion about sustainable development there is a lack of political will to create new regulations about reasonable use of raw materials, recycling and reutilization of wastes. Most of the countries have tough environmental protection laws so that the factories are supposed to adopt suitable treatment and disposal procedures for their industrial wastes. Nevertheless, AbstractThis work deals with the properties of alternative mortars destined to strengthen metal sheets of sinks. The performance of these mortars was compared to that of a basic mortar made of cement, sand, and water, named standard mortar (SM). One of these mortars, named alternative mortar 2 (AM2), and composed of cement, textile residue, polyurethane, polypropylene fibers and water, was developed recently to replace the current one, named alternative mortar 1 (AM1), composed of cement, sand, polystyrene, polypropylene fibers and water. These mortars were manufactured and aged in a room in atmospheric environment for 7, 14, 28, 60 and 90 days, either with or without initial drying in a furnace. After cure of 90 days the flexion strength stress of the SM, AM1 and AM2 mortars was 5.21, 3.84, and 1.42 MPa, respectively. The SM and AM1 mortars were constituted of C-S-H phases, Ca(OH) 2 , SiO 2 , AFm and AFt (monossulphate/ ettringite) phases. The AM2 mortar presented, apart from the compounds mentioned above, CaCO 3 . This compound is from the textile residue that is composed essentially of CaCO 3 and Ca(OH) 2 . The reduction in flexion strength of AM1 mortar, compared to SM mortar, is caused by the polystyrene whereas the lowering mechanical strength of the AM2 is due to both polyurethane and textile residue. Even so, its mechanical strength is acceptable because the flexion strength stress required for the industrial application is 1.0 MPa. Keywords: mortar, industrial waste, sink, stainless steel. Resumo O objetivo desse trabalho foi estudar as propriedades de argamassas alternativas usadas para reforço de chapas metálicas de pias de cozinha. O desempenho de...

In order to contribute to the sustainability of the foundry and construction industrial sectors, this work investigated the possibility of employing used foundry sand (UFS) in soil-cement bricks. Modular bricks were prepared with percentages of 10 wt% cement, 0-25 wt% commercial sand, 0-65 wt% used foundry sand, 25-65 wt% clay, and 15-30 wt% gravel dust. A content of 10 wt% Portland cement was adopted to ensure economic feasibility, and gravel was used to improve mechanical strength. The modular bricks were tested to determine their technical properties. The interfaces between the constituent materials were observed by scanning electron microscopy. In durability tests, the bricks showed water absorption and weight loss in accordance with current technical standards. The addition of UFS together with gravel dust reduced water absorption and provided an acceptable level of mechanical resistance, in accordance with established soil-cement standards. Keywords: soil-cement brick, used foundry sand, building ceramics, solid industrial waste. Resumo A fim de contribuir para a sustentabilidade de indústrias de fundição e de construção, este artigo estudou a possibilidade de areia descartada de fundição (ADF) ser incorporada em tijolos de solo-cimento. Tijolos modulares foram preparados com