Resumo O silicato de sódio é a fonte complementar utilizada na reação de geopolimerização. Entretanto, esse reagente é produzido em alta temperatura ou em autoclave a alta pressão, o que gera muito impacto ambiental. Visando a produção de geopolímeros mais ecológicos, produziu-se um silicato de sódio alternativo (ASW) a partir da dissolução da sílica presente na cinza de casca de arroz (CCA). Foram preparados geopolímeros nas razões molares SiO2/Al2O3 de 3,0, 3,5 e 4,0 e com concentrações de NaOH de 8 e 10 M. Os corpos de prova foram submetidos a ensaios de resistência à compressão (7 e 28 dias), FTIR e DRX. O desempenho mecânico dos geopolímeros produzidos com ASW foi semelhante aos produzidos com silicato de sódio comercial. A análise do comportamento mecânico e dos espectros de infravermelho sugeriu que ocorreu maior dissolução da CCA com o aumento da relação molar SiO2/Al2O3 e da concentração do álcali.
Even though we know that the construction industry is constantly evolving, due to the emergence of construction techniques and materials, we note that there are still challenges to be faced: pathological manifestations. These, in turn, compromise the performance and useful life of the elements. Its occurrences are mainly due to the reduction of deadlines, inadequate design solutions, improper use of materials, unskilled labor, lack of maintenance, lack of inspection, among other aspects. The evaluation of a structural element is based on the precedence of guaranteeing durability and quality to ensure the integrity of users. Therefore, this article analyzed structural elements of a reinforced concrete bridge located in the city of Correntes-PE. The main objective of the work was to characterize the main pathological manifestations affecting the structural elements of the bridge. The process of characterization of degrading agents was carried out through non-destructive tests, such as the carbonation front, as provided for in EN 14630 (DIN, 2007) and the evaluation of surface resistance, through the sclerometry test, according to NBR 7584 (ABNT, 2012). The results allowed to characterize the strength of the concrete and the degree of degradation. Points with incidence of carbonation and exposed reinforcement were identified, denoting the need for preventive and corrective intervention, in order to prolong the useful life and performance of the evaluated artwork.
In view of the improvement of construction techniques and technological innovations, civil construction still faces numerous problems. Uncontrolled exploitation of natural resources has caused major environmental impacts, in addition to the generation and accumulation of debris in urban areas. Thus, recycling appears as a sustainable alternative to reduce the accumulation of this waste. As an option, there is the use of Recycled Aggregates, obtained through Construction and Demolition Waste (CDW). In this sense, the present study aimed to analyze the feasibility of using the CDW through its application in the production of recycled coarse aggregates in concrete. For the tests, the coarse aggregate was replaced in the proportions of 0 (reference line), 10, 20, 30, 40, 50 and 100%, with three samples for each line and age. The dosage of the strokes followed the parameters established by the IPT / EPUSP method. The concretes were analyzed for compressive strength at 7, 14 and 28 days and the samples were evaluated for properties in an anhydrous, fresh and hardened state. The data collected in the tests were tabulated and analyzed for the degree of addition and its correlation with the characteristic resistance. The results allowed to conclude that the use of the residue in the form of aggregate for the concrete, in the proportions of 10% and 20%, does not affect the compressive strength, making it a good alternative.
The search for methods that provide savings greatly drives the search for alternatives when it comes to cost reduction. The obsession with aesthetics and cheaper alternatives for civil construction, can lead to unexpected and dangerous results. The reduction of the dimensions of the columns can be done consciously, always keeping in mind the compliance with normative standards combined with structural optimization. The objective of this work was to evaluate the efforts resulting from the reduction of the minimum dimensions beyond that established by NBR 6118 (ABNT, 2014) and compare with the considerations of NBR 15575 (ABNT, 2013) about a possible permission to reduce the minimum dimensions of columns. For this, the software MathCAD, Eberick and SAP2000 were used to implement the calculation and design methods of the columns. The variables evaluated were the steel area of columns with different cross sections, length of buckling and the necessary anchoring length that a beam would need to anchor in the columns. As a result, it was found that in relation to the steel area, the decrease in the section resulted in increases in the steel area. The buckling was not acceptable (λ> 140) with a cross-section column less than 19 cm for situations of double height up to 6 m in height, according to NBR 15575 cites. The criterion of anchoring the beam reinforcement in a column with section smaller than 14 cm was not feasible for all situations.
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