No abstract

The residues of ornamental rocks, especially quartzite, cause great environmental impact. More impulse has been given to research on the recycling of these residues over the last years, particularly for use as aggregates in concrete and mortar. Nevertheless, the studies conducted so far do not mention the behavior of the mortar blended with aggregates coming from residues of ornamental rocks when under chemical attacks in sulfate-rich environment. Thus, in the present study it was sought to add quartzite residues to the mortar, verifying its mechanical behavior and its durability when attacked by sodium sulfate (Na2SO4). The durability of the mortar blended with quartzite residues under sulfate attack was evaluated by the dimensional variation of the test specimens when immersed in sodium sulfate solution, according to the methodology of the NBR 13583 standard. Were used the following complementary techniques: simple compressive strength, X-ray diffraction and thermogravimetric and differential analysis. From the tests, it was verified that the mortars, after attack of sodium sulfate, presented dimensional expansions superior to 0.06%, as well as increased mechanical strength. Therefore, although it was found that the specimens incorporated with quartzite residues were attacked by sulfate, it was observed that it was not able to form sufficient secondary ettringite to mechanically damage the specimens submitted to the sodium sulfate attack.

Tailing incorporation into mortars has been the subject of much research in recent years. Despite this, most of these studies did not investigate the harmful effects resulting from the exposure of such mortars to an environment containing aggressive agents. This work investigated the effects of perlite tailing addition into mortars containing cement CP V-ARI MAX and hydrated lime. The raw materials were subjected to chemical characterization (X-ray fluorescence (XRF)) and mineralogical (X-ray diffraction (XRD)), while the samples immersed in 1 N NaOH solution were characterized by XRD, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and compression strength (CS). The results showed the harmful effects of incorporating perlite tailings into the mortar investigated. Such a degradation was proven by linear expansion and compressive strength experiments accomplished in the samples after the test of resistance to an alkali–silicate reaction.

Este trabalho tem como objetivo realizar a caracterização físico-química da água de dois poços tubulares, no período de três meses, localizados na zona rural do município de Parelhas, Estado do Rio Grande do Norte, e posteriormente, analisar a viabilidade de utilização da água bruta para consumo humano. Em relação às analises físico-químicas, foram determinados 15 parâmetros, tanto para a amostra A, como para a amostra B, a fim de caracterizá-las: pH, condutividade elétrica, temperatura na fonte, bicarbonato (HCO3-), cloreto (Cl-), dureza total (CaCO3), dureza (Ca2+), dureza (Mg2+), alcalinidade, sólidos totais dissolvidos, oxigênio dissolvido, nitrogênio amoniacal, nitrito (NO2-), nitrato (NO3-) e ferro. De acordo com os ensaios, as águas sob análise, apresentaram discordâncias em relação a Portaria de Potabilidade 2914/2011 nos seguintes parâmetros: Alcalinidade, sólidos totais dissolvidos, nitratos, nitritos e ferro. Somando-se a isso, as águas foram classificadas como duras (amostra B) e muito duras (amostra A), apresentaram condutividade extremamente elevada, superior a 590 μS.cm-1 e baixo teor de oxigênio dissolvido. Por fim, este trabalho conclui, a partir dos resultados dos parâmetros físico-químicos da amostra A e amostra B, que as água brutas dos poços estão inapropriadas ao consumo humano.

The mixture of mortars with quartzite residues is a recycling technique that has been widely used to promote the adequate management of solid waste generated in the municipality of Várzea-PB, Brazil. However, there are no reports in the literature that prove the durability of the mortar mixed with these residues when subjected to environmental conditions over time. Thus, the present work has as objective to study the durability of mortars incorporated with quartzite residues when submitted to natural aging.  The reference mortar and incorporated with quartzite were prepared according to NBR 13281 and submitted to natural aging for 28, 60, 120, 180 and 360 days. Then, they were characterized by x-ray diffraction, thermogravimetric analysis and simple compression strength and carbonation and pozzolanic measurements. The results showed that, despite the decrease in compressive strength of quartzite containing mortars, the durability was not compromised, since the values were maintained in the range suggested by NBR 13281. Finally, it was concluded that mortars produced with quartzite residues presented good mechanical behavior when submitted to natural aging.