Alternativas anal��ticas para determina����o de ferro e tit��nio em cimento Portland

In the present work four different analytical methodologies were studied for the determination of iron and titanium in Portland cement. The cement samples were dissolved with hot HCl and HF, being compared Fe and Ti concentrations through four analytical methods: molecular absorption spectrophotometry using the reagents 1,2-hydroxybenzene-3,5-disulfonic acid (Tiron) and the 5-chloro-salicylic acid (CSA), inductively coupled plasma atomic emission spectrometry (ICP-AES) and flame atomic absorption spectrophotometry (FAAS). In the spectrophotometric determinations were studied pH conditions, reagents addition order, interferences, amount of reagents, linear range and stability of the system. In the techniques of ICP-AES and FAAS were studied the best lines, interferences, sensibility and linear range. The obtained results were compared and the agreement was evaluated among the methods for the determination of the metals of interest.

Uso de lodo de esta����o de tratamento de ��gua centrifugado em matriz de concreto de cimento portland para reduzir o impacto ambiental

An alternative application of the humid sludge from the Passa��na WTP, located in Curitiba's metropolitan area, is proposed for concrete structures, partially replacing aggregates and cement. For the investigation, a reference concrete and four concrete mixtures with sludge were produced, and from these, two mixtures, containing 4% and 8% of sludge (m/m), were analyzed by different techniques: X ray fluorescence, X ray diffraction, thermo-gravimetric analysis, physicochemical analysis, compressive strength, etc. The properties were evaluated and the results indicate that the mixtures can be applied in different situations as cast structures for construction of concrete walls. Mixtures with more than 4% of sludge are restricted to applications where the workability of the concrete is not required, such as for residential pavements, sidewalks and stepping floors.

Desempenho f��sico-qu��mico e mec��nico de concreto de cimento Portland com borracha de estireno-butadieno reciclada de pneus

Physicochemical and mechanical techniques were carried out to characterize three concrete tyre-rubber waste dosages such as 5, 10 and 15%, w/w. The elastomeric material was identified as styrene-butadiene rubber (SBR). It was observed that the growing SBR content in the mixture decreased the concrete performance. The best results were presented by 5% w/w tyre-rubber waste concrete sample. This composition was tested at Mour��o hydroelectric powerplant spillway as repairing material.

Biofouling e biodeteriora����o qu��mica de argamassa de cimento portland em reservat��rio de usina hidroel��trica

Last decade Brazilian rivers experimented progressive biofouling of Limnoperna fortunei communities and Cordylophora caspia hydroids. The microhabitat is so favorable that in around 1.5 years L. fortunei increased from 0.39 to nearby 149,000 units/m��. Ten Portland cement mortar samples were produced with 1: 3.5: 0.4 dosages and installed for 1 year at Salto Caxias Brazilian Power Plant reservoir in 0.5 m and 1.0 m deep to investigate the biofouling influence on hydraulic civil structures. SEM, EDS, visual investigation and XRF results indicate none direct chemical interrelationships between L. fortunei and the mortar samples. However C. caspia diminished the mortar surface resistance and caused cement paste leaching.

Efeito da adi����o de serragem de couro tratada quimicamente nas propriedades do cimento Portland

The sheave leather was subjected to chemical treatment in an attempt to immobilize chromium ion in a matrix of cement. Cementitious pastes were obtained by adding different proportions of waste treated solutions (5 and 10% compared to the cement mass) and the pH and setting time (hardening) were measured. Aiming to check the leather influence in Portland cement pastes, the phases formation were observed by X-ray diffraction (XRD). The results showed that the pretreatment was effective for the waste dissolution and the pH of treated waste chemical solutions did not influence significantly the characteristics of cement paste, with a slight increase in setting time results.

Method for determining the photocatalytic potential of portland cement mortar containing TiO2 for decomposing the pollutant nitrogen monoxide

Photocatalytic materials can minimize atmospheric pollution by decomposing certain organic and inorganic pollutants using sunlight as an energy source. In this paper, the development of a methodology to measure the photocatalytic potential of mortar containing TiO2 nanoparticles is reported. The results indicate that up to 40% of NOx can be degraded by Portland cement mortar containing 30-50% of TiO2, which validates the method developed for evaluating the photocatalytic potential of materials.

OBTEN����O DE COMP��SITOS H��BRIDOS BASEADOS EM HIDROG��IS E CIMENTO PORTLAND

In this study, a novel hybrid composite based on biodegradable hydrogel and Portland cement with promising technological properties was reported. In the first step, a full 23 with central point factorial design was utilized to obtain the enhanced polyacrylamide-carboxymethylcellulose hydrogel compositions. A mathematical model was devised, indicating that the 3 main variables were significant and the AAm and MBAAm variables positively contributed to the mode and showing that the CMC variable had the opposite contribution. In the second step, these compositions were mixed with Portland cement to obtain the hybrid composites. The presence of cement improved the mechanical properties of polymeric matrices, and electronic microscopic micrographics revealed that the hydrogels were well adhered to the cement phase and no phase separation between hydrogel and cement was detected. Finally, using the energy dispersive X-ray technique, the elements Na, Mg, Al, Si, S, K, Ca and Fe were detected in the polymeric matrix, consistent with the hybrid composite formation.

Avalia����o dos efeitos de pr��-tratamentos da madeira de Eucalyptus benthamii Maiden & Cambage no grau de compatibilidade com cimento Portland

O objetivo deste trabalho foi avaliar o efeito de cinco diferentes tipos de pr��-tratamento na compatibilidade entre a madeira do Eucalyptus benthamii e o cimento Portland. A madeira foi pr��-tratada com ��gua fria, ��gua quente, hidr��xido de s��dio, cloreto de c��lcio ou hidr��xido de c��lcio. O grau de compatibilidade foi determinado atrav��s do estudo do calor de hidrata����o nas primeiras 24 h e pela resist��ncia �� compress��o axial ap��s 28 dias dos comp��sitos formados por cimento e p�� de madeira na rela����o de peso de 13,3:1. A resist��ncia �� compress��o axial ap��s 28 dias tamb��m foi avaliada em comp��sitos formados com cimento e part��culas de madeira na rela����o 2,75:1. Os resultados dos testes feitos com a madeira em p�� indicaram que a adi����o de 3% de cloreto de c��lcio �� o tratamento mais eficiente para reduzir a capacidade de inibi����o da esp��cie, enquanto o tratamento do p�� da madeira com hidr��xido de c��lcio afetou negativamente a compatibilidade. Entretanto, a combina����o do aditivo cloreto de c��lcio com part��culas carbonatadas, pelo tratamento com hidr��xido de c��lcio, foi o que apresentou a maior resist��ncia �� compress��o axial nos comp��sitos feitos na rela����o cimento:madeira de 2,75:1. A madeira de Eucalyptus benthamii apresentou potencial para a fabrica����o de pain��is madeira-cimento. O uso da metodologia de carbonata����o das part��culas em solu����o de hidr��xido de c��lcio tamb��m �� vi��vel como pr��-tratamento, independentemente dos resultados apontados pelos m��todos tradicionais de medi����o do grau de compatibilidade.

Caracteriza����o f��sica e mec��nica de argamassas �� base de cimento Portland e cinza de casca de arroz residual

A casca de arroz, utilizada como fonte de energia em ind��strias de beneficiamento de arroz, converte-se, depois da queima, em uma cinza residual. Esse res��duo, ainda sem um destino adequado, �� muitas vezes depositado em grandes ��reas abertas e provoca elevado impacto ambiental. Este trabalho teve como objetivo avaliar a viabilidade de utiliza����o da cinza de casca de arroz (CCA) residual na produ����o de argamassas, como substituta parcial do cimento. A caracteriza����o da CCA foi realizada por meio da an��lise de fluoresc��ncia de raios-X (composi����o qu��mica), an��lise do teor de carbono e difra����o de raios-X; tamb��m foi realizada an��lise granulom��trica a laser. Os corpos de prova foram submetidos a dois tipos de exposi����o: ambientes externo e interno, com dura����o m��xima de cinco meses. Foram realizados os ensaios de resist��ncia �� compress��o simples e n��o destrutivo (velocidade do pulso ultrass��nico - VPU). Embora as argamassas tenham apresentado bom desempenho mec��nico, os ensaios de pozolanicidade indicaram que a cinza de casca de arroz residual utilizada n��o �� uma pozolana, mas pode ser utilizada em matrizes ciment��cias como material inerte (filler).

Analysis of proteins from membrane and soluble fractions of Giardia duodenalis trophozoites of two Brazilian axenic strains

In the present study, we have analyzed by sodium docecyl sulphate - polyacrilamide gel electrophoresis (SDS-PAGE), immunoblotting and Concanavalin A blotting (Con A blotting) proteins of membrane fractions and soluble fractions obtained from Giardia duodenalis trophozoites of two axenic strains isolated in Brazil from a symptomatic (BTU-11) and an asymptomatic patient (BTU-10), as compared to the reference strain Portland 1. Both Brazilian strains showed a complex and homogeneous electrophoretic pattern of proteins, but some differences could be observed. Several glycoproteins were detected, particularly the proteins of 81, 72, 59 kDa and the protein of 62 kDa in the membrane proteins and cytosol, respectively. Many antigenic components were revealed by anti-Giardia rabbit IgG antibodies in the immunoblotting analysis. Among these components, the membrane protein of 32 kDa and the cytosol protein of 30 kDa could be related to giardin, as previously demonstrated.

Plancto e hidrobiologia sanit��ria de tanques tropicais com d��fnias e rot��feros

The engineers of the modern University City are constructing a graceful bridge, named PONTE OSWALDO CRUZ, that crosses a portion of the Guanabara Bay (Fig. 1). The work at west pillar stopped for 3 years (The concret structure in Est. 1). As it will be seen from n.�� 1 �� 5 of the fig. 1, Est. I, the base of the structure will have five underground boxes of reinforcement, but, to-day they are just like as five uncovered water ponds, until at present: May 1963. (Est. I �� fig. 3, n.�� 3 �� pond n.�� 3; A. �� old level of the water; B.�� actual level of the water; c.�� green water; E.�� mass of bloom of blue algae Microcystis aeruginosa). Soon after SW portion, as 5 cells in series, of the pillar abutments, and also the NE portion nearly opposite in the Tibau Mount will be filled up with earth, a new way will link Rio City and the University City. We see to day Est. I, fig. 1 �� the grasses on the half arenous beach of the Tibau Point. These natural Cyperaceae and Gramineae will be desappear because of so a new road, now under construction, when completed will be 33 feet above the mean sea level, as high as the pillar, covering exactly as that place. Although rainfall was the chief source of water for these ponds, the first water (before meterorological precipitations of whatever first rain it might fall) was a common tap water mixed with Portland Cement, which exuded gradually through the pores of the concret during its hardenning process. Some data of its first cement water composition are on the chemical table, and in Tab. n.�� 4 and "Resultado n.�� 1". The rain �� receiving surface of each pond were about 15 by 16 feet, that is, 240 square feet; when they were full of water, their depth was of 2 feet 3", having each pond about 4,000 gallons. Climatic conditions are obviously similar of those of the Rio de Janeiro City: records of temperature, of precipitation and evaporation are seen on the graphics, figs. 2, 3, 4. Our conceptions of 4 phases is merely to satisfy an easy explanation thus the first phase that of exudation of concrete. We consider the 2nd. phase formation of bacterian and cyanophycean thin pellicel. 3rd. phase - dilution by rains, and fertilisation by birds; the 4th phase - plankton flora and fauna established. The biological material arrived with the air, the rains, and also with contaminations by dusts; with big portion of sand, of earth, and leaves of trees resulted of the SW wind actions in the storming days (See - Est. I, fig. 3, G. - the mangrove trees of the Pinheiro Island). Many birds set down and rest upon the pillar structure, its faeces which are good fertilizers fall into the ponds. Some birds were commonly pigeons, black ravens, swallows, sparrows and other sea mews, moor hens, and a few sea birds of comparatively rare occurence. We get only some examples of tropical dust contaminated helioplankton, of which incipient observations were been done sparcely. See the systematic list of the species of plankters. Phytoplankters - Cyanophyta algae as a basic part for food of zooplankters, represented chiefly by rotiferse, water-fleas Moinodaphnia and other Crustacea: Ostracoda Copepoda and Insecta: Chironomidae and Culicidae larvae. The polysaprobic of septic irruptions have not been done only by heating in summer, and, a good reason of that, for example: when the fifth pond was in polysaprobic phase as the same time an alike septic phase do not happened into the 3rd. pond, therefore, both were in the same conditions of temperature, but with unlike contaminations. Among the most important aquatic organisms used as indicatiors of pollution - and microorganisms of real importance in the field of sanitary science, by authorities of renown, for instance: PALMER, PRESCOTT, INGRAM, LIEBMANN, we choose following microalgae: a) The cosmopolite algae Scenedesmus quadricuada, a common indicator in mesosaprobio waters, which lives between pH 7,0 and it is assimilative of NO[3 subscripted] and NH[4 subscripted]. b) Species of the genus Chlamydomonas; it is even possible that all the species of theses genus inhabit strong-mesosaprobic to polysaprobic waters when in massive blooms. c) Several species of Euglenaceae in fast growing number, at the same time of the protozoa Amoebidae, Vorticellidae and simultaneous with deposition of the decaying cells of the blue algae Anacystis cyanea (= Microcystis) when the consumed oxygen by organic matter resulted in 40 mg. L. But, we found, among various Euglenacea the cosmopolite species (Euglena viridis, a well known polysaprobic indicatior of which presence occur in septic zone. d) Analcystis cyanea (= M. aeruginosa) as we observed was in blooms increasing to the order of billions of cells per litter, its maximum in the summer. Temperatures 73��F to 82��F but even 90��F, the pH higher than 8. When these blue algae was joined to the rotifer Brachionus calyflorus the waters gets a milky appearance, but greenished one. In fact, that cosmopolite algae is used as a mesosaprobic indicator. Into the water of the ponds its predominance finished when the septic polysaprobic conditions began. e) Ankistrodesmus falcatus was present in the 5th pond from 26the. April untill the 26th July, and when N.NH[4 subscripted] gets 1.28 mg. L. and when chlorinity stayed from 0.034 to 0.061 mg. L. It never was found at N.NH[4 subscripted] higher than 1 mg. L. The green algae A. falcatus, an indicatior of pollution, lives in moderate mesosaprobic waters. f) As everyone knows, the rotifer eggs may be widely dispersed by wind. The rotifer Asplanchna brightwelli in our observation seemed like a green colored bag, overcharged by green cells and detritus, specially into its spacious stomach, which ends blindly (the intestine, cloaca, being absent). The stock of Asplanchna in the ponds, during the construction of the bridge "PONTE OSWALDO CRUZ" inhabits alkaline waters, pH 8,0 a 8,3, and when we observed we noted its dissolved oxygen from 3.5 to 4 mg. L. In these ponds Asplanchna lived in 0,2 P.PO[4 subscripted]. (Remember the hydobiological observations foreign to braslian waters refer only from 0.06 to 0,010 mg. L. P.PO[4 subscripted]; and they refer resistance to 0.8 N.NH[4 subscripted]). By our data, that rotiger resist commonly to 1.2 until 1.8 mg. L.N.NH[4 subscripted]; here in our ponds and, when NO[2 subscripted] appears Asplanchna desappears. It may be that Asplanchna were devoured by nitrite resistant animals of by Culicidae or other mosquitoes devoured by Due to these facts the number and the distribution of Asplanchna varies considerabley; see - plates of plankton successions. g) Brachionus one of the commonest members of class Rotatoria was frquently found in abundance into the ponds, and we notice an important biological change produce by the rotifer Brachonus colyciflorus: the occurence of its Brachionus clayciflorus forms pallas, is rare in Brazil, as we know about this. h) When we found the water flea MOinodaphnia we do not record simultanous presence of the blue algae Agmenellun (= Merismopedia).

Protease activity in Giardia duodenalis trophozoites of axenic strains isolated from symptomatic and asymptomatic patients

We have examined by gelatin-SDS-PAGE the protease activity in cell lysates of Giardia duodenalis trophozoites of two axenic strains isolated in Brazil from a symptomatic patient (BTU-11) and an asymptomatic carrier (BTU-10), and the reference strain Portland 1 (P1). The proteolysis band patterns showed differences among strains isolated from asymptomatic and symptomatic individuals. The lysate of the strain BTU-10, showed only five hydrolysis bands, while a greater number of bands (10-11 bands) was seen in strains BTU-11 and P1. The protease activity in all lysates was inhibited by cysteine (E-64 and iodoacetamide) and serine proteases (TPCK and TLCK) inhibitors, but not by PMSF and EDTA. In general, the results revealed protease activities in G. duodenalis trophozoites of Brazilian axenic strains and the predominance of cysteine proteinases. It should be stressed the inter-strain difference in hydrolysis band patterns observed between strains isolated from symptomatic patients and the strain obtained from an asymptomatic carrier.

Classifica����o tecnol��gica de solos e res��duos industriais, com e sem tratamento t��rmico, para fins rodovi��rios

Estudou-se o comportamento mec��nico das misturas solo-alcatr��o, solo-cal-alcatr��o e solo-cimento-alcatr��o, com base nos ensaios de limites de liquidez e plasticidade, CBR, compress��o simples e permeabilidade, visando a aplicabilidade destas em rodovias. Trabalhou-se com tr��s amostras de solos (ETA, NV e VS), representativos das ocorr��ncias da microrregi��o de Vi��osa-MG. Foram empregados alcatr��o, nos quantitativos de 0,25, 0,5, 1, 2, 4 e 6%, cal hidratada e cimento Portland, em conjunto com o alcatr��o, na dosagem de 2%, considerando-se a energia do ensaio de compacta����o AASHTO Normal. A adi����o de alcatr��o reduziu significativamente os valores de LL dos solos, mas com pouca varia����o nos valores de IP. Conclui-se que o alcatr��o contribuiu para melhorar as caracter��sticas mec��nicas e hidr��ulicas dos solos, para alguns tratamentos, n��o atingindo, entretanto, os padr��es de resist��ncia mec��nica exigida pelo DNER para camadas de sub-base de pavimentos flex��veis. Quanto ��s misturas solo-cal-alcatr��o e solo-cimento-alcatr��o, constatou-se melhoria substancial nos par��metros de resist��ncia mec��nica em rela����o aos solos, principalmente devido �� a����o cimentante da cal e do cimento, e que para alguns tratamentos esta a����o foi potencializada pelo alcatr��o, incidindo em resist��ncia mec��nica superior �� das misturas solo-cal e solo-cimento. O alcatr��o, em alguns tratamentos, ocasionou decr��scimos na permeabilidade das misturas, com rela����o ao solo, de at�� dez vezes. O alcatr��o mostrou ser um estabilizante de interesse para fins rodovi��rios apenas para determinadas condi����es, envolvendo tipo de solo e tipo e teor de alcatr��o, o que indica que estudos nesta dire����o devem apresentar uma caracter��stica regional.

Efeito de aditivos minerais sobre as propriedades de chapas cimento-madeira

O objetivo deste trabalho foi avaliar o efeito da adi����o de dois tipos de aditivos minerais (micross��lica e metacaulim) sobre as propriedades de chapas de cimento-madeira, aplicando-se diferentes teores aditivos (0, 20 e 30%). O aglomerante empregado na produ����o dos pain��is foi o cimento Portland tipo ARI, juntamente com part��culas de madeira de Eucalyptus urophylla. Os resultados indicaram que a adi����o dos aditivos minerais n��o causou melhorias significativas nas propriedades mec��nicas avaliadas. J��, em rela����o ��s propriedades f��sicas, o efeito positivo da adi����o de 20% de micross��lica p��de ser observado no ensaio de absor����o em ��gua ap��s a imers��o em 2 e 24 horas. O aditivo metacaulim n��o apresentou tend��ncia clara, por��m, de forma geral, a sua adi����o causou redu����o na qualidade das chapas.

Mistura de tr��s esp��cies de reflorestamento na produ����o de pain��is cimento-madeira

Este trabalho teve por objetivo avaliar a viabilidade t��cnica de produ����o de pain��is cimento-madeira compostos por diferentes propor����es de res��duos das madeiras de cedro-australiano (Toona ciliata M. Roem.), Pinus taeda e clone de h��brido de Eucalyptusgrandis x Eucalyptus urophylla,utilizando-se dois processos distintos de cura: vaporiza����o e climatiza����o. Foi utilizado o cimento Portland CP V - ARI/Plus como aglomerante e o cloreto de c��lcio como aditivo qu��mico. As part��culas de madeira foram previamente tratadas em ��gua fria durante 24 h. Foram considerados os seguintes par��metros: rela����o madeira/cimento - 1/2,75; rela����o ��gua/cimento - 1/2,5 (base peso do cimento); taxa de ��gua de hidrata����o/cimento - 25% (base peso do cimento); aditivo qu��mico - 4% (base peso do cimento); densidade nominal - 1,10 g/cm��; e dimens��es dos pain��is - 480 x 480 x 150 mm. Os par��metros de prensagem foram: temperatura ambiente, press��o espec��fica de 40 kgf/cm�� e tempo de 10 min. O tempo de grampeamento foi de 24 h. As propriedades avaliadas foram absor����o de ��gua e inchamento em espessura ap��s 24 h, flex��o est��tica, compress��o e liga����o interna. O experimento foi instalado segundo um delineamento inteiramente casualizado com tr��s repeti����es e seis tratamentos, arranjados num esquema fatorial de tr��s composi����es x dois processos de cura. Os pain��is compostos pela mistura de T. ciliata com o clone de Eucalyptus apresentaram valores m��dios superiores para inchamento em espessura e resultados inferiores para a maioria das propriedades mec��nicas. A cura a vapor melhorou as propriedades f��sicas, mas afetou negativamente a maioria das propriedades mec��nicas.