Influence of lime type and curing conditions on lime and lime-metakaolin mortars

Durability of Building Materials and Components (Vasco Peixoto de de Freitas, J.M.P.Q. Delgado, eds.), Building Pathology and Rehabilitation, vol. 3, VIII, 105-126. ISBN: 978-3-642-37474-6 (Print) 978-3-642-37475-3 (Online). Springer-Verlag Berlin Heidelberg. DOI: 10.1007/978-3-642-37475-3_5

Desarrollo sustentable de geoestructuras compuestas por suelo loéssico compactado mejorado con agregado de materiales estabilizantes. Sustainable development of compacted loess soil geo-structures with addition of stabilizing materials.

Los suelos estabilizados mediante compactación, permiten obtener materiales con ventajas ténicas y economicas en diferentes tipos de obras de ingeniería. Ejemplos de su uso se tiene en bases viales de autopistas, rutas o calles urbanas, pistas de aterrizaje, barreras de contención para enterramientos sanitarios o lagunas de estabilización, apoyos de plateas para fundación de edificios, losas industriales, entre otras aplicaciones. Las fallas en este tipo de construcciones pueden resultar en catástrofes ambientales, sociales y elevadas pérdidas económicas, por lo que resulta de gran importancia optimizar el diseño e incrementar la seguridad de este tipo de construcciones. Las obras con estas características involucran grandes volúmenes y/o superficies que requieren controles sistemáticos durante su desarrollo, a los fines de garantizar el cumplimiento de las propiedades de los materiales establecidos en la etapa de diseño. De esta forma, es necesario contar con ensayos de campo sencillos, confiables y eficientes que permitan identificar propiedades físicas, mecánicas e hidráulicas. Las geoestructuras generadas mediante la compactación del suelo próximo al sector de construcción pueden funcionar adecuadamente, con reducidos costos de material y transporte. Su estabilización puede ejecutarse en forma natural, o con la incorporación de agregados minerales como bentonita, cal o cemento. Estas incorporaciones mejoran las propiedades hidráulicas y mecánicas del material, optimizando el comportamiento requerido para la obra. Para establecer la forma en la que estos minerales modifican el comportamiento del suelo local compactado deben realizarse investigaciones especiales con los materiales involucrados. En el ámbito internacional existen numerosas investigaciones sobre comportamiento de suelos compactados, no obstante, si bien aportan antecedentes para la planificación de estudios locales, sus resultados no pueden trasladarse de manera directa. Las características propias del suelo local constituye la principal variable debido a la diversidad en las propiedades geotécnicas de cada Región. Esta investigación, se focaliza en el empleo de suelos limosos de la formación loéssica de la zona central de Argentina. Los suelos de la llanura cordobesa poseen comportamientos particulares, los cuales son contemplados en los diseños presentados como resutado de las investigaciones internacionales. Esta particularidad se relaciona con su inestabilidad, lo que los clasifica como suelos colapsables. Los resultados obtenidos en este trabajo podrán ser extendidos a una gran superficie de la Provincia de Córdoba y a la Región Pampeana en general, a los fines de establecer recomendaciones de diseño y construcción para la confección de Pliegos de Especificaciones Técnicas de diferentes tipos de obras públicas y privadas. El estudio contempla la ejecución de un plan experimental a escala de laboratorio y campo. Los materiales corresponden a suelo limosos puros, y diferentes agregados tales como bentonita, cal y cemento. Se planifican ensayos para evaluar el desempeño del material, a partir de la confección de muestras preparadas con diferentes condiciones de compactación (energía, humedad y método), y en forma de mezcla con los distintos tipos de agregados. Se realizarán ensayos de permeabilidad en celdas de pared rígida y flexible, junto a ensayos mecánicos de compresión confinada, simple y triaxial. Para el trabajo experimental de campo se prevé la ejecución de terraplenes de prueba instrumentados con tensiómetros e infiltrómetros para evaluar el comportamiento hidraúlico en el tiempo, junto con ensayos de penetración y plato de carga para la caracterización mecánica. En forma conjunta se propone el desarrollo de modelos numéricos de caracterización hidromecánica. Stabilized soils by compaction, produce materials technical and economic advantages in different types of engineering works. For example, road bases in highways, roads or city streets, containment barriers for sanitary landfill or stabilization ponds, foundation support of building, industrial flat, and other applications. Failures can result in environmental catastrophes, social, and economic loss, so it is important to optimize the design and increase the safety of such buildings. These works involve large surfaces that require systematic tests during construction, so it is necessary to have simple field tests, reliable and efficient to identify physical, mechanical and hydraulic properties. The geo-structures generated by local soil compaction have reduced material and transportation costs. Stabilization can be naturally, or with the addition of mineral aggregates as bentonite, lime and cement. These additions improve the hydraulic and mechanical properties of the material. So, special investigations should be conducted with the materials involved. There are many international studies on compacted soils behavior but their results can not be transferred directly due to the particularities of regional soils. For this research silty soils of central Argentina are the main focus. The soils of Córdoba plains are instability, so are classified as collapsible soils. The results obtained in this work may be extended to a large area of the Province of Cordoba and the Pampas region in general, in order to establish design and construction recommendations. The study includes laboratory and field tests. The materials are pure silty soil, and different aggregates such as bentonite, lime and cement. Tests are planned to evaluate the performance. Laboratory includes rigid and flexible wall cells, confined, triaxial and simple compression tests. For field experimental instrumented embankments will be constructed. A numerical hydromechanical model will be developed.

The effect of linseed oil on the properties of lime-based restoration mortars

The traditional lime mortar is composed of hydrated lime, sand and water. Besides these constituents it may also contain additives aiming to modify fresh mortar´s properties and/or to improve hardened mortar´s strength and durability. Already in the first civilizations various additives were used to enhance mortar´s quality, among the organic additives, linseed oil was one of the most common. From literature we know that it was used already in Roman period to reduce water permeability of a mortar, but the mechanism and the technology, e.g. effects of different dosages, are not clearly explained. There are only few works studying the effect of oil experimentally. Knowing the function of oil in historical mortars is important for designing a new compatible repair mortar. Moreover, linseed oil addition could increase the sometimes insufficient durability of lime-based mortars used for reparation and it could be a natural alternative to synthetic additives. In the present study, the effect of linseed oil on the properties of six various lime-based mortars has been studied. Mortars´ compositions have been selected with respect to composition of historical mortars, but also mortars used in a modern restoration practise have been tested. Oil was added in two different concentrations – 1% and 3% by the weight of binder. The addition of 1% of linseed oil has proved to have positive effect on mortars´ properties. It improves mechanical characteristics and limits water absorption into mortar without affecting significantly the total open porosity or decreasing the degree of carbonation. On the other hand, the 3% addition of linseed oil is making mortar to be almost hydrophobic, but it markedly decreases mortars´ strength. However, all types of tested lime-based mortars with the oil addition showed significantly decreased water and salt solution absorption by capillary rise. Addition of oil into mortars is also decreasing the proportion of pores which are easily accessible to water. Furthermore, mortars with linseed oil showed significantly improved resistance to salt crystallization and freeze-thaw cycles. On the base of the obtained results, the addition of 1% of linseed oil can be taken into consideration in the design of mortars meant to repair or replace historic mortars.

Control Of The Properties Of Porous Chitosan-alginate Membranes Through The Addition Of Different Proportions Of Pluronic F68.

This work addresses the development and characterization of porous chitosan-alginate based polyelectrolyte complexes, obtained by using two different proportions of the biocompatible surfactant Pluronic F68. These biomaterials are proposed for applications as biodegradable and biocompatible wound dressing and/or scaffolds. The results indicate that thickness, roughness, porosity and liquid uptake of the membranes increase with the amount of surfactant used, while their mechanical properties and stability in aqueous media decrease. Other important properties such as color and surface hydrophilicity (water contact angle) are not significantly altered or did not present a clear tendency of variation with the increase of the amount of surfactant added to the polyelectrolyte complexes, such as real density, average pore diameter, total pore volume and surface area. The prepared biomaterials were not cytotoxic to L929 cells. In conclusion, it is possible to tune the physicochemical properties of chitosan-alginate polyelectrolyte complexes, through the variation of the proportion of surfactant (Pluronic F68) added to the mixture, so as to enable the desired application of these biomaterials.

Minas-type fresh cheese developed from buffalo milk with addition of L. acidophilus

Effective incorporation of a probiotic into foods requires the culture to remain viable all along processing and storage, without adverse alterations to sensory characteristics. The objective of this work was developing Minas-type fresh cheese with probiotic properties from buffalo milk. Four batches of Minas-type fresh cheese were prepared using buffalo milk: batch T1 in which neither culture nor lactic acid added; batch T3 in which only lactic acid added; batches T2 and T4 , both added of Lactobacillus acidophilus LAC 4, but T4 was also acidified. Resulting cheeses were evaluated for probiotic culture stability, texture profile, sensory acceptance, and changes in pH. The T4 probiotic cheese presented hardness, gumminess, and chewiness significantly lower than the other treatments. However, values for springiness and cohesiveness did not differ between all cheeses, and no sensory differences (p > 0.05) were found between treatments for texture, taste, and overall acceptance. The addition of probiotic to the acidified cheese (T4) yielded best aroma. The populations of L. acidophilus were greater than 10(6) CFU g-1 after 28 days of storage all products. Minas-type fresh cheese from buffalo milk is a suitable food for the delivery of L. acidophilus, since the culture remained viable during the shelf life of the products and did not negative affect analysed parameters.

Evaluation of elephant grass silage with the addition of cassava scrapings

The objective of this experiment was to evaluate the effects of adding cassava scrapings on gas and effluent losses, dry matter recovery, pH, contents of N-NH3, organic acids and volatile fatty acids and the bromatological composition of elephant grass silages. It was used a randomized complete design, with four levels of cassava scrapings (0, 7, 15 or 30% natural matter) each one with four replications per level. The grass was cut at 50 days of regrowth and ensiled in 15-L silos, equipped with a Bunsen valve to allow gas outflow. The gas losses decreased quadratically with the addition of cassava scrapings, whereas effluent losses decreased linearly. Dry matter recovery increased quadratically with the addition of cassava scrapings. Dry matter (DM) concentration increased but crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose (HEM) decreased linearly with the addition of cassava scrapings. The pH value and lactic acid concentration increased quadratically with the addition of cassava scrapings. Contents of N-NH3 and butyric acid decreased quadratically with the addition of cassava scrapings, whereas acetic acid content decreased linearly. Addition of cassava scrapings reduced gas and effluent losses and improved the fermentation profile of elephant grass silages and the level of 7% already ensures this improvement.

MgB(2) Superconductors With Addition of Other Diborides and SiC

The discovery of superconductivity at 39 K in MgB(2) has been catching the attention of scientists due to the possibility of applying the material in magnets and electronic devices operating with cryocoolers (temperatures around 20 K). In the present work, a methodology to optimize the critical current densities of this material is described. MgB(2) bulk samples were prepared and analyzed with the addition of other diborides with the same C32 hexagonal structure as MgB(2) (TaB(2), ZrB(2), VB(2), and AlB(2)) and with simultaneous addition of SiC. Microstructural characterization, performed using SEM+EDS and XRD, was extremely important to determine the distribution and compositional characterization of the superconducting phase. Magnetic superconducting characterization using SQUID was performed to determine the best material addition. As a result we could analyze the behavior of each addition on the current transport capacity, including an analysis of the magnetic flux pinning mechanisms.

Flux Pinning Optimization of MgB(2) Bulk Samples Prepared Using High-Energy Ball Milling and Addition of TaB(2)

MgB(2) is considered to be an important conductor for applications. Optimizing flux pinning in these conductors can improve their critical currents. Doping can influence flux pinning efficiency and grain connectivity, and also affect the resistivity, upper critical field and critical temperature. This study was designed to attempt the doping of MgB(2) on the Mg sites with metal-diborides using high-energy ball milling. MgB(2) samples were prepared by milling pre-reacted MgB(2) and TaB(2) powders using a Spex 8000M mill with WC jars and balls in a nitrogen-filled glove box. The mixing concentration in (Mg(1-x)Ta(x))B(2) was up to x = 0.10. Samples were removed from the WC jars after milling times up to 4000 minutes and formed into pellets using cold isostatic pressing. The pellets were heat treated in a hot isostatic press (HIP) at 1000 degrees C under a pressure of 30 kpsi for 24 hours. The influence that milling time and TaB(2) addition had on the microstructure and the resulting superconducting properties of TaB(2)-added MgB(2) is discussed. Improvement J(c) of at high magnetic fields and of pinning could be obtained in milled samples with added TaB(2) The sample with added 5at.% TaB(2) and milled for 300 minutes showed values of J(c) similar to 7 x 10(5) A/cm(2) and F(p) similar to 14 GN/m(3) at 2T, 4.2 K. The milled and TaB(2)-mixed samples showed higher values of mu(0)H(irr) than the unmilled-unmixed sample.

Evaluation of the anaerobic degradation of black liquor from a Kraft pulp plant with addition of organic co-substrates

The purpose of this study was to assess the anaerobic degradation of black liquor with and without additional carbon sources. Batch experiments were conducted using black liquor, from an integrated pulp and paper mill adding ethanol, methanol and nutrients. The PCR/DGGE technique was used to characterize the structure of the microbial community. The addition of extra sources of carbon did not significantly influence the degradation of black liquor under the conditions evaluated and the microbial community was similar in all experiments. It was observed an increase in some members of the archaeal in reactors that had the best efficiencies for removal of black liquor (around 7.5%). Either ethanol or methanol can be used as co-substrates because the produce the same quantitative and qualitative effect.

Effect of the processing conditions and the addition of trans-polyoctenylene rubber on the properties of natural rubber/styrene-butadiene rubber blends

In this study, the influence of the processing conditions and the addition of trans-polyoctenylene rubber (TOR) on Mooney viscosity, tensile properties, hardness, tearing resistance, and resilience of natural rubber/styrene-butadiene rubber blends was investigated. The results obtained are explained in light of dynamic mechanical and morphological analyses. Increasing processing time produced a finer blend morphology, which resulted in an improvement in the mechanical properties. The addition of TOR involved an increase in hardness, a decrease in tear resistance, and no effect on the resilience. It resulted in a large decrease in the Mooney viscosity and a slight decrease in the tensile properties if the components of the compounds were not properly mixed. The results indicate that TOR acted more as a plasticizer than a compatibilizer. (c) 2008 Wiley Periodicals, Inc.

Calcium: magnesium ratio in amendments of soil acidity: nutrition and initial development of corn plants in a Humic Alic Cambisol

The variation in the Ca:Mg ratio in amendments used to neutralize soil acidity is one way of altering the availability of those nutrients to the plants in acid soils. The objective of the work was to evaluate the effect of different proportions of calcium and magnesium in the form of CaCO(3) and MgCO(3) Oil the nutrient uptake, and initial production of dry matter by corn plants. The study was carried out in greenhouse conditions, in Lages, SC, with a completely randomized experimental design, with three replications. The treatments were the application of equivalent to 21.0 t ha(-1) of lime, using mixtures of CaCO(3) and MgCO(3) in several proportions to obtain different Ca:Mg ratios (1: 1, 2:1, 4:1, 8:1, 16:1 and 32:1), on a Humic Alic Cambisol, with 310 g kg(-1) of clay. The application of treatments caused the following Ca:Mg ratios in the CEC: 1. 1: 1, 2.1:1, 4.0:1, 8.1:1, 16.4:1 and 31.8:1. The high concentrations of exchangeable Ca in soil caused by addition of lime with high Ca content inhibited the uptake of Mg and K by the corn plants. The increase in the soil Ca:Mg ratio reduced the dry matter production and height of plants in the initial stage of development.

Nucleophilic Addition of Potassium Alkynyltrifluoroborates to D-Glucal Mediated by BF(3)center dot OEt(2): Highly Stereoselective Synthesis of alpha-C-glycosides

A convenient, mild and highly stereoselective method for C-glycosidation (alkynylation) of D-glucal with various potassium alkynyltrifluoroborates, mediated by BF(3)center dot OEt(2) and involving oxonium intermediates, preferentially provides the alpha-acetylene glycoside products with good yields.

Nucleophilic addition of potassium organotrifluoroborates to chiral cyclic N-acyliminium ions: stereoselective synthesis of functionalized N-heterocycles

The stereoselective nucleophilic addition of potassium aryl- and alkynyltrifluoroborates to cyclic N-acyliminium ion derivatives from N-benzyl-3,4,5-triacetoxy-2-pyrrolidinone, affording the respective 5-substituted 2-pyrrolidinone is described. The products were obtained in moderate to good yields and with preference for the syn diastereomer. (C) 2008 Elsevier Ltd. All rights reserved.

Public health implications of new guidelines for lead in drinking water: a case study in an area with historically high water lead levels

Concern about the neurotoxicity of lead, particularly in infants and young children, has led to a revision of blood lead levels which are considered to involve an acceptable level of human exposure. Drinking water guidelines have also been reviewed in order to reduce this source of population exposure to lead. In the last 20 years, guidelines have been reduced from 100 to 50 to 10 mu g/litre. Lead in tap water used to be a major public health problem in Glasgow because of the high prevalence of houses with lead service pipes, the low pH of the public water supply and the resulting high levels of lead in water used for public consumption. Following two separate programmes of water treatment, involving the addition of lime and, a decade later, lime supplemented with orthophosphate, it is considered that maximal measures have been taken to reduce lead exposure by chemical treatment of the water supply. Any residual problem of public exposure would require large scale replacement of lead service pipes. In anticipation of the more stringent limits for lead in drinking water, we set out to measure current lead exposure From tap water in the population of Glasgow served by the Loch Katrine water supply. to compare the current situation with 12 years previously and to assess the public health implications of different limits. The study was based on mothers of young children since maternal blood lead concentrations and the domestic water that mothers use to prepare bottle feeds are the principal sources of foetal and infant lead exposure. An estimated 17% of mothers lived in households with tap water lead concentrations of 10 mu g/litre (the WHO guideline) or above in 1993 compared with 49% in 1981. Mean maternal blood lead concentrations fell by 69% in 12 years. For a given water lead concentration, maternal blood lead concentrations were 67% lower. The mean maternal blood lead concentration was 3.7 mu g/litre in the population at large, compared with 3.3 mu g/litre in households with negligible or absent tap water lead. Nevertheless, between 63% and 76% of cases of mothers with blood lead concentrations of 10 mu g/dl or above were attributable to tap water lead. The study found that maternal blood lead concentrations were well within limits currently considered safe for human health. About 15% of infants may be exposed via bottle feeds to tap water lead concentrations that exceed the WHO guideline of 10 mu g/litre. In the context of the health and social problems which affect the well-being and development of infants and children in Glasgow, however, current levels of lend exposure are considered to present a relatively minor health problem. (C) 2000 Elsevier Science Ltd. All rights reserved.

Effects of the addition of methyltestosterone to combined hormone therapy with estrogens and progestogens on sexual energy and on orgasm in postmenopausal women

Objective To evaluate the effect of the addition of methyltestosterone to estrogen and progestogen therapy on postmenopausal sexual energy and orgasm. Methods Sixty postmenopausal women in a stable relationship with a partner capable of intercourse, and presenting sexual complaints that appeared after menopause, were randomly divided into two groups: EP (n=29) received one tablet of equine estrogens (CEE) 0.625mg plus medroxyprogesterone acetate (MPA) 2.5mg and one capsule of placebo; EP+A (n=31) received one tablet of CEE 0.625mg plus MPA 2.5mg and one capsule of methyltestosterone 2.0mg; The treatment period was 12 months. The effects of treatment on sexual energy were assessed using the Sexual Energy Change Scale. The ability to reach orgasm in sexual relations with the partner was verified through monthly calendars and by calculating the ratio between monthly frequency of orgasms in sexual relations and monthly sexual frequency. Results There was a significant relationship between improvement in level of sexual energy and the addition of methyltestosterone to CEE/MPA treatment (p=0.021). No significant effect on orgasmic capacity was noted after the treatment period. Conclusion Addition of methyltestosterone to CEE/MPA therapy may increase sexual energy, but might not affect the ability to obtain orgasm in sexual relations.