O uso adequado de pozolanas de boa qualidade possibilita a produção de cimentos especiais, de menor custo de fabricação e de maior durabilidade que os correspondentes sem adição. O emprego de pozolanas proporciona, adicionalmente, ganhos significativos em termos de produtividade e uma extensão da vida útil dos equipamentos de produção e do próprio jazimento calcário. A diversidade de características e desempenhos das pozolanas dificulta sobremaneira a seleção e qualificação dos diversos materiais disponíveis. Face às limitações dos métodos tradicionais de determinação da \"atividade pozolânica\", propõe-se uma metodologia alternativa, na qual as pozolanas são investigadas sob diferentes conteúdos de Ca(OH)2. A metodologia proposta proporciona uma melhor definição da qualidade e desempenho da pozolana e, paralelamente, o conhecimento da exata proporção de hidróxido de cálcio que a mesma fixa após um determinado período de reação. No que se refere à evolução da resistência mecânica, verifica-se que o desempenho dos cimentos aditivados com pozolanas de argila é variável e grandemente dependente das características da pozolana, do teor de adição e do tempo de cura considerado. Os cimentos de melhor evolução de resistência foram obtidos com as pozolanas mais reativas (de rápida reação) e que desenvolvem produtos de reação de grande capacidade cimentícia. As argilas calcinadas que apresentam elevados teores de quartzo (>30%) e demandam maior quantidade de água são de desempenho inferior. Constata-se, por outro lado, que a resistência dos cimentos aditivados não cresce linearmente com a capacidade de fixação de hidróxido da pozolana. As pozolanas de argila de grande capacidade de fixação de Ca(OH)2 são particularmente adequadas para aquelas situações onde se requer pastas com a menor basicidade possível. Quando adicionadas em elevadas proporções (acima de 40%), todavia, a parcela de clínquer do cimento não produz hidróxido suficiente para a completa reação dessas pozolanas, verificando-se, nestes casos, uma sensível redução nos valores de resistência mecânica dos cimentos. Embora em geral não utilizadas pela indústria cimenteira, as argilas que originalmente exibem uma certa quantidade de carbonatos associados podem proporcionar pozolanas de excelente desempenho. A queima necessária à ativação dos argilominerais (700-800º) promove uma descarbonatação parcial dos carbonatos e a geração simultânea de fases hidraulicamente ativas (\"proto-clínquer\"). Obtém-se, como consequência, uma pozolana de maior reatividade e que proporciona cimentos de melhor evolução de resitência nas idades iniciais. O menor requerimento de Ca(OH)2 das mesmas, face ao caráter pouco mais básico, permite que sejam adicionadas em elevadas proporções (até 50-60%), sem que se esgote o hidróxido liberado pelo clínquer. Mesmo nessas proporções, a resistência pode superar o limite de 32 MPa imposto por norma. As características mineralógicas e composicionais dos clínqueres também influenciam o desempenho mecânico dos cimentos aditivados. As influencias do clínquer são entretanto menos expressivas que aquelas decorrentes das alterações na constituição, reatividade e teor da adição pozolânica. Idealmente, o clínquer empregado na produção de cimentos com pozolanas deve exibir um elevado teor de alita (65-70%), ser constituído de cristais pequenos e reativos (dimensão média próxima de 30µm) e, adicionalmente, mostrar uma relação C3A/C4AF superior a 1. / The proper use of good quality pozzolans assures the production of special cements of lower manufacturing costs and higher durability than the corresponding cement without possolan. In addition, the use of pozzolans allows significant productivity gain and also increases the useful life of equipments and limestone deposits. However, the different characteristics and performance of pozzolans raise difficulties for the adequate selection and qualification of the available materials. In view of the inaccuracy of the tradicional \"pozzolanic activity\" determination methods, an alternative methodology is proposed, whereby the pozzolans are investigated under different contents of calcium hydroxide. The proposed methodology outlines a better prediction of the pozzolan quality and performance and permits, at the same time, the knowledge of the correct proportion of calcium hydroxide combined by the pozzolan, after a given reaction period. Regarding the mechanical strength evolution, it has been found cements added with clay pozzolans have a variable performance, wich is influenced by the pozzolan characteristics, the admixture content and curing time. Cements with the best strength evolution were obtained from reactive pozzolans, which usually develop reaction products of a high binding capacity. Burned clays which have a high content of quartz (>30%) and require a greater quantity of water showed a poorer performance. On the other hand, it is realized that cements with pozzolanic admixtures do not show a linear increase of the strength with the hydroxide combining capacity of the employed pozzolan. Clay pozzolans with great Ca(OH)2 combining capacity are particularly suitable to situations where pastes with a minimum basicity are required. However, when such pozzolans are added in large quantities (over 40%), the remaining clinker does not produce enough hydroxide for the complete reaction of the pozzolan, in which case the mechanical strength of the cements undergoes a substancial reduction. Although in general not used by the cement industry, clays which originally show a certain amount of associated carbonates can produce pozzolans of excellent performance. The burning required for the activation of clay minerals (700 - 800ºC) causes a partial decomposition of the carbonates and a simultaneous generation of hydraulically active phases (\"protoclinker\"). As a consequence, a pozzolan of higher reactivity is obtained which allows the manufacturing of cements of better strength evolution at earlier ages. The smaller requirement of Ca (OH)2, in view of its more basic nature, allows the addition of high percentages (up to 50-60%) of such pozzolans, without exhausting the hydroxide released by the clinker. Even with such contents, the strength after 28 days reaction can exceed the limit of 32 MPa dictated by brasilian standards. The mineralogical and compositional characteristics of the clinker also affect the mechanical performance of the blended cements. The effects of clinker alternations are however less expressive than those derived from changes in composition, reactivity and content of pozzolanic admixture. Ideally, the clinker used for the production of pozzolan blended cements should exhibit a high content of alite (65-70%), should consist of small and reactive crystals (with average dimensions of approximately 30µm) and should also show a C3A/C4AF ratio greater than 1.

Thesis (Doctor of Engineering in Civil Engineering)--Cape Peninsula University of Technology, 2018. / Rheological properties of most ordinary Portland cements are dictated by the hydration reactions that their different phases experience. Cement clinker has four main phases with aluminate being the most reactive. Once in contact with water, the aluminate phase reacts rapidly and generally impedes the early hydration of other cement compounds such as calcium silicates that are responsible for the strength of cement systems. Consequently, the obtained matrix is stiff without much strength. Alternatively, calcium sulphate bearing materials are added within the clinker as set regulators of the aluminate phase hydration. For this purpose, natural gypsum is moslty gound with cement clinker as a source of sufficient sulphate, thereby keeping the cement paste plastic for a certain amount of time, allowing the hydration of silicate phases that are responsible for the early and later strength. However, the heat generated within the mill during the grinding process of clinker and gypsum causes a partial dehydration of natural gypsum into hemihydrate. The final ground cement product is thus comprised of two unexpected types of calcium sulphate bearing materials in an unpredictable proportion. Due to the difference in their solubility, the hydration of the aluminate phase can variably be altered which consequently affects the rheokinetics of the cement paste. Currently, the effect of the available amount of hemihydrate and natural gypsum in the cement sulphate phase, on both the hydration and rheology of ordinary Portland cements (OPC), are not well-understood. An ordinary Portland cement clinker was sampled during the production process of CEM I under stable kiln operations at a local cement plant. This was ground without any form of calcium sulphate bearing material and the final product was considered as relatively pure cement clinker. The degree of natural gypsum degeneration was achieved by partially replacing fractions of hemihydrate with those of natural gypsum. Firstly, the individual effect of these calcium sulphate bearing materials on the hydration kinetics was studied by varying their concentrations from 2-7% within the cement system. Secondly, the effect of their mix proportions at an optimum calcium sulphate concentration on cement paste rheokinetics was investigated. This research confirmed the findings of previous investigations relative to the effect of calcium sulphate on the hydration kinetic , giving new insight on the rheokinetics of cement paste with mix proportions of various calcium bearing materials. Results showed that the reaction rates of cement systems with hemihydrate were faster than those with natural gypsum and generally tended to decrease with the increase in their concentrations. Cements with hemihydrate experiencing shorter dormant durations than those with natural gypsum, likely due to the fact that the consumption rate of calcium sulphate was higher in cement systems with hemihydrate than those with natural gypsum. Consequently, before the exhaustion of sulphate ions, cement systems with hemihydrate had higher degrees of hydration and became almost similar thereafter. More ettringite and portlandite were formed in cement systems with hemihydrate as compared to those with natural gypsum. The amount of ettringite increased with the increase in calcium sulphate concentration up to 4% and thereafter remained constant. Conversely, the amount of portlandite decreased with the increase in calcium sulphate and also remained unchanged after 4%. The strength development of the cement microstructure depended on the concentration of hemihydrate within the suspension. The rigidification of the newly formed network was affected at higher hemihydrate fractions. Rheological parameters were more pronounced when the concentration of hemihydrate exceeded 50%. Below this hemihydrate concentration, cements had almost similar flow properties as those with only natural gypsum. Large changes in yield stress values and variation in plastic viscosity values of approximately 50% were observed. The trend of mixes dynamic yield stress were similar to their corresponding strength rate developments. This rheological behaviour was primarily attributed to the morphology change of ettringite that was triggered by the presence of a higher hemihydrate concentration. It was also noticed that physical performances of cement systems depended on their respective microstructure developments.

This study investigated the effects of selfesteem, controllability, and optimism, the constructs inherent in positive illusions, on perceived racism. The perceived racism scale in this study was found to contain two dimensions, Equal Opportunity (EO) racism and Authority (AUT) racism. Thirty-seven AfricanAmerican, 64 Asian-American and 100 White-American students at Portland States University {101 females, 100 males and mean age of 25 years) served as subjects. The findings revealed that both African- and AsianAmerican students perceived a racist atmosphere from peer students {EO racism) significantly higher than did the White-American students. However, only AfricanAmerican students perceived greater racism from faculty members (AUT racism) than the White-American students. None of the illusions had an effect on perceived EO racism. However, all types of illusions (self-esteem, controllability and optimism) had a significant effect on perceived racism from faculty members {AUT racism). Higher perception of AUT racism was correlated with less self-esteem(~= -.089, R = .12), less controllability(~= -.319, R < .001), and less optimism (~ = -.144, R = .03). The results of this study support empirical evidence showing that the illusions, especially controllability, change individuals in how they perceive racism when the racism is practiced by authorities.

This exploratory study is designed to investigate the role of pre-counseling client expectancy as it affects the outcome of initial-interview counseling. To facilitate investigation into this area it was necessary to develop a measuring instrument whereby an individual's expectation of the success of counseling could be assessed. This instrument was then administered to beginning clients at two counseling facilities.

Between 1905 and 1926. developers. real estate speculators, and the Port of -Portland filled in Guild's Lake, a riparian marsh that had been the location for Portland's 1905 Lewis and Clark.: Exposition and Oriental Fair. There were two phases in the filling process. The first phase, which began before the fair ended and lasted until 1914, involved developers using high-pressured hydraulic hoses to sluice soil from nearby hills into the lake. Their primary goal was to terrace the hillside to create a high-end view neighborhood; Guild's Lake was a convenient "dump" for the gravel and dirt. During the second phase. from 1919 to 1926. Portland's elite business leaders teamed up with the city and the Port of Portland to use dredge spoils from a Willamette River channel change and deepening for a more comprehensive filling operation at Guild's Lake. Although city and citizen planning efforts to establish a publicly-owned industrial area at Guild's Lake failed, private landowners at Guild's Lake negotiated with the Port of Portland to fill the lake.

This study examines the spatial and temporal characteristics of the surface air temperature in Portland, Oregon. Spatial temperature patterns indicate that the dominant control factors on seasonal temperature distribution are local topography, elevation, and urban-rural differences in surface structure. A heat island exists in the Portland area; the intensity of the heat island rang€s from 4° to 10° F, and varies throughout the year. The strongest heat island is found in the July minimum temperature. Temperature distribution in Portland and the adjacent area is affected by winds and rainy conditions, but less influenced under overcast skies. The long-term temperature over the last century shows that Portland's mean annual temperature trends are 0.057° F/yr and 0.052° F/yr in the two warming periods 1900-1940 and 1961-1984, respectively, and these warming trends are largely due to warming in spring and early summer as well as in winter months except January. Comparisons between Portland and other local non-urban climatic stations show a general warming trend in Portland since the end of the last century, which is 0.028° F/yr in the mean annual temperature, and 0.017° F/yr in maximum temperature after the regional trends are removed. Monthly mean temperature in July and January demonstrate a warming by 0.023° F/yr and 0.015° F/yr at Portland, respectively. All these warming trends are due mainly to the impact of urbanization. It is found that the cooling effect on the northern Willamette Valley due to the presence of the Columbia Gorge is most noticeable in the daytime and in January.

The construct internal-external locus of control was utilized to examine the Soviet Pentecostal refugees' perception of life experiences in the United States as defined by three dimensions: social, economical, and political. Unlike the majority of immigration research, which focuses on structural variables, this research further addressed the concept of acculturation as a long term process of resettlement. Subjects completed an anonymous forced choice questionnaire consisting of the Rotter (1966) locus of control instrument scale. Pearson Product moment correlation coefficients were calculated to examine the strength of the relationships between the internal-external locus of control scores and five factor analyzed life experience categories. Positive and sometimes strong correlations could be found between the internal-external locus of control scores and the five life experience factors. All five hypotheses were confirmed by the results.

Forest Park, a 5,000 acre heavily-forested park within the city limits of Portland, Oregon was selected as the study area for performing a fire simulation analysis. A well-documented fire swept over a large area of the park in 1951, and provides both direct inputs, including the ignition point, and context for the present day fire simulations. The goal of the research was two fold. First, determine the difference between small area simulations using standard and custom surface fuel models. Second, determine if fire simulation can be an effective tool in assessing fire danger and behavior in a wildland-urban interface environment like Forest Park.

Recent management efforts in the Smith and Bybee Lakes Wildlife Area (SBL), a 700-ha preserve in north Portland, Oregon, have included using a water control structure to suppress invasive reed canarygrass (Phalaris arundinacea L.) by flooding during spring and early summer growth periods. For the first year of managed flooding, I sought to determine: (a) the extent and distribution of reed canarygrass at SBL; (b) the effectiveness of the change in water level at suppressing reed canarygrass; and ( c) the effects of the change in water level on other plant species. I established 30 vegetation transects throughout SBL before completion of the water control structure. These transects were randomly distributed, placed perpendicularly to the shorelines of the wetlands, and had a cumulative length of 3.1 km. I measured vegetation on the transects in autumn 2003 and autumn 2004 using the line intercept method at 10-cm intervals. I surveyed the transects to generate elevation profiles, accurate to 0.15 cm, to determine depth and duration of flooding, which I correlated with vegetative changes. I also monitored inundation depth, growth, and phenological response of individual stands of reed canarygrass during the 2004 growing season.

The purpose of this research study was to examine the impact of the consulting teacher model on referral and verification rates to special education. A population of schools which implemented the model (N = 17) was compared with a randomly selected comparison group of schools which did not (N = 30). All schools were from the Portland, Oregon, Public School District. The research was designed to cover a three school year period of time (1987 to 1990). Three different types of data were collected: the number of children who were discussed at regular education pre-referral meetings, the number of children who were referred for special education assessment and the number of children who verified as eligible for special education services. Three primary research questions addressed (a) the impact of the consulting teacher model on the number of children in the process, (b) the longitudinal impact of the model on referral rate accuracy and (c) referral rate accuracy differences between the consulting teacher and comparison group schools. Results from the first question indicated a difference in the numbers of children discussed at the initial regular education pre-referral step; 17 more children were discussed in the consulting teacher schools. Differences were also found between the 1987-88 school year and every other year; seven more children were in the process in the first year of the study than in the later years. Results from the second question found that length of time on the model does have a significant effect on referral rate accuracy in the consulting teacher schools. Two differences were found in this question: an increase in referral rate accuracy between years three and four and a decrease in referral rate accuracy between years four and five. Results from the third question indicated no differences between the type of school and school year. Referral rate accuracy remained the same in both the consulting teacher and comparison group schools throughout all three years of this study. / Graduation date: 1992