Syfte: Syftet med denna studie var att undersöka resistens mot marginala missfärgningar av en adhesivt cementerad keram till emalj beroende på typ av cement, teknik för avlägsnande av överskottscement och kombinationen av de två faktorerna.Metod: 60 extraherade tänder preparerades i emalj med en slipmaskin till en 90° vinkel. Sintrat IPS E-max CAD preparerades till 60 bitar med måtten 3x3x1mm. Glaskerambitarna cementerades med Variolink®Veneer, Variolink®II och Panavia™F 2.0 enligt bruksanvisning med en kraft på 5kg. Varje cementgrupp bestod av 20 provkroppar där cementöverskottet avlägsnades med putsning eller konventionell teknik. Detta ledde till totalt 6 grupper med 10 provkroppar i varje grupp. Provkropparna termocyklades i 5000 cyklar i destillerat vatten med temperaturen 5° C till 55° C, därefter placerades provkropparna 4 dagar i kaffe och 4 dagar i rött vin. Missfärgningsgraden av det marginala cementet avlästes i en blindad studie under mikroskop av två observatörer med signifikant klinisk erfarenhet inom dentala keramer. Resultat: Variolink®Veneer var det minst missfärgande cementet oberoende av avlägsningsteknik, men resultatet var inte statistiskt signifikant. Putsning visade bättre motstånd gällande missfärgning jämfört med konventionell teknik och detta resultat var statistiskt signifikant. Variolink®II tillsammans med putstekniken var det minst missfärgande kombinationerna.Signifikans: Inom de begränsningar en in vitro studie medför kan följande slutsats dras; den viktigaste parametern gällande resistens av marginal missfärgning är ej val av cement utan tekniken för avlägsning av överskottscement. / Purpose: The aim of this study was to investigate the resistance to marginal discoloration of an adhesively cemented bondable ceramic to enamel depending on choice of cement, the technique used for removing excess cement and a combination of the two factors. Method: 60 extracted teeth were prepared in the enamel with a grinding machine to an approximately 90° angle. A block of IPS E-max CAD was sintered and thereafter sliced into 60 pieces with the measurement 3x3x1mm. The ceramic pieces were cemented with Variolink®Veneer, Variolink®II and Panavia™F 2.0 following the manufacturer’s instructions with a force of 5kg (20 specimens in each group). The excess cement was removed by either polishing technique or conventional technique leading to 6 groups with 10 specimens in each group. The specimens were thermocycled for 5000 cycles in 5° C and 55° C distilled water baths and after placed in coffee for 4 days and red wine for 4 days. The discoloration degree of the cement margin was analysed blindly under microscope by two observers with significant clinical experience in dental ceramics.Results: Variolink®Veneer was the least discolored cement but the result was not statistical significant. When comparing polishing and conventional technique, polishing showed least discoloration independent of choice of cement. Variolink®II together with the polishing technique showed least discoloring mean and median value of the 6 groups.Significance: Within the restrictions an in vitro study has, the following conclusion can be made; the most important parameter regarding resistance to marginal discoloration is not the choice of cement but how the excess cement is removed.

<p>The use of supplementary cementitious materials (SCM) decreases the environmental impact of the cement industry. SCMs are commercial by-products that possess pozzolanic properties. Recycled glass powder, classified as a SCM, when added as a cement replacement reacts with the available lime in the cement to form calcium silicate hydrate (C-S-H) products. In contrast with other SCMs, glass is siliceous and thus the reaction can also cause alkali silica reaction (ASR) which causes expansion and cracking. This study was completed in order to characterize the chemical reactions and their rate using a simplified system that mimics glass particles in hardened cement paste.</p> <p>Silica powder was added to solutions containing calcium hydroxide and/or sodium hydroxide. The rate of dissolution of the silica was monitored as well as the composition of the reaction products. Dissolution rates of silica with varying concentrations of silica, calcium hydroxide and sodium hydroxide, were fitted to the Hixson-Crowell cubic root law. The precipitate composition of the reaction product was represented by means of triaxial plots. It was found that silicate ions enter the solutions containing sodium hydroxide and containing both sodium hydroxide and calcium hydroxide. The rate is proportional to the quantity of sodium ions in the solution and to the pH. Also, higher concentrations of silica generally cause higher dissolution rates. The solutions with a pH of 13.48 and with lower silica concentrations created reaction products that were similar to C-S-H while the solutions with higher pH levels formed ASR after thirty days. The C-S-H prevented further dissolution of the silica. The formation of the ASR reaction products did not prevent further dissolution of the silica and they continued to dissolve until most of the silica had entered the solution.</p> / Master of Applied Science (MASc)

Workability has traditionally been used as one of the measures for controlling concrete mixture proportioning. This metric has provided limits on the water content in the concrete mixture for given aggregate size and type. The slump test, which is commonly used as an assessment of workability, is not adequate for characterizing the flow behaviour / rheology of fresh concrete. Studies have shown that Bingham's rheological properties, namely yield stress and plastic viscosity, provide good description of the flow behaviour of fresh concrete. In this thesis, an experimental program was designed on the basis of factorial design to evaluate the method of Cement Association of Canada for designing and controlling concrete mixture. The variables included in the mix design are water-cement ratio, water content, coarse aggregate size, silica fume, slag and bulk volume of coarse aggregate. In addition, Neuro-Fuzzy network has been adopted to correlate the current mixture proportioning method to the rheological properties of concrete. The network was constructed using experimental data tested in this study. Such correlation allowed the determination of water-cement ratio, water content, fine aggregate and coarse aggregate from compressive strength, yield stress and plastic viscosity. / Thesis / Master of Applied Science (MASc)

no / Marls were identified from a range of European sources and assessed for their Cementation Index, as proposed by Eckel. Two were selected for calcination in a laboratory kiln; one from Folwark in Poland (CI 1.75) and one from Lillienfeld in Austria (CI 2.03). Analysis of historical documents, while not revealing precise kiln conditions, does suggest that they were such as not to yield complete decarbonation of the calcite. Consequently, a series of calcinations was undertaken in which the peak temperature control of the kiln was set in the range 730°C to 1100°C, with residence times in the range 150 to 1250 min. The airflow through the kiln was sufficient to maintain a minimum oxygen content of at least 12 %. The resulting clinker was ground to comply with the 19th century Austrian Norme. Pastes were produced at w/c = 0.65 and assessed for setting time and strength development (6 h to 1 year). Both parameters were highly dependent upon calcination conditions with both ¿low¿ and ¿high¿ calcinations producing slower setting and slower strength development than intermediate conditions. Two strength development profiles were identified; one being the expected continuous increase of strength, albeit with a declining rate of increase with time, while the other showed a three-step sequence of high initial strength, a dormant period which could last for many weeks and a final increase in strength to an age of one year. The cements were compared using X-ray diffraction (XRD). Considerable variation in the composition was noted and related to the calcination conditions. Of particular interest is the formation of both ¿'-belite and ß-belite under differing calcination conditions. Clinker particles were also compared using the SEM in back-scattered electron imaging mode and the development of morphology observed.

No / The setting of Roman cement is so rapid as to make the use of retardation essential in most practical mortars. This work reports an approach to retardation of Roman cement mortars by means of a pre-hydration process in which pre-determined amounts of water (de-activation water) are added to the cement prior to subsequent mortar formation. It is shown that this process yields both monocarboaluminate and a carbonated AF(m) phase, the balance of which is modified by storage time; the belite phases are not affected. Increases in both de-activation water and pre-hydrated mix storage time yield a longer workable life and slightly lower strength of the mortar. An increase in de-activation water also yields an increase in shrinkage whilst an increase in storage time results in a reduction in shrinkage. Other parameters such as mixing protocol and re-mixing affect workable life without compromising the strength. (C) 2013 Elsevier Ltd. All rights reserved.

An investigation into the reasons behind the water shortage on Gotland. The project investigated several key factors and proceeded with the design of a surface water treatment plant in one of Gotlands old quarries left behind by the cement industry. The project also investigated and questioned the traditional methods of designing infrastructural buildings through a more architectural lens. The hope was to show a proposal that works but also acts as a pedagogical invitation to learn about where our most important resource comes from.

The importance of moisture in concrete is unquestionable. However, quantifying the moisture in concrete is very difficult as concrete microstructure water interactions are not well understood. Concrete is a very complex material spanning the range from the atom to the civil infrastructure. It is the medium that controls moisture at the FRP/concrete interface. Concrete is also a composite material at the level of concrete/rebar, aggregate/sand/cement paste and at the hydration product level. Water is vital in concrete microstructure development, properties and concrete durability. A moisture sensor based on the dielectric and resistive properties of cement paste was developed. Impedance spectroscopy techniques are used to explore the moisture behavior in relation to dielectric and resistive properties of the sensors. The sensor capacitive response is frequency dependent and it has been described with a multi-linear curve. Resistance values are related to capacitance through a power Law. Both the capacitance/moisture and capacitance/resistance behaviors were observed in all four cement/sand/aggregate mixtures considered. Although the dielectric constants of water and dry cement paste are not frequency dependent with in the 400 kHz and 10 MHz frequencies considered, the effective dielectric constant of the mixture is frequency dependent Mixing rules cannot predict the effective dielectric constant of the dielectric medium used in the sensors. Impedance analysis indicated also multiple time constants exist within the cement paste. Using the observation from the experimental results in conjunction to the high conductivity of cement pore solution a random R-C network model was developed to explore the impedance behavior of cement paste. / Ph. D.

Small amounts of cementation in a sand increase its ability to sustain static and dynamic loads, even in a liquefaction type environment. This has been shown in previous research examining the behavior of both naturally cemented and artificially prepared samples. Cemented sands are present in many parts of the world and can be caused by either a variety of cementing agents or by cold welding at points of grain contact. They are generally quite difficult to sample, but artificially cemented sands have been shown to aptly model the behavior of natural materials, and allow for better test controls. Consequently, artificial samples were used exclusively for the present investigation which has three major objectives: to investigate the effects of a weakly cemented lens within a stronger mass; to determine how cementation affects the volume change characteristics of statically loaded samples; and, to describe the pore pressure generation of sands subjected to cyclic loading. Prior to commencing the test program, a number of index tests were performed on the uncemented and cemented sand used during the laboratory investigation. It was revealed that cementation leads to increased void ratios which distort relative density calculations used to compare cemented and uncemented samples of similar dry unit weight. The practice of identifying samples by dry unit weight was adopted for this report. Static triaxial compression tests were performed on 17 samples. Test results indicate that although the magnitude of volumetric strain at failure does not seem to be dictated by the level of cementation, there is a relationship with cementation and the rate of volume change at failure. A weak lens was seen to lower the static strength of the stronger mass. 26 stress controlled cyclic triaxial tests revealed that a weak lens lowers the liquefaction resistance of the stronger mass. The cyclic strength of the nonhomogeneous material, however, is higher than the independent strength of the weak lens. A weak lens has greater influence at relatively higher levels of cyclic stress. Pore pressure generation in cemented sands are seen to be controlled by strain. At shear strain levels below about 1%, cemented sands behave similarly to uncemented sands with pore pressures increasing more rapidly beyond that amount of strain. Consequently, pore pressure development during cyclic loading is described by a broken-back curve which is defined in the early stages by existing empirical relationships for uncemented sand. Pore pressure prediction may then be achieved using an equation for cemented sand, such as that developed in the present work. / Master of Science

Portland cement concrete (PCC) structures deteriorate with age and need to be maintained or replaced. Early detection of deterioration in PCC (e.g., alkali-silica reaction, freeze/thaw damage, or chloride presence) can lead to significant reductions in maintenance costs. However, it is often too late to perform low-cost preventative maintenance by the time deterioration becomes evident. Non-destructive evaluation (NDE) methods are potentially among the most useful techniques developed for assessing constructed facilities. They are noninvasive and can be performed rapidly. Portland cement concrete can be nondestructively evaluated by electrically characterizing its complex dielectric constant. The real part of the dielectric constant depicts the velocity of electromagnetic waves in PCC. The imaginary part describes the conductivity of PCC and the attenuation of electromagnetic waves, and hence the losses within the PCC media. Dielectric properties of PCC have been investigated in a laboratory setting using a parallel plate capacitor operating in the frequency range of 0.1MHz to about 40MHz. This capacitor set-up consists of two horizontal-parallel plates with an adjustable separation for insertion of a dielectric specimen (PCC). While useful in research, this approach is not practical for field implementation In this research, a capacitance probe has been developed for field application. The probe consists of two planar conducting plates and is made of flexible materials for placement on exposed surfaces of the specimens to be tested. The calibration method of both capacitive systems has been extensively studied to minimize systematic errors in the measurement process. These two measurement systems will be discussed and compared to one another on the basis of sensitivity and measurement repeatability. / Master of Science

For decades, cement mortar relining has been used successfully to extend the life of drinking water pipelines, although, few quantitative data exist on the short-term water quality impacts of this process. This study investigated mortar lining impacts on disinfectant by-product formation, alkalinity, metal leaching, pH and disinfectant consumption, and odor generation shortly after in-situ installation. The experimental design used a 30-day, coupon immersion procedure that simulated a relined 4-inch diameter pipe located in a low-flow system. Four water regimes were utilized; no disinfectant, chlorine (2 mg/L at pH 6 .5 and 8), and chloramines. Flavor Profile Analysis panels evaluated odors of samples and controls. Additionally, the affects of three different phosphate-based corrosion prevention additive regimes were evaluated. Cement mortar leachates impacted water quality significantly during the first week of exposure. Alkalinity, hardness and pH increased dramatically after initial exposure, rising to approximately 600 mg/L as CaCO3 alkalinity, 770 mg/L as CaCO3 hardness, and pH 12 in the first two days. Sharp declines in alkalinity and hardness did not occur until after day 9 when the cement mortar was substantially cured and release of calcium hydroxide lessened. Chlorinated water residual disinfectant decay rate was increased substantially during the initial 24 hours and remained elevated until day 9. After day 1, there was not a significant increase in the formation of regulated haloacetic acids or trihalomethanes. Significant levels of aluminum (< 700 ug/L) and chromium (< 75 ug/L) were released at various times during the test period but their concentrations did not exceed USEPA water quality standards. Cement odor intensity levels were significantly higher than controls, persisted for 14 days, and were of an intensity that would be readily noticeable to consumers. The polyphosphate-based corrosion preventative resulted in less severe water quality effects than other phosphate additives or water without added phosphate. / Master of Science