Orientador: João Neudenir Arioli Filho / Banca: Sérgio Russi / Banca: Sergio Sualdini Nogueira / Banca: Cláudia Helena Lovato da Silva / Banca: Helena de Freitas Oliveira Paranhos / Resumo: O objetivo deste estudo foi analisar a influência da incorporação de três desinfetantes (hipoclorito de sódio a 1%, glutaraldeído alcalino a 2% e digluconato de clorexidina a 2%) em duas diferentes porcentagens de substituição da água da espatulação (50 e 100%) de dois gessos tipo IV, FujiRock EP (M1) e Rock Plus (M2), avaliando-se a resistência à compressão e à tração diametral. Os corpos-de-prova foram obtidos a partir de matrizes metálicas bipartidas com 20 mm de diâmetro e 40 mm de altura (resistência à compressão) e 20 mm de diâmetro e 10 mm de altura (resistência à tração diametral). As matrizes foram fixadas sobre uma placa de vidro, o gesso foi manipulado na proporção água/pó recomendada pelos fabricantes (M1:20ml/100g e M2:19 ml/100g), em um espatulador mecânico por 30 segundos, e vazado sob vibração. Para cada ensaio foram confeccionados sete grupos para cada gesso (n=10). Os grupos foram: CONTROLE (Água destilada), G50 (substituição de 50% da água de espatulação por glutaraldeído), G100 (100% de glutaraldeído), C50 (substituição de 50% da água por clorexidina), C100 (100% de clorexidina), H50 (substituição de 50% da água por hipoclorito) e H100 (100% de hipoclorito). Após a presa os corpos-de-prova foram removidos das matrizes e armazenados à temperatura ambiente. Os ensaio de compressão e tração diametral foram realizados 24 horas após o vazamento, em uma máquina de ensaios MTS-810, com célula de carga de 100 KN à velocidade de 0,5mm/min. Os valores médios de resistência à compressão e à tração diametral (MPa) foram submetidos à análise de variância e teste de Tukey, com nível de significância de 95%, permitindo concluir que: (a) a incorporação das substâncias desinfetantes estudadas afetou a resistência à compressão de ambos os gessos analisados; (b) as diferentes proporções de incorporação das substâncias... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The purpose of this study was to evaluate the compressive and diametral tensile strength of two Type IV dental stones, FujiRock EP (M1) e Rock Plus (M2), mixed with three disinfectant solutions (sodium hypochlorite 1%, chlorhexidine digluconate 2% and glutaraldehyde 2%) in two different proportions of gauging water (50% and 100%). Compressive samples consisted of cylindrical specimens, each having a diameter of 20 mm and length of 40 mm, and diametral tensile specimens consisted of discshaped specimens, having a diameter of 20 mm and length of 10 mm, obtained from split metal molds. The stone was mixed with the solutions previously outlined at the water-powder ratio recommended by the manufacturers (M1:20ml/100g e M2:19 ml/100g), mechanically spatulated under vacuum (Turbomix) for 30 seconds, and gently vibrated in the molds. Seven groups were prepared for each test, with 10 samples each, as follows: CONTROL (distilled water), G50 (substitution of 50% of gauging water by glutaraldehyde), G100 (only glutaraldehyde), C50 (substitution of 50% of gauging water by chlorhexidine digluconate), C100 (only chlorhexidine digluconate), H50 (substitution of 50% of gauging water by sodium hypochlorite) and H100 (only sodium hypochlorite). Specimens were removed from the molds after they set. Compressive strength and diametral tensile strength was determined 24 hours the specimens were cast, in an MTS-810 testing machine, with a cross-head speed of 0,5mm/min. Mean compressive and diametral tensile strength was calculated and expressed in megapascals (MPa). Data from both tests were analyzed by ANOVA and Tukey test, showing that: (a) chemical disinfectants incorporation reduced the compressive strength of type IV dental stones evaluated; (b) the use of two different proportions of gauging water substitution by disinfectants (50% and 100%) has affected the compressive strength of only one die stone (M1); (c) chemical disinfectants incorporation did not reduced. / Doutor

A comparison of concrete containing recycled concrete coarse aggregates and natural coarse aggregates subjected to high strain, low cycle compressive fatigue is presented. Using a strain based feedback control loop, concrete cylinders are compressed at 15µε/s to a specified strain then unloaded to zero stress for 10 cycles. After cycling, all samples are loaded to a strain of 0.008. Direct concrete material variables are the water to cement (w/c) ratio, taken as 0.60, 0.45, and 0.39, and percent coarse recycled concrete aggregate content, varied from zero to 100 percent. The primary testing variable is the specified unloading strain. Unloading strains include 60, 75, 90, 100, and 120 percent of the strain at peak stress. Ten batches of concrete were made, generating a total of 224 samples for testing. Findings confirm previous research showing a reduction in strength with increasing recycled concrete coarse aggregate content, an equivalent concrete with only 25 percent replacement of natural coarse aggregates and an equivalent strength concrete with a decrease in the w/c ratio and 100 percent recycled concrete coarse aggregates. Fatigue testing indicates that each cycle’s maximum stress remains unchanged, but the stiffness degrades more rapidly with increasing recycled aggregate content and a constant w/c ratio.

The objective of this investigation was to assess the influence of the SO3 content on the durability and strength of portland cement. Four portland cements were used in this study. The cements had a variable tricalcium silicate, tricalcium aluminate, and alkali contents, as well as differences in the amount and form of calcium sulfates. The SO3 content of the cements was increased by replacing part of the cement by gypsum according to ASTM C 452-95. Mortar bars and cubes were prepared for the as-received as well as for the cements with an SO3 content of 3.0% and 3.6%. The durability of the as-received and doped cements was determined by measuring the length change of the mortar bars that were exposed to sodium sulfate environment. The compressive strength of the mortar cubes prepared for the same mixes was measured at different ages for sets of cubes cured both in sodium sulfate solution and in saturated lime solution. It was concluded at the end of this study that there is an optimum SO3 content for the lowest expansion that is different from that determined for the highest compressive strength. Optimum values also differed from one cement to another and from one age to another for the same cement. The results also indicate the dependence of SO3 content on tricalcium aluminate and alkali content of cements. In addition, for all cements examined in this study with alkali content of less than 0.60%, increasing the SO3 content above 3.0% had negative effects on durability assessed by strength or expansion measurements. For the cement with highest alkali and tricalcium aluminate content, increasing the SO3 content from 3.0% to 3.6% delayed the onset of strength drop; however, at 360 days the strength drop experienced by both doping levels was the same.

El tema de esta investigación se centra en el diseño y la evaluación de concreto elaborado a partir de aguas residuales domesticas tratadas mediante dos tipos diferentes de procesos biológicos (lodos activados y humedales artificiales) como alternativa al uso de agua potable en Lima Metropolitana. Actualmente, se conoce que la disponibilidad de agua potable en la ciudad de Lima no es abundante y las proyecciones a futuro indican que la demanda por el incremento poblacional generará problemas de escasez de este recurso. Debido a ello, es importante tomar medidas al respecto que permitan ahorrar este valioso recurso en industrias que consumen más agua como la de producción de concreto. Ante esta problemática, el uso de aguas residuales tratadas se muestra como una posible opción para reemplazar al agua potable en la elaboración de concreto. La presente tesis se desarrolla en 7 capítulos detallados a continuación: En Capítulo 1, se presenta el marco teórico, el cual incluye las principales bases teóricas utilizadas. En el Capítulo 2 se definen las características de los materiales empleados y la metodología de la investigación. En el Capítulo 3 se muestran los resultados de los ensayos y evaluaciones realizadas. En el Capítulo 4 se realiza la verificación de los resultados y luego la discusión de los mismos. En el Capítulo 5 se presentan las conclusiones y en el Capítulo 6 se detallan las recomendaciones. Finalmente, en el Capítulo 7 se muestran las referencias de otras investigaciones citadas en la presente Tesis y, adicionalmente, se muestran los anexos de la investigación. Al final de la investigación, se determinó que el concreto elaborado con aguas residuales domesticas tratadas mediante el proceso biológico de lodos activados si es una alternativa factible al uso de agua potable al presentar resultados similares a los del grupo de control. / The subject of this research focuses on the design and evaluation of concrete made from domestic wastewater treated by two different types of biological processes (activated sludge and artificial wetlands) as an alternative to the use of drinking water in the city of Lima. Currently, it is known that the availability of drinking water in the city of Lima is not abundant and future projections indicate that the demand due to population increase will generate water shortage problems. Because of this, it is important to take measures to save this valuable resource in industries that consume more water, such as concrete production. Given this problem, the use of treated wastewater is shown as a possible option to replace drinking water in concrete production. This thesis is developed in 7 chapters detailed below: In Chapter 1, the theoretical framework is presented, which includes the main theoretical bases used. Chapter 2 defines the characteristics of the materials used and the methodology of this investigation. Chapter 3 shows the results of the tests and evaluations carried out. In Chapter 4, the results are verified and then discussed. In Chapter 5 the conclusions are presented and in Chapter 6 the recommendations are detailed. Chapter 7 shows the references of other research cited in this Thesis and, finally the annexes of the thesis are shown. At the end of the investigation, it was determined that concrete made with domestic wastewater treated by the biological process of activated sludge is a feasible alternative to the use of potable water when presenting results similar to those of the control group. / Tesis

Geopolymers (GPs) are a new class of inorganic polymers that have been considered as good candidate materials for many applications, including fire resistant and refractory panels, adhesives, and coatings, waste encapsulation material, etc. The aim of this study is to establish relationship between structural and mechanical properties of geopolymers with different chemical compositions. The metakaolin-based geopolymers were prepared by mechanically mixing metakaolin and alkaline silicate aqueous solutions to obtain samples with SiO2/Al2O3 molar ratio that ranges from 2.5 to 5, and Na/Al or K/Al atomic ratios equal to 1. Geopolymer samples were cured in a laboratory oven at 80°C and ambient pressure for different times in the sealed containers. Structural characterization of the samples with different chemical compositions was carried out using X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Nuclear Magnetic-Resonance (NMR) spectroscopy and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). The mechanical characterization included Micro-indentation, Vickers indentation and fracture toughness measurement, as well as compressive testing. It was found that structure and mechanical properties of GPs depend on their chemical composition. The Na-GPs with ratio 3 have a highest compressive strength and Young‘s modulus of 39 MPa and 7.9 GPa, respectively. The results of mechanical testing are discussed in more detail in this thesis and linked to structural properties of processed geopolymers.

Accelerating and mineral admixtures, one of the major ingredients in concrete, are primarily used to modify the properties of both fresh and hardened concrete. Within the scope of this thesis, there were four types of cements having almost identical fineness. The mixes were prepared by using natural pozzolan, blast furnace slag and limestone conforming to TS EN 197-1 and two types of accelerating admixtures, namely triethanolamine (TEA) and calcium formate (CF). The effect of set accelerating admixtures with different cement types on the setting time, water demand and compressive strength has been analyzed by an experimental study in accordance with relevant ASTM standards. Finally, it has been observed that the amount of the accelerating admixtures used is suitable because of their effects on the water demand, setting and strength. Due to the density difference of mineral admixtures and clinker, the normal consistency and 110% flow water content should be considered on a volumetric basis. The effectiveness of the accelerating admixtures on the normal consistency water, 110% flow water content and setting time depends on the type and amount of mineral admixtures. The increase caused by CF in the normal consistency and 110% flow water content is higher than that by TEA. The accelerating effect of TEA and CF on the setting times is more significant for cements incorporating 6% mineral admixture. The effects of accelerating admixtures on the compressive strength change with specimen age, type and amount of mineral admixtures. Generally, for all cement types, early age compressive strengths increase with the increase of TEA, however long term strengths increase by increasing CF.

Cement production which is one of the most energy intensive industries plays a significant role in emitting the greenhouse gases. Blended cement production by supplementary cementitious materials such as fly ash, ground granulated blast furnace slag and natural pozzolan is one of the smart approaches to decrease energy and ecology related concerns about the production. Fly ash has been used as a substance to produce blended cements for years, but bottom ash, its coarser counterpart, has not been utilized due to its lower pozzolanic properties. This thesis study aims to evaluate the laboratory performance of blended cements, which are produced both by fly ash and bottom ash. Fly ash and bottom ash obtained from Seyit&ouml / mer Power Plant were used to produce blended cements in 10, 20, 30 and 40% by mass as clinker replacement materials. One ordinary portland cement and eight blended cements were produced in the laboratory. Portland cement was ground 120 min to have a Blaine value of 3500&plusmn / 100 cm2/g. This duration was kept constant in the production of bottom ash cements. Fly ash cements were produced by blending of laboratory produced portland cement and fly ash. Then, 2, 7, 28 and 90 day compressive strengths, normal consistencies, soundness and time of settings of cements were determined. It was found that blended fly ash and bottom ash cements gave comparable strength results at 28 day curing age for 10% and 20% replacement. Properties of blended cements were observed to meet the requirements specified by Turkish and American standards.

This research investigates complete recycling and utilization of waste concrete to produce new structural concrete through geopolymerization. The investigation was conducted through both macro-and micro/nano-scale studies. First the geopolymer paste synthesized using a mixture of waste concrete fines (WCF) and class F fly ash (FA) as the source material and a mixture of NaOH solution (N) and Na2SiO3 solution (SS) as the alkaline activating agent was studied. Various NaOH concentrations, SS/N ratios, and WCF contents were used to produce geopolymer paste specimens in order to study their effect on the properties of the geopolymer paste. Uniaxial compression tests were conducted to measure the strength of the geopolymer paste specimens. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), and Fourier transform infrared spectroscopy (FTIR) analyses were performed to investigate the micro/nano-structure, morphology and phase/surface elemental compositions of the geopolymer paste and the effect of calcium (Ca) on them. The results indicate that by using 10 M NaOH solution, SS/N of 2 and 50% WCF, the highest geopolymer paste strength can be obtained. Second, the interfacial transition zones (ITZs) between geopolymer (GP) and recycled aggregates (RA) were studied. Considering that RA consist of the stone particles and the attached paste/mortar from the original ordinary Portland cement (OPC) concrete, both the ITZs between GP and natural aggregate (NA) and those between GP and residual OPC paste/mortar (ROPM) were studied. For comparison, the ITZs between OPC paste and NA and those between OPC paste and ROPM were also investigated. 4-point bending tests were conducted to measure the bonding strength of the different types of ITZs at water to solid (W/S) ratio of 0.30, 0.35 and 0.40 for the geopolymer and OPC pastes after 7 and 14 days curing, respectively. SEM imaging was performed to investigate the microstructure of the ITZs. The results indicate that when NA is used, the bonding strength of both the GP-NA and OPC-NA ITZs decreases with higher water to solid (W/S) ratio. When ROPM is used, higher W/S ratio leads to smaller bonding strength for the GP-ROPM ITZ but greater bonding strength for the OPC-ROPM ITZ. Based on the measured bonding strength values for NA- and ROPM-based ITZs, the bonding strength of the GP-RA and OPC-RA ITZs was estimated by considering the average area coverage of ROPM on the RA surface. The GP-RA ITZ has the highest bonding strength among the different ITZs, implying the great potential for utilizing waste concrete (both the WCF and the RA) to produce geopolymer concrete. Third, based on the studies on geopolymer paste and ITZs, geopolymer concrete (GPC) was produced and studied using WCF and FA as the cementitious material and RA as the aggregate. For comparison, GPC using NA was also produced and studied at similar conditions. Various NaOH concentrations, SS/N ratios, and cement (WCF and FA) to aggregate (C/A) ratios were used to produce GPC specimens in order to study their effect on the behavior of GPC. The effect of water content and curing temperature on the initial setting time and 7-day unconfined compressive strength (UCS) of the GPC was also studied. The results show that the GPC produced from RA has higher UCS than the GPC from NA at both room curing temperature and 35°C curing temperature. Based on this study, it can be concluded that waste concrete can be completely recycled and used to produce new structural concrete based on the geopolymerization technology. Fourth, considering that the Si/Al and Na/Al ratios have great effect on the geopolymerization process and the properties of the final geopolymer product, a study was conducted on copper mine tailings (MT)-based geopolymer containing different amount of aluminum sludge (AS). The results indicate that by including AS and utilizing appropriate amount of NaOH, the UCS can be increased significantly. The main reason is because the addition of AS along with utilization of appropriate amount of NaOH makes both the Si/Al and Na/Al ratios reach the optimum values for geopolymerization, leading to higher degree of geopolymerization and more compact geopolymer microstructure. It is noted that although this study is not directly on waste concrete, it provides useful information for optimizing the design on complete recycling and utilization of waste concrete to produce new GPC. Finally, to better understand the effect of Ca on the geopolymerization process and the properties of geopolymer, molecular dynamics (MD) simulations were performed on geopolymer at different Ca contents. The molecular models at different Ca contents were constructed and uniaxial compression test was then performed on the numerical specimens. The results indicate that MD simulation is an effective tool for studying the effect of Ca on the properties of geopolymer at nano-scale.

Παρουσιάζεται μία εναλλακτική μέθοδος έμμεσου προσδιορισμού της θλιπτικής (μονοαξονικής) αντοχής των πετρωμάτων με βάση μία τροποποιημένη μορφή της δοκιμής επιφανειακής διείσδυσης. Χρησιμοποιήθηκαν δύο έμβολα με σφαιρικά άκρα με ακτίνες 1,585mm και 5mm. Τα αποτελέσματα συγκρίνονται με αυτά της διαδεδομένης μεθόδου σημειακής φόρτισης. Αποδεικνύεται πειραματικά ότι για τα τρία ασβεστολιθικά πετρώματα που μελετήθηκαν, η δοκιμή επιφανειακής διείσδυσης δίνει σημαντικά ακριβέστερα αποτελέσματα και μπορεί να εφαρμοστεί τόσο στο εργαστήριο όσο και στο πεδίο. Επιπλέον αποδείχθηκε ότι η δοκιμή προσφέρει την δυνατότητα μη καταστροφικού ελέγχου των δοκιμίων ιδιαίτερα με το άκρο με την μικρή σφαίρα. / An alternative indirect method to determine the unconfined compressive strength of rocks based on a modified Indentation (Punch) test is presented. Two indenters with spherical tips of 1.585mm and 5mm were used. The results are compared with those of the Point Load test that is commonly used in practice. It is experimentally proved that for the three calcareous rock materials tested, this method gives significantly more accurate results and can be applied to the laboratory as well as in situ. In addition it has been proved that this test offers the possibility of non destructive testing especially when the small spherical tip is used.

Betonas – viena seniausių statybinių medžiagų pasaulyje. Netgi Egipto piramidžių perdangos yra betoninės (t.y. 3600 metų p.m.e.), dalis Didžiosios Kinijos sienos yra betoninė (300 metų p.m.e.), keletas statinių Indijoje, Romoje ir kitose vietose. Šiuo metu pagrindinės šiuolaikinės statybinės medžiagos yra betonas ir gelžbetonis. Pastaraisiais metais betono gamyba siekia apie 6 milijardus m3 ir jokios kitos statybinės medžiagos pasaulyje tokiais kiekiais nėra gaminamos. Betonas ir gelžbetonis – labai plačiai naudojama kelių, hidrotechnikos statinių, požeminių tunelių, namų ir t.t. statybai. Lietuvoje įvairiais laikotarpiais buvo statomi įvairūs HTS. Svarbesnėms jų priklauso užtvankos, kurių paskirtis užtvenkti upę, upelį ar kanalą. Daugiausia šalyje yra pastatyta žemės užtvankų su betoninėmis ir gelžbetoninėmis konstrukcijomis. Kupiškio rajone yra 14 žemių užtvankų, įtrauktų į potencialiai pavojingų hidrotechnikos statinių sąrašą (Lietuvos, 2001). Daugiausia jų pastatyta 1973 m.- 1986 m. Šiuo laikotarpiu pastatyta 10 užtvankų. Didžiausias patvankos aukštis 13 m. Dominuoja šachtinio tipo perteklinio vandens pralaidos, iš 14 tik viena slenkstinė. Hidrotechnikos statiniai naudojami sudėtingomis sąlygomis. Juos veikia atmosfera, vandens aplinka, ledas, ižas, žema temperatūra, atmosferiniai krituliai, vėjas, saulės radiacija ir kt. Daugumoje tirtų hidrotechnikos statinių vyksta paviršinė ir vidinė korozija, pastebimi plyšiai, atskirų elementų nuosėdžiai. Hidrotechnikos statinių... [toliau žr. visą tekstą] / There are many hydraulic structures in Lithuania and in most of them concrete and reinforced concrete is used. Erosion in most concrete and reinforced concrete structures has been started already and it is very important to do research, investigations and determine stage of corrosion. The main task of this work is to determine the state of earth dams’ concrete and reinforced concrete structures, as well as to determinate durability and compressive strength of concrete. In Kupiškis district 5 earth dams were researched and technical conditions were determined using non-destructive and destructive methods. Achieved results. It was determined that in 52% of investigated concrete constructions concrete compressive strength was less than in those shown in technical project. By using scale o defentiveness is determited that 16 % of researched constructions are in good condition, 38 % - in middle stage and 46 % are in very bad stage.