• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 2
  • 1
  • Tagged with
  • 9
  • 9
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of bond strength in hydraulic lime mortared brickwork

Zhou, Zhaoxia January 2012 (has links)
The first recorded use of hydraulic lime in construction can be traced back to at least two thousand years ago. Hydraulic lime, produced through either adding pozzolanic materials or calcining clay containing limestone, unlike air lime, can set and harden under water, developing strength through initial hydration reaction and subsequent carbonation. After WWII Portland cement mortars had almost completely replaced lime based mortars in modern construction. However, through conservation and specialist construction the benefits of hydraulic lime are becoming increasingly recognised. To support wider usage of these mortars there is a need for systematic study on the mortar properties and structural performance of lime mortared masonry. This thesis presents findings from a research programme conducted to develop understanding of the mechanical properties of natural hydraulic lime (NHL) mortared brickwork. The work focussed on the flexural strength of NHL mortared brickwork. A variety of material and environmental factors, including lime grade and supplier, mix proportion, sand type and age, have been investigated. In addition the research has completed an in-depth study on the influence of brick absorption characteristics on bond development. The two methods of flexural wall panel and bond wrench testing to establish flexural strength have been compared. In addition to flexural strength, initial shear strength and compressive strength of brickwork has also been investigated. A greater understanding of NHL mortared brickwork performance has been developed through this work. Performance of the brickwork has been related to properties of constituent materials and environmental factors. Recommendations for design performance of materials have been provided.
2

Filling Method Implementing Hydraulic Lime for Reusing Mine Tailings and Improve Sustainability in Conventional Peruvian Underground Mines

Altamirano-Soto, Pablo, Supa-Urrutia, Jorge, Pehovaz-Alvarez, Humbero, Raymundo, Carlos, Mamani-Macedo, Nestor, Dominguez, Francisco 01 January 2020 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Mining in Peru has existed for several decades, and for several years, there has been no proper environmental management of the impact of this activity on the environment and society in general, whether it be gas emissions, the presence of acidic water, or the generation of mining tailings. One of the most prominent examples involve mine tailings; these are by-products of mining processing plants and are stored in a dam known as a tailings dam. Like any extraction activity, mining generates large amounts of waste material that could become potential risks to the environment and society. Using hydraulic fills, the mine tailings contained in tailings dams could be reused. These fills seek to decrease the volume of stored tailings to prevent any future dam collapses, as observed in Brazil with the Vale mining company, where its tailings dam collapsed and caused more than 200 deaths.
3

Karbonatisering av modernt kalkputs med hydraulisk inblandning / Carbonation of modern lime mortar whith hydraulic mix

Hossainy, Shokoufeh January 2022 (has links)
Kalkbruk har använts i tusentals år som byggnadsmaterial i byggkonstruktioner.Senare, under 1800-talet, började en variant av hydraulisk kalk, kallad vattenkalk, att användas. Det hydrauliska kalkbruk som används idag i byggnadskonstruktioner såsom fasadmurning, putsning, fogning av murverk har blivit mer vanligt att använda i stället för cementbruk, eftersom det finns fler fördelar med kalkbruk som har hydraulisk inblandning än med det cementbaserade bruket. Kalkbruk används särskilt till renovering av äldre byggnader där kalk eller hydrauliska kalkbruk sedan tidigare har använts. Det hydrauliska kalkbruket utvinns från kalksten men den hydrauliska kalk som bränns av oren kalksten kallas naturligt hydraulisk kalk och tillverkas av Saint-Astier i Frankrike. Kalken har inga hydrauliska tillsatsmedel som cement, gips, flygaska eller puzzolana material. Enligt SS-EN 459–1:2015 klassas den naturliga hydrauliska kalken efter hållfasthet, och tillverkas i tre klasser: NHL 2, NHL 3,5 och NHL 5.Naturliga hydraulisk kalkbruken har för- och nackdelar, Produktens fördelar avses av de som använder bruket överväga nackdelarna. NHL-bruk passar bättre i fuktiga miljöer, det kan återanvändas, är miljövänligt, rent och naturligt, tål mer påfrestningar och driftstiden är mindre. Bakgrunden till arbetet är att NHL-bruks användning har blivit allt vanligare under de senaste decennier vid renovering av äldre kalkputsade byggnader. Väderförhållande och temperatur är av stor betydelse för att ha ett hållbart resultat inom kalkputsarbetet och således kan orsaka en viss försening i tidplaner och byggtider. Emedan nya metoder ska utreda och utvärderas för att få det optimala resultatet.Litteraturstudier, laboratorietester och intervjuer har använts för att kunna nå examensarbetets mål. Flera små tester har gjorts för att undersöka karbonatiseringsprocessen under olika väderförhållandet. Testerna visar att det naturliga kalkbruket karbonatiserar bättre och snabbare i en fuktig miljön, vilket passar det klimat som råder i Norden och i kustklimat. Det naturliga hydrauliska kalkbruket är dock ett material som kräver mer erfarenhet för att kunna uppnå bästa resultat för detta ändamål. Att vädret har stort betydelse för karbonatiseringsprocessen är ett resultat som framkommit i tidigare studier och forskning, vilket också de tester som utförts under detta arbete visar. Arbete med hydrauliska kalkbruk bör därför ske under perioder som passar kalkputsarbetet för att det ska hinna karbonatisera innan det riskerar att utsättas för påfrestning. En lämplig period är därför maj till oktober som den bästa perioder för kalkputsarbete.Naturliga hydrauliska kalkbruk utvecklas kontinuerligt, vilket kan bidra till att de kan ersätta det cementbaserade kalkbruket i framtiden utan några negativa konsekvenser såsom frostsprängning och låg hållfasthet. / The aim of the work was to analyze the carbonation of modern lime plaster with hydraulic mixing. Requirements for a certain carbonation can cause delays in schedules and construction time. The hydraulic lime mill is obtained from limestone, while the hydraulic lime burned by crude limestone is called natural hydraulic lime, which is manufactured by Saint-Astier in France. the lime has no hydraulic additives such as cement, plaster, fly ash or puzzolana materials. Natural Hydraulic lime mills fit better in the humid environment, it can be reused, is environmentally friendly, is clean and natural, can withstand more stress and the operating time is less. During the work, a study visit was made to an ongoing work process at Elin Wägnerskolan in Växjö, which Karlssons fasad AB had taken over the restoration responsibility. Interviews were conducted with one of the players at Målarkalk AB, which is one of the largest suppliers in the lime industry and project manager at Karlssons Fasad AB. Several small tests have been done to see the carbonation process under different weather conditions. The tests show that natural lime farming carbonates better and faster in a humid environment, which suits the Nordic countries and coastal environments. Natural hydraulic lime mills are well suited to replace cement-based mortars in the future without any negative impact.
4

Properties and performance of lime mortars for conservation : the role of binder chemistry and curing regime

Figueiredo, Cristiano January 2018 (has links)
The selection of mortar for conservation of historic and heritage buildings can be challenging. Achieving compatibility with the historic fabric, durability and efficient use of materials within a practical timeframe often requires the use of hydraulic lime-based mortars which set more rapidly than the more traditional air lime mortars. These are considered to be more compatible with historic fabric than cement-based mortars, although, due to the modern production techniques and their natural variability, a deeper knowledge of their chemical and physical properties is needed to minimise damage due to incompatibility and make the decision process easier and safer. Natural hydraulic lime (NHL) binders are currently classified under EN 459-1:2015 in three designations, NHL 2, NHL 3.5 and NHL5, with the suffix representing the minimum compressive strength (in MPa) of a standard mortar mix at 28 days. The performance of NHL binders, manufactured by burning a naturally impure limestone, can be difficult to predict due to the inherent variability of both their physical and chemical characteristics. At the same time, the tolerance values for each classification allow for binders with significantly compressive strength differences to be classified by the same designation. The main aim of this research was to study a range of NHL binders, understand and quantify the variability of their characteristics and to establish how these properties influence the performance of mortars cured under standard and simulated weather conditions. In the first stage of the project, a selection of NHL binders from different origins and distinct designation were rigorously examined through physical, chemical and mineralogical characterisation to elucidate surface area, particle size distribution, oxide composition and crystalline phase composition. The characteristics of the binders were found to vary greatly, particularly amongst binders from the same classification and distinct origins, and in one particular case even from the same origin. A change of properties over time was also identified, binders manufactured in different years could have very different properties, even though, as far as could be ascertained from the packaging, it was the same product. Starting from a selection of 11 NHLs and 1 hydrated lime, the next step involved the manufacture of mortar samples using a sand aggregate appropriate for a conservation mortar with 1:2 ratio (binder:aggregate by volume). Sufficient water was added to produce a spread by flow table of 165 ± 10 mm. These mortars were cured under standard conditions and for a smaller group of binders under simulated weather conditions. For the standard cure conditions, the properties of the binders were compared to the physical properties in terms of strength (from 7 to 1080 days), porosity, capillary water absorption, water vapour permeability and freeze-thaw resistance of mortars made with the binders. The carbonation was also studied by phenolphthalein stain after all the flexural strength tests and after 2 years by XRD. The mortars under climate simulation were studied in terms of mechanical properties (up to 360 days) and carbonation. For comparison purposes, cement-lime (1:1:6 and 1:2:9 cement:lime:aggregate volumetric ratio), lime-metakaolin (MK) (with MK addition of 5, 10 and 20% of the lime mass) and lime putty mortars were manufactured to the same workability as the NHL mortars. These were studied in terms of strength up to 360 days, porosity and water absorption by capillarity action. The strength of the studied mortars does not follow the classification of the binders, with one binder, specified as NHL 2, resulting in a stronger mortar than another binder specified as NHL 5, and one NHL 3.5 mortar surpassing all the other mortars in terms of mechanical strength. The mechanical strength was found to correlate with the hydraulic phases, alite and belite, identified within the binders. The relative long-term performance of the mortars manufactured with the different binders can therefore be predicted based on the mineral properties rather than the standard classification. Pore related properties, such as water vapour permeability and water absorption by capillarity, were found to be related to the water/binder ratio of the NHL mortars. Later in the project, using the standard cured mortars data, a model was developed to predict compressive strength based on the proportion of crystalline phases present in the mortars, the surface area and the water/binder ratio. This model, applied to the studied mortars, was found to predict, with low error, the measured performance of the mortars, meaning that the model can be used as tool to predict mortar strength. The outcomes of this thesis demonstrated that with sufficient knowledge of the underlying chemistry of NHL binders, it is possible to establish the relative performance of mortars, thus making the decision on which binder to use easier and safer for the historic fabric.
5

Hydrauliskt kalkbruk : Komparativ studie av bindemedlets inverkan på murverkets egenskaper / Hydraulic lime mortar : A comparative study of the properties of mortar binders

Boström, Dan January 2020 (has links)
Hydrauliskt kalk är ett bindemedel i mur- och putsbruk som idag främst används vid restaureringar. Likt bruk med cement som bindemedel härdar hydrauliskt kalkbruk även under vatten. Hydrauliskt kalkbruk når en högre hållfasthet än luftkalkbruk men lägre än cementbruk. Enligt EU:s avfallsdirektiv ska återanvändning eller materialåtervinning ske av merparten av icke-farligt avfall en avfallsgrupp till vilket tegel och murbruk hör. Likt luftkalkbruk kan tegel murat med hydrauliskt kalkbruk rensas från bruket och sedan återbrukas i nyproduktion. Denna möjlighet tillsammans med god hållfasthet och de hydrauliska egenskaperna gör det intressant att titta på hydrauliskt kalkbruk som ett alternativ till de idag vanligt förekommande bruken på marknaden. Syftet med denna rapport är att redogöra för egenskaperna hos hydrauliskt kalkbruk och jämföra dessa med de cementbaserade bruk som framförnallt används idag. Typiska faktorer som påverkar valet av murbruk är ekonomi, funktion, tillgång, hållfasthet samt fukttekniska och andra byggnadsfysikaliska egenskaper. Arbetet utfördes genom litteraturstudie samt genom ett praktiskt försök genom provning av den kapillära absorptionsförmågan. Provningen utfördes för att bestämma fukttekniska egenskaper hos bruket och se om de liknar det diffusionsöppna luftkalkbruket. Försöket utfördes med hydrauliskt kalkbruk samt två referensbruk i tegelmurar. En litteraturstudie genomfördes för att ingående kartlägga egenskaperna hos hydrauliskt kalkbruk. Brukets sammansättning studerades och uppbyggnadens påverkan på brukets fuktbetingelser analyserades. Denna analys låg till grund för genomförandet av absorptionsproven. De viktigaste egenskaperna vid val av bruk sammanställs även för andra, typiskt förekommande, brukssorter och jämförs med det hydrauliska kalkbruket. Vid proven simulerades slagregn mot fasaden genom att en testplatta fästes vid murverkets yta. Genom ett stigrör anslutet till plattan tillfördes vatten varpå murens absorption skulle bestämmas. Resultat från litteraturstudien visar på god hållfasthet och god tillgång till råvara samt indikerar miljömässiga fördelar jämfört med cementbaserade bruk. Priset och kunskapsbrist hos projektörer och entreprenörer ligger idag i den andra vågskålen, till det hydrauliska kalkbrukets nackdel.Provningen resulterade tyvärr inte i någon användbar data. Problem med tätning mellan utrustningen och murverket ledde till ofullständiga och osäkra resultat. Någon slutsats om absorptionen hos det hydrauliska kalkbruket jämte murcement- och kalkcementbruk i oliksugande tegel kan således inte dras. Ytterligare försök vore intressanta, under rätt för-utsättningar, genom absorptionstest eller genom uttorkningsprov för att bestämma det hydrauliska kalkbrukets fuktegeskaper. De allt större miljömässiga kraven som ställs i samhället och i byggbranchen kan öppna uppför ett ökat användande av hydrauliskt kalkbruk i framtiden. / Much like mortars with cement binders mortar with hydraulic lime hardens in contact with water. Eventually, as the process of carbonation starts, the hardening will be more similar to that of non-hydraulic lime. The compresive strength of hydraulic mortar lies inbetween the weaker non-hydraulic lime and the stronger mortars with Porland cement as binder. According to the european union directive 2006/12/EC on waste 70% of all non-hazardous waste should be reused, recykled or in other ways material recovered. Bricks layed with lime binders can be scraped of hardened mortar and reused in new buildings. This trait together with the strengthand hydraulic properties of hydraulic lime opens up for the mortar as a more widely used alternative to the more commonly used mortars of today containing cement as binders. This project aims to give a thorough presentation of the properties of hydraulic lime and give a comparison with mortars containing Portland cement as binder. Price and access together with strength and functionare all traits that can be of interest in regard to properties of mortar. By performing absorption test on hydraulic lime mortar together with two cement based mortars the moisture movement through mortar joints are compared. The tests are perfomed on multiple sample walls consisting of three different facade clay bricks with low, normal and high suction after 28 days of curing. A litterature study has been performed in support of the experimental study in wich the structure of hydraulic lime has been analysed. The absorption and desorption and it’s connection to the porus structure of mortar is investigeted. This is the basis for the absorption tests performedby the use of test plates applied to the masonry. Wind driven rain is simulated with the use of RILEM-tubes connected to the test plates afterwhich the absorption can be determined. Unfortunaly the experiment did not result in conclusive data because of problems with the equipment. It was not possible to achieve a tight seal between the equipment and the masonry so water leaked out during testing. As a result it was not possible to draw any conclusions regarding the moisture properties of hydraulic lime. Future testing should be done in better conditons or by using another method.
6

Vliv mineralogického složení suroviny na vznik fází při výpalu hydraulického vápna a přírodního cementu / Influence of the mineralogical composition of raw material on phases formed during the burning of hydraulic lime and natural cement

Kozlovcev, Petr January 2018 (has links)
Natural hydraulic lime and natural cement have been used in the building industry for centuries. These inorganic hydraulic binders are called "traditional" or "alternative" because they can, in some cases, substitute modern Portland cement. The recent increased interest in these binders is due not only to their use in restoration practices, but also because their production and use is less energetically demanding than in modern cements. Historically, many types of hydraulic binders were produced in the regions of Bohemia and Moravia. However, much information has been lost about their manufacturing process, which raw materials were used, and we are uncertain of the exact character and properties of the burned material. To date, studies have only addressed the impact of the chemical composition of raw material on the parameters of the burned material - all this is well known for Portland cement, much less for other types of hydraulic binders. The aim of this dissertation was to study the various types of raw materials (limestone containing non- carbon admixtures) and to understand the characteristics of their respective hydraulic lime and natural cement. This was done by analyzing the impact of conditions (highest achieved burning temperature and time of burning) and the mineral and chemical...
7

Možnosti využití odkalů po vypírce vápence / The possibilities of use of sludges from limestone wash

Švec, Jiří January 2011 (has links)
In modern point of view of waste management is desirable to effectively process the grates possible amount of wastes. Sediments from cleaning of mined lime stones contains a lot of clay components, but there is also indispensable share of soft calcite. This composition makes these sediments a promising material for preparation of hydraulic binders. Production of common hydraulic binders, especially Portland cement, is very energy-intensive plus loads environment with considerable amount of combustion gases, therefore it is necessary to explore possibilities of alternative low - energy binders production and usage.
8

Příprava a vlastnosti románského cementu / Preparation and Properties of Roman Cement

Opravil, Tomáš January 2009 (has links)
The Ph.D. thesis deals with the preparation of highly hydraulic binders based on roman cement. Roman cement (natural cement) is recently not available on the market due to uneconomic production of such a specific binder. On the other hand there is a big lack of information on this hydraulic binder. These results in failure in meeting the basic principle of modern approaches to restoration of historical buildings or monuments made of such kind of materials, which is such, that the materials used for restoration should be compatible with original material. Recognition of the processes of roman cement preparation based on progressive methods of study can provide substantial information for more efficient raw material selection or even for nontraditional utilization, for example for artworks. This work hence is aimed at studying and selection of traditional natural as well as nontraditional raw materials such as clay. This work also studies the preparation of highly hydraulic binders based on roman cement and the kinetics of burning and hydration processes
9

Vliv etherů celulózy na vlastnosti hydraulického vápna / Effect of cellulose ethers on properties of hydraulic lime

Skoupil, Jakub January 2019 (has links)
This diploma thesis deals with the study of the influence of cellulose ethers on the properties of hydraulic lime mortars. The availability and price of cellulose ethers in the industrial market is very favorable, but we can´t meet with studies using cellulose ethers in building materials, where lime is used as a binder. Cellulose ethers are commonly used as thickening agents in cement-based materials. The purpose of this diploma thesis is to review if cellulose ethers are appropriate for use in hydraulic lime mortars, either as water retention agents that contribute by water retention to better hydration of hydraulic binder components or to affect the properties of mortar in the fresh state. The theoretical part is dedicated to cellulose ethers, especially their production and how they influence the properties of building materials. In the practical part, the thesis deals with the influence of the dose of five different types of cellulose ethers on the properties of hydraulic lime. The properties in the fresh state and the physical-mechanical properties of mortars were monitored over time.

Page generated in 0.2126 seconds