Dissertations / Theses on the topic 'Fly ash/GGBS Mixture'

With the pressure on the construction industry to lower CO2 emissions it has become increasingly important to utilise materials that supplement Portland cement (CEM I) in concrete. These include additions such as ground granulated blast-furnace slag (GGBS) and fly ash, which have found greater use due to the benefits they provide to many properties of the material (in addition to environmental impact). While studies have investigated these materials in binary blends with CEM I, little work has examined the effect of combining materials in ternary blend concretes. A wide-ranging study was, therefore, set up to examine this for the range of more commonly available additions. This thesis reports on research carried out to investigate the effects of cement combinations based on CEM I / GGBS with either fly ash or limestone. The experimental programme investigated these materials in both paste and concrete and covered fresh properties, compressive strength, permeation and durability properties (using standard water curing for the latter three) and considered, for the hardened properties, how these may be balanced with environmental cost. The mixes covered a range of w/c ratios (0.35. 0.50 and 0.65), which was the main basis of comparison, and combinations of CEM I with GGBS (at levels of 35%, 55% and 75%), and fly ash and LS part-replacing this (at levels of 10 to 20 % and 10 to 35% respectively), after consideration of the relevant standards and related research. The initial phase of the study examined the characteristics of the materials, which indicated that they conformed to appropriate standards and were typical of those used in the application. Studies with cement paste (0.35 and 0.50 w/c ratio) indicated that there were reductions in water demand with the use of addition materials (binary and ternary) compared to CEM I. The setting times of the cement pastes were also affected, generally increasing with GGBS level for the binary mixes, although the effect was influenced by w/c ratio. Whilst fly ash and limestone delayed setting at the higher w/c ratio, the opposite occurred as this reduced, compared to the binary mixes. It was also found that the yield stress increased with GGBS level and further with the addition of ternary materials (particularly limestone) compared to CEM I. The superplastiser (SP) dosage requirement in concrete was found to decrease with increasing w/c ratio, and ternary additions reduced this compared to binary and CEM I concrete with the effect most noticeable at low w/c ratio. Early strength development was less than CEM I for binary concretes and differences increased with GGBS level. Improvements with the introduction of fly ash compared to the binary concretes were noted with increasing GGBS levels and w/c ratio. In general, the addition of LS gave reduced early strength for all concretes. Although at the 35% GGBS level binary concretes achieved similar strength to those of CEM I, the others generally gave reductions at all ages to 180 days, with differences increasing with GGBS level. However, with increasing w/c ratio and GGBS level improved strength development of ternary concretes, was noted compared to those of CEM I from 28 days. Permeation (absorption (initial surface absorption and sorptivity) and permeability (water penetration and air permeability)) and durability properties (accelerated carbonation and chloride ingress) of the test concrete were also investigated. At 28 days, for low GGBS levels, the binary concretes gave reduced absorption properties compared to CEM I, while the reverse occurred at high level. The effect of the ternary concretes gave further improvements at the lower GGBS levels and with increasing w/c ratio and curing time compared to CEM I. At the higher GGBS level the effect of the ternary additions was less noticeable but, in the case of limestone, improvements were still seen with increasing w/c ratio compared to CEM I. Similar effects were noted for the sorptivity results. The air permeability results gave higher values at 28 days for the binary and ternary concretes compared to CEM I, but significant improvements in the long-term at the lower GGBS level across the range of w/c ratios compared to CEM I concrete. Similar trends were found with water penetration tests. Accelerated carbonation increased with GGBS level for binary concretes compared to CEM I. These differences increased further with the introduction of fly ash and LS, particularly the former. In contrast rapid chloride tests indicated improvements with increasing GGBS levels compared to CEM I and further benefits with the inclusion of fly ash and limestone. Embodied CO2 (ECO2) was calculated based on published British Cement Association (BCA) values for each component of the mix and was shown to reduce with increasing w/c ratio and addition level in concrete. For concrete of an equal strength of 40N/mm2 the ECO2 could be almost halved (reduced from 343 kg/m3 for the CEM I to 176 kg/m3) for the ternary concretes at higher GGBS levels. These combination concretes also gave enhanced durability with regard to chloride ingress and at the lower w/c ratio comparable properties to CEM I in the case of carbonation. Overall, the results suggest that there is potential for ternary concretes to be used in the concrete industry given their ability to reduce ECO2, without compromising strength, permeation and durability properties of concrete.

Master of Science
Department of Civil Engineering
Kyle Riding
Corrosion of reinforcing steel is one of the most common and serious causes of reinforced concrete deterioration. While corrosion is normally inhibited by a passive layer that develops around the reinforcing steel due to the high pH environment of the surrounding concrete, chlorides will break down this protective layer, leading to reinforcement corrosion. Decreasing the diffusivity of the concrete would slow the ingress of chlorides into concrete, and is one of the most economical ways to increase the concrete service life. Optimized concrete mixtures blending portland cement and supplementary cementing materials (SCMs) have become popular throughout the construction industry as a method of improving both fresh and long-term concrete properties such as workability, strength and porosity. It has been shown that use of Class F fly ash, silica fume and ground granulated blast furnace slag (GGBFS) in binary concrete mixture blends can result in a significant reduction in concrete diffusivity. This study investigates the ability of Class C fly ash and ternary concrete mixture blends to also aid in diffusivity reduction. In order to study the effect of incorporation of SCMs into concrete, mixtures containing Class C and Class F fly ash, silica fume and GGBFS were tested following the ASTM C 1556 procedures to measure the concrete’s apparent chloride diffusivity. Structure life cycles were modeled using the measured apparent chloride diffusivities with two finite-difference based life-cycle analysis software packages. To determine whether a correlation between diffusivity and deterioration due to freezing and thawing exists, samples were also tested for their ability to resist deterioration from freezing and thawing cycles using a modified ASTM C 666 Procedure B test. Results show that the use of Class C fly ash yields some service life improvements as compared to the portland cement control mixtures, while ternary mixture blends performed significantly better than the control mixture and equal to or better than the binary SCM mixtures tested. Freeze-thaw tests showed all mixtures to be equally resistant to deterioration due to freezing and thawing.

In 2017, the Swedish Parliament stated a new climate law with the goal that Sweden should be climate neutral by 2045. The concrete industry has developed a roadmap on how the goal for 2045 can be achieved, where one way to reduce the carbon emissions from concrete is by replacing a part of the cement clinker with alternative binders in the concrete mix. Ground granulated blast furnace slag (GGBS), fly ash, silica fume and trass are alternative binders that are possible to use in concrete mixes to reduce the amount of ordinary Portland cement (OPC). GGBS, fly ash and silica fume are by-products from other industries, while trass is volcanic ash that can be extracted. Besides the positive environmental impact that comes from using alternative binders and reducing the amount of cement clinker, the alternative binders have other properties, both positive and negative, that affect the concrete. The aim of this thesis was to investigate whether concrete with alternative binders does fulfill the regulations set by Swedish standards and how concrete with alternative binders does affect the material parameters. The concrete mixes were divided into three different types of concrete: concrete for bridges (w/c ratio 0.4), hydropower structures (w/c ratio 0.45) and wind powerplant foundations (w/c ratio 0.55). A total of seven concrete mixes were cast in a laboratory and the concrete mixes were investigated in the three hardening stages of concrete: fresh, young and hardened. The analyzed material parameters were compressive strength, shrinkage, frost resistance, workability, air voids and temperature development. Beyond the experimental testing, a global warming potential (GWP) comparison was made to compare the reduction of GWP for each concrete mix compared to a reference concrete for each usage area. The mix containing a CEM II/A-V fly ash cement and 15% GGBS showed great potential regarding the different material parameters. This mix, however, is according to Swedish standards not possible to certify for structures in exposure class XF4, such as bridges, but is possible to certify for structures in exposure class XF3, such as wind powerplant foundations. The mix containing 30% GGBS and 5% silica fume also showed beneficiary properties, but superplasticizers are required in this mix to ensure good workability. For hydropower structures, the mix containing 35% GGBS showed a great compressive strength but a high temperature development and low workability. The mix containing trass had a notably low temperature development, but with an increase in shrinkage and low workability. Moreover, all concrete mixes showed a frost resistance which, according to standard, is classified as “Very Good”.
Sveriges regering antog 2017 ett nytt klimatpolitiskt ramverk med målet att Sverige ska ha noll nettoutsläpp av växthusgaser år 2045. Betongindustrin har tagit fram en färdplan för hur betong kan bli klimatneutralt, där ett sätt att reducera klimatpåverkan från betong är att byta ut en del av cementklinkern mot alternativa bindemedel. Mald granulerad masugnsslagg (GGBS), flygaska, silikastoft och trass är alternativa bindemedel som är möjliga att använda i betongblandningar för att reducera mängden Portlandcement. GGBS, flygaska och silikastoft är restprodukter från andra industrier medan trass är en vulkanisk aska som kan utvinnas. Utöver den positiva miljöeffekten som erhålls när alternativa bindemedel ersätter cementklinker, så har de alternativa bindemedlen andra egenskaper, både positiva och negativa, som påverkar betongen. Målet med denna studie var att undersöka och jämföra om betongblandningar där en del av cementklinkern har ersatts med alternativa bindemedel når upp till de krav som ställs i nuvarande regelverk. Utöver det så undersöktes även hur betongblandningarnas materialparametrar påverkades av alternativa bindemedel. Betongblandningarna delades in i tre olika typer av betong: betong för broar (vct 0.4), vattenbyggnader (vct 0.45) och vindkraftverksfundament (vct 0.55), där totalt sju betongblandningar tillverkades i ett laboratorium. Betongblandningarna undersöktes i de tre olika faserna för hårdnande av betong, vilka är färsk, ung och hårdnad betong. De materialparametrar som analyserades var tryckhållfasthet, krympning, frostresistens, arbetbarhet, luftporhalt och temperaturutveckling. Förutom de experimentella testerna gjordes en jämförelse kring hur mycket koldioxid som kan reduceras för varje betongblandning, jämfört med en referensbetong för varje användningsområde. Betongblandningen med ett CEM II/A-V flygaska-cement och 15% GGBS visade stor potential med avseende på de olika materialparametrarna. Denna blandning är dock enligt svensk standard inte möjlig att certifiera för betongbyggnad i exponeringsklass XF4, exempelvis broar, men kan certifieras för betongbyggnad i exponeringsklass XF3, exempelvis fundament för vindkraftverk. Blandningen med 30% GGBS och 5% silikastoft visade även positiva egenskaper, men flyttillsatsmedel måste användas i denna blandning för att erhålla en god arbetbarhet. För vattenbyggnadsbetong så visade blandningen med 35% GGBS en hög tryckhållfasthet, men samtidigt en hög temperaturutveckling och en låg arbetbarhet. Blandningen med trass hade en noterbart låg temperaturutveckling, men med ökad krympning samt låg arbetbarhet. Avslutningsvis så uppvisade alla blandningar en frostresistens som enligt standard klassificeras som ”Mycket bra”.

Stockholm Vatten has decided to close down the Bromma waste water treatment plantand manage the waste water from Bromma together with the waste water from the formerEolshällsverket to Henriksdal’s waste water treatment plant. Henriksdals wastewater treatment plant will be expanded for higher purification requirements and loads,estimated to be finished until 2040. This entails extensive renovations and additionsto the existing treatment plant in and on Henriksdalsberget, as well as a major expansionof the Sickla plant.The purpose of the study is to investigate an environmentally friendly alternative tothe standard concrete that will be used for the expansion of the Sickla plant. The largestenvironmental villain in concrete is the cement. The aim of this study has beento replace the cement with environmentally friendly additives in the largest possibleamount, thus reducing the negative impact of the cement on the environment.In the present study, a review was made of obtained data with exposure classes, then aliterature study was performed to gain knowledge in the area. With help from experts,two fictitious recipes for each exposure class have been calculated for the standardconcrete and the green concrete. In this way, a careful comparison between the concretetypes was made of the cement’s impact on global warming. Thereafter, a study wascarried out on existing EPDs, which were incorporated into the One Click LCA (2015)software. An LCA in the mentioned software was carried out, which enabled data to becompiled and a comparison of the climate impact between the four different fictitiousrecipes has been done.Compiled and compared data from LCA and analysis of EPDs show that 70% of thestructure with exposure class XD2 gets a 47% reduction in global warming when usinggreen concrete instead of standard concrete. Furthermore, the results show that theremaining 30% of the structure with exposure class XF3/XC4 gets a 20% reductionwhen using green concrete instead of standard concrete. The total reduction in globalwarming when using green concrete instead of standard concrete for the expansion ofSickla treatment plant was calculated to be 40%.
Stockholm Vatten har beslutat att lägga ned Bromma reningsverk och leda avloppsvattnetfrån Bromma tillsammans med avloppsvattnet från det forna Eolshällsverkettill Henriksdals reningsverk. Henriksdals reningsverk ska byggas ut för högre reningskravoch belastningar beräknade till år 2040. Detta medför omfattande om- och tillbyggnationeri det befintliga reningsverket i och på Henriksdalsberget samt en storutbyggnad av Sicklaanläggningen.Syftet med detta arbete är att undersöka ett miljövänligare alternativ till standardbetongensom ska användas vid utbyggnaden av Sicklaanläggningen. Då den främsta”miljöboven” i betongen är cementet har målet med denna studie varit att ersätta cementetmed miljövänliga tillsatsmaterial i största möjliga mängd, i syfte att minskacementets negativa inverkan på miljön.I föreliggande arbete har en genomgång utförts på erhållna data med exponeringsklasser,därefter påbörjades en litteraturstudie i syfte att inhämta kunskaper inomområdet. Med hjälp av experter har två fiktiva recept för respektive exponeringsklassräknats fram för standardbetongen och den gröna betongen. Med denna metod genomfördesen noggrann jämförelse mellan de olika recepten avseende cementets inverkanpå den globala uppvärmningen. Därefter undersöktes existerande EPD:er, vilka infogadesin i programvaran One Click LCA (2015). En LCA i den nämnda programvaranutfördes, vilket möjliggjorde att data kunde sammanställas och en jämförelse av klimatpåverkanmellan de fyra olika fiktiva recepten kunde genomföras.Sammanställd och jämförd data från LCA och analys av EPD:er visar att 70% av konstruktionenmed exponeringsklass XD2 får en reducering på 47% på den globala uppvärmningenvid användning av grön betong istället för standardbetong. Vidare visarresultatet att resterande 30% av konstruktionen med exponeringsklass XF3/XC4 fåren reduktion på 20% vid användning av grön betong istället för standardbetong. Dentotala reduktionen på den globala uppvärmningen vid användning av grön betongistället för standardbetong för utbyggnaden av Sickla reningsverk beräknades till 40%.

Production wastes for which a direct use in another production is found become secondary raw materials. There are several institutions in Czech Republic and in the world, which are currently dealing with the issue. This thesis deals with the issue of cementitious spray concrete mixtures and deals with the possibilities of using secondary raw materials and waste from production as partial replacement of binder and filler in these mixtures. The aim of this theses is to optimize the composition of additives in the recipe of the commercially produced pray mixture and to verify the influence of the degree of substitution of binder or filler by secondary raw materials on its physical-mechanical properties. The aim is to maintain or increase these properties while substituting the binder and filler as much as possible. After the evaluation of results, it is possible to say, by suitable optimization of the additives it is possible to achieve a significant improvement of the physical-mechanical properties of the mass and furthermore, from the results of this thesis follows, that by substitution of 100% fine filler in combination with substitution of 30% binder it is possible to maintain or increase the physical-mechanical properties after 28 days of curing and to significantly increase these properties after 90 days of curing. The results of this thesis are also related to the reduction of economic impact on production of the spray mixture, mainly due to the use of secondary raw materials.

ABSTRACT This thesis deals with the development of silicate based reverse grouts for the purpose of rehabilitation of sewers. The work also examines the possibility of substitution of basic input raw materials with secondary raw materials, meaning replacements of both filler components and binder components. As secondary raw materials, we refer to wastes from the production process which, after the necessary treatment, are used in another production. The development and experimental verification of the functionality of the developed grout was focused mainly on the use of secondary raw materials as much as possible, while maintaining or even improving its physical and mechanical properties. Based on the results of the work, it can be stated that with a 100% replacement rate of filler components in combination with 20% replacement rate of binder components, it is possible to largely maintain the properties of the material, or even optimize them. The results of the thesis also point to the possibility of reducing the economic and environmental demands of production of building materials.

Дисертацію присвячено підвищенню якості розмежування гірських порід і нафтогазоносних горизонтів на площах ДДз за рахунок розробки та впровадження нових термостійких тампонажних матеріалів, що розширюються при твердінні. На підставі теоретичного аналізу результатів пошукових експериментальних досліджень розроблено базові рецептури як основу тампонажних матеріалів, що розширюються при твердінні. Обґрунтовано оптимальні співвідношення низькоактивних в’яжучих композицій, досліджено фазовий склад продуктів твердіння і кінетику розширення, вивчено технологічні властивості. Розроблено технологію приготування тампонажних сумішей та удосконалено технологію цементування свердловин. Промислові впровадження зольних і цементно-доломітових сумішей підтвердили їх ефективність при кріпленні свердловин на площах ДДз.
Диссертация посвящена повышению качества разобщения горных пород и нефтегазоносных горизонтов на площадях Днепровско-Донецкой впадины (ДДв) за счет разработки и внедрения термостойких расширяющихся тампонажних материалов нормальной и облегченной плотности. На основе анализа горно-геологических условий и опыта крепления скважин на площадях ДДв сформированы направления совершенствования качества цементирования обсадных колон: повышение термостойкости тампонажных материалов для обеспечения температурной стабильности и долговечности цементного камня; разработка и применение расширяющихся тампонажных материалов для преодоления эффекта усадочной деформации и каналообразования в цементном камне; усовершенствование технологии цементирования путем улучшения качества замещения бурового раствора тампонажным для повышения качества цементировочных работ. В качестве объекта для исследований выбраны термостойкие расширяющиеся тампонажные смеси на основе зольных и цементнодоломитовых композиций. Обоснованы оптимальные соотношения ингредиентов термостойких расширяющихся зольных и цементно-доломитовых смесей. Проведены экспериментальные исследования фазового состава продуктов твердения новых тампонажных материалов, изучен механизм их расширения. Установлено, что при длительных сроках автоклавирования, под действием гидротермальной обработки с высокими температурами и давлениями, в образцах камня зольных смесей среди новообразований присутствуют: гиролит, афвилит, ксонотлит, тоберморит и гидрогранат состава С3АSН4. Среди новообразований в цементно-доломитовых смесях присутствуют низкоосновной гидросиликат кальция CSH(B), тоберморит, трехкальциевый гидроалюминат С3АН6, четырехкальциевый гидроалюминат С4АН13, гидромоносульфоалюминат. Из проведенных исследований видно, что на поздних стадиях твердения у новых тампонажных материалов преобладают низкоосновные гидросиликаты кальция и гидрогранаты - новообразования, которые характеризуются термодинамической стабильностью. Проведены исследования технологических свойств тампонажных растворов и цементного камня на основе разработаных зольных и цементнодоломитовых тампонажных материалов. Установлено, что растворы на основе новых тампонажных материалов имеют широкий диапазон плотностей от облегченного до нормального, их водоотделение практически не отличается от стандартных портландцементов, час загустевания легко регулируется с помощью замедлителей твердения. Процесс расширение таких материалов происходит на ранних стадиях твердения до образования в структуре прочных кристаллизационных контактов, поэтому он не влияет на механические свойства камня в сторону их ухудшения. Камень на основе новых та мпонажных материалов обладает высокими технологическими свойствами. Сила его сцепления с металлом у 2 - 7 раз больше, чем у стандартных цементов. Разработано технологию приготовления новых тампонажных смесей и усовершенствовано технологию цементирования скважин. Высокая эффективность применения такой технологии достигается за счет повышенных абразивных качеств комбинированной буферной жидкости параллельно с ее низкими реологическими параметрами, которые обеспечивают турбулентный режим восходящего потока в заколонном пространстве и соответственно, высокую степень замещения бурового Разработаны нормативные документы - руководящие нормативные документы отрасли, регламентирующие компонентный состав и технологию применения зольных и цементно-доломитовых расширяющихся смесей. Промышленные испытания и внедрение зольных и цементнодоломитовых расширяющихся материалов на скважинах ДП "Черниговнефтегазгеология", ДП "Полтавнефтегазгеология", и ДП "Укрбургаз" подтвердили их высокую экономическую и технологическую эффективность.
The dissertation is devoted to increase of quality of dissociation of mountain rocks and oil and gas content of horizons on the areas of the Dnieper-Donetsk Depression at the expense of development and introduction of new heat-resistant expanding cement of materials. On the basis of the theoretical analysis of results of search experimental researches the basis expanding cement of materials is developed base compositions as. The optimum proportions low active of cement compositions are justified, the phase composition of yields harden and kinetics of expansion is studied, is investigated technological properties. Is developed technology of preparation cement of mixes and is improved technology-of cementation of wells. Industrial implementation of ash-fly and cement-dolomite mixtures have affirmed their efficiency at cementation wells on the areas of the Dnieper-Donetsk Depression.

Fly ash and blast furnace slag are the two major industrial solid by-products generated in most countries including India. Although their utilization rate has increased in the recent years, still huge quantities of these material remain unused and are stored or disposed of consuming large land area involving huge costs apart from causing environmental problems. Environmentally safe disposal of Fly ash is much more troublesome because of its ever increasing quantity and its nature compared to blast furnace slag. Bulk utilization of these materials which is essentially possible in civil engineering in general and more particular in geotechnical engineering can provide a relief to environmental problems apart from having economic benefit. One of the important aspects of these waste materials is that they improve physical and mechanical properties with time and can be enhanced to a significant level by activating with chemical additives like lime and cement. Class-C Fly ashes which have sufficient lime are well utilized but class-F Fly ashes account for a considerable portion that is disposed of due to their low chemical reactivity. Blast furnace slag in granulated form is used as a replacement for sand to conserve the fast declining natural source. The granulated blast furnace slag (GBS) is further ground to enhance its pozzolanic nature. If GBS is activated by chemical means rather than grinding, it can provide a good economical option and enhance its utilization potential as well. GGBS is latent hydraulic cement and is mostly utilized in cement and concrete industries. Most uses of these materials are due to their pozzolanic reactivity. Though Fly ash and GGBS are pozzolanic materials, there is a considerable difference in their chemical composition. For optimal pozzolanic reactivity, sufficient lime and silica should be available in desired proportions. Generally, Fly ash has higher silica (SiO2) content whereas GGBS is rich in lime (CaO) content. Combining these two industrial wastes in the right proportion may be more beneficial compared to using them individually. The main objective of the thesis has been to evaluate the suitability of the class-F Fly ash/GGBS mixtures with as high Fly ash contents for Geotechnical and Geo-environmental applications. For this purpose, sufficient amount of class-F Fly ash and GGBS were collected and their mixtures were tested in the laboratory for analyzing their mechanical behavior. The experimental program included the evaluation of mechanical properties such as compaction, strength, compressibility of the Fly ash/GGBS mixtures at different proportions with GGBS content varying from 10 to 40 percent. An external agent such as chemical additives like lime or cement is required to accelerate the hydration and pozzolanic reactions in both these materials. Hence, addition of varying percentages of lime is also considered. However, these studies are not extended to chemically activate GBS and only GGBS is used in the present study. Unconfined compressive strength tests have been carried out on various Fly ash/ GGBS mixtures at different proportions at different curing periods. The test results demonstrated rise in strength with increase in GGBS content and with 30 and 40 percent of GGBS addition, the mixture showed higher strength than either of the components i.e. Fly ash or GGBS after sufficient curing periods. Addition of small amount of lime increased the strength tremendously which indicated the occurrence of stronger cementitious reactions in the Fly ash/GGBS mixtures than in samples containing only Fly ash. Improvement of the strength of the Fly ash/GGBS mixtures was explained through micro-structural and mineralogical studies. The microstructure and mineralogical studies of the original and the stabilized samples were investigated by scanning electron microscopy (SEM) and X-Ray diffraction techniques respectively. These studies together showed the formation of cementitious compounds such as C-S-H, responsible for imparting strength to the pozzolanic materials, is better in the mixture containing 30 and 40 percent of GGBS content than in individual components. Resilient and permanent deformation behavior on an optimized mix sample of Fly ash and GGBS cured for 7 day curing period has been studied. The Resilient Modulus (Mr) is a measure of subgrade material stiffness and is actually an estimate of its modulus of elasticity (E). The permanent deformation behavior is also important in predicting the performance of the pavements particularly in thin pavements encountered mainly in rural and low volume roads. The higher resilient modulus values indicated its suitability for use as subgrade or sub-base materials in pavement construction. Permanent axial strain was found to increase with the number of load cycles and accumulation of plastic strain in the sample reduced with the increase in confining pressure. Consolidation tests were carried on Fly ash/GGBS mixtures using conventional oedometer to assess their volume stability. However, such materials develop increased strength with time and conventional rate of 24 hour as duration of load increment which requires considerable time to complete the test is not suitable to assess their volume change behavior in initial stages. An attempt was thus made to reduce the duration of load increment so as to reflect the true compressibility characteristics of the material as close as possible. By comparing the compressibility behavior of Fly ash and GGBS between conventional 24 hour and 30 minutes duration of load increment, it was found that 30 minutes was sufficient to assess the compressibility characteristics due to the higher rate of consolidation. The results indicated the compressibility of the Fly ash/GGBS mixtures slightly decreases initially but increase with increase in GGBS content. Addition of lime did not have any significant effect on the compressibility characteristics since the pozzolanic reaction, which is a time dependent process and as such could not influence due to very low duration of loading. Results were also represented in terms of constrained modulus which is a most commonly used parameter for the determination of settlement under one dimensional compression tests. It was found that tangent constrained modulus showed higher values only at higher amounts of GGBS. It was also concluded that settlement analysis can also be done by taking into account the constrained modulus. The low values of compression and recompression indices suggested that settlements on the embankments and fills (and the structures built upon these) will be immediate and minimal when these mixtures are used. In addition to geotechnical applications of Fly ash/GGBS mixture, their use for the removal of heavy metals for contaminated soils was also explored. Batch equilibrium tests at different pH and time intervals were conducted with Fly ash and Fly ash/GGBS mixture at a proportion of 70:30 by weight as adsorbents to adsorb lead ions. It was found that though uptake of lead by Fly ash itself was high, it increased further in the presence of GGBS. Also, the removal of lead ions increased with increase in pH of the solution but decreases at very high pH. The retention of lead ions by sorbents at higher pH was due to its precipitation as hydroxide. Results of the adsorption kinetics showed that the reaction involving removal of lead by both the adsorbents follow second-order kinetics. One of the major problems which geotechnical engineers often face is construction of foundations on expansive soils. Though stabilization of expansive soils with lime or cement is well established, the use of by-product materials such as Fly ash and blast furnace slag to achieve economy and reduce the disposal problem needs to be explored. To stabilize the soil, binder comprising of Fly ash and GGBS in the ratio of 70:30 was used. Different percentages of binder with respect to the soil were incorporated to the expansive soil and changes in the physical and engineering properties of the soil were examined. Small addition of lime was also considered to enhance the pozzolanic reactions by increasing the pH. It was found that liquid limit, plasticity index, swell potential and swell pressure of the expansive soil decreased considerably while the strength increased with the addition of binder. The effect was more pronounced with the addition of lime. Swell potential and swell pressure reduced significantly in the presence of lime. Based on the results, it can be concluded that the expansive soils can be successfully stabilized with the Fly ash-GGBS based binder with small addition of lime. This is also more advantageous in terms of lime requirement which is typically high when Fly ash, class-F in particular, is used alone to stabilize expansive soils. Based on the studies carried out in the present work, it is established that combination of Fly ash and GGBS can be advantageous as compared to using them separately for various geotechnical applications such as for construction of embankments/fills, stabilization of expansive soils etc. with very small amount of lime. Further, these mixtures have better potential for geo-environmental applications such as decontamination of soil. However, it is still a challenge to activate GBS without grinding.

Fly ash and blast furnace slag are the two major industrial solid by-products generated in most countries including India. Although their utilization rate has increased in the recent years, still huge quantities of these material remain unused and are stored or disposed of consuming large land area involving huge costs apart from causing environmental problems. Environmentally safe disposal of Fly ash is much more troublesome because of its ever increasing quantity and its nature compared to blast furnace slag. Bulk utilization of these materials which is essentially possible in civil engineering in general and more particular in geotechnical engineering can provide a relief to environmental problems apart from having economic benefit. One of the important aspects of these waste materials is that they improve physical and mechanical properties with time and can be enhanced to a significant level by activating with chemical additives like lime and cement. Class-C Fly ashes which have sufficient lime are well utilized but class-F Fly ashes account for a considerable portion that is disposed of due to their low chemical reactivity. Blast furnace slag in granulated form is used as a replacement for sand to conserve the fast declining natural source. The granulated blast furnace slag (GBS) is further ground to enhance its pozzolanic nature. If GBS is activated by chemical means rather than grinding, it can provide a good economical option and enhance its utilization potential as well. GGBS is latent hydraulic cement and is mostly utilized in cement and concrete industries. Most uses of these materials are due to their pozzolanic reactivity. Though Fly ash and GGBS are pozzolanic materials, there is a considerable difference in their chemical composition. For optimal pozzolanic reactivity, sufficient lime and silica should be available in desired proportions. Generally, Fly ash has higher silica (SiO2) content whereas GGBS is rich in lime (CaO) content. Combining these two industrial wastes in the right proportion may be more beneficial compared to using them individually. The main objective of the thesis has been to evaluate the suitability of the class-F Fly ash/GGBS mixtures with as high Fly ash contents for Geotechnical and Geo-environmental applications. For this purpose, sufficient amount of class-F Fly ash and GGBS were collected and their mixtures were tested in the laboratory for analyzing their mechanical behavior. The experimental program included the evaluation of mechanical properties such as compaction, strength, compressibility of the Fly ash/GGBS mixtures at different proportions with GGBS content varying from 10 to 40 percent. An external agent such as chemical additives like lime or cement is required to accelerate the hydration and pozzolanic reactions in both these materials. Hence, addition of varying percentages of lime is also considered. However, these studies are not extended to chemically activate GBS and only GGBS is used in the present study. Unconfined compressive strength tests have been carried out on various Fly ash/ GGBS mixtures at different proportions at different curing periods. The test results demonstrated rise in strength with increase in GGBS content and with 30 and 40 percent of GGBS addition, the mixture showed higher strength than either of the components i.e. Fly ash or GGBS after sufficient curing periods. Addition of small amount of lime increased the strength tremendously which indicated the occurrence of stronger cementitious reactions in the Fly ash/GGBS mixtures than in samples containing only Fly ash. Improvement of the strength of the Fly ash/GGBS mixtures was explained through micro-structural and mineralogical studies. The microstructure and mineralogical studies of the original and the stabilized samples were investigated by scanning electron microscopy (SEM) and X-Ray diffraction techniques respectively. These studies together showed the formation of cementitious compounds such as C-S-H, responsible for imparting strength to the pozzolanic materials, is better in the mixture containing 30 and 40 percent of GGBS content than in individual components. Resilient and permanent deformation behavior on an optimized mix sample of Fly ash and GGBS cured for 7 day curing period has been studied. The Resilient Modulus (Mr) is a measure of subgrade material stiffness and is actually an estimate of its modulus of elasticity (E). The permanent deformation behavior is also important in predicting the performance of the pavements particularly in thin pavements encountered mainly in rural and low volume roads. The higher resilient modulus values indicated its suitability for use as subgrade or sub-base materials in pavement construction. Permanent axial strain was found to increase with the number of load cycles and accumulation of plastic strain in the sample reduced with the increase in confining pressure. Consolidation tests were carried on Fly ash/GGBS mixtures using conventional oedometer to assess their volume stability. However, such materials develop increased strength with time and conventional rate of 24 hour as duration of load increment which requires considerable time to complete the test is not suitable to assess their volume change behavior in initial stages. An attempt was thus made to reduce the duration of load increment so as to reflect the true compressibility characteristics of the material as close as possible. By comparing the compressibility behavior of Fly ash and GGBS between conventional 24 hour and 30 minutes duration of load increment, it was found that 30 minutes was sufficient to assess the compressibility characteristics due to the higher rate of consolidation. The results indicated the compressibility of the Fly ash/GGBS mixtures slightly decreases initially but increase with increase in GGBS content. Addition of lime did not have any significant effect on the compressibility characteristics since the pozzolanic reaction, which is a time dependent process and as such could not influence due to very low duration of loading. Results were also represented in terms of constrained modulus which is a most commonly used parameter for the determination of settlement under one dimensional compression tests. It was found that tangent constrained modulus showed higher values only at higher amounts of GGBS. It was also concluded that settlement analysis can also be done by taking into account the constrained modulus. The low values of compression and recompression indices suggested that settlements on the embankments and fills (and the structures built upon these) will be immediate and minimal when these mixtures are used. In addition to geotechnical applications of Fly ash/GGBS mixture, their use for the removal of heavy metals for contaminated soils was also explored. Batch equilibrium tests at different pH and time intervals were conducted with Fly ash and Fly ash/GGBS mixture at a proportion of 70:30 by weight as adsorbents to adsorb lead ions. It was found that though uptake of lead by Fly ash itself was high, it increased further in the presence of GGBS. Also, the removal of lead ions increased with increase in pH of the solution but decreases at very high pH. The retention of lead ions by sorbents at higher pH was due to its precipitation as hydroxide. Results of the adsorption kinetics showed that the reaction involving removal of lead by both the adsorbents follow second-order kinetics. One of the major problems which geotechnical engineers often face is construction of foundations on expansive soils. Though stabilization of expansive soils with lime or cement is well established, the use of by-product materials such as Fly ash and blast furnace slag to achieve economy and reduce the disposal problem needs to be explored. To stabilize the soil, binder comprising of Fly ash and GGBS in the ratio of 70:30 was used. Different percentages of binder with respect to the soil were incorporated to the expansive soil and changes in the physical and engineering properties of the soil were examined. Small addition of lime was also considered to enhance the pozzolanic reactions by increasing the pH. It was found that liquid limit, plasticity index, swell potential and swell pressure of the expansive soil decreased considerably while the strength increased with the addition of binder. The effect was more pronounced with the addition of lime. Swell potential and swell pressure reduced significantly in the presence of lime. Based on the results, it can be concluded that the expansive soils can be successfully stabilized with the Fly ash-GGBS based binder with small addition of lime. This is also more advantageous in terms of lime requirement which is typically high when Fly ash, class-F in particular, is used alone to stabilize expansive soils. Based on the studies carried out in the present work, it is established that combination of Fly ash and GGBS can be advantageous as compared to using them separately for various geotechnical applications such as for construction of embankments/fills, stabilization of expansive soils etc. with very small amount of lime. Further, these mixtures have better potential for geo-environmental applications such as decontamination of soil. However, it is still a challenge to activate GBS without grinding.

Extensive amounts of waste materials and by-products are generated by human, industrial and commercial activities. It has become difficult to handle huge amount of waste which leads to environmental problems. Rapid utilization of natural resources, generation of huge amount of industrial wastes and environmental pollution needs new solution for sustainable economic development. During past decades more concern is shown towards the utilization of industrial wastes and by-products in civil engineering works. Utilizing the waste is a partial solution to ecological and environmental problems. If the industrial wastes are used in production of cement, concrete and in some other construction materials as a replacement to conventional materials then the manufacturing /project cost will be reduced and reduces the land fill area. Geopolymerization is the present technology, which can transform waste materials containing silica and alumina into useful products with excellent physical and chemical properties. The main principle involved in geopolymerization is the chemical reaction between alumino silicate materials and highly alkaline solution to form amorphous to semi crystalline inorganic polymers. Red mud, granulated blast furnace slag and fly ash are the industrial waste materials which have the potential application in civil engineering constructions when they are utilized properly. Red mud is alkaline by-product which is generated during the processing of bauxite. Generally red mud is considered as a waste material which is dumped into large areas. Red mud contains large amount of Fe2O3, Al2O3 and small amounts of CaO, SiO2 and some valuable metals such as titanium. As red mud is highly alkaline, it can be stabilized by adding waste materials rich in aluminosilicates. In the present research work an attempt has been made to stabilize red mud using ground granulated blast furnace slag (GGBS) and fly ash separately. Fly ash is added in the percentages of 0%, 10%, 20%, 40%, 60%, 80% and 100% to the red mud. Similarly slag is added to red mud in the same amounts. For each proportion of red mud-fly ash and red mud-slag Atterberg’s limits, pH values, differential free swell (DFS) value, OMC and MDD corresponding to light compaction and heavy compaction and unconfined compressive strength (UCS) are determined. Cylindrical samples of are prepared by compacting to MDD and OMC. The wax coated specimens are kept for curing about 0, 3, 15, 30 and 60 days. These specimens are tested to determine the unconfined compressive strength. NaOH is added in the percentages of 2%, 4%, 8%, 12% of dry mass to red mud, fly ash, slag and the above proportions of red mud-fly ash, red mud-slag and unconfined compressive strength is determined. It is observed that as the amount of fly ash increases the liquid limit, plastic limit and shrinkage limit increases. As the amount of slag in red mud is increased then plastic limit and shrinkage limit reduces but the liquid limit is found to be decreased up to 40% slag content thereafter with further increase in slag content the liquid limit increases. Red mud-slag and red mud-fly ash mixes exhibits negative values of differential free swelling. Red mud shows moderate decrease in pH values with increase in slag content. With the replacement of red mud by fly ash in red mud-fly ash mixes, resulted in substantial decrease of pH values. It is observed that, in red mud-fly ash mixture, as the percentage of fly ash increases, the maximum dry density decreases whereas the optimum moisture content increases. In red mud-slag mixture, as the percentage of slag added to red mud is increased, the maximum dry density increases up to 40% slag and further addition of slag resulted in decrease of MDD value. Virgin red mud possesses UCS value of 0.22 MPa which is increased to 5.2MPa with the addition of 40% slag at curing period of 60 days. The addition of fly ash to red mud does not result in an appreciable increase in unconfined compressive strength. For 60% Red mud and 40% fly ash maximum strength of 0.33 MPa is obtained at 60 days. Addition of alkali i.e. NaOH solution enhances the strength remarkably for red mud-slag mixes. With the addition of 40% slag and 4% NaOH, red mud attains an unconfined compressive strength of 14.02 MPa at 60 days of curing. An addition of 4% NaOH to 60% red mud and 40% fly ash results an unconfined compressive strength of 1.21 MPa after a curing period of 60 days. This may be due to absence of sufficient amount of reactive alumina and silica in the fly ash specimen. Red mud is a highly alkaline material which can be stabilized effectively by addition of 40% slag through geopolymerization process. It reduces the environmental pollution and it can be used in the construction works such as embankments, structural fills, etc.

Cement is a conventional binding agent for concrete and it is also used as a stabilizing agent to soil and aggregates. This causes enormous increase of carbon dioxide emission all over the world causing fast degradation of environment. One ton carbon dioxide gas is released in to the atmosphere for each one ton production of OPC. Global cement production is expected to reach 5000 million tonnes in the year 2050. Furthermore researchers reported that the stabilization of soil using cement and lime is very costly. Due to the high costs of cement, effort is being intensified by engineers/researchers to examine the possibilities of utilizing cost-effective locally available industrial wastes for replacing cement. Reduction of CO2 emission has become a priority and it has become a necessity to move forward with environmental friendly alternatives for cement. Ordinary Portland Cement contributes 5-7% of the overall green house emissions which is a threat to the global environment. Overall cement production all over the world is increasing rapidly. Due to these reasons the need for an environment friendly alternative for cement has increased. Studies reported that cement produced from ground grannulated blast furnace slag (GGBS) showed 80% less emission of green house gases and 80-90% in case of fly ash. These industrial by products has excellent binding property which make them a perfect substitute for OPC. Geopolymer is a new group of materials produced by the alkaline activation of aluminosilicate compounds. Earlier researches around the world proposed that concrete from geopolymer binder exhibited superior engineering, thermal and durability properties than ordinary Portland cement (OPC) concrete, such as higher mechanical strengths, higher resistivity to sulphate and acid attacks and higher thermal resistivity. Geopolymers are generally made from activation of aluminosilicate powders by highly concentrated sodium hydroxide and or sodium silicate solutions, known as liquid-activated geopolymer. The interest of this paper is to investigate the influences of synthesis parameters on compressive strength of a geopolymer. Geopolymer samples are prepared using industrial by- products such as fly ash and ground granulated blast furnace slag (GGBS) with KOH as alkaline activator. With sol/solid=0.2, 0.3, 0.4, 0.5 and KOH molarity of 4M, 8M, 12 geopolymer samples are prepared and cured at 7 and 28 days under ambient temperature of 270C. Compressive strength of these samples are found out and the optimum mix proportion is found out. Geopolymer samples made of GGBS with 8M KOH and sol/solid ratio 0.3 cured at 28 days in ambient tempeature showed maximum compressive strength of 24.37 MPa. Further, the effects of curting temperature on compressive strength has been investigated. Temperature curing study of samples prepared at this mix proportion was carried out by curing at 600C and 900C in hot air oven and in water, each for a curing period of 7 and 28 days. Variation of compressive strength for different curing condition is analysed. Positive results were obtained for samples cured at 600C and those cured at 900C showed redution in strength as compared to sample cured at ambient temperature(270C ) and 600C. Finally, the geopolymer paste was added with a weak soil and its improvement in strength properties was observed. UCS and compcation characteristics of the soil sample improved. 20% geopolymer addition gave compressive strength of 2.03 MPa for a curing period of 14 days. This was about 8 times the compressive strength of the virgin soil. From this study it could be concluded that variation of molar concentration of alkali activator, alkali to source material ratio, and percentage addition of the source material. It was also observed that the slag content is the most dominating factor affecting the compressive strength of the geopolymer.

The present work discusses the preparation and characterization of mullite based ceramics from bauxite-fly ash mixture. Two different varieties of bauxites viz. Bauxite 1 (B1) and Bauxite 2 (B2) were used, and each bauxite variety was mixed with different weight percent (30, 40, 50 and 70) of same fly ash (FA). The B1-FA compositions were processed through two stage firing, and the B2-FA mixture was processed through single stage firing schedule. Both the B1- FA and B2 – FA compositions were sintered at 1400, 1450 and 1500oC. The mullitization reaction in the bauxite-fly ash commenced with the dissolution quartz and corundum followed by the appearance of mullite and corundum. The fraction of quartz and alumina decreased from 900oC onwards while that of mullite and glass increased. The mullite percentage in the sintered bauxite-fly ash samples was dependent on the bauxite type and the higher percentage of mullite in B1 –FA compositions could be attributed to the finer crystallite size of B1. No difference in the mullite percentage was observed between single stage and two stage firing schedule. High bauxite compositions had corundum and mullite, whereas, high fly ash compositions had cristobalite and mullite. The microstructure of the sintered B1-FA samples showed dense crystalline microstructure for 30% FA samples and mullite grains and more glassy phase for 70% FA sample. The B2 microstructure showed the presence of glassy phase and porous microstructure both for 30% and 70% FA. Equiaxed primary mullite was present in 30% FA containing samples. The bending strength and ISB fracture toughness was measured using Ring on Ring test method. A linear relationship was observed between the fracture strength and fracture toughness, particularly, for the compositions sintered at the highest temperature. In the B1-FA compositions, samples with predominantly mullite phase had low strength and toughness while the samples with a combination mullite and another phase had high strength, hardness, and toughness. In the B2-FA compositions, the strength and toughness were high in 40 and 50 % FA containing compositions. It was also observed that the samples that exhibited high strength and toughness had two different type of elongated mullite grains. Some of the selected samples were also subjected to thermal shock from 1250oC for 5 cycles. The samples did not show any visible crack but showed a change in the mullite and glass content after cycling.

碩士
國立臺灣海洋大學
河海工程學系
93
This study is aimed to evaluate the effect of elevated temperature curing on the strength development of cementitious materials, in which various percentages (20%, 40%) of fly ash and ggbs/fly ash are added to partially replace Portland cement. Testing variables include curing condition and mix proportion of cementitious materials. Standard curing condition ((23℃, 28day), hot water curing condition (60℃, 80℃, 100℃, 1day), and autoclave curing condition (180℃, 1MPa) are taken into account. Mortar specimens were cast with reference to the specifications of ASTM standards and tested to obtain compressive strength, tensile strength, absorption, surface condition, and internal pore structure using universal testing machine, optical microscope, mercury intrusion porosimetry, etc. With standard curing, 91-day strength is improved for specimens with 20% fly ash replacement (w/b=0/35, 0.55), 40% ggbs replacement (w/b=0.35), and 20% ggbs replacement (w/b=0.55), respectively. adopted. Autoclave curing condition is very beneficial for 20% ggbs replacement specimens to obtain higher early strength. Absorption may be changed with curing condition. Autoclave-cured specimens have higher absorption. MIP results indicate lower porosity and finer pore size were observed in specimens with fly ash or ggbs addition. The effect of autoclave curing may be more prominent in higher water/binder ratio specimens.

Lining systems are primarily used to prevent a potential pollutant in a waste containment from migrating to surface water, ground water and thus polluting them. Even though compacted sand-bentonite mixture is most widely used as liner material in hazardous and nuclear waste containment, use of large quantities of sand is limited keeping in view of the economic and environmental concern. This forms the scope to explore the alternative liner material. Fly ash is generated in huge quantities from thermal power plants. Effective disposal of fly ash is always a concern. Using fly ash as an alternate material to sand in hydraulic barrier can address two problems: 1. Effective disposal of fly ash and, 2. Alternate liner material to sand. Hydraulic conductivity and strength characteristics are essential for performance assessment of liner materials. This work was planned to investigate the potential of fly ash-bentonite mixture as effective alternate liner material. In this investigation, fly ash and bentonite are blended in different proportions by weight percentage i.e., 85:15, 90:10 and 95:5 respectively. For this, prepared samples were compacted at optimum moisture content and maximum dry density which are obtained from four different compaction energy such as reduced standard Proctor, standard Proctor, reduced modified Proctor and modified Proctor; and their corresponding coefficient of permeability were determined. It was found that, with increase in bentonite content, the hydraulic conductivity of fly ash and bentonite mixture has decreased. And with increase in compaction energy, the hydraulic conductivity for a fly ash-bentonite mix has decreased. To determine the effect of bentonite on the unconfined compressive strength of fly ash and bentonite mixtures, UCS tests were conducted on fly ash-bentonite samples with bentonite content 5%, 10% and 15% by weight. It was found that the unconfined compressive strength has increased with increase of bentonite content and compaction energy. Geotechnical laboratory tests such as plasticity, shrinkage, free swell index have been carried out and it was found that increase in bentonite content has increased the plasticity and swelling characteristics of the mix.

The present work discusses the preparation and characterization of mullite based ceramics from fly ash-alumina mixture. Two different varieties of aluminas namely, White tubular alumina (WTA) and Technical alumina fines (TA) were used, and each variety was mixed with different weight percent of fly ash (FA) giving 3 batches in molar ratios of 1.72 (excess alumina batch), 1.5(stoichiometric batch) and 1.28 (lean alumina batch). All the batches were mixed in solid condition, pressed and fired in a single stage firing process at temperatures of 1400, 1450, 1500 and 1550oC, each having a soaking time of 2 hours. The mullitization reaction commenced with the dissolution of quartz, cristobalite and corundum followed by the appearance of mullite, sillimanite and pyrope (for MgO addition). Quartz,cristobalite and corundum were found to decrease from 1400oC onwards, while the fraction of mullite and glass increased. At 1550 oC high compositions of alumina (1.72) had corundum,sillimanite and mullite, whereas, lower compositions (1.28) had more cristobalite, sillimanite and mullite. The stoichiometric ratio (1.50) showed mainly mullite and sillimanite phases. The diametral strength was measured using the Brazilian Disc test method. The batches that were both milled and added with MgO which showed higher densification values (~3gm/cc), also showed good strength values (>45 MPa) as compared to the other batches. Only milled batches showed more promise in terms of density and strength as compared to MgO added batch and the batch having just a mixture of the precursor powders. It was observed that finer particle size lead to a better densified matrix, seconded by the microstructure analysis which showed reducing porosities and higher packing of the mullite crystals. Addition of MgO to and/or milling of the precursor powders changed the acicular structure of mullite to a rod shaped structure having flat faces thereby increasing the packing of the structure.

碩士
東海大學
環境科學與工程學系
95
Preparation of Light-weight Aggregate with Mixture of Reservoir Sediments and Incinerator Fly Ash Abstract Fly ashes discharged from incinerators have proven to be hazardous. Discharge of reservoir sediment in Taiwan has been a serious problem. In this study a washed （pre-washed, mix-washed）incinerator fly ash was mixed with reservoir sediment to prepare usable lightweight aggregate samples through sintering with/without vesicant processes at three temperatures 1050, 1100, and 1150 ºC for 20 minutes. Chemical compositions of the fly ash and sediment were determined via total acid digestion followed by measurement using inductively coupled plasma-atomic emission spectrometer (ICP-AES). The weight fraction of fly ash in the mixture was 0-30%, and the shaping pressure was 3000 and 5000 psi prior to the sintering and vesicant processes. The results indicate that the samples, that contain up to 30% washed fly ash , heated at 1050 ºC are characterized with bulk density of 2.0-2.2 g/cm3 and moisture absorption rate of 8.0-16.5%. These samples can meet Chinese National Standard (CNS) brick standard for construction purpose. The sample containing 15% mix-washed fly ash shaped at 5000 psi and heated at 1150 ºC exhibits best performance in vesicant process, showing a bulk density of 0.8 g/cm3 and moisture absorption rate of 2.2%. In general, addition of <5% washed fly ash does not considerably alter sediment sintering (with/without vesicant process). In contrast, addition of >25% washed fly ash can significantly change sediment sintering performance, thus resulting in unacceptable properties in terms of bulk density and moisture absorption rate. X-ray diffraction, X-ray absorption spectroscopy, scanning electron microscopy, and thermal gravimetric analyzer with differential scanning calorimetry were used to investigate sintering and vesicant process.

碩士
國立成功大學
資源工程學系
86
The approach of this project is to study the mixture of coalfly ash sediments and ShihMen reservoir sludge and to treat it as a raw material of construction materials.The fly ash fromthe coal combustion plant is added into reservoir sludge as thewater absorbent of sludge. The mixture is tested by strength,density, water content and plastic index in the extrusion, drying and sintering operations to find the formula for manufacturing of construction brick. The important tested results were obtained as following:(1) The green strength of the mixture under the fly ash content lower than 50% was suitable for brickmaking. However, the water content in the mixture have to control within the liquid limit and the plastic limit of the mixture. (2) The sintering conditions of the mixture is suggested in the range of 900℃ to 1000℃ with the duration of 10 hours. In the sintering temperature range, the higher sintering temperature will get the products of greater brick strength.(3) The bulk density of sintering product was governed by fly ash content. The porosity of bricks increased with increasing fly ash content. The cost of this process was evaluated under the production rate of 2 million pieces per month in the traditional brickmaking plant. If the plant produces the bricks with adding 30% of flyash into the sludge, that will consume 4770 tons of sludge per month,and the cost will be increased about 15% comparing with the traditional brickmaking plant.

碩士
國立聯合大學
防災科技研究所
95
How to treat the Municipal solid waste was a difficulty problem of modern civilization, because being damage to the earth sustainable development. At present, incineration is still a suitable way of problem-solving for municipal solid wastes. But MSWI fly-ash contained large quantity of heavy metal harmful to mankind. It need to be recycled as useful resources. In this study, municipal solid waste incinerator (MSWI)fly ash was melted into slag ,the slag was then pulverized to powder with sized less than #400 sleeve (38um)for experimental study, slag– cement mortar specimens were molded by 0~40% cement replacement with slag powder. The results revealed that the 90-day compressive strength of the 20% cement replacement specimen was the best.The pulverized slag was used to substitute 20 wt % of cement for molding slag-blended concrete cylinder specimen. Compressive strength of specimens of various ages were compared with those of control specimens(plain cement concrete).The results revealed that the compressive strength of 20 wt % slag-blended cement concrete was below that of control group in the early stage. However, the compressive strength were 109% and 120% of those of control group for ages of 60 days and 90days, respectively. The results of porosity (MIP) analyses showed that the average pore sizes of the 60-day and 90-day spEcimens were both smaller than that of 28-day specimen. This is the evidence that all the slag-blended specimens exhibited a pozzolanic reaction. This decreased tendency of pore sized is in accordance with that of the increased compressive strengths of the specimens. The slumps (workability) and setting times of both the slag-blended and control group specimens were similar. The results of this study revealed that MSWI slag-blended cement concrete is feasible for practical application.

M. Tech. Civil Engineering
Black cotton soils are fertile and very good for agriculture, horticulture, sericulture and aquaculture. However, they are not good as road construction material because of their undesirable engineering properties and, therefore, need to be removed from site or modified to meet the minimum design standards required for roads subgrade material. This type of clay is very expansive and causes significant damages and problems on South African roads. Roads that are built on expansive clays are adversely affected by the behaviour of the expansive clay. Conventional methods of road design and construction over such material has proved to be very costly. It has been a practice in road construction to remove black cotton soil and replace with better quality soil. This results in high construction costs. The use of by-product and waste materials for modification and stabilization of engineering properties of expansive clays has environmental and economic benefits. On the other hand, problematic material may be treated in its natural state "in situ", thereby leading to reduction in cost. Thus, the modification of Black cotton soils using a mix proportion of fly ash and slagment may improve the engineering properties of the material. The overall objective of the study was to investigate and determine the appropriate mix proportion of fly ash and ground granulated blast furnace slag in the modification of engineering properties of black cotton soil for use in road construction.

碩士
國立中央大學
環境工程研究所
99
Municipal incinerator fly ash (MSWI fly ash) and electeric arc furnace dust (EAF dust) account for the main of the industrial hazadours waste in the past decade. For environmental concerns, the safe treatment and recycling of such waste has been in great demand in the nation. This study explores the properties of glass-ceramic prepared by combined vitrification/recrystallization approach from a mixture of MSWI fly ash, EAF dust and waste glass cullet. The experimental procedures involving the modification of fly ash and controlled crystallization heat-treatments were performed to convert modified ash into useful glass-ceramic composites. The re-crystallization behavior and kinetics of a waste-derived glass-ceramic was evaluated under non-isothermal conditions using differential thermal analysis (DTA). With respect to the modification of MSWI fly ash compositions, it was found that a relatively stable slag-derived glass with suitable glass-forming ability, chemical durability and higher the re-crystallization tendency could be obtained by mixing 60 wt.% MSWI fly ash, 20 wt.% EAF dust, and 20 wt.% waste glass cullet. Pre-nucleation experimental results indicated that the temperature and time of maximum nucleation rate were 700 oC and 30 min, respectively. The crystallographic and microstructural analysis of the produced glass-ceramic that nucleated at 700 oC for 30 min and crystallized at 750-1000 oC for 1 h, revealed the presence of three major crystalline phases, melilite (gehlenite (Ca2Al2SiO7)-akermanite (Ca2MgSi2O7) solid solutions), augite (diopside–hedenbergite solid solutions, Ca(Mg,Fe)Si2O6) and uvarovite (Ca3Cr2(SiO4)3) together with an equiaxed grain morphology that was embedded in the glassy matrix. But third crystalline phase of uvarovite begins to appear at crystallization treatment temperature of above 900°C and the amount of augite and uvarovite increased with increasing crystallization temperature. The activation energies (Ec) of the crystallization of the annealed and pre-nucleated glass samples, determined by modified Kissinger and Ozawa equations, were in the range of 367.4-395.2 and 199.8-214.6 kJ/mol, respectively, and the obtained Avrami constant (n) was 1.8 for the annealed glass and 1.5 for the pre-nucleated glass. These results verify that the difference between the Ec values of the annealed and pre-nucleated glasses is very significant, suggesting that mixed ash-based glass is suitable for use in the two-stage crystallization thermal-treatment in this study. The best physical, microstructural, mechanical and chemical durability properties of the glass-ceramic were produced at 950-1000°C for 1 hour heat-treatment, making them suitable for use as construction and decoration materials.

Yes
The impact behavior of deflection-hardening High Performance Fiber Reinforced Cementitious Concretes (HPFRCs) was evaluated herein. During the preparation of HPFRCs, fiber type and amount, fly ash to Portland cement ratio and aggregate to binder ratio were taken into consideration. HPFRC beams were tested for impact resistance using free-fall drop-weight test. Acceleration, displacement and impact load vs. time graphs were constructed and their relationship to the proposed mixture parameters were evaluated. The paper also aims to present and verify a nonlinear finite element analysis, employing the incremental nonlinear dynamic analysis, concrete damage plasticity model and contact surface between the dropped hammer and test specimen available in ABAQUS. The proposed modelling provides extensive and accurate data on structural behavior, including acceleration, displacement profiles and residual displacement results. Experimental results which are further confirmed by numerical studies show that impact resistance of HPFRC mixtures can be significantly improved by a proper mixture proportioning. In the presence of high amounts of coarse aggregates, fly ash and increased volume of hybrid fibers, impact resistance of fiberless reference specimens can be modified in a way to exhibit relatively smaller displacement results after impact loading without risking the basic mechanical properties and deflection-hardening response with multiple cracking.

Geopolymers are a relatively new class of materials that have many broad applications, including use as substitute for ordinary Portland cement (OPC), use in soil stabilisation, fire resistant panels, refractory cements, and inorganic adhesives. Geopolymers are an alternative binder to Portland cement in the manufacture of mortars and concrete, as its three-dimensional alumino silicate network develops excellent strength properties. Use of geopolymers in place of ordinary Portland cement is also favoured owing to the possible energy and carbon dioxide savings. Geopolymer is typically synthesized by alkali activation of pozzolanas at moderate temperatures (< 1000C). The focus of the thesis is synthesis and characterization of geopolymers as construction materials. In this context, the role of compositional factors, such as, pozzolana type (fly ash, kaolinite, metakaolinite, ground granulated blast furnace slag, red soil), alkali (sodium hydroxide is used in this study) activator concentration, Si/Al (Si= silicon, Al = aluminium) ratio of the pozzolana and environmental factors, namely, curing period and temperature are examined. Besides synthesizing geopolymers that could be an alternate to concrete as construction material, sand-sized aggregates were synthesized using geopolymer reactions. This was done as river sand is becoming scarcer commodity for use as construction material. Several compositional and environmental factors were varied in geopolymer synthesis in order to identify the optimum synthesis conditions that yield geopolymers with maximum compressive strength. Besides varying external (compositional and environmental) factors, the role of internal microstructure in influencing the compressive strength of the geopolymer was examined. Micro-structure examinations were made using X-ray diffraction (XRD), scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) studies. The studies on compositional and environmental factors in geopolymer synthesis brought out several interesting results. The results firstly brought out that amongst the pozzolanas studied, ASTM class F fly ash is most suited for maximum compressive strength mobilization upon geopolymer reactions. Moderate temperature (75-1000C) was adequate to mobilize large compressive strengths. Room temperature curing needed more than 7 days before the pozzolana-NaOH paste began to develop strength. Curing period of 56 days was needed for the geopolymer to develop significant strength (19.6MPa). A similar range of compressive strength could be developed by the pozzolana-NaOH paste upon curing for 3 days at 1000C. Likewise curing the pozzolana-NaOH paste at temperatures > 1000C led to reduction in compressive strength from shrinkage and breakage of bonds. A caustic soda (NaOH) concentration of 10 M was adequate to develop maximum compressive strength of the geopolymer. Caustic soda concentrations in excess of 10 M did not result in further improvement of strength. The Si/Al ratio also contributes to strength mobilization. The Si/Al ratio of the geopolymer was enhanced by mixing commercially obtained silica gel with the pozzolana. Maximum strength mobilization was observed at Si/Al ratio = 2.45 corresponding to 6.5 % silica gel addition to the pozzolana (on dry mass basis). Comparing compressive strengths of geopolymers with varying silica gel contents, geopolymer specimens with least water content and largest dry density did not exhibit maximum compressive strength indicating that the physico-chemical (bond strength, micro-structure) played a pivotal role than physical parameters (dry density, water content) in dictating the strength of the geopolymer. MIP results showed that bulk of the porosity in fly ash geopolymer specimens is contributed by macro pores and air voids. Geopolymerization leads to bulk consumption of cenospheres in fly ash and forms polymerized matrix with network of large pores. After geopolymerization, all the main characteristic peaks of Al–Si minerals observed in fly ash persisted, suggesting that no new major crystalline phases were formed. Presence of small amount of inorganic contaminants in fly ash can drastically reduce the strength of the fly ash geopolymer. For example, 5-20 % presence of red soil reduces the strength of fly ash geopolymer by 16 to 59 %. Presence of unreacted clay coupled with less porous structure is responsible for the reduction in compressive strength of fly ash geopolymer subjected to red soil addition. MIP studies with geopolymers also revealed that there is good bearing between compressive strengths and maximum intruded volume (from MIP test) of geopolymers. For example, fly ash geopolymer specimen exhibits highest total intruded volume (0.3908 cc/g) and largest compressive strength of 29.5 MPa, while red soil geopolymer specimen exhibit least intruded volume (0.0416 cc/g) and lowest compressive strength (5.4 MPa). Further, analysis showed that specimens with larger airvoids+macropores volume had larger compressive strength, suggesting that geopolymers with more porous microstructure develop larger compressive strength. All geopolymer specimens exhibited tri-modal nature of pores i.e. macro-pore mode (entrance pore radius: 25-5000 nm), mesopore mode (entrance pore radius: 1.25 to 25 nm) and air void mode (entrance pore radius >5000 nm). The micro pores (entrance pore radius < 1.25 nm) do not contribute to porosity of the geopolymer specimens. Sand particles prepared from geopolymer reactions (FAPS or fly ash geopolymer sand) predominated in medium sized (2mm to 0.425 mm) sand particles. Their particle size distribution characteristics (uniformity coefficient and coefficient of curvature) classified them as poorly graded sand (SP). Dissolution, followed by polymerization reactions led to dense packing of the Si–O–Al–O– units that imparted specific gravity of 2.59 to FAPS particles which is comparable to that of river sand (2.61). Dissolution in strongly alkaline medium imparted strongly alkaline pH (12.5) to the FAPS particles. The river sand is characterized by much lower pH (7.9). Despite being characterized by rounded grains, the FAPS particles mobilized relatively high friction angle of (35.5o) than river sand (∅ = 28.9o). The river sand-mortar (RS-M) and fly ash geopolymer sand-mortar (FAPS-M) specimens developed similar 28-day compressive strengths, 11.6 to 12.2 MPa. Despite its higher water content, FAPS-mortar specimens developed similar compressive strength and initial tangent modulus (ITM) as river sand-mortar specimens. The FAPS-M specimen is more porous (larger intruded volume) with presence of larger fraction of coarser pores. Total porosity is majorly contributed by macro-pores (67.92%) in FAPS-M specimen in comparison to RS-M specimen (macro-pores = 33.1%). Mortar specimens prepared from FAPS and river sand exhibit similar pH of 12.36 and 12.4 respectively. FAPS-mortar specimens have lower TDS (1545 mg/L) than river sand-mortar specimens (TDS = 1889 mg/L). The RS-M and FAPS-M specimens exhibit leachable sodium levels of 0.001 g Na/g RS-M and 0.007 g Na/g-FAPS-M respectively in the water leach tests. The larger leachable sodium of FAPS-M specimen is attributed to residual sodium hydroxide persisting in the FAPS even after washing. The ultra-accelerated mortar bar test (UAMBT) shows that the percentage expansion of FAPS-M and RS-M specimens are comparable and range between 0.07 to 0.08 %.

Geopolymers are a relatively new class of materials that have many broad applications, including use as substitute for ordinary Portland cement (OPC), use in soil stabilisation, fire resistant panels, refractory cements, and inorganic adhesives. Geopolymers are an alternative binder to Portland cement in the manufacture of mortars and concrete, as its three-dimensional alumino silicate network develops excellent strength properties. Use of geopolymers in place of ordinary Portland cement is also favoured owing to the possible energy and carbon dioxide savings. Geopolymer is typically synthesized by alkali activation of pozzolanas at moderate temperatures (< 1000C). The focus of the thesis is synthesis and characterization of geopolymers as construction materials. In this context, the role of compositional factors, such as, pozzolana type (fly ash, kaolinite, metakaolinite, ground granulated blast furnace slag, red soil), alkali (sodium hydroxide is used in this study) activator concentration, Si/Al (Si= silicon, Al = aluminium) ratio of the pozzolana and environmental factors, namely, curing period and temperature are examined. Besides synthesizing geopolymers that could be an alternate to concrete as construction material, sand-sized aggregates were synthesized using geopolymer reactions. This was done as river sand is becoming scarcer commodity for use as construction material. Several compositional and environmental factors were varied in geopolymer synthesis in order to identify the optimum synthesis conditions that yield geopolymers with maximum compressive strength. Besides varying external (compositional and environmental) factors, the role of internal microstructure in influencing the compressive strength of the geopolymer was examined. Micro-structure examinations were made using X-ray diffraction (XRD), scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) studies. The studies on compositional and environmental factors in geopolymer synthesis brought out several interesting results. The results firstly brought out that amongst the pozzolanas studied, ASTM class F fly ash is most suited for maximum compressive strength mobilization upon geopolymer reactions. Moderate temperature (75-1000C) was adequate to mobilize large compressive strengths. Room temperature curing needed more than 7 days before the pozzolana-NaOH paste began to develop strength. Curing period of 56 days was needed for the geopolymer to develop significant strength (19.6MPa). A similar range of compressive strength could be developed by the pozzolana-NaOH paste upon curing for 3 days at 1000C. Likewise curing the pozzolana-NaOH paste at temperatures > 1000C led to reduction in compressive strength from shrinkage and breakage of bonds. A caustic soda (NaOH) concentration of 10 M was adequate to develop maximum compressive strength of the geopolymer. Caustic soda concentrations in excess of 10 M did not result in further improvement of strength. The Si/Al ratio also contributes to strength mobilization. The Si/Al ratio of the geopolymer was enhanced by mixing commercially obtained silica gel with the pozzolana. Maximum strength mobilization was observed at Si/Al ratio = 2.45 corresponding to 6.5 % silica gel addition to the pozzolana (on dry mass basis). Comparing compressive strengths of geopolymers with varying silica gel contents, geopolymer specimens with least water content and largest dry density did not exhibit maximum compressive strength indicating that the physico-chemical (bond strength, micro-structure) played a pivotal role than physical parameters (dry density, water content) in dictating the strength of the geopolymer. MIP results showed that bulk of the porosity in fly ash geopolymer specimens is contributed by macro pores and air voids. Geopolymerization leads to bulk consumption of cenospheres in fly ash and forms polymerized matrix with network of large pores. After geopolymerization, all the main characteristic peaks of Al–Si minerals observed in fly ash persisted, suggesting that no new major crystalline phases were formed. Presence of small amount of inorganic contaminants in fly ash can drastically reduce the strength of the fly ash geopolymer. For example, 5-20 % presence of red soil reduces the strength of fly ash geopolymer by 16 to 59 %. Presence of unreacted clay coupled with less porous structure is responsible for the reduction in compressive strength of fly ash geopolymer subjected to red soil addition. MIP studies with geopolymers also revealed that there is good bearing between compressive strengths and maximum intruded volume (from MIP test) of geopolymers. For example, fly ash geopolymer specimen exhibits highest total intruded volume (0.3908 cc/g) and largest compressive strength of 29.5 MPa, while red soil geopolymer specimen exhibit least intruded volume (0.0416 cc/g) and lowest compressive strength (5.4 MPa). Further, analysis showed that specimens with larger airvoids+macropores volume had larger compressive strength, suggesting that geopolymers with more porous microstructure develop larger compressive strength. All geopolymer specimens exhibited tri-modal nature of pores i.e. macro-pore mode (entrance pore radius: 25-5000 nm), mesopore mode (entrance pore radius: 1.25 to 25 nm) and air void mode (entrance pore radius >5000 nm). The micro pores (entrance pore radius < 1.25 nm) do not contribute to porosity of the geopolymer specimens. Sand particles prepared from geopolymer reactions (FAPS or fly ash geopolymer sand) predominated in medium sized (2mm to 0.425 mm) sand particles. Their particle size distribution characteristics (uniformity coefficient and coefficient of curvature) classified them as poorly graded sand (SP). Dissolution, followed by polymerization reactions led to dense packing of the Si–O–Al–O– units that imparted specific gravity of 2.59 to FAPS particles which is comparable to that of river sand (2.61). Dissolution in strongly alkaline medium imparted strongly alkaline pH (12.5) to the FAPS particles. The river sand is characterized by much lower pH (7.9). Despite being characterized by rounded grains, the FAPS particles mobilized relatively high friction angle of (35.5o) than river sand (∅ = 28.9o). The river sand-mortar (RS-M) and fly ash geopolymer sand-mortar (FAPS-M) specimens developed similar 28-day compressive strengths, 11.6 to 12.2 MPa. Despite its higher water content, FAPS-mortar specimens developed similar compressive strength and initial tangent modulus (ITM) as river sand-mortar specimens. The FAPS-M specimen is more porous (larger intruded volume) with presence of larger fraction of coarser pores. Total porosity is majorly contributed by macro-pores (67.92%) in FAPS-M specimen in comparison to RS-M specimen (macro-pores = 33.1%). Mortar specimens prepared from FAPS and river sand exhibit similar pH of 12.36 and 12.4 respectively. FAPS-mortar specimens have lower TDS (1545 mg/L) than river sand-mortar specimens (TDS = 1889 mg/L). The RS-M and FAPS-M specimens exhibit leachable sodium levels of 0.001 g Na/g RS-M and 0.007 g Na/g-FAPS-M respectively in the water leach tests. The larger leachable sodium of FAPS-M specimen is attributed to residual sodium hydroxide persisting in the FAPS even after washing. The ultra-accelerated mortar bar test (UAMBT) shows that the percentage expansion of FAPS-M and RS-M specimens are comparable and range between 0.07 to 0.08 %.

Doctoral Thesis for PhD degree in Civil Engineering.
Ultra-high performance concrete (UHPC) is a promising type of self-compacting steel fiber-reinforced concrete, which exhibits extraordinary performances in its fresh and hardened states. It not only demonstrates ultra-high strength in compression, but also exhibits ultra-high durability characteristics. Since sustainability-related issues have become major priorities in the world ahead in recent years, therefore, a special attention to any product and service, particularly those used with an increasing pace and embrace considerable carbon footprint and substantial economic impacts, such as UHPC with high content of cement and silica fume, would be of great significance. In this scope, this research aimed to develop an eco-efficient type of UHPC as an innovative and high-tech material through partially substitution of cement and silica fume by other pozzolanic industrial-waste materials. Response surface methodology (RSM), as a statistical mixture design tool, was applied in order to create a scientific basis for developing the optimum composition with higher environmental and economic efficiency. The performance of the optimum composition, nominated as eco-efficient UHPC (EEUHPC), was evaluated through standard test methods in its fresh and hardened states. Furthermore, an effective low-energy mixing procedure, with the aim of improved flowability, was introduced. Finally, the autogenic self-healing ability of the material was studied as an important issue regarding the life cycle of the material and its capacity for structural recovery. The tests were carried out in short and long-term life of the material. Effect of different crack widths on self-healing capacity of cracked specimens was investigated as well as influence of steel fibers on energy absorption of samples in post-cracking stage.
O betão de ultra elevado desempenho (BUED) é um tipo de betão autocompactável reforçado com fibras bastante promissor e que é dotado de um desempenho extraordinário tanto no estado fresco como no estado endurecido. Este tipo de betão não só apresenta ultra elevada resistência à compressão como, também, é caracterizado por ultra elevada durabilidade. Nos últimos anos as questões relacionadas com a sustentabilidade passaram a ser consideradas prioritárias em todo o mundo. Portanto, passou a ser de importância acrescida garantir especial atenção a qualquer produto ou serviço, em particular os de utilização crescente compreendendo uma considerável da pegada de carbono e impacto económico substancial, tal como o BUED, fabricado geralmente com um teor de cimento e sílica de fumo elevados. Neste âmbito, este trabalho teve como objetivo desenvolver um material inovador e de alta tecnologia, um BUED eco-eficiente, produzido com recurso à substituição parcial de cimento e sílica de fumo por subprodutos industriais com características pozolânicas. A definição das composições foi efetuada recorrendo à metodologia de superfície de resposta (MSR), uma ferramenta estatística que permitiu determinar, com base científica, as composições ótimas, com maior eficiência ambiental e económica. O desempenho da composição ótima, designada BUED eco-eficiente (BUEDEE), foi avaliado por intermédio de ensaios laboratoriais, realizados tanto no estado fresco como no estado endurecido. Além disso, foi também desenvolvido um processo de mistura eficaz e de baixa energia, concebido com o objetivo de melhorar a fluidez. Finalmente, a capacidade de autorreparação autogénea do material foi estudada como uma questão importante relacionada com o ciclo de vida do material e com a sua capacidade de recuperação estrutural. Os testes foram realizados tanto em idades iniciais como a longo prazo. O efeito da abertura de fenda na capacidade de autorreparação dos provetes fendilhados foi avaliado, assim como a influência da presença das fibras metálicas na capacidade de absorção de energia de provetes em estado pós-fendilhado.