Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Civil Engineering. / Microfiche copy available in Archives and Engineering. / Bibliography: leaf 116. / M.S.

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O presente trabalho avaliou o comportamento hidráulico e reativo de um solo argiloso compactado na energia proctor modificada, com adição de cimento Portland, para fins de aplicação em barreiras impermeáveis de fundo em aterros de resíduos sólidos industriais e de mineração, quando submetido à ação de carga estática de resíduos e em contato com lixiviado ácido enriquecido com os metais cádmio e chumbo. Um Latossolo argiloso residual da cidade de Passo Fundo - RS foi utilizado para moldagem de corpos de prova. A adição de cimento nas proporções de 0% a 2% teve como objetivo melhorar as condições reativas da barreira. Para verificação do comportamento hidráulico foram executados ensaios de condutividade hidráulica. O comportamento reativo foi avaliado por meio de ensaios de difusão, os quais foram realizados com aplicação de carga estática variável (0 kPa a 500 kPa). Soluções contaminantes contendo respectivamente 10 mg/L de cádmio e 10 mg/L de chumbo foram elaboradas com pH variando na faixa de 1 a 6. A partir de ensaio de difusão foram determinados o fator de retardamento (Rd), o coeficiente de distribuição (Kd) e o coeficiente de difusão efetiva (D*), para cada combinação de pH, % cimento e carga estática aplicada. Os resultados obtidos para a mistura compactada investigada indicaram um baixo coeficiente de condutividade hidráulica (<10-9 m/s) e valores que sofreram redução com o acréscimo de cimento. Em relação ao comportamento reativo, os valores de Rd e Kd sofreram incrementos, principalmente com o aumento do pH da solução contaminante, evidenciando o aumento da retenção dos metais. O D* não sofreu influência para os ensaios com Cd e sofreu redução devido à intensa precipitação química em solução que ocorreu devido ao acréscimo de cimento nos ensaios com Pb. A ação conjunta do aumento do pH e da adição de cimento à barreira ocasionou a maior ocorrência de reações de precipitação na barreira, do que reações de adsorção, o que não foi favorável porque possibilita que o contaminante permaneça em solução e possa ser solubilizado em presença de meio ácido. Nesse sentido, a condição que se apresentou mais favorável para o projeto de uma barreira impermeável e reativa foi de 0% de cimento para Pb e 1% de cimento para Cd, as quais desencadearam maiores os valores de Rd e Kd, considerando o contaminante na sua condição mais ácida (pH 1). Em relação à magnitude dos parâmetros Rd e Kd, Pb apresentou maiores valores do que Cd, indicando menor mobilidade. / This study evaluated the hydraulic and reactive behavior of a clayey soil compacted at modified energy proctor, with and without the addition of Portland cement, aiming at its use as containment barriers for industrial and mining solid waste disposal facilities, when subjected to the action of a static load simulating the solid waste mass and to an acid leachate enriched with metals cadmium and lead. A clayey residual Oxisol from Passo Fundo - RS was used for molding specimens. The cement addition in the proportions of 0% to 2% aimed to improve the reactive potential of barrier. Tests of hydraulic conductivity were performed to investigate the hydraulic behavior. The reactive behavior was evaluated through diffusion tests which were conducted with variable static load (0 kPa to 500 kPa). Contaminant solutions were prepared with pH varying from 1 to 6 and 10 mg/L, for both cadmium and lead. The retardation factor (Rd), the distribution coefficient (Kd) and the effective diffusion coefficient (D*) were determined for each combination of pH, % cement and static load. The results obtained showed a low hydraulic conductivity coefficient (<10-9 m/s) and values that decreased with the increasing cement content. Regarding the reactive behavior, the values of Kd and Rd increased mainly with the pH solution increment, causing the increase of metals retention. D* was not affected in the tests with Cd, but was reduced in the tests with Pb, probably by the intense chemical precipitation that occurred due to the cement addition. The combined action of increasing both the pH and the cement addition caused a higher level of precipitation reactions, which allows the contaminant to remain in solution and be solubilized in acid environment. In this sense, the condition which was most favorable for the design of an reactive and impermeable barrier was 0% cement for Pb and 1% cement for Cd, which provided the highest Rd and Kd values, considering the contaminant at its most acidic condition. Regarding the parameters Rd and Kd magnitudes, Pb showed higher values than Cd, indicating less mobility.

O presente trabalho avaliou o comportamento hidráulico e reativo de um solo argiloso compactado na energia proctor modificada, com adição de cimento Portland, para fins de aplicação em barreiras impermeáveis de fundo em aterros de resíduos sólidos industriais e de mineração, quando submetido à ação de carga estática de resíduos e em contato com lixiviado ácido enriquecido com os metais cádmio e chumbo. Um Latossolo argiloso residual da cidade de Passo Fundo - RS foi utilizado para moldagem de corpos de prova. A adição de cimento nas proporções de 0% a 2% teve como objetivo melhorar as condições reativas da barreira. Para verificação do comportamento hidráulico foram executados ensaios de condutividade hidráulica. O comportamento reativo foi avaliado por meio de ensaios de difusão, os quais foram realizados com aplicação de carga estática variável (0 kPa a 500 kPa). Soluções contaminantes contendo respectivamente 10 mg/L de cádmio e 10 mg/L de chumbo foram elaboradas com pH variando na faixa de 1 a 6. A partir de ensaio de difusão foram determinados o fator de retardamento (Rd), o coeficiente de distribuição (Kd) e o coeficiente de difusão efetiva (D*), para cada combinação de pH, % cimento e carga estática aplicada. Os resultados obtidos para a mistura compactada investigada indicaram um baixo coeficiente de condutividade hidráulica (<10-9 m/s) e valores que sofreram redução com o acréscimo de cimento. Em relação ao comportamento reativo, os valores de Rd e Kd sofreram incrementos, principalmente com o aumento do pH da solução contaminante, evidenciando o aumento da retenção dos metais. O D* não sofreu influência para os ensaios com Cd e sofreu redução devido à intensa precipitação química em solução que ocorreu devido ao acréscimo de cimento nos ensaios com Pb. A ação conjunta do aumento do pH e da adição de cimento à barreira ocasionou a maior ocorrência de reações de precipitação na barreira, do que reações de adsorção, o que não foi favorável porque possibilita que o contaminante permaneça em solução e possa ser solubilizado em presença de meio ácido. Nesse sentido, a condição que se apresentou mais favorável para o projeto de uma barreira impermeável e reativa foi de 0% de cimento para Pb e 1% de cimento para Cd, as quais desencadearam maiores os valores de Rd e Kd, considerando o contaminante na sua condição mais ácida (pH 1). Em relação à magnitude dos parâmetros Rd e Kd, Pb apresentou maiores valores do que Cd, indicando menor mobilidade. / This study evaluated the hydraulic and reactive behavior of a clayey soil compacted at modified energy proctor, with and without the addition of Portland cement, aiming at its use as containment barriers for industrial and mining solid waste disposal facilities, when subjected to the action of a static load simulating the solid waste mass and to an acid leachate enriched with metals cadmium and lead. A clayey residual Oxisol from Passo Fundo - RS was used for molding specimens. The cement addition in the proportions of 0% to 2% aimed to improve the reactive potential of barrier. Tests of hydraulic conductivity were performed to investigate the hydraulic behavior. The reactive behavior was evaluated through diffusion tests which were conducted with variable static load (0 kPa to 500 kPa). Contaminant solutions were prepared with pH varying from 1 to 6 and 10 mg/L, for both cadmium and lead. The retardation factor (Rd), the distribution coefficient (Kd) and the effective diffusion coefficient (D*) were determined for each combination of pH, % cement and static load. The results obtained showed a low hydraulic conductivity coefficient (<10-9 m/s) and values that decreased with the increasing cement content. Regarding the reactive behavior, the values of Kd and Rd increased mainly with the pH solution increment, causing the increase of metals retention. D* was not affected in the tests with Cd, but was reduced in the tests with Pb, probably by the intense chemical precipitation that occurred due to the cement addition. The combined action of increasing both the pH and the cement addition caused a higher level of precipitation reactions, which allows the contaminant to remain in solution and be solubilized in acid environment. In this sense, the condition which was most favorable for the design of an reactive and impermeable barrier was 0% cement for Pb and 1% cement for Cd, which provided the highest Rd and Kd values, considering the contaminant at its most acidic condition. Regarding the parameters Rd and Kd magnitudes, Pb showed higher values than Cd, indicating less mobility.

O presente trabalho avaliou o comportamento hidráulico e reativo de um solo argiloso compactado na energia proctor modificada, com adição de cimento Portland, para fins de aplicação em barreiras impermeáveis de fundo em aterros de resíduos sólidos industriais e de mineração, quando submetido à ação de carga estática de resíduos e em contato com lixiviado ácido enriquecido com os metais cádmio e chumbo. Um Latossolo argiloso residual da cidade de Passo Fundo - RS foi utilizado para moldagem de corpos de prova. A adição de cimento nas proporções de 0% a 2% teve como objetivo melhorar as condições reativas da barreira. Para verificação do comportamento hidráulico foram executados ensaios de condutividade hidráulica. O comportamento reativo foi avaliado por meio de ensaios de difusão, os quais foram realizados com aplicação de carga estática variável (0 kPa a 500 kPa). Soluções contaminantes contendo respectivamente 10 mg/L de cádmio e 10 mg/L de chumbo foram elaboradas com pH variando na faixa de 1 a 6. A partir de ensaio de difusão foram determinados o fator de retardamento (Rd), o coeficiente de distribuição (Kd) e o coeficiente de difusão efetiva (D*), para cada combinação de pH, % cimento e carga estática aplicada. Os resultados obtidos para a mistura compactada investigada indicaram um baixo coeficiente de condutividade hidráulica (<10-9 m/s) e valores que sofreram redução com o acréscimo de cimento. Em relação ao comportamento reativo, os valores de Rd e Kd sofreram incrementos, principalmente com o aumento do pH da solução contaminante, evidenciando o aumento da retenção dos metais. O D* não sofreu influência para os ensaios com Cd e sofreu redução devido à intensa precipitação química em solução que ocorreu devido ao acréscimo de cimento nos ensaios com Pb. A ação conjunta do aumento do pH e da adição de cimento à barreira ocasionou a maior ocorrência de reações de precipitação na barreira, do que reações de adsorção, o que não foi favorável porque possibilita que o contaminante permaneça em solução e possa ser solubilizado em presença de meio ácido. Nesse sentido, a condição que se apresentou mais favorável para o projeto de uma barreira impermeável e reativa foi de 0% de cimento para Pb e 1% de cimento para Cd, as quais desencadearam maiores os valores de Rd e Kd, considerando o contaminante na sua condição mais ácida (pH 1). Em relação à magnitude dos parâmetros Rd e Kd, Pb apresentou maiores valores do que Cd, indicando menor mobilidade. / This study evaluated the hydraulic and reactive behavior of a clayey soil compacted at modified energy proctor, with and without the addition of Portland cement, aiming at its use as containment barriers for industrial and mining solid waste disposal facilities, when subjected to the action of a static load simulating the solid waste mass and to an acid leachate enriched with metals cadmium and lead. A clayey residual Oxisol from Passo Fundo - RS was used for molding specimens. The cement addition in the proportions of 0% to 2% aimed to improve the reactive potential of barrier. Tests of hydraulic conductivity were performed to investigate the hydraulic behavior. The reactive behavior was evaluated through diffusion tests which were conducted with variable static load (0 kPa to 500 kPa). Contaminant solutions were prepared with pH varying from 1 to 6 and 10 mg/L, for both cadmium and lead. The retardation factor (Rd), the distribution coefficient (Kd) and the effective diffusion coefficient (D*) were determined for each combination of pH, % cement and static load. The results obtained showed a low hydraulic conductivity coefficient (<10-9 m/s) and values that decreased with the increasing cement content. Regarding the reactive behavior, the values of Kd and Rd increased mainly with the pH solution increment, causing the increase of metals retention. D* was not affected in the tests with Cd, but was reduced in the tests with Pb, probably by the intense chemical precipitation that occurred due to the cement addition. The combined action of increasing both the pH and the cement addition caused a higher level of precipitation reactions, which allows the contaminant to remain in solution and be solubilized in acid environment. In this sense, the condition which was most favorable for the design of an reactive and impermeable barrier was 0% cement for Pb and 1% cement for Cd, which provided the highest Rd and Kd values, considering the contaminant at its most acidic condition. Regarding the parameters Rd and Kd magnitudes, Pb showed higher values than Cd, indicating less mobility.

Mittels künstlichen neuronalen Netzen wurden die in den rekultivierten Tagebaukippen im Nordraum Lausitz (Tagebaue Schlabendorf und Seese) auftretenden Geländedeformationen infolge Bodenverflüssigung für die Jahre 2009 - 2013 als Zeitreihe modelliert. Das Modell ist in der Lage, grob die zeitliche Entwicklung und exakt die räumliche Lage des in den Kippen auftretenden Gefährdungspotenzials nachzuvollziehen und als Funktion des sich ändernden Grundwasserspiegels und der sich ändernden Oberflächenmorphologie in die Zukunft zu prognostizieren. Das Modell zeigt dynamisch das Entstehen neuer Risikoflächen in bisher scheinbar stabilen Bereichen des Untersuchungsgebietes. Die Korrektheit des Modells wurde mittels verschiedener Tests geprüft sowie anhand einer Prognoserechnung für das Jahr 2014 und des Vergleichs mit den real in 2014/2015 gegangenen Ereignissen nachgewiesen. Folgende Gefährdungsfaktoren wurden ermittelt: Destabilisierend wirken eine möglichst einförmige Lithologie folgender Zusammenset-zung: 31 % Feinsand, 34 % Mittelsand, 31 % Grobsand, 3 % Schluff, < 1 % Kies, < 1 % Kalk, < 1 % Ton, < 1 % Kohle, kf-Werte zwischen 10-4 und 10-4,5 m/s, ein Grundwasserflurabstand bei 3,45 m (Medianwert), möglichst hohe Gradienten der nicht lithologisch kontrollierten Parameter: Tagebauoberfläche, Grundwasseroberfläche, Grundwasserflurabstand und Mächtigkeit der gesättigten Kippe. Stabilisierend wirken vor allem eine möglichst große Heterogenität der Lithologie auf kleinem Raum (möglichst hohe Gradienten der lithologisch kontrollierten Parameter (z.B. Kiesgehalt, Sandgehalt, Tongehalt, Kohlegehalt)), ein möglichst geringer Sandanteil, möglichst hohe Anteile an Kies, Schluff, Ton, Kalk, bzw. Kohle, ein möglichst großer Grundwasserflurabstand sowie möglichst geringe Gradienten der nicht lithologisch kontrollierten Parameter: Tagebauoberfläche, Grundwasseroberfläche, Grundwasserflurabstand, Mächtigkeit der gesättigten Kippe sowie wechselnde kf-Werte 10-7 bzw. >10-2 m/s. Für die Bearbeitung wurden ausschließlich die bei der LMBV vorhandenen bzw. laufend flächendeckend erhobenen Daten genutzt: Lage des Grundwasserspiegels, Relief der Tagebauoberfläche, Liegendes der Kippe, geologische Daten der Vorfeldbohrungen. Das Modell kann als dynamisches Instrument zum Risikomanagement vor bzw. während der Sanierungsmaßnahmen genutzt werden. Mittels der Variation der prozesskontrollie-renden Parameter können die geotechnischen Auswirkungen verschiedener Sanierungsszenarien (z.B. Gestaltung der Tagebauoberfläche, Schüttung der Kippen, Grundwasseranstieg) auf die Stabilität der Kippen prognostiziert werden. / Geotechnical events (terrain deformation due to soil liquefaction) in lignite mining waste rock piles of the northern Lausitz area (opencast pits Schlabendorf and Seese), have been modeled as time series for the years 2009 – 2013 by using artificial neural networks. The model has clearly recognized the influences of various lithological and non-lithological controlled parameters on the occurrence of geotechnical events, and these have been quantified and weighted in terms of their importance. The model is able to predict the tem-poral evolution and the exact spatial location of the events occurring in the dumps as a function of changing groundwater levels and surface morphology. The model shows dynamically the emergence of new risk areas in hitherto seemingly stable areas. The correctness of the model was confirmed by means of various tests and its predictive success was demonstrated through forecasting of events for the years 2014 and 2015 and their comparison with the observed events of those years. The following main risk factors were identified: Important destabilizing factors are a monotonous lithology with the following composition: 31% fine sand, 34% medium sand, 31% coarse sand, 3% silt, <1% gravel, <1% lime, <1% clay, <1% coal, kf-values between 10-4 and 10-4.5 m/s, a surface to groundwater distance of 3.45 meters (median value), high gradients of non-lithological controlled parameters: waste dump surface, groundwater level, depth to groundwater and thickness of saturated dump. 2. Important stabilizing factors are a high heterogeneity of lithology (high gradients of the lithological controlled parameters: e.g. gravel content, sand content, clay content, carbon content), a low proportion of sand in the dump composition, high proportions of gravel, silt, clay, lime, or coal, a high depth to groundwater, low gradients of non-lithological controlled parameters: open pit surface, groundwater surface, depth to groundwater, thickness of saturated dump, strongly changing kf values between 10-7 and 10-2 m/s. The model can be used as a dynamic tool for risk management before and during the re-habilitation of lignite waste dumps, and for constructing stable waste dumps. By means of varying the model parameters (e.g. design of the dump surface, composition of dumped rocks, rising groundwater) the geotechnical effects of dump design and remediation scenarios can be predicted.

Cemented paste backfill (CPB) is a novel technology developed in the past few decades to better manage mining wastes (such as tailings) in environmentally friendly way. It has received prominent interest in the mining industry around the world. In this technology, up to 60% of the total amount of tailings is reused and converted into cemented construction material that can be used for secondary support in underground mine openings (stopes) and to maximize the recovery of ore from pillars. CPB is an engineered mixture of tailings, water, and hydraulic binder (such as cement), that is mixed in the paste plant and delivered into the mine stopes either by gravity or pumping. During and after placing it into the mine stopes, the performance of CPB mainly depends on the role of the hydraulic binder, which increases the mechanical strength of the mixture through the process of cement hydration. Similar to other fine-grained soils undergoing cementations, CPB’s behavior is affected by several conditions or factors, such as cement hydration progress (curing time), chemistry of pore water, mixing and curing temperature, and filling strategy. Also, it has been found that fresh CPB placed in the mine stopes can be susceptible to many geotechnical issues, such as liquefaction under ground shaking conditions. Liquefaction-induced failure of CPB structure may cause injuries and fatalities, as well as significant environmental and economic damages. Many researches studied the effect of the aforementioned conditions on the static mechanical behavior of CPB. Other researches have evaluated the liquefaction behavior of natural soils and tailings (without cement) during cyclic loadings using shaking table test technique. Only few studies investigated the CPB liquefaction during dynamic loading events using the triaxial tests. Yet, there are currently no studies that addressed the liquefaction behavior of CPB under the previous conditions by using the shaking table technique. In this Ph.D. study, a series of shaking table tests were conducted on fresh CPB samples (75 cm × 75 cm ×70 cm), which were mixed and poured into a flexible laminar shear box (that was designed and build for the purpose of this research). Some of these shaking table tests were performed at different maturity ages of 2.5 hrs, 4.0 hrs, and 10.0 hrs, to investigate the effect of cement hydration progress on the liquefaction potential of CPB. Another set of tests were conducted to assess the effect of the chemistry (sulphate content) of the pore-water on the cyclic response of fresh CPB by exposing cyclic loads on couple of CPB models that contain different concertation of sulphate ions of 0.0 ppm and 5000 ppm. Moreover, as part of this study, series of shaking table test was conducted on CPB samples that were prepared and cured at different temperatures of 20oC and 35oC, to evaluate the effect of temperature of the cyclic behavior of CPB. Furthermore, the effect of filling strategy on the cyclic behavior of fresh CPB was assessed by conducting set of shaking tables tests on CPB models that were prepared at different filling strategies of continuous filling, and sequential or discontinuous (layered) filling. The results obtained show that CPB has different cyclic behavior and performance under these different conditions. It is observed that the progress of cement hydration (longer curing time) enhances the liquefaction resistance of CPB, while the presence of sulphate ions diminishes it. It is also found that CPB mixed and cured in low temperature is more prone to liquefaction than those prepared at higher temperatures. Moreover, the obtained results show that adopting the discontinuous (layered) filling strategy will improve the liquefaction resistance of CPB. The finding presented in this thesis will contribute to efficient, cost effective and safer design of CPB structures in the mine areas, and will help in minimizing the risks of liquefaction-induced failure of CPB structures.

As a consequence of new coal mining practices, coal preparation plants have been inundated with increased loads of coal and clay particles in their wastewaters. Traditionally, the industry has employed primary sedimentation as the fundamental treatment scheme for these sediment-laden blackwaters. This study was undertaken to determine the effects of a combination of coagulant addition and rapid mixing on the settleability of these particles. After initial testing, aluminum sulfate and two low molecular weight cationic polymers, Cyanamid Magnifloc 513C and Cyanamid 515C, were chosen as primary coagulants for use in this work. An artificial wastewater was prepared from finely powdered (62 to <38 microns) raw coal samples and tap water, after initial tests indicated that typical frothing and/or collector agents had no demonstrable effect on coagulant function. Initially determined optimum coagulant dosages, as well as flocculation and sedimentation times, were kept constant while rapid mix intensities were varied at G values of 330 sec⁻¹, 700 sec⁻¹, 2000 sec⁻¹ and 7000 sec⁻¹ for each sample. Using a combination of residual turbidity and particle size analyses to determine the effectiveness of each rapid mix intensity, it was discovered that only the highest mixing intensities and durations (G(t) values) caused floe disintegration due to overmixing. At the lower G(t) matrices floe formation and settleability was consistently good. When aluminum sulfate was used as a coagulant, the wastewater was tested at a high pH of 8.1 to 8.3 and a low pH of 5.5 to observe floe behavior under different conditions of coagulant mechanism. The test results were similar for both pH values except at the lowest mixing intensities where the high pH samples settled well, resulting in low residual turbidities, but the low pH samples had relatively high turbidities. / Master of Science

Over the past decades, cemented paste backfill (CPB) has become a common, environmentally friendly method of managing mine wastes (such as tailings). This technology allows up to 60% of the total amount of tailings to be reused and filled in the mine stopes after converting them into cemented material. Beside reducing the environmental risks associated with the traditional disposal of these materials, turning them into cemented material and placing them in the underground mine stopes can also provide secondary support for these stopes in addition to minimizing the risk of ground subsidence in the mine area. CPB is an engineered mixture of tailings, water, and hydraulic binder (such as cement, blast furnace slag, and fly ash) that is mixed in the paste plant and delivered into the mine stopes through a gravity or pumping based transportation system. During the transportation of CPB through the delivery system pipelines, the flowability of CPB depends on the rheology of the transported CPB, which is affected by different factors, such as the transportation time, temperature variation, binder type, and chemical composition of these mixtures. In addition, the performance of CPB, after placing the CPB mixture into the mine stopes, is mainly dependent on the role of the hydraulic binder, as it increases the mechanical strength of the mixture through the process of cement hydration. The mechanical strength is also influenced by different factors, such as time progress, temperature variation, and presence of chemical additives. It has previously been found that fresh CPB transported and/or placed in the mine stopes can be susceptible to temperature variation of different sources, such as the climatic effects, heat generated from the surrounding rocks, and heat generated during the process of cement hydration. Unsuitable flowability of CPB through the delivery system might lead to significant financial losses due to clogging of pipelines with unexpected hardening of CPB during transportation, which will cause delay in work and possible damages to the pipelines. Also, failure of CPB structure in the mine stopes due to inappropriate mechanical strength may cause casualties to the mine workers as well as significant environmental and economic damages. Many researchers studied the rheological properties and/or strength development of CPB under the individual effect of any of the aforementioned factors. Additionally, many researchers have evaluated the coupled effect of some of these factors on the rheology and mechanical strength of CPB material. Hitherto, there are currently no studies that addressed the combined effect of all these conditions on the rheological properties and strength development of CPB. At the first stage of this M.A.Sc. study, a series of experimental tests was conducted on fresh CPB in order to determine the combined effect of time, temperature, binder content, and chemical additives on the rheological properties of CPB. These experiments include rheological properties test (yield stress and viscosity), microstructural analysis (thermal analysis and XRD), chemical analysis (pH and Zeta potential), and monitoring tests (electrical conductivity), which were conducted on 125 CPB samples that were mixed and prepared at different temperatures (2oC, 20oC, 35oC) and cured for different curing time (0 hrs., 0.25 hrs., 1 hr., 2hrs, and 4 hrs.). These samples were prepared with different blends of hydraulic binders (PCI, PCI/Slag, and PCI/FA) and contained different dosages of sodium silicate (0%, 0.1%, 0.3%, and 0.5%). The results obtained show that rheology of CPB increases with the progress of curing time. It also increases with the increase in the initial (mixing and curing) temperature and content of sodium silicate. It was also found that the partial usage of slag and FA reduces the rheological properties. However, CPBs containing PCI/FA as binder have lower rheological properties, and thus better flowability, than those that contain PCI/Slag as binder. At the second stage of this M.A.Sc. study, in order to understand the combined effect of time, temperature and sodium silicate content on the strength development of slag-CPB, unconfined compression (UCS) test, microstructural analysis (thermal analysis and MIP), and monitoring tests (electrical conductivity, suction, and volumetric water content) were conducted on 72 CPB samples that were prepared with PCI-Slag as a binder, cured for different times (1 day, 3 days, 7 days, and 28 days) under different curing temperatures of (2oC, 20oC, 35oC), and contained different dosages of sodium silicate (0%, 0.3% and 0.5%). The results obtained at this stage showed that the strength development of slag-CPB increases with the progress of curing time and temperature. It also increases with the increase in the sodium silicate content. Also, the combined effect of high temperature, high dosage of sodium silicate and longer curing time showed significant enhancement in the mechanical strength of slag-CPB. The findings of this M.A.Sc. research will contribute to cost effective, efficient, and safer design of CPB structures in the mine areas. It will also help in minimizing financial loss associated with unsuitable flowability of CPB transported in the CPB delivery system besides reducing the risks of human loss, and the environmental and economic damages associated with the failure of CPB structures.