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  • 1.
    Makusa, Gregory
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Stabilization-solidification of high water content dredged sediment: Strength, compressibility and durability evaluations2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dredging activities at ports and harbors are inevitable for safe navigation of ships and vessels. The outcomes of dredging are huge volumes of dredged materials, which can range from very fine and contaminated sediments to sands and gravels. The coarse sands and gravels can be directly used in civil engineering applications. The fine dredged sediments (DS) are usually associated with high water content, low shear strength, high compressibility and presence of contaminants. However, these unfavorable properties do not exclude the suitability of fined dredged sediments for use in geotechnical applications. Stabilization-solidification technology provides a comprehensive treatment method for improving strength, reducing the compressibility and mobilizing the contaminants to be less mobile.These properties make the stabilized fine dredged material (SDM) suitable for use in civil engineering applications (e.g. road embankment or structural backfill in land reclamation).However, stabilization-solidification is not a magic wand by which every geotechnical property is improved for better. In cold region climates, repetitive freeze–thaw cycles have detrimental effects to the strength and hydraulic properties of the SDM. Consequently, the applications and long term performance of the SDM under repetitive freeze-thaw cycles are still uncertain.Successful stabilization–solidification of the DS and the performance of the SDM depend on stabilization methods and materials. Process stabilization-solidification (PSS) is convenient technology for amending high water content DS with binders. The use of composite binders for stabilization–solidification of the DS is increasing due to increased artificial pozzolanas that can be used as supplementary cementitious materials (SCM). Primary binders such as cement can be supplemented with SCM (e.g. fly ash and ground granulated blast furnace slag). Cement hydration is a complex process with a complex series of unknown chemical reactions. The hydration of cement incorporating SCM is more complicated due to the co–existence of cement hydration and the pozzolanic reactions of the SCM. The fabric of dredged sediments formed under different physicochemical environments affects the reactivity of binders. The physic ochemical interactions between binders and the DS that influences the strength, compressibility and durability of high water content stabilized dredged sediment are examined and presented in this thesis. The findings of this study show that the use of fly ash (FA) and ground granulated blast furnace slag (GGBS) delays strength development of composite binder (CB)-treated DS. Irrespective of the amounts of CB, the improved strength depends on the amount of cement in the blend. The unconfined compressive strength increases with increasing the cement quantity Three phases of hydration mechanisms determine the compressibility behaviour of the SDM during curing. These are induction phase (IP), nucleation and crystallization phase (NCP), andhardening phase (HP). The IP occurs immediately after mixing. A protective layer is formed on the particle surface of binders, which prevent further penetration of water and then increases resistance to deformations. The evaluated tangent modulus increases to maximum value followed by abrupt drop to lower values at effective vertical stress, which is equals topreconsolidation stress. NCP follows when the protective layer changes to a more permeable membrane, which permits inward flow of water molecules, and outward migration of calcium ion and silicate ions. The tangent modulus of the SDM in NCP is small and increases linearly with effective vertical stress. The SDM in NCP is characterized by loss in apparent preconsolidation stress and tangent modulus. HP occurs as a result of increased thickness and stiffness of the protective layer. The compressibility of the SDM in HP is reduced significantly due to increased apparent preconsolidation pressure and tangent modulus. It is concluded that the maximum tangent modulus of untreated DS determines the maximum deformation of the SDM in all phases of hydration processes.Healing of the damaged SDM due to repetitive freeze-thaw action depend on the type of binder. The inclusion of SCM on one hand increases the healing of the SDM with reduced strength. This occurs during thaw consolidation. On the other hand, inclusion of SCM causes increased HC of the SDM. Considering healing potential on the damaged SDM with reduced strength, increased hydraulic conductivity causes increased rate of dissipation of excess pore pressure, reducedundrained conditions, and improved strength (enhanced outcome). In order to maintain its strength and hydraulic conductivity, the SDM requires protection from severe damage of repetitive freeze–thaw cycles. It can be beneficial to place the SDM below frost depth or use protective cover of geosythetic clay liners (GCL)

  • 2. Makusa, Gregory
    et al.
    Macsik, Josef
    Ecoloop Stockholm.
    Holm, Göran
    Swedish Geotechnical Institute, Linkoping.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Process Stabilization- Solidification and the Physicochemical Factors Influencing the Strength Development of Treated Dredged Sediments2016In: Geo-Chicago 2016: sustainable waste management and remediation : selected papers from sessions of Geo-Chicago 2016, August 14-18, 2016, Chicago, Illinois / [ed] Nazli Yesiller; Dimitrios Zekkos; Arvin Farid; Anirban De; Krishna R Reddy, Reston, Va: American Society of Civil Engineers (ASCE), 2016, p. 532-545Conference paper (Refereed)
    Abstract [en]

    Process stabilization-solidification (PSS) is a convenient technology for amending high water content dredged sediments (DS) with binders. The PSS equipment comprises of a chassis that carries a pugmill and silos of up to four binders. Primary binders such as cement can be supplemented with pozzolanas materials. In this study, physicochemical interactions of single and composite (ternary) binders on strength development of treated DS are examined based on laboratory and a large-scale field tests. The findings of this study show that the unconfined compressive strength (UCS) depends on the amount of cement in the blend. The UCS decreased with increasing water/cement ratio. It is concluded that (i) the use of constant amounts of composite binder at increasing initial water content of the DS contributes to increased water/cement ratio; (ii) underwater discharge of stabilized DS prior to the initial setting increases the water/cement ratio of stabilized mass; and (iii) presence of mineral admixture hinders strength development of treated dredged sediments

  • 3.
    Makusa, Gregory
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mácsik, Josef
    Strategic services & Sustainable Development at Ecoloop, Luleå tekniska universitet, SCC/Ramböll, Ecoloop, Stockholm.
    Holm, Göran
    Statens Geotekniska Institut, Linköping, Luleå tekniska universitet.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A laboratory test study on effect of freeze–thaw cycles on strength and hydraulic conductivity of stabilized dredged sediments2016In: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 53, no 6, p. 1038-1045Article in journal (Refereed)
    Abstract [en]

    Dredged sediments with initial water content between 200% and 400% were treated with single and composite binders. Samples were subjected to open and semi-closed freeze-thaw (f-t) cycles to investigate the impact of f-t cycling on hydraulic conductivity (HC) and unconfined compressive strength (UCS). A grace period (GP) for thaw consolidation is included to assess healing potential of the affected stabilized mass. The findings of this study show that the impact of f-t cycles depend on initially achieved UCS and HC values prior to the f-t cycling and time of testing after f-t cycles. The HC of specimens with initially UCS value of 87 kPa increased with number of f-t cycles. The UCS values decreased in the range of 50%-80% when specimens were tested directly after the thaw period and values decreased in the range of 14%-60% when specimens were tested at the end of GP. The HC of specimens with initial UCS value of 299 kPa remained almost the same. These samples experienced permanent loss in the UCS values, irrespective of time of testing. Detrimental effects of the freezing action on the UCS were greater under semi-closed than open freezing conditions.

  • 4.
    Makusa, Gregory
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mácsik, Josef
    Ecoloop, Stockholm.
    Holm, Göran
    Statens Geotekniska Institut, Linköping.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Process stabilization–solidification and physicochemical factors influencing strength development of treated dredged sediments2016In: Geo-Chicago 2016: Sustainable Waste Management and Remediation / [ed] Nazli Yesiller; Dimitrios Zekkos; Arvin Farid; Anirban De; Krishna R. Reddy, Chicago, Illinois: American Society of Civil Engineers (ASCE), 2016, Vol. GSP 273, p. 532-545Conference paper (Refereed)
    Abstract [en]

    Process stabilization–solidification (PSS) is a convenient technology for amending high water content dredged sediments (DS) with binders. The PSS equipment comprises of a chassis that carries a pugmill and silos of up to four binders. Primary binders such as cement can be supplemented with pozzolanas materials. In this study, physicochemical interactions of single and composite (ternary) binders on strength development of treated DS are examined based on laboratory and a large–scale field tests. The findings of this study show that fixed amount of cement content at increasing initial water content of the DS contribute to decreased level of calcium ions in the blend. Organic matter in the DS retains calcium ions liberated during cement hydration. This causes delay in formation of calcium hydroxide (CH), nucleation and crystallization of calcium silicate hydrates (CSH). Delay in the formation of CH hinders pozzolanic reaction of mineral admixture. Furthermore, increased amount of free water surrounding the stabilized mass causes weakening effect on CSH bond and pH neutralization. It is concluded that strength development of dredged sediments will depend on the amount of cement in the blend in relation to mineral admixture, initial water content of the DS, and the amount of organic matters.

  • 5.
    Makusa, Gregory Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A review of geotechnical behavior of stabilized soils: Design and analysis considerations2013Report (Other academic)
    Abstract [en]

    Utilization of stabilization technology for improving the engineering properties of soft soils and sediments for structural backfill, such as land reclamation is increasing. Mass stabilization solidification provides a comprehensive technology for improving the geotechnical properties of the problematic soils for civil engineering applications; hence, solving the problem of scarcity of natural resources, meanwhile, providing a sustainable solution for management of contaminated sediments.In geotechnical context, stabilized soils might pose considerable challenges to engineers during the design process, which include obtaining the design parameters, selecting the constitutive model and evaluating loading condition. In many cases, the traditional design approaches are utilized to obtain mechanical parameters for geotechnical design and analysis of structures to be found on in-situ stabilized mass. Stiffness and strength properties obtained from laboratory test results on such materials may differ significantly from those attained during the in-situ stabilization.The purpose of this literature study is to gain insight into mechanical behaviors of in-situ stabilized soils for geotechnical applications. The focus is on design and analysis considerations for structures founded on such soil.

  • 6.
    Makusa, Gregory Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mechanical properties of stabilized dredged sediments: for sustainable geotechnical structures2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dredging activities at Ports and Harbors are inevitable for the safe navigation of ships and vessels. Dredged material may range from very fine and contaminated sediments to sand and gravels. While, granular dredged material can be directly utilized in civil engineering applications, fine sediments may require further treatment before use. In geotechnical context, fine sediments are characterized by low shear strength and high compressibility. However, these unfavorable properties do not rule out the suitability of these fine dredged sediments for use in geotechnical construction, such as, road embankment, building foundation or as structural backfill in land reclamation. Mass stabilization solidification provides a comprehensive technology for amending fine sediments at high initial water content, resulting into construction materials of improved strength and reduced compressibility. The ultimate in-situ soil behavior types, stiffness and strength properties of stabilized mass depend on various factors such as binders, mixing equipment, curing temperature, in-situ boundary conditions and mostly important the applied preloading weight during the period of curing. However, despite improved mechanical properties for geotechnical applications, the performance of treated materials becomes susceptible to repeated freeze-thaw cycles. Understanding geotechnical design process, which includes evaluation of material properties, loading condition and selection of appropriate constitutive model, is an important task for settlement and stability analysis of structures founded on stabilized mass. The selection of suitable material model is vital for successful finite element analysis. Nevertheless, among all existing constitutive soil models, none of them can capture all aspects of soil behavior. Therefore, the meaningful and quantifiable predictions of field behaviors are possible only if, undisturbed samples or in-situ tests are used for determination of mechanical properties, and the predictive capacity of selected constitutive model comes from the comparison with field observations In the present research work, utilization of cone penetration test (CPT) data for evaluating the mechanical properties of stabilized dredged sediments for geotechnical design and analysis was presented. A large-scale field test at the Port of Gävle was utilized as a case study, to verify the simulated settlement of preloaded stabilized dredged sediments. The stabilized mass–soil classification behavior type was studied utilizing CPT classification charts. Computation of the primary consolidation settlement due to preloading weight were carried out in PLAXIS 2D geotechnical software and verified against field measurements. A suggestion to protect the stabilized mass against severe weather condition was discussed.

  • 7.
    Makusa, Gregory Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Soil stabilization methods and materials in engineering practice: State of the art review2013Report (Other academic)
    Abstract [en]

    The knowledge of soil Stabilization in geotechnical engineering has been well documented. Journal articles and text books on stabilization technology are available to the students, practicing and consulting engineers in the field of geotechnical engineering. This state of the art review brings up to date trends in stabilization practice with the main focus in stabilization methods and materials. The first part of this review discusses the effect of various binders on stabilized soils. The second part describes stabilization methods and equipment. The review describes in brief modernized stabilization methods and equipment to practicing engineers.

  • 8.
    Makusa, Gregory Paul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Bradshaw, Sabrina, L.
    University of Wisconsin-Madison.
    Berns, Erin
    University of Wisconsin-Madison.
    Benson, Craig, H.
    University of Wisconsin-Madison.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Freeze-thaw cycling and the hydraulic conductivity of geosynthetic clay liners concurrent with cation exchange2014In: Canadian geotechnical journal (Print), ISSN 0008-3674, E-ISSN 1208-6010, Vol. 51, no 6, p. 591-598Article in journal (Refereed)
    Abstract [en]

    Tests were conducted to assess the effect of cation exchange coincident with freeze-thaw cycling on the hydraulic conductivity of a geosynthetic clay liner (GCL). GCLs were prehydrated by contact with silica flour moistened with synthetic subgrade pore water and subsequently permeated with a solution representing the pore water in the cover soil over a tailings facility. Control tests were conducted using the same procedure except deionized water (DI) was used as the permeant liquid to preclude cation exchange from the permeant liquid. The GCLs were subjected to 1, 3, 5, 15, and 20 freeze-thaw cycles, and the hydraulic conductivity and exchange complex were determined after each freeze-thaw increment to assess chemical changes that occurred during freezing, thawing, and permeation. GCLs undergoing freeze thaw cycling experienced little to no cation exchange until 15 freeze-thaw cycles. After 20 freeze-thaw cycles, however, 50% of the sodium (Na) initially in the exchange complex was replaced by calcium (Ca). Dissolution of calciate within the bentonite is a likely source of the Ca. Hydraulic conductivity of GCLs exposed to freeze-thaw cycling was lower than the hydraulic conductivity of a new GCL permeated with DI water (< 2.2x10-11 m/s). A small increases in hydraulic conductivity (~2.3 times), which may have been caused by cation exchange, occured at 15 and 20 freeze-thaw cycles but the hydraulic conductivity remained below that obtained by direct permeation with DI water.

  • 9.
    Makusa, Gregory Paul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Investigation of increased hydraulic conductivity of silty till subjected to freeze–thaw cycles2013In: no STP 1568, p. 33-46, article id STP156820120139Article in journal (Refereed)
    Abstract [en]

    The hydraulic conductivity of silty till increases when the till is subjected to freeze–thaw cycles. A dramatic increase normally occurs after the first freeze–thaw cycle, and the magnitude generally depends on the initial or molding water content. Freezing of silty till causes aggregations of clods and the formation of macrostructure. The initial or molding water content determines the number of freeze–thaw cycles required to complete the agglomeration of clods and the formation of stable macrostructures, which in turn controls the hydraulic conductivity of compacted specimens frozen and thawed in the laboratory. The findings of this study show that for specimens compacted wet of the optimum water content, a significant increase in the hydraulic conductivity was measured after the first freeze–thaw cycle. When specimens were compacted at the optimum water content, a number of freeze–thaw cycles were required in order to obtain the corresponding significant increase in the hydraulic conductivity.

  • 10.
    Makusa, Gregory Paul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Shear strength evaluation of preloaded stabilized dredged sediments using CPT2014Conference paper (Refereed)
    Abstract [en]

    The undrained shear strength of preloaded stabilized dredged sediments increases with curing time. Evaluation of in-situ undrained shear strength using cone penetration test (CPT) data normally requires calibration of the CPT data with known undrained shear strength from vane shear test to obtain the cone factor, which is normally utilized in CPT empirical correlation to estimate the undrained shear strength. In this study, a new CPT empirical correlation for evaluation of in-situ undrained shear strength is presented. The proposed empirical correlation utilizes the effective vertical stress characteristic ratio to estimate the CPT induced stress, which was correlated to the in-situ undrained shear strength. The undrained shear strength computed using the proposed empirical correlation agrees reasonably well with the undrained shear strength estimated using the established empirical correlation at a large-scale field test.

  • 11.
    Makusa, Gregory Paul
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mattsson, Hans
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Knutsson, Sven
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Verification of field settlement of in-situ stabilized dredged sediments using cone penetration test data2012In: The Electronic journal of geotechnical engineering, ISSN 1089-3032, E-ISSN 1089-3032, Vol. 17, no Y, p. 3665-3680Article in journal (Refereed)
    Abstract [en]

    Utilization of in-situ mass stabilization for geotechnical applications is increasing. Laboratory tests may have drawbacks on valuations of engineering parameters for estimations of settlement of in-situ stabilized soil mass. Factors such as compression, mixing work, homogeneity and curing temperature may influence the differences in mechanical properties between laboratory test results and achieved field values. Therefore, utilization of appropriate in-situ mechanical parameters may be required during design analyses. Various in-situ tests are available for use in geotechnical context. Among others, cone penetration test (CPT) is one of most widely used in-situ tests. Numerous CPT empirical correlations are available for use in conventional soils. Utilization of such CPT empirical correlations for in-situ stabilized soils has to be examined. In this paper, the in-situ constrained modulus was evaluated using conventional CPT empirical correlation and utilized as oedometer modulus in finite element analysis for estimation of settlement of preloaded in-situ stabilized dredged sediments. The results show that, computed settlement values fall within the range of measured one. These findings suggest that, the cone penetration test and its empirical correlations, which were established for conventional soils, can also be utilized in stabilized soils.

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