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  • 1.
    Al-Jabban, Wathiq
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Soil Modification By Adding Small Amounts of Soil Stabilizers: Impact of Portland Cement and the Industrial By-Product Petrit T2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This licentiate thesis presents results of laboratory experiments regarding the effectiveness of adding small amounts of binders in order to modify and improve the mechanical performance of low organic clayey silt soil. Two types of binders have been used i.e. cement and an industrial by-product named Petrit T. The study covered both the immediate and longterm effects on the soil material. Binder content was added by soil dry weight, Petrit T at 2, 4 and 7% and cement at 1, 2, 4 and 7%. An experimental program has been carried out, including tests of consistency limits, unconfined compressive strength, density, solidification, grain size distribution (by laser particle size analyzer) and pH. The tests were conducted on the treated soil with varying binder contents and after different curing periods, i.e. after 7, 14, 28, 60 and 90 days. Results show that cement is more effective in improving the physical and engineering properties than Petrit T. Plasticity index decreases after treatment and leads to an immediate increase in workability. This is found directly after treatment and it increases with time. Soil density increased, whilst water content decreased, with increasing binder content and curing time. Particle size distribution of soil is changed toward the granular side by the reduction of the particles in clay size fraction and increasing silt size particles after 28 days of treatment. Both binder types resulted in an immediate effect on the soil pH value. This value increased to 12.3 after adding 7% of the binder and then it gradually decreased as curing time increased. The cement treated soil exhibits a more brittle failure behavior than the soil treated with Petrit T. In this case a more ductile behavior was observed. The findings confirmed that adding small binder contents of cement and by-product Petrit T significantly improved the physical and mechanical properties of soil, which can contribute to reduce the environmental threats and costs that are associated with using high binder contents in various construction projects.

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  • 2.
    Al-Jabban, Wathiq Jasim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Soil Modification by adding small amounts of binders: A laboratory study2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Soil stabilization through addition of a hydraulic binder is a method frequently used to modify and improve engineering properties of soft soils. Additives like cement and lime are typically used as stabilizers. More recently, industrial by-products, such as fly ashes, cement kiln dust, blast furnace slags and other slags have been used. The chemical reaction between the soil and the stabilizer alters the physical and engineering properties of the soil and thus desired strength and durability are obtained. The choice of appropriate type and quantity of stabilizer (binder) depends largely on factors such as soil type, moisture content, organic content, sulfate content, curing conditions (time and temperature) and the desired improvement.

    The objective of this thesis is to increase knowledge and understanding of how small amounts of binders change various engineering properties of stabilized soils in short- and longtime perspective. Extensive laboratory and field programs have been carried out. They cover immediate and long-term effects on the engineering properties by adding various binders. Cement, Multicem, and by-products Petrit T and Mesa were used as binders. Binder was added to the soil at various quantities: 1%, 2%, 4%, 7% and 8% of soil dry weight. The field and laboratory investigation included tests of consistency limits, sieving and hydrometer, unconfined compressive strength, density, solidification, grain size distribution using laser particle size analyzer, leaching tests and pH value. The tests were carried out on the treated soil with different binder contents and after different curing times i.e. 7, 14, 28, 60, 90 days for laboratory tests and 7 and 35 days for field investigation.

    The unconfined compression tests were used to show the effects of different binders on the enhancement in strength and stiffness over time. Consistency limits were determined to investigate the effects of the binders on the consistency limits, directly after treatment and over time. Laser particle size analyzer tests were conducted to investigate the effects of different binders on the particle size distribution (PSD) before and after treatment. The pH tests were conducted to investigate the effects of different binders on the alkalinity of the soil immediately after treatment and over time. This was used to give an indication of soil-binder reactions. MRM leaching tests were conducted to investigate the acidification potential of soils before and after treatment. Freeze-thaw cycles were conducted to investigate the strength characteristics after freezing and thawing in short- and long-term perspectives. Visual observation and standard dry sieving tests were conducted to optimize the proper mixing times to disintegrate or homogenize the soils by decreasing the size of agglomerated soil particles.

    The results show, that the variation in soil strength and stiffness of the treated soils are linked to different chemical reactions. Cement is most effective in improving the physical and engineering properties compared to the other binders studied. The plasticity index of soil decreases after treatment and over time. Liquidity index and the ratio of water content to plastic limit are introduced as new indices to illustrate the improvement in workability of treated soil by measuring the reduction in the liquidity index. This is found directly after treatment and it increases with time when the liquidity index is within the plastic range or when the water/plastic vi limit ratio is more than one. Increase of binder content and using longer curing times result in increase of soil density and decrease of water content. Particle size distribution of soil is changed by reducing the clay size fraction and increasing the silt size particles after treatment. This shows that an aggregation of particles take place resulting in coarser material than the initial. The cement-treated soils exhibit a more brittle failure in the unconfined compression tests compared to soils treated with other binder types where a more ductile behavior is observed. Applying freezing-thawing-cycles reduces the strength and stiffness of the treated soil.

    The appropriate length of time to homogenize and disintegrate the natural soil prior to treatment depends on several factors, such as soil type, water content, and plasticity properties of soil. For high plasticity soil, the disintegration time should be kept as short as possible. The homogenizing and disintegration time is less important for low plasticity soils with low water content than for medium to high plasticity soils.

    The acidification potential of soils are related to the addition of cementitious binders. The effect is found directly after treatment and over time. The treated soil exhibits higher resistance to decrease in pH value. The strength and stiffness properties found in the field investigation agree in general with those obtained from the laboratory investigation for the same binder type.

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  • 3.
    Al-Jabban, Wathiq
    et al.
    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.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Modification-Stabilization of Clayey Silt Soil Using Small Amounts of Cement2017In: Journal of Earth Sciences and Geotechnical Engineering, ISSN 1792-9040, E-ISSN 1792-9660, Vol. 7, no 3, p. 77-96Article in journal (Refereed)
    Abstract [en]

    This paper presents the effects of using a small percentage of cement to stabilize clayey silt with a low organic content. Cement was added at percentages of 1, 2, 4 and 7% by dry weight. The physical and mechanical properties of the treated and untreated soil were evaluated by laboratory tests including tests of consistency limits, unconfined compressive strength, soil density, solidification and pH values. These tests have been conducted after 7, 14, 28, 60 and 90 days of curing time. Workability is defined as how easily the soil can be control or to handle physically. Results showed that the engineering properties of the clayey silt were improved. The soil exhibited better workability directly after treatment, and the workability increased with time. Soil density increased, while water content decreased, with increasing cement content and longer curing time. The pH value was immediately raised to 12 after adding 7% cement content, and then it gradually decreased as curing time increased. An increase of unconfined compressive strength and stiffness was observed, while strain at failure decreased. A gradual change in failure mode from ductile behavior to brittle failure was observed. The findings are useful when there is a need for modification and stabilization of clayey silt in order to increase the possibilities for different use which will reduce transportation and excavation.

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  • 4.
    Al-Jabban, Wathiq
    et al.
    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.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Stabilization of Clayey Silt Soil UsingSmall Amounts of Petrit T2017In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 9, no 6, p. 540-562Article in journal (Refereed)
    Abstract [en]

    Effects of using small amounts of a Petrit T, a by-product of manufacture sponge iron, to modify clayey silt soil were investigated in this study. Petrit T was added at 2%, 4% and 7% of soil dry weight. A series of unconfined compressive strength tests, consistency limits tests and pH tests were conducted at 7, 14, 28, 60 and 90 days of curing periods to evaluate the physical and mechanical properties of treated soil. Results indicated improving in the unconfined compressive strength, stiffness and workability of treated soil directly after treatment and over time. Increasing in soil density and decreasing in water content were observed, with increasing Petrit T content and curing time. The pH value was immediately increasing after treatment and then gradually decreased over time. Failure mode gradually changed from plastic to brittle behavior with increasing binder content and curing time. The outcomes of this research show a promising way of using a new by-product binder to stabilize soft soils in various engineering projects in order to reduce the costs which are associated with of excavation and transportation works.

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  • 5.
    Al-Jabban, Wathiq
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    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.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    A Comparative Evaluation of Cement and By-Product Petrit T in Soil Stabilization2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 23, article id 5238Article in journal (Refereed)
    Abstract [en]

    This study presents a comparison between the effectiveness of adding low binder amounts of industrial by-product Petrit T as well as cement to modify and improve fine-grained soil. Binder amount was added by soil dry weight; cement at 1%, 2%, 4% and 7% and Petrit T at 2%, 4% and 7%. The unconfined compressive strength (UCS) was used as an indicator of soil strength. In addition, the consistency limits, laser particle size analysis, and pH tests were also conducted on the treated soil. The samples were cured at 20 °C for different periods from 7 to 90 days before testing. Results indicate that cement is more effective at improving the physical and engineering properties of the treated soil. Soil plasticity index decreases after treatment and with time. Liquidity index and the water content to plastic limit ratio are introduced as new indices to define the improvement in the workability of treated soil. Soil particle size distribution is changed by reducing the clay size fraction and increasing the silt size fraction after treatment. The findings confirm that adding small binder contents improve soil properties, which subsequently reduce the environmental threats and costs that are associated with using a high amount of binder.

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  • 6.
    Al-Jabban, Wathiq
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    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.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Briefing: Common laboratory procedures to prepare and cure stabilised soil specimens: a short review2020In: Geotechnical Research, ISSN 2052-6156, Vol. 7, no 1, p. 3-10Article, review/survey (Refereed)
    Abstract [en]

    Soil stabilisation is used extensively to improve the physical and mechanical properties of soils to achieve the desired strength and durability properties. During the design process, laboratory investigation is conducted firstly to obtain an enhancement in soil strength and stiffness, in addition to the type and amount of binder required. The methods of preparing and curing specimens of soil–binder mixtures directly influence the properties of the stabilised soils. The most common laboratory protocols used for preparing and curing the specimens of stabilised soil are presented in this short review. The review focuses on several aspects such as homogenisation of the natural soil, mixing type and duration, mould type, moulding techniques and curing time and condition. This review can assist various construction projects that deal with soil improvement to choose an appropriate method for preparing and curing a soil–binder mixture to simulate the field conditions as much as possible and obtain uniform soil–binder mixtures.

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  • 7.
    Al-Jabban, Wathiq
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Engineering Dept., University of Babylon, Babylon, Iraq.
    Laue, Jan
    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.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Effect of Disintegration Times of the Homogeneity of Soil prior to Treatment2019In: Applied Sciences, E-ISSN 2076-3417, Vol. 9, no 22, article id 4791Article in journal (Refereed)
    Abstract [en]

    This paper presents an experimental study to investigate the effect of various disintegration times on the homogeneity of pre-treated natural soil before mixing with cementitious binders. Various disintegration times were applied, ranging from 10 s to 120 s. Four different soils were used with different characteristics from high, medium and low plasticity properties. Visual and sieving assessment were used to evaluate the best disintegration times to allow for a uniform distribution of water content and small-sized particles that would produce a uniform distribution of the binder around the soil particles. Results showed that a proper mixing time to homogenize and disintegrate the soil prior to treatment depended on several factors: soil type, water content and plasticity properties. For high plasticity soil, the disintegration time should be kept as short as possible. Increasing the disintegration time ha negative effects on the uniformity of distribution of the binder around soil particles. The homogenizing and disintegration time were less important for low plasticity soils with low water content than for medium to high plasticity soils. The findings could assist various construction projects that deal with soil improvement through preparation of soil before adding a cementitious binder to ensure uniformity of distribution of the binder around soil particles and obtain uniform soil–binder mixtures

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  • 8.
    Rothhämel, Mirja
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Al-Jabban, Wathiq
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Influence of low temperature curing and  freeze-thaw-cycles on the stiffness of silt stabilised with hydraulic binder2019In: / [ed] DGGT - German Geotechnical Society, Essen, Germany, 2019Conference paper (Refereed)
    Abstract [en]

    Silt is a high frost susceptible soil that requires actions in construction works in re-gions with frost. To improve the engineering conditions of silt and other fine-grained soils with hydraulic binder is common in regions with moderate climate, but seldom in cold climate. This publication presents a laboratory study of a Swedish clayey silt stabilised with Petrit T, a by-product from sponge iron production. The samples were cured at +4°C, similar to conditions in northern Sweden, for 14, 28 and 90 days. The stress-strain-curves were plotted while testing the unconfined compression strength (UCS). The study contains also samples that were exposed to 12 freeze-thaw-cycles as well as subsequent curing time. One third of the samples were always conducted to a surcharge, one third during the freeze-thaw-cycles and the subsequent curing time, the rest had no surcharge. The results show differences in both stiffness and strength, with lower values of both for the samples that had endured freeze-thaw-cycles. The results of the samples with surcharge show higher stiffness and strength than those without surcharge at the same testing time

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    Rothhämel_AlJabban_Laue__FST2019_Pages432_437
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