https://discovery.dundee.ac.uk/ws/files/39206549/1_s2.0_S0886779819307400_main.pdf

Implications of volume loss on the seismic response of tunnels in coarse-grained soils

Approximately 7 million tons of fly ash and slag are produced in thermal power plants in Serbia every year, only 3% of which is used in the cement industry. About 300 million tons of the ash-slag mixture are disposed in landfills, occupying an area of approximately 1600 hectares and generating environmental issues. Fly ash from Serbian power plants has pozzolanic properties and due to low concentration of calcium compounds (less than 10% CaO), they do not have self-cementing properties. According to the ASTM C618-15, this ash is from class F. According to the European Standard EN 197-1:2011, this ash is siliceous (type V) ash. From April 2014 to May 2015, an investigation of engineering properties of fly ash and mixtures of fly ash and slag from landfill (without or with binders of cement/lime) was conducted at the Laboratory of Soil Mechanics at the Faculty of Civil Engineering of the University of Belgrade (Serbia) and at the Institute for Testing of Materials – IMS Institute in Belgrade. The laboratory test results were showed in the study ‘Utilization of fly ash and slag produced in the TPP JP EPS thermal power plants for construction of railways’. Four kinds of waste materials from Serbian power plants were laboratory tested: (a) an ash-slag mixture from landfills at the ‘Nikola Tesla A’ thermal power plant; (b) fly ash from silos in the ‘Nikola Tesla B’ thermal power plant; (c) an ash-slag mixture from landfills at the ‘Kostolac A’ and ‘Kostolac B’ thermal power plants and ‘Srednje kostolacko ostrvo’ landfill; (d) fly ash from the ‘Kostolac’ thermal power plant. The following physical and mechanical properties of ash and mixtures were investigated: grain size distribution, Atterberg limits, specific gravity, moisture-density relationship, shear strength parameters in terms of effective stresses, California Bearing Ratio (CBR), and deformation parameters. The paper presents the results of laboratory tests of the materials with and without binders, and based on the laboratory results and previous research, the paper presents possibilities of using fly ash and slag for the construction of railway substructure in the planned construction and reconstruction of railway network in Serbia. The obtained results indicate that tested fly ash and ash-slag mixture have met the technical requirements and that they have the potential to be used in railway substructure.
First published online 12 December 2016

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Fly ash and slag utilization for the Serbian railway substructure

Influence of fly-ash on the engineering characteristics of stabilised clay soil

This paper deals with actual European “modal shift to rail transport” concept and related environmental issues and experience in the Republic of Serbia The planned increase in volume of railway transport and planned railway electrification should reduce air pollution in Serbia, particularly in the urban environment On the other hand, achieving this goal would lead to the increase in noise level in the urban environment and environmental issues in the region of thermal power plants, which are the main sources of electricity in Serbia This paper suggests concrete measures to reduce the railway carbon footprint and noise level during the planning, design and service life of railway infrastructure

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The modal shift to sustainable railway transport in Serbia

\n Serious soil erosion can endanger human survival and sustainable development. Therefore, simple and highly efficient soil stabilizers that can be used to treat loess soil, which has poor water stability and easily disintegrates, are a topic of concern for researchers. In this work, a biomass-based polymeric soil stabilizer (CXZ) was prepared using a “green” strategy with polymerization of carboxymethyl cellulose and xanthan gum. A direct shear test, unconfined compressive strength properties, water stability, and erosion resistance were systematically investigated to test the stabilization performance. The stabilizer agglomerated small loess particles into large aggregates through “coating” and “weaving” effects to increase the cohesion, water stability, and erosion resistance significantly, as demonstrated by Fourier transform infrared spectroscopy and scanning electron microscope. Furthermore, in a 30-day growth experiment, the number of alfalfa plants and the plant height in stabilized loess both increased with the increase in CXZ stabilizer concentration. This work provides insight into a novel biomass-based soil-curing agent, broadening its applications in loess remediation and soil erosion control.

Stabilization Behavior and Performance of Loess Using a Novel Biomass-based Polymeric Soil Stabilizer

Results of laboratory research focusing on soil stabilization, using fly ash without activators, are presented in the paper. Two types of fine-grained soils were tested: low to medium plasticity clay and very expansive, medium to high plasticity clay. Soil-fly ash mixtures were prepared at optimum fly ash contents (15 and 20 %). The effects of fly ash on the soil plasticity, moisture-density relationship, unconfined compressive strength, shear strength parameters, CBR (California Bearing Ratio) values, deformation parameters, and swell potential, were evaluated. Results obtained show that the use uf fly ash can significantly contribute to the improvement of soil properties.

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Stabilization of fine-grained soils with fly ash

/pdf/analiza-slijeganja-povrsine-terena-uslijed-izgradnje-tunela-m2nmsdkpfi.pdf

Analiza slijeganja površine terena uslijed izgradnje tunela

U radu su prikazani rezultati laboratorijskog ispitivanja stabilizacije tla letecim pepelom bez primjene aktivatora. Ispitivane su dvije vrste sitnozrnatog tla: glina niske do srednje plasticnosti te vrlo ekspanzivna glina srednje do visoke plasticnosti. Mjesavine tla i leteceg pepela su pripremljene s optimalnom kolicinom pepela (15 i 20 %). Ispitivan je utjecaj leteceg pepela na plasticnost tla, odnos vlage i gustoce, jednoosnu tlacnu cvrstocu, vrijednosti parametara posmicne cvrstoce, vrijednosti CBR-a (California Bearing Ratio-CBR), deformacije i potencijal bujanja. Dobiveni rezultati pokazuju da primjena leteceg pepela može znacajno poboljsati svojstva tla.

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Snežana Maraš-Dragojević

Papers

Stabilization of fine-grained soils with fly ash

Analiza slijeganja površine terena uslijed izgradnje tunela

Stabilizacija sitnozrnatog tla letećim pepelom