cement- based soil mixing

The stabilization technology by Deep Soil Mixing is based on introducing and mixing additives (stabilizing agents) into the ground, as powder or as a suspension, using special equipment, with the main goal to improve volume stability, strength, permeability and durability of the soil. The development of better strengths than the initial ones is possible due to the reduction of the initial void volume, by replacing the fluid in the structure of the soil with the stabilizing agent used, so the particles and the aggregates get closer together, increasing the number of contact points and at the same time preventing the swelling. 
This soil treatment can be used as a practical, economic and environmental solution for a wide range of engineering applications. Some of the soil-mixing applications are road/rail embankments, lime, cement or lime/cement columns for excavation support, marine clays improvement for offshore platforms, shallow foundations, dam reinforcement, slope stability amelioration, silos foundations and reduction of seismic pile displacement
The most used materials for this technology are cement and lime, but there are many other materials that can be used as stabilizing agents. The most used materials used in the stabilization by unique binder or mixed with other binders include: volcanic ash, bentonite, silica fume, bitumen, grinded furnace slag etc. These stabilizers are added either in dry form or in the form of a slurry in different proportions, these specifications being based on the study of the behavior of the mechanical parameters and of various complex mixtures by means of laboratory tests. 

geosynthetic membranes

The geotextile/geomembrane interfaces can be used for both liner and cover systems of the landfills. Geomembranes are typically used as a hydraulic barrier and geotextiles protect it from damages that may occur in some situations, such as high normal stresses and angular soil particles.
Geomembranes are essentially impermeable polymeric lining materials used as fluid barriers in geotechnical engineering applications. Geomembranes can have a smoother or textured surface. The textured surface provides enhanced friction characteristics which can be important in certain applications. Geosynthetic clay liners (GCLs) are made of a thin layer bentonite clay between two layers of non-woven geotextiles. GCLs are used in containment applications, often in conjunction with a geomembrane.
Th e use of geomembranes and geosynthetic clay liners (GCLs) has increased over the years as traditional liners, such as concrete, asphalt, as well as compacted clay soils, have proven ineffective in the prevention of fluid migration into subsurface soils.

RED MUD CONCRETE

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​Red mud (RM) is an aluminum industry by-product that is generated during the process of extraction of alumina from bauxite ore. It is discharged in a high-alkaline state at a pH in the range of 10–13 owing to the influence of caustic soda (NaOH) which is added in the process. In general,1–1.5 tons of RM are generated when a ton of alumina is produced. Accordingly, 90–150 million tons are estimated to be discharged each year worldwide. To this date, large amounts of RM have been managed, either by (a) storing them, (b) using them as landfill in open fields, or by (c) dumping them at sea. It has been reported that various heavy metals contained in RM and their high pH values may cause various environmental problems.
The continuous industrial growth depends on the stable treatment of waste and the conservation of natural resources. Therefore, in the global aluminum industry, the treatment and effective recycling of RM which has minor influences on the natural environment has attracted increased attention. Fortunately, industrial by products can be recycled as raw materials in replacement of natural resources because many of them contain minerals that can be obtained from natural resources.  RM, which contains alumina, iron oxide, and titanium, can also be recycled in various forms in different industries as other industrial by-products. In fact, the methods of recovering and reusing rare earth elements contained in RM, or the use of RM itself as a pigment and an additive for wastewater treatment and soil remediation, have also been introduced.
In the construction industry, the reduction of CO2 emissions from cement production has been a major issue. Cement is one of the most important materials in the construction industry, and has been extensively used in many countries. The production of one ton of clinker is estimated to emit one ton of CO2 gas. Additionally, it has been reported that approximately 7% of global CO2 emissions
is related to cement production. In the construction industry, the most effective method used to reduce CO2 emissions is to decrease the use of cement. Industrial by-products, such as fly ash, ground granulated blast-furnace slag, and silica fume, have been used as admixtures for concrete. RM is an industrial by-product, and can be used as an admixture for cement-based materials, such as mortar
and concrete. Moreover, if the RM is used as a construction material, it can be utilized in large quantities, and the environmental problems caused by its disposal can be solved.
In many prior studies, the effects of RM on the fluidity, hardening properties (microstructure,water absorption, and mechanical properties), and durability (chloride penetration and whitening) of mortar and concrete have been experimentally evaluated. A number of studies, however, reported experimental results in which the mortar or concrete that used RM exhibited degraded fluidity and mechanical performance.The physical properties of RM, whose particles are smaller than those of cement, have been pointed out as the cause. As RM adsorbs more moisture than cement in the unhardened state, the fluidity of concrete is degrade. In addition, cement-based hardening bodies mixed with RM have high-water absorption and low-mechanical performances because they contain many capillary pores with diameters in the range of 10 to 1,000 nm. Despite these problems, it has been confirmed that mortar or concrete mixed with RM can attain the required mechanical performance for a construction material if the application conditions of RM are properly selected.
Thus, RM is still an industrial by-product with increased potential for use as a construction material. To accomplish the active use of RM in the construction industry, it is imperative that it is properly used, and that various examinations are conducted in terms of material composition, including the cement type.
RM is discharged as sludge from the Bayer process with a moisture content of 50%. It is very difficult to manage constant moisture content because it is significantly affected by environmental conditions.
Therefore, RM, which is used as an admixture for mortar and concrete, is utilized as dried powder after high-temperature drying and grinding processes. These processes are energy-intensive steps that require additional energy input. They cause increases in the manufacturing costs and hinder the recycling of RM.

​SOURCE: Mechanical Properties of Concrete Containing
Liquefied Red Mud Subjected to Uniaxial
Compression Loads
Gyeongcheol Choe ​

pile driving offshore

  • A good foundation design not only results in an efficient installation, but also it reduces the overall cost of a platform.
  • Premature refusal could cost millions of dollars exceeding the original price for the platform installation itself. Therefore, to reduce this risk, a proper driveability study during the design phase is required. 
  • ​Remedial work on the pile foundation could take weeks. This delay may jeopardise the first production date of the platform and incur costs for remedial work.
  •  In a good pile design, the pile wall thickness must be sufficient to transfer the hammer’s energy.
  • An optimal pile design allows for a more powerful hammer to be stabbed when harder than expected driving is encountered.
  •  Installation aspects, such as allowable freestanding pile lengths versus required hammer energy, should be considered for the final pile make-up.
  •  The accuracy of a pile driveability study can be highly optimised by incorporating other knowledge, such as performing back analyses using the observed blow counts of the as-installed piles of a nearby platform. 
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