Alternative fill materials

In case no suitable quartz sands are available from a borrow area within a reasonable distance to the site, or from maintenance dredging or capital dredging, other fill materials may have to be used such as clay, carbonate sand or rock. These materials have a different mineralogy, particle size distribution, grain shape, etc. which results in different and/or unexpected fill mass properties. However, by adequately addressing the typical properties of these materials, it may be possible to construct a reclamation that meets the specifications. The possibilities and restrictions of the use of these materials for fill is described in Chapter 9. 

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Change of the grading as a result of Alternative fill materials... 

Example of the use of an alternative fill material in Bremerhaven (Nooy van der Kolff et al, 2010)... 

Dentistry. Mercury is used in dental amalgams for fillings in teeth (see Dental materials). Dental uses have accounted for 2—4% of total U.S. mercury consumption since 1980 and generally 3—6% before that time (3). Dental amalgams used to fill cavities in teeth are approximately 50% mercury by weight. Dental use of mercury can be expected to continue to decrease, in part because of more effective cavity prevention as well as development and increasing use of alternative dental materials such as plastics and ceramics, and increasing awareness of the environmental and health effects of mercury. 

Earlier we have said that the flow of filled materials can be raised by modification. One of the modification alternatives consists in using a combination ( flexible ) filler. As shown in [366], addition of a small quantity of glass balls to composites filled with chalk caused a sudden increase of the flow of the system, provided the filler concentration is below critical. Similar behavior was also observed in fiber-filled systems when a small quantity of dispersed particles were added [33],... 

Construction technique consists of excavating a trench kept full of slurry to the desired length and depth, then displacing the slurry with suitable, impervious backfill. This may consist of the excavated soil mixed with the slurry, or the excavated soil may be mixed with clay, or with cement. Imported soil or other fill material may be used, but is more costly than using the on-site soil. (If the wall is to be permanently exposed, and appearance is important, the slurry may be replaced with precast concrete panels). After the backfill is in place, but still fiuid, reinforcing steel may put in place. Alternatively, the steel may be placed in the slurry, which is then displaced by concrete tremied to the bottom of the trench. Displaced slurry is moved into one or more holding basins on-site, so that unwanted solids may settle out before the slurry is reused. 

Stockpiled RAP material may also be used as a granular fill or base for embankment or backfill construction, although such an application is not widely used and does not represent the highest or most suitable use for the RAP The use of RAP as an embankment base may be a practical alternative for material that has been stockpiled for a considerable time period, or may be commingled from several different project sources... 

Use as an embankment base or fill material within the same right of way may also be a suitable alternative to the disposal of excess asphalt concrete that is generated on a particular highway project... 

Alternative pigments can be used to enhance Ti02 s effectiveness or to replace it. Barium sulfate can serve as an extender or "spacer" in li02-filled materials, separating pigment 1102 particles to optimal distribution so that the pigment... 

Mounting can be accomplished by inserting the getter in a recess cut in the filling material. Alternatively, if the filler is sufficiently soft, as is the case for open cell PU, the getter can be simply pressed into it. 

Slope reinforcement is also employed in the construction of embankments, and as an alternative to some retaining walls. To provide slope stability, multiple layers of geogrids, or woven/knitted geotextiles, may be placed during construction in the fill material used to make the slope. 

Raman spectra show the least dependence on physical form and so provide the most straightforward means of identification. However, they are not readily obtained from carbon-filled materials. For these samples photoaconstic spectroscopy was the most versatile alternative. Provided that the sample has a shiny snrface, external reflection is a useful identification method. Its usefulness is restricted by the dependence of the spectra on the surface texture and form of the sample. 

Ordered fill materials are a less sensitive but more expensive alternative. 

Fine to medium quartz sands are to be preferred as fill material. If this is not available lesser quality material may have to be accepted such as carbonate sand, silt, clay or other alternative materials. This may, however, have an impact on the design, the work method which may possibly include ground improvement, equipment and therefore also on the cost. 

If the potential fill material has a cohesive nature, in-situ vane shear tests may be performed to determine the undrained shear strength (see section 3.4.2.1 and Appendix B.2.3.2). Alternatively, Cone Penetration Tests could be undertaken to indirectly assess the undrained shear strength using existing correlations (see Appendix C). Undisturbed samples of the cohesive strata could be recovered from boreholes which are subsequently tested in the laboratory. For more details on slope stability analysis reference is made to section 8.4.3.7 of this Manual. 

If quality control after the construction of a reclamation reveals that certain parts do not have the specified fill mass properties then it is occasionally required to remove the poor quality fill material. However, ground improvement could be a viable alternative (in respect of quality, time and cost) to repair these deficiencies without the need to replace the inferior fill by higher quality material. 

In some cases, the use of cohesive or fine-grained soils like silt and clay can be an economical alternative for the use of sand as fill material, for instance, when only cohesive soils are (economically) available in the vicinity of the reclamation area or when large volumes of cohesive soils become available from excavation or dredging at the project area itself. As an alternative to granular material like sand, some of these cohesive soils can be (made) suitable for use as hydraulic fill. 

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