Use of Fibres Waste in Sediments Stabilization / Solidification
Type:
Presented during:
WODCON XX: "The Art of Dredging" - 2013, Brussels, Belgium
Authors:
Levacher D, Liang Y
Abstract: Stabilization/solidification processes applied to none or contaminated dredged materials have been known some developments and significant progress during these recent years. In practice only few techniques are available for large volumes of dredged sediments stored in land disposal facilities. Most of applications are proposed for sub layers in road construction, embankments, landscaped ridges, or pathways. But it is the concern of many authorities involved in the sustainable sediment management to increase the potential beneficial uses so as to reduce the volumes to be disposed of. To tend towards a sustainable management, they must consider together economic, environmental and societal constraints and more and more restrictive regulations.
Many technical options are available for properly conditioned and pre-treated dredged sediments. But the effective cost and the efficiency of the global process depend on the number and the type of required pretreatments. To get a better ratio cost/performance, an innovative concept is to valorize dredged materials and other waste using a binder-based process as stabilization and/or solidification technique. Industrial by-products are first concerned dredged materials-mixtures for sub layers in road and platform construction. Usual mixtures of sediment-cement-lime are proposed in which some by-products - fly ash, silica fumes, furnace slag, granulated rubber tire crumbs - are more or less added.
A challenge is to co-valorize different waste, i.e. dredged materials plus waste so as to decrease the cost of the treatment and mixture operations by incorporating other waste materials. An example of such co-valorization may be performed with natural or artificial waste fibers. Vegetal fibers have been first considered and used such as dry fruit fibers, textile fibers and palm fibers. The use of natural fibers contributes to low cost, low density, low-energy production, and it is environmental friendly. Non-biodegradable fibers waste i.e. geo synthetic threads, ropes, fishing nets has been also considered.
Some of these different types of fibers – flax and geo synthetic threads- have been mixed with dredged marine sediments and quarry fillers. Mechanical performance obtained through testing are reported and discussed. As the focused beneficial reuse are sub layers in road and pathways engineering, testing concerns the unconfined compressive and tensile strength resistances.
Also inherent problems linked to the use of fibers are mentioned concerning: preparation of fibers, fibers water absorption, and adherence phenomenon of fibers in the based matrix and the behavior of fibers during the hardening time and at failure. The paper reports also on other aspects such as type of mixtures, developed resistances and influence of addition of fibers on. Finally the highlights of this new approach are clearly given and investigations needed are listed.
Keywords: dredged material, filler, fibers, reinforcement, stabilization process, sediment valorization, road sub layer, waste recycling