FSM2C
Scheda del progetto
Dipartimento di Ingegneria dell'Ambiente, del Territorio e delle Infrastrutture
Prof.ssa Associata Marilena Cardu
Dottorando Andrea Carigi
Prof. Ordinario Alberto Godio
The project aims to use “marmettola” as an ingredient in the preparation of two-component grout (2CG), a technology used for backfilling in the mechanised excavation of tunnels using shielded machines.
The development of the idea makes it possible to improve the quality of the "tunnel product," durability and hydraulic sealing capacity (thus reducing long-term maintenance) on the one hand, and facilitate the disposal of a waste from the mining industry in a virtuous process of circular economy on the other.
The goal of the PoC is to take the technology to the level of industrial demonstration by experimenting with the preparation of backfilling mortar using turbo mixers commonly used on tunnel construction sites.
The cultivation of ornamental rock requires cutting and sawing operations that produce a very fine detritus that is called sawing detritus or "marmettola" (50-95 dm3 of marmettola per m3 of processed stone). Material with high fineness and consequent ease of entering aqueous suspension.
- Step 1: Identification of the best type of detritus obtained by cutting ornamental rock for 2CG application. This selection is based on a mineralogical and granulometric study;
- Step 2: identification of optimised dosages (mix design to be further investigated with the demonstrator);
- Step 3: verification with the demonstrator of the actual possibility of producing 2CG mortar with devices similar to those used in tunnel excavation sites.
At the end of the PoC, the optimisation of a 2CG mixture with limited cement and water dosages compared to current technology is expected. The properties of the mortar produced with sawing waste from ornamental stone processing (rheological, mechanical and elastic properties) are expected to be comparable to those of classic 2CG mortar. The main difference will be a greener technology. These differences can be schematised as follows:
- substitution of valuable and often scarcely available ingredients on excavation sites (such as water) or whose production is particularly energy-intensive (cement) with more environmentally-friendly ingredients (the fines obtained by cutting ornamental stones);
- the non-landfilling of cutting debris from ornamental stone processing.
The technology is potentially applicable in tunnel excavation sites with shielded machines. Regardless of the business model used, the technology is designed to reach tunnel excavation sites where 2CG mortar is planned to be used for backfilling. To be considered is the possibility that the technology will lead to the emergence of a new 'ingredient', a product to be used in the turbo-mixers of construction sites, identified with a specific commercial name.