Recovery & Recycling of Excavated Tunnel Waste

Rock excavated in an average tunneling project is often considered waste and mostly finds its way to a landfill. Depending on the geology and excavation method used, the extracted material can have significant quality deviations and may be unsuitable for use as construction aggregates because of varying geometric, physical, and chemical characteristics. However, if this waste is suitably treated and processed, it can be recycled and used as a substitute for conventional mineral aggregates at a construction site.

The processing of tunneling rock wastes into usable products is popularly known as tunnel excavation rock recycling. The most common application of the processed material is as aggregates for concrete or as a sub-base for road building, which is good for both environment and business. Benefits include:
  • Generates more value than simply being dumped in a landfill or to fill up old quarries
  • Utilisation of rock is usually near a processing facility or a concrete batching plant which significantly reduces the need for transporting aggregate
  • Lesser need for landfills creates a positive environmental impact
  • The project being almost self-sustained in construction aggregates results in the investment cost of the facility getting repaid quickly.
TBMs: Tunnel Boring Machines are one of the most popular methods of tunneling. TBMs create rock particles with excessive fines - a problem affecting the quality for both sub-base and concrete aggregates. Mechanical screening (scalping screener), which usually is the first stage of processing tunnel rock in a TBM removes rock particles below 16-20mm diameter. This process aims to get rid of the high amounts of fines that are created by tunneling in hard rock.

By 2018, there were seven confirmed projects worldwide that were recycling tunnel rock on an industrial level. These projects are all placed in hard rock, the details of which are given in table:

recycled material

The above data indicates that, on an average, around 20% of the tunnel debris was successfully recycled. The low percentage of recycled material can be attributed to the large portion of fines generated during the drilling process. In industrial concrete, such fines destroy the flow of the concrete in its fresh state due to agglomeration that adversely affects concrete batching.

One of the ways to increase the yield from tunneling waste is to create concrete aggregates of 8 mm or 4 mm fractions that are free of silt. It requires a more advanced processing facility for size control of finer particles. It also needs an accurate classification technique to achieve the desired particle size range for concrete making. Removing fines is often done using water as a medium, which requires a water treatment plant to clean the water and recirculate it into the system.

Recovery & Recycling of Excavated Tunnel Waste

Apart from silt removal and generating products as per specified particle size distribution, treating excavated waste needs prior removal of contaminants like various types of scrap (wood chips, plastic, and other trash material) most likely to be generated during drilling. In many cases, depending on the characteristics of the rock, there could be incidences of low specific gravity minerals and various particles with flat elongated structures. Special techniques are necessary to address these.

The environment-friendly, patented wet processing technology from CDE Asia addresses all the issues and has the following key features:
  • Zero waste discharge to atmosphere
  • 95% re-circulation of process water
  • Removal of scrap such as wood chips, plastic, other trash material
  • Minimum space for installation
  • Skid mounted portable units
  • Suitable for shifting from location to location
  • Minimum unit power requirement
  • Less than 80db noise level
It can recycle finer materials of under 20mm fractions and generate construction-grade aggregates and sand, both for concrete and plaster. Bentonite, an expensive mineral used in the drilling process, can also be recovered and recycled from the finer particles. The increased utilization of excavated material can have a significant positive financial impact on the project.

References: Wikipedia
Click Here
To Know More or to Contact the Manufacturer
Please let us know your name.
Invalid Input
Please let us know your Designation.
Please let us know your Contact Number.
Please let us know your email address.
Please brief your query.
Our other Value-Added Services:

To receive updates through e-mail on Products, New Technologies & Equipment, please select the Product Category(s) you are interested in and click 'Submit'. This will help you save time plus you will get the best price quotations from many manufacturers, which you can then evaluate and negotiate.

Invalid Input
Invalid Input
Invalid Input
Sandvik's fully automatic, DT 922i and semi-automatic, DT 821C jumbo drills are enabling Max Infra to attain lower drilling costs per meter, with higher machine availability during the ongoing construction of the access tunnel

Read more ...

Rakesh Kumar Khali, Project Director-Hydro, Hindustan Construction Company Limited, Mumbai, describes the type of risks involved in underground construction projects, gives important guidelines to the tendering authorities and contractors

Read more ...

Safety in infrastructure sector means preventing accidents, loss and damage to human life and equipment. Being adequately trained and aware of the equipment in use is imperative, especially in the case of heavy equipment

Read more ...

Authors C.P Singh, S.K Ganji, and Madhur Goel elucidate the issues and precautions taken during full face mining, using a TBM for the construction of JPW to Krishna Park Downline Tunnel of Package DC-06. This 5.8 m internal diameter

Read more ...

Uttar Pradesh Metro Rail Corporation Limited Underground Construction On 25 November 2013, LMRCL (now UPMRCL) was incorporated as a Special Purpose Vehicle (SPV) under the Companies Act, 1956. The construction of phase I A of Lucknow Metro (Transport Nagar to Charbagh) started on 27 September 2014

Read more ...

India’s economic growth is closely associated to its energy demand; in fact, India is the 3rd largest energy consumer in the world. A robust growth is expected in the country’s oil and gas sector, which will make the sector

Read more ...

Brijesh Ashokbhai Wala, Engineer, National Highways and Infrastructure Development Corporation Limited (NHIDCL), presents the vagaries and challenges in underground construction, with case studies of projects constructed or planned

Read more ...

Anirban Sen, Business Line Manager – Underground Division, Epiroc Mining (India), explores the technologies, methods and benefits of modern intelligent face drilling equipment, the reasoning behind selection of ‘smarter’ face drills

Read more ...

This case study of the Sewa H.E. Project (120MW) in the Kathua district of Jammu and Kashmir, covers the planning process and various construction features of a 10.02km long, 3.3m diameter horseshoe shaped concrete lined tunnel

Read more ...

Strabag AG implements complex construction projects, particularly in tunneling and infrastructure development, and is represented in around 30 countries worldwide. It has been active in the fields of building construction, civil

Read more ...

Construction is underway on a tunnel as part of a bypass to relieve traffic for communities in Toggenburg, Switzerland. For Doka’s formwork experts, keeping in view the conditions of this project, their new, rentable tunnel system

Read more ...

On 22nd September 2021, hard rock/slurry TBM Urja (DZ670) manufactured by China Railway Construction Heavy Industry Cooperation Limited (CRCHI) achieved a breakthrough from the Cantonment Station to the Shivaj Nagar Station

Read more ...

Hard Rock Tunnel Boring Machine (TBM) is the first choice for the construction of hard rock tunnels because it is a fast, safe, and environmental-friendly construction method. As overburden increases, the ground stress of

Read more ...

The Mumbai-Nagpur Expressway is delayed until 2022 due to Covid-19. In the meantime, a machine with remarkable operational reliability was specially flown in from the supplier in Germany to help speed up the project.

Read more ...

US Tunnel Boring Equipment manufacturer, The Robbins Company, will continue to make owning and operation of its TBMs cost-effective for Indian contractors. It will also explore newer vistas of engagement with

Read more ...

Geo Constech Druc Svelta Resin Capsules
Geo Constech (GCPL), one of the leading solution providers of material and technology, introduces Druc-Svelta, Druc-Si’ment Cap, Druc-Stone, Druc-Colata 41, and Druc-Tyrocrete. With an objective

Read more ...

Horizontal Bores
Trenchless construction is a method of laying services under the ground without disturbing the surface structures. The imported underground horizontal drilling machines are available

Read more ...

Mobile Sinking Winch
The "DEEP SHAFT COAL MINE" consists of essentially two vertical shafts, one to hoist men and materials, and the other for winding coal from deeper seems."MINE SHAFT" surface structures

Read more ...

Slag Crushed in Crusher
For the last 20 years, the use of by products of various origins in the production of concrete has become an increasingly widespread practice in the world. The main advantages are all the elimination of scraps

Read more ...

×
Sign-up for Free Subscription
'India Construction Week'
Weekly e-Newsletter on Construction Industry
Get the latest news, product launches, projects announced / awarded, government policies, investments, and expert views.