Tunnel Muck Research Articles

Enhancing tunnel muck properties with ternary industrial solid wastes: optimal mixing ratios and microscopic mechanisms

Calcium carbide slag (CCS), phosphogypsum (PG), and red mud (RM), three types of industrial solid wastes, were employed to improve tunnel muck for assessing the feasibility of their reuse. A series of indoor tests were conducted to investigate the effects of their contents on the physical and mechanical properties of the improved tunnel muck. Microscopic tests were also conducted to reveal the improvement and interaction mechanisms involved. Results indicate that the incorporation of CCS, PG, and RM can significantly improve and enhance the physical and mechanical properties of tunnel muck. The improved tunnel muck containing 2% PG and 6% RM shows higher early strengths as CCS content exceeds 4%. However, after curing for more than 14 days, the unconfined compressive strength (UCS) of the tunnel muck with 4% PG and 4% RM is the maximum regardless of the CCS content. Microscopic analysis shows that reactive substances in industrial solid waste react chemically with soil components, exchanging ions and forming cementitious products such as calcium hydroxide, calcium silicate hydrate (C-S-H), calcium aluminosilicate hydrate (C-A-S-H), and ettringite (AFt). They bind, fill, and encapsulate soil particles, compacting the soil and significantly enhancing the physical and mechanical properties of tunnel muck. Moreover, there is a notable mutual synergy between PG and RM, primarily attributed to their acid-base neutralization and the complementary action of reactive ions. The improved tunnel muck containing 4% CCS, 4% PG, and 4% RM demonstrates the highest enhancement efficiency.

Carbonation curing and long-term shrinkage performance of manufactured sand concrete with different strength grades from tunnel muck

Carbonation curing and long-term shrinkage performance of manufactured sand concrete with different strength grades from tunnel muck

A Novel K+ Slow-Release Cementitious Material Developed from Subway Tunnel Muck for Ecological Concrete Applications

This study explored a novel cementitious material developed from subway tunnel muck (STM) intended for ecological concrete (EC) preparation. The effects of three alkaline activators (NaOH, KOH, and CaO) on the properties of the cementitious materials were systematically examined. The results indicated that NaOH exhibited the most effective activation performance, followed by KOH, with CaO being the least effective. The NaOH-activated materials exhibited the highest compressive strength (reaching up to 12.15 MPa), the densest microstructure (characterized by the lowest porosity and smallest average pore size), the most substantial gel formation (evidenced by the highest mass loss in thermogravimetric analysis), and the optimal gel structure (indicated by the pronounced peak sharpening in Fourier transform infrared spectroscopy) after a 28-day curing period. Moreover, the crystallization of potassium salts under KOH activation detrimentally impacted the microstructure of KOH-activated materials. To balance the need for structural strength and nutrient provision, NaOH + KOH-activated materials were selected for the preparation of EC. Notably, the application of NaOH + KOH-activated materials resulted in a significant increase in K+ concentration in the soil layer, compared to common soil. Furthermore, NaOH + KOH-activated materials exhibited a slow-release effect, thereby offering sustained nutrient support conducive to plant development.

Alkali-Activated Slag as Sustainable Binder for Pervious Concrete and Structural Plaster: A Feasibility Study.

In the realm of sustainable construction materials, the quest for low-environmental-impact binders has gained momentum. Addressing the global demand for concrete, several alternatives have been proposed to mitigate the carbon footprint associated with traditional Portland cement production. Despite technological advancements, property inconsistencies and cost considerations, the wholesale replacement of Portland cement remains a challenge. This study investigates the feasibility of using alkali-activated slag (AAS)-based binders for two specific applications: structural plaster and pervious concrete. The research aims to develop an M10-grade AAS plaster with a 28-day compressive strength of at least 10 MPa for the retrofitting of masonry buildings. The plaster achieved suitable levels of workability and applicability by trowel as well as a 28-day compressive strength of 10.8 MPa, and the level shrinkage was reduced by up to 45% through the inclusion of shrinkage-reducing admixtures. Additionally, this study explores the use of tunnel muck as a recycled aggregate in AAS pervious concrete, achieving a compressive strength up to 20 MPa and a permeability rate from 500 to 3000 mm/min. The relationship between aggregate size and the physical and mechanical properties of no-fines concretes usually used for cement-based pervious concrete was also confirmed. Furthermore, the environmental impacts of these materials, including their global warming potential (GWP) and gross energy requirement (GER), are compared to those of conventional mortars and concretes. The findings highlight that AAS materials reduce the GWP from 50 to 75% and the GER by about 10-30% compared to their traditional counterparts.

Performance evaluation of marginal materials in geosynthetic reinforced base layers

The high-altitude regions are prone to natural disasters such as landslides, and tunnelling that generate substantial amounts of debris. Utilising these waste (marginal) materials in the pavement sector offers a viable solution. This study aims to stabilise tunnel muck, landslide debris, and Reclaimed Asphalt Pavement using geosynthetics (geogrid, geocell, double geogrid, and geogrid + geocell) for the base course. Cyclic Plate Load tests were performed on pavement prototypes built with available marginal materials and conventional GSB as the base/subbase course, with Black cotton and silty soil subgrades. The results indicated that geosynthetic reinforcement significantly improved the performance of marginal materials by lowering permanent deformation and increasing design life. The pavement prototypes reinforced with double geogrid and geogrid + geocell indicated rutting performance equivalent to conventional GSB for specific combinations. Additionally, incorporating geosynthetics in pavement layers increased the structural strength of the base layers by a layer coefficient ratio factor ranging from 1.1 to 2.5.

Mechanical properties and microstructure of lime-treated shield tunnel muck improved with carbide slag and soda residue

Mechanical properties and microstructure of lime-treated shield tunnel muck improved with carbide slag and soda residue

Mechanical properties and micro-mechanism of improved shield tunnel muck with phosphogypsum and lime

Mechanical properties and micro-mechanism of improved shield tunnel muck with phosphogypsum and lime

Mechanical properties and microstructure of SWGA-BF improved rock muck discharged from slurry shield tunnels

Mechanical properties and microstructure of SWGA-BF improved rock muck discharged from slurry shield tunnels

Laboratory Evaluation of Marginal and Industrial Waste Material in Geocell-Reinforced Pavements under Cyclic Loading

ABSTRACT The availability of quality materials for the construction of pavements has been a problem in some regions. This scarcity enforced geosynthetic materials as one of the quests for su1stainability in the pavement industry. This study attempted to stabilize marginal (tunnel muck, reclaimed asphalt pavement material) and industrial waste (zinc slag) materials by employing high density polyethylene geocell to appraise the effectiveness of geosynthetic reinforcement in enhancing the characteristics of pavement materials and mitigating their rutting. The cyclic plate load tests are performed on marginal and industrial waste material with geocell-reinforced and unreinforced base layers over black cotton soil as the subgrade. The tests were conducted following the trapezoidal loading pattern with a 0.77-Hz frequency. The geocell-reinforced pavement performance was evaluated for resilient deformation, accumulated permanent deformation, rut depth reduction, traffic benefit ratio, and base layer thickness reduction. The mechanistic empirical pavement design guide (MEPDG) permanent deformation performance (PDP) model framework was used to predict the accumulated permanent deformation in unbound granular layers and to differentiate the rutting performance in geocell-reinforced and unreinforced sections. This study determined the material constants of the MEPDG PDP model for marginal and industrial waste materials used in the pavement section for quantifying the reduction in base layer thickness.

Preliminary study on preparation of unfired bricks using filter cake from tunnel muck

Preliminary study on preparation of unfired bricks using filter cake from tunnel muck

Chemical Stabilization Used to Reduce Geogenic Selenium, Molybdenum, Sulfates and Fluorides Mobility in Rocks and Soils from the Parisian Basin

Rocks and soils excavated from civil works frequently present high concentrations of naturally occurring leachable (oxy-)anions. This situation raises concerns regarding the potential transfer of contaminants to groundwater in a storage scenario. This study was carried out to give practical insights on the ability of various stabilizing agents to reduce molybdenum (Mo), selenium (Se), fluorides and sulfates mobility in four types of naturally contaminated excavated materials. Based on standardized leaching tests results, Mo and Se were effectively immobilized after zero valent iron or iron salts additions. Although alkaline materials were found to effectively reduce fluorides and sulfates mobility, their addition occasionally caused a subsequent increase in Mo and Se leaching due to pH increase. None of the reagents tested allowed a simultaneous immobilization of all (oxy-)anions sufficient to reach regulatory threshold values. The remaining difficulties were related to: (i) sulfates leaching from gypsum-rich samples, (ii) fluorides leaching from clayey samples and (iii) Mo and sulfates mobility from tunnel muck. Altogether, the study revealed that the choice of stabilizing agents should be made depending on the speciation of the contaminant or else an opposite impact (i.e., increase in contaminant mobility) might be triggered.

Assessment of Molybdenum and Antimony speciation in excavated rocks and soils from the Parisian basin using mineralogical and chemical analyses coupled to geochemical modelling

Assessment of Molybdenum and Antimony speciation in excavated rocks and soils from the Parisian basin using mineralogical and chemical analyses coupled to geochemical modelling

Mechanical Properties of Tunnel Muck with Fly‐Ash Geopolymer

The tunnel muck has a great potential to be used as a recyclable engineering material in transit and other civil work projects instead of being deposited as construction waste. In this work, the geopolymer is generated by alkali‐activated fly ashes, which act as cementitious materials to strengthen the tunnel muck. The tunnel muck has to be dehydrated, grinded, and screened before being treated by alkali‐activated fly ash. The effect of the mass ratio between fly ash and tunnel muck (Mfa/Mtm), the mass ratio between Na2SiO3 solution and NaOH solution (), the ratio between liquid and solid (Mliquid/Msolid), and molarity of NaOH on the strength of geopolymer were systematically studied by conducting the uniaxial compression experiments. The experimental results indicate that the liquid‐to‐solid ratio is the most important parameter to the geopolymer strength after the alkali‐activated fly ash treatment. On the contrary, molarity of NaOH is less effective on the geopolymer strength. Moreover, the optimum scheme is concluded according to the experimental results as follows: the mass ratio between tunnel muck and fly ash, the mass ratio between Na2SiO3 solution and NaOH solution, the ratio between liquid and solid, and molarity of NaOH are 1 : 2, 1.8, 0.18, and 10 mol/L, respectively. Meanwhile, the SEM images indicate that flocculence from the active substance in fly ash is a crucial component as the cementing material.

Field study on the use of gravelly tunnel muck for frost heave and thaw settlement prevention in soft subgrades, northwest China

Fine-grained valley sediments in cold mountain regions can cause frost heave and thaw settlement problems to infrastructure. These processes have caused major issues along a highway between Tanchang County and Diebu County in south Gansu province (the TDH), northwest China. A planned high-speed railway between Chengdu and Xi’ning, the capitals in the Sichuan and Qinghai provinces, will likely face the same problems. To mitigate the effects of frost heave and thaw settlement, new engineering techniques were tested in a valley region along the TDH. These included replacing frost-susceptible subgrade soils with gravels from a tunnel excavation as an anti-frost fill layer, and installing dewatering seepage drains. Two highway test sections were constructed, one with a 1.0-m fill layer and the other with 2.0-m fill layer, to test the performance of the coarse tunneling material as an anti-frost heaving technique. Ground temperature, water table, and deformation measurements indicated that the two sections experienced very limited post-construction settlement (1.5 mm and 1.7 mm). The maximum frost heave at the two sections was 4.0 mm and 10.7 mm, respectively, much lower than the admissible amount in the Chinese standards (50 mm). These results indicate that coarse-grained waste material from tunneling can be used to effectively control frost heaving. The dewatering measures, which served to lower the water table and thus limit the water supply for ice segregation, are also suggested as important implement in rainy valley regions with ground high water tables. The installation of an anti-frost fill layer and drainage measures are effective and economical techniques to mitigate frost heaving and settlement of infrastructure in cold mountain regions.

Performance-based re-use of tunnel muck as granular material for subgrade and sub-base formation in road construction

Performance-based re-use of tunnel muck as granular material for subgrade and sub-base formation in road construction

The Use of Tunnel Muck as Industrial Raw Material: Two Case-Studies

The re-use of rock as an industrial material requires more treatments than those foreseen for the reuse of muck as an aggregate for concrete and for road construction. The treatments always start with comminution, which has the goal of liberating the rock-forming minerals. Liberation is achieved with the appearance of grains which are composed of only one mineral. The subsequent treatment steps are based on the physical–mechanical–chemical properties of the different minerals, that is, density, magnetic susceptibility, wettability etc. Magnetic separation and flotation, the two techniques examined in this research, are the two most common techniques used in industrial mineral production plants. The mucks that were analysed are from the Omegna and Brennero tunnels, both of which are granitic rocks with different textures. From the analysis and comparison of the preliminary treatment results, it has been possible to optimise the treatment method. Petrographic, mineralogic and firing tests have been conducted to evaluate the obtained results. High-gradient magnetic separation (HGMS) on defined grain sizes appears to be suitable to obtain a product with a high feldspar–quartz content which could be used in the ceramic field.

Main Aspects of Tunnel Muck Recycling

Italy is one of the first countries in the world as far as the number of tunnels is concerned. Many new tunnels are currently under construction or have been planned (300 km of railway tunnels and 150 km of road tunnels, some more than 500 m long, but also metropolitan tunnels). Tunnels are usually excavated in mountain areas of great value: the longest ones in Italy are in fact located in the Alps or in the Apennine mountain range. Approach: If the re-use of excavated material is not taken into account each time a tunnel is excavated, new quarries are required to obtain aggregates for cement, asphalt and concrete and new landfills are created, to allocate the tunnel muck. If the planned tunnel is large (in size and length), numerous quarries and landfills can be expected in the vicinity of the tunnel, with a consequent considerable amount of environmental damage. Results and Conclusion: For these reasons and not only for the obvious economic reasons, it is necessary to develop all the technologies that make the re-use of muck possible as an aggregate for cement and asphalt and as material for road and railways embankments

Remote construction noise monitoring.

Los Angeles was constructing an underground 12 ft in diameter sewage tunnel stretching 25 km. The project includes nine construction access shafts where tunnel boring machines, muck trains, and materials were lowered into the ground. The excavated tunnel material was transported from the tunnel head to the access shafts by muck train, removed by a crane, and carried away via heavy haul trucks. A state of art remote construction noise system was developed and installed near each of the shaft sites, which was collecting noise, audio, and video data 24 h a day. Noise levels were recorded whenever a noise limit threshold is exceeded. Data were then transmitted via modem to a central location where noise specialists review and analyze the data. A portion of these noise limit exceedances were correlated to the audio and video files to determine if the exceedances were due to the construction activities or other non‐construction related events. Construction noise at the noise sensitive sites adjacent to each shaft were minimized by constructing sound walls as high as 10 m.

トンネル掘削で発生するずりのコンクリート骨材への有効利用

Effective utilization of tunnel muck was discussed. In the system proposed by the authors, the muck is reused as concrete aggregate and the muck waste is considerably reduced. This muck utilization system was examined from economical and technical viewpoints.As the results of carefully investigation of tunnel muck, it was found that relatively small particle was short and the shape was not appropriate to concrete aggregate. Therefore the tunnel muck cannot be used directly as concrete aggregate and, at least, a simple crushing plant with an impact crasher and screens is necessary.The muck was gathered in a tunnel and several experiments and testing including crushing, sieving and quality verification were conducted to obtain the data required to discuss the feasibility of this system. Finally, it was found that utilization of tunnel muck as concrete aggregate is possible with reasonable benefit.

Determination of support reaction curve for steel-supported tunnels

Determination of support reaction curve for steel-supported tunnels