Performance Of Grout Research Articles

Experimental Study of the Application of Calcined Shield Muck Powder as a Substitute for Fly Ash in Synchronous Tunnel Grouting Materials

During shield tunnel construction, waste mud is a significant source of urban construction waste. However, the disposal of waste mud has always been a challenge in engineering. Addressing the challenge of harmlessly disposing of, or repurposing, mud cakes formed after pressure filtration of shield mud remains a pressing issue for many cities. To address the challenge of shield mud disposal and explore the utilization technology of this resource, this study focuses on shield mud obtained from the Shenzhen subway tunnel. Calcined shield mud powder (CSMP) was prepared by activating its potential pozzolanic properties through a calcination process. Compressive strength tests revealed that, while CSMP exhibits some pozzolanic activity, its performance is limited. When 30% of the cement is replaced, the mortar’s maximum strength activity index (SAI) is only 82.6%, which makes it unsuitable as a supplementary cementitious material for concrete applications. At the same time, CSMP was also evaluated as a partial replacement for fly ash in the formulation of synchronous grouting materials, with performance metrics including fluidity, bleeding rate, hardening rate, setting time, and compressive strength systematically tested. The experimental results showed that, while CSMP reduces the fluidity of grouting, it significantly improves volumetric stability, shortens setting time, and enhances mechanical performance. Compared to the fly ash used in the study, CSMP exhibited better pozzolanic reactivity, promoting the formation of C-S-H and C-A-S-H phases, optimizing the pore structure, and increasing the density and overall performance of the grouting material. When the substitution rate is below 60%, the performance of grouting meets standard requirements, indicating the strong feasibility of utilizing CSMP to replace fly ash in synchronous grouting materials.

Evaluation for anti-cracking performance of polyurethane grout based on overlay test

Polyurethane grouting has garnered increasing attention in road maintenance, owing to its exceptional interfacial adhesion, mechanical robustness, and chemical resilience. In comparison to conventional SBS-modified asphalt, polyurethane grout offers superior durability and demonstrates an enhanced capacity to inhibit crack propagation within asphalt mixtures. This study investigates the anti-cracking performance of polyurethane grout in comparison to traditional SBS-modified asphalt, utilizing the Overlay Test (OT) to simulate real-world conditions of reflective cracking in asphalt pavements. Results demonstrate that polyurethane grout significantly enhances the crack resistance of asphalt mixtures, manifesting superior durability and resistance to crack propagation at a controlled temperature of 25°C, with a marked increase in the number of loading cycles relative to the control. However, the performance of polyurethane grout is notably diminished under adverse conditions of low temperatures and water immersion. The investigation employs a multi-index evaluation, with gray correlation analysis delineating the efficacy of various indices in appraising crack resistance. Recommending the use of loading cycles, allowable failure times, and cumulative fracture energy as key metrics.

Comparative Analysis of the Performance and Study of the Effective Anchorage Length of Semi-Grouted and Fully-Grouted Sleeve Connection

Based on the insufficient data on bonding performance and effective anchorage length of sleeve grouting in assembled structure. Combining the existing studies, the sleeve grouting joint test for the static unidirectional tensile test was designed, and the influencing factors are reinforcement diameter and reinforcement anchorage length. Then, the failure mode, load-displacement relationship, energy consumption capacity and bearing capacity of the grouting sleeve connection are analysed, and the stress mechanism of the specimen in the one-way tensile state is expounded. This paper considers the actual damage state of the joint, according to the failure of the reinforcement outside the joint and the sleeve; referring to the reinforcement-concrete bond strength research theory, the effective anchorage length formula is proposed. When the steel bar is pulled out, the bond strength and bearing capacity mainly depend on the effective anchorage length. However, when the specimen breaks the steel bar outside the joint, it depends on the material performance of the steel bar itself. The research results of this paper can lay a theoretical foundation for the application of sleeve grouting joints.

Experimental studies on the interfacial shear characteristics between joint concrete and foamed polymer in cross-river shield tunnel

The inadequate grouting performance in cross-river shield tunnels is primarily due to the insufficient bonding strength between the grouting material and the tunnel segments. In this study, a series of tests were conducted to compare foamed polymer and common grouting materials, focusing on the tangential bonding performance of the interface with tunnel segment concrete under varying humidity conditions. The applicability of polymer for treating leaks in cross-river shield tunnels was explored. The effects of polymer density, interfacial humidity, interfacial roughness, and normal stress on the shear strength of the polymer-concrete interface were investigated. A mathematical model reflecting the interface shear characteristics between polymer and concrete was established and validated. The test results have shown that, due to the fast reaction speed and high expansion rate, foamed polymer was found to be a feasible solution for addressing leakage in cross-river shield tunnels. Compared with common grouting materials, the density of foamed polymer is controllable, and the shear strength between foamed polymer and concrete segments is less affected by humid conditions. The minimum shear strength of the interface between foamed polymer and concrete is 1.2 MPa, while the maximum is 2.0 MPa. Foamed polymer can meet the needs of leakage treatment of cross-river shield tunnel. The interfacial shear strength between foamed polymer and concrete segments is directly proportional to the polymer density, interfacial roughness, and normal stress, and inversely proportional to the level of humid in the tunnel. The influence of various factors on interfacial strength is ranked as follows: polymer density > interfacial humidity > normal pressure > interfacial roughness. The residual error of linear regression mathematical model for the shear strength of interface between foamed polymer and segment concrete follows a normal distribution. The fitting results were proven to be accurate, allowing for the intuitive prediction of the quantitative relationship between shear strength and multiple influencing factors.

Performance and microstructural characterization of fiber-reinforced cement-based grout incorporating waste tailing sand and fly ash

A fiber-reinforced cement and tailing sand-based grout (FRCTG) was proposed to improve the utilization of solid waste in construction. Different grout specimens were prepared using various proportions of ordinary Portland cement, iron tailing sand (ITS), fly ash (FA), basalt fibers (BFs), and water as raw materials. Used single-factor test, orthogonal test and artificial neural network model that provided a comparative analysis of the change in the rheological and mechanical properties of different grout mixes according to their component ratios. Furthermore, microscopic characterization techniques were used to reveal the intrinsic physicochemical mechanisms underlying the structural evolution of the considered grouting materials. The results indicate that ITS significantly increases the rheological properties of the grouting material. The maximum strength of the grouting material is achieved when the length of BF is 6 mm and the dosage is 0.2 %. An 8 % dosage of FA can effectively improve the rheological properties of the grouting material and enhance its flexural strength. Microscopic tests reveal that SiO2 in ITS exists in the form of quartz with low reactivity, thereby inhibiting the hydration reaction of the binder material. Different distribution patterns allow BF to serve both as reinforcement for the matrix and as a framework for hydration products, effectively enhancing the density between the BF and the surrounding matrix. The surface of FA is covered in layers by hydration products, forming a chain-like structure that improves bonding strength with the material. The results of this research offer a high-performance, low-cost, and environmentally friendly grouting material for construction grouting projects, which is of significant importance for promoting innovation in comprehensive utilization of solid waste.

Performance and Mechanism of Double-Row Capsule Grouting to Protect Tunnels Adjacent to Excavation

Performance and Mechanism of Double-Row Capsule Grouting to Protect Tunnels Adjacent to Excavation

Experimental study on the performance of shield tunnel tail grout in ground

Shield tail grouting is an important measure to control tunnelling-induced ground deformation by injecting prepared grouting materials to fill the tail gap. The working performance of grout is usually invisible and hard to obtain in construction. This paper carries out an experimental study to investigate the tail grout behavior in ground. In the current research, a testing device is developed to explore the grout behavior in varying soils. The grout working performance is evaluated not only by the liquid grout properties such as fluidity, consistency, bleeding rate, stone rate and compressed deformation but also solid grout properties such as unconfined compressive strength and permeability. Three typical grouts are chosen and their behaviors in the various soils are observed. To take an insight on the behaviors, scanning electron microscopy and mercury intrusion porosimetry analysis are employed. The microstructure of solid grout is a sign of its working performance. The observation shows that the solid grout micro-structure is influenced by grout proportions, pressure, and ground permeabilities. The experimental results are applied in the case of Beijing Metro Line 12 for validation and as a result, the ground movement is inhibited due to high performance of tail grout.

Study on Grouting Performance Optimization of Polymer Composite Materials Applied to Water Plugging and Reinforcement in Mines.

With the increasing drilling depth of mines, the cross-complexity of fissures in the rock body, and the frequent occurrence of sudden water surges, polymer slurry, with its advantages of good permeability and strong water plugging, is increasingly used in mine grouting projects. Additional research is needed in order to further improve the grouting performance of polymer slurry, ensure the safety of mining operations, and reduce the grouting cost. In this paper, a polymer composite grouting material was prepared with diphenyl methyl diisocyanate, polyether polyol, and fly ash, as the main raw materials, with coupling agent and catalyst as auxiliary reagents. The performance of the composite grouting material in terms of mechanical properties, thermal stability, hydrophobicity, and bonding was explored. This study's findings indicated that incorporating fly ash led to notable enhancements in the thermal stability and water resistance of the polymer slurry. Furthermore, the introduction of fly ash notably raised the starting degradation temperature of the polymer, boosted the water contact angle of the composite material, and reduced the density and reaction temperature of the composite material. In addition, the catalyst and coupling agent as auxiliary reagents affected the polymers in terms of mechanical properties; in this paper, dibutyltin dilaurate was used as the catalyst, and organosilanes were used as the coupling agent. The catalyst successfully sped up the polymer's gel time, however, an excessive quantity of catalyst compromised the polymer's mechanical characteristics. The addition of organosilanes has a positive effect on the dynamic mechanical properties of the composites, fracture toughness, compression, bending, and bond strength. The research can offer a theoretical direction for creating polymer mixtures in mine grouting projects.

Study on grout ratio and performance of backfill grouting in water-rich strata

The grout of backfill grouting in water-rich strata is at risk of dilution and loss. To facilitate the rational selection of grout in water-rich strata, an analysis based on engineering statistical data was conducted on the application of grout types, materials, and ratios. For commonly employed single-component grout, the sensitivity of performance to ratios was investigated through performance tests. Correlation analysis was employed to explore the relationships among ratios, ratios and performance, as well as performance with performance. Through multivariate nonlinear regression analysis, the relationship between performance and ratios was established to elucidate the application of grout performance in engineering. By comparing the performance requirements in engineering, a reference basis for grout performance in wter-rich strata was provided. Based on the performance application and requirements in engineering, a standard for evaluating single grout performance was proposed. Utilizing principal component analysis (PCA), a comprehensive method and standard for evaluating overall grout performance were developed, providing guidance for assessing grout performance.

Designing prepacked aggregate concrete for improved mechanical properties and its field application in constructing steel tube concrete

Prepacked aggregate concrete (PAC) is made by placing coarse aggregates of various sizes into a formwork and then filling the voids between coarse aggregate and grout. The mechanical performance of PAC is dominated by the compactness due to grout filling, but few study considered the pouring methods and grout performance synchronously. The coupled effect of pouring methods and grout performance on the compactness of PAC is investigated in this study. The results show that the gravity pouring method is only suitable for grouts with good flowability. The pump pouring method is more widely used. It can be adapted to grout with poorer fluidity and coarse aggregate with greater apparent density. The ultrasonic pulse velocity test method provides a relatively accurate evaluation of the compactness of PAC. Furthermore, due to the enhanced mechanical properties of PAC, the filed application potential in the preparation of steel tube concrete columns has also been confirmed, where the results exhibited that PAC based steel tube concrete contributed to an enhanced ductility and autogenous shrinkage.

Potential Utilization of Loess in Grouting Materials: Effects of Grinding Time and Calcination Temperature

There is a huge reservation of loess in the Shanxi mining area in China, which has great potential for preparing supplementary cementitious materials. Loess was modified via mechanical and thermal activation, and the pozzolanic activity was evaluated using an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Moreover, the workability of grouting materials prepared using modified loess was assessed. The experimental results revealed that the number of ultrafine particles gradually increased with the grinding time, enhancing the grouting performance. The coordination number of Al decreased upon the breakage of the Al–O–Si bond post-calcination at 400 °C, 550 °C, 700 °C, and 850 °C. Moreover, the breaking of the Si–O covalent bond produced Si-phases, and the pozzolanic activity of loess increased. Furthermore, the modified loess was hydrated with different cement proportions. With increasing grinding time, the overall setting time increased until the longest time of 14.5 h and the fluidity of the slurry decreased until the lowest fluidity of 9.7 cm. However, the fluidity and setting time decreased with increasing calcination temperature. The lowest values were 12.03 cm and 10.05 h. With the increase in pozzolanic activity, more ettringite was produced via hydration, which enhanced the mechanical properties. The maximum strength of the hydrated loess after grinding for 20 min reached 16.5 MPa. The strength of the hydrated loess calcined at 850 °C reached 21 MPa. These experimental findings provide theoretical support for the practical application of loess in grouting.

Study on the Properties of Waste Stone Powder-clay Slurry based on the Influence of Filter Press

A grouting material pressure effect simulation device (FSD) was used to study the performance of grout considering grouting pressure, slurry rheology, clay ash, slurry concentration and particle size composition of waste stone powder (FSD influencing factors). After the effect of filter pressing, the alkaline environment of the slurry became stronger, the number of active particles increased, and the CaCO3 and clay crystals were fully agglomerate, and the degree of crystallization increased. The cation exchange capacity increased, and the formation of calcium-silicon-aluminum matrix phase and aluminosilicate aggregates increased. The surface water between the matrix particles supports the crystal layer, and the plastic viscosity and yield stress are reduced. The free calcium oxide decreased, and the consolidation shrinkage rate after slurry hardening was less than 1%. The water-cement ratio is reduced, and the total time for slurry to be poured into the fracture to consolidate and form a mold and intermittent is shortened. The use of waste stone powder and clay in the coal mine grouting industry can not only reduce project costs, but also reduce soil erosion and soil pollution.

Study on load-bearing behaviors of prestressed post-grouting tubular piles in the karst region of northern Fujian Province, China

The karst that is dominated by medium-weathered limestone and caves with various spatial features is widely distributed in the northern Fujian Province. This paper discusses the load-bearing behaviors of post-grouting tubular piles in karst region of north Fujian Province with reference to the prestressed tubular piles adopted in the residential buildings of Haixi Comprehensive Trade City Phase II Project in Sanming City. The load-settlement curve, pile side friction resistance, and pile end resistance of tubular piles are analyzed by finite element numerical simulations and field static load tests. The load-bearing behaviors of prestressed tubular piles under karst geological conditions with two different spatial features are comparatively investigated, and the effectiveness of tubular pile reinforcement is verified by field settlement observation. The results reveal that the finite element numerical model can effectively simulate the tubular pile-soil interaction. The use of pile end post-grouting of prestressed tubular piles in the karst region can significantly increase their load-bearing capacities. The top settlements of grouted tubular piles under the maximum test load can be reduced by 16.8%–22.3% compared with these of ungrouted test piles, and the theoretical simulated ultimate load-bearing capacity can be increased by 27.3%. The adoption of pile end post-grouting technique can reduce the pile end displacement of tubular piles and improve the proportion of pile end resistance. Plastic-hard plastic breccia silty clay can be used as a bearing stratum for post-grouting to achieve excellent grouting performance. The bead-shaped karst caves are more unfavorable to the exertion of load-bearing capacity of the tubular piles than the karst caves filled with plastic-hard plastic breccia silty clay to which the piles have direct access. The field monitored average settlements of the 19# and 17# buildings under karst geological conditions with two different spatial features are −12.88 mm and −8.98 mm, respectively, both of which do not exceed the warning value, indicating that it is feasible for the project to adopt the pile end post-grouting technique of the tubular piles. The achievements of this study help to further reveal the load-bearing mechanism of this type of pile, which can provide a basis for its engineering design and construction optimization.

Experimental Study on Water-Plugging Performance of Grouted Concrete Crack.

In this paper, ordinary Portland cement, ultrafine cement, polyurethane, and epoxy resin were selected as typical grouting materials. Grouting simulation tests were first conducted to prepare the grouted concrete crack sample. The effect of concrete crack parameters (i.e., crack aperture and roughness), grout water-cement ratio, and grouting pressure on the water-plugging performance of different grouting materials was explored through the impermeability test. The microstructure of grouted concrete cracks was analyzed by means of scanning electron microscopy (SEM) and computed tomography (CT), and the difference in water-plugging performance of different grouting materials was explained at the micro level. The results show that the impermeability of the four grouting materials was ranked as follows: Epoxy resin > polyurethane > ultra-fine cement > ordinary Portland cement. The concrete cracks grouted by epoxy resin have the highest plugging failure water pressure and the lowest permeability, which is the optimal grouting material. The effectiveness of crack grouting in water-plugging was directly proportional to the grouting pressure, provided the pressure did not exceed a certain value. When the pressure surpassed the threshold, the increase in pressure did not have a significant impact on the water plugging performance. For the two cement-based materials, the threshold pressure was 1 MPa, while for the other two chemical grouts, it was 2 MPa. The two cement-based grouts with a water-cement ratio of 0.8 showed optimal water-plugging performance. The water-plugging performance of ordinary Portland cement paste, ultra-fine cement pastes, and polyurethane grout was negatively correlated with crack aperture and positively correlated with crack roughness. However, the water-plugging performance of epoxy resin grout was not affected by crack aperture or roughness.

Experimental Investigation on the Grouting Performance of Foam-CNT Composite Grouts in Vertical Inclined Fractures Under Flowing Condition

Abstract Grouting is an effective method to solve the problem of water inrush in tunnel and underground engineering. However, rock fractures are often simplified as horizontal and smooth fractures in most grouting studies, while studies on vertical inclined fractures are still rare. To investigate the diffusion law in vertical inclined fractures, a vertical inclined fracture grouting simulation device was developed. A new type of cement slurry with low weight and high flowing water resistance was developed by combining carbon nanotube (CNT) slurry with foamed cement. Physical simulation experiments were conducted to investigate various factors (initial flowing water, inclination angle, sand content, and grouting rate) on the sealing efficiency of grouting. Results show that the high foam content has a negative effect on the compressive strength of the slurry, and has a positive effect on the fluidity and water resistance. The optimum ratio of slurry is 30% foam content, 1.0% CNT content, 1.3 water/cement ratio, and 3% additive content. The inclination angle and inclination direction of the fracture have a great influence on the sealing efficiency of grouting. Foam-CNT composite grouts can meet the requirement of flowing water grouting in vertical inclined fractures.

Valorization of Cappadocia waste earth in the production of sustainable lime-based grouts

Historical structures and natural landscapes in Turkey's Cappadocia Region, a popular tourist spot, have been designated mixed heritage sites on the World Heritage List since 1985. The region's old rock-cut and masonry constructions have been damaged for various reasons. Furthermore, the waste volcanic tuff excavated during the construction of rock-cut structures in the region totals around 10 million tons of waste material per year. It creates severe visual concerns since it cannot be used effectively in the area. Because repairing ancient buildings needs precision, the restoration method and material should be selected based on the structures' structural system and material attributes. Grouting is one of the most common ways of repairing and strengthening masonry buildings or fissured architectural pieces with adequate connected voids. This technique aims to restore damaged structures' continuity, cohesiveness, and strength while keeping their morphology and load-bearing system intact. This research explores the potential use of waste earth from rock-cut structures in the Cappadocia Region in hydraulic lime-based grouts. Thus, an injection material that can be used to repair fairy chimneys and historical rock-cut and masonry structures in this region will be produced. Various lime-based grout types containing Cappadocia waste earth (CWE) were produced in this scope. The evaluation of grout performance encompassed assessments in the fresh state (Fluidity, Penetrability, and Volume Stability) and the hardened state (Flexural and Compressive strength). Furthermore, this research delved into how Cappadocia waste earth (CWE) influences the physical and microstructural characteristics of lime-based grouts. Thanks to this study, both environmental pollution will be reduced, and sustainability will be contributed.

In situ resource reutilization of earth pressure balance (EPB) shield muck for the generation of novel synchronous grouting materials

The utilization of large quantities of shield muck resources is a pressing issue that requires immediate attention and resolution. In this paper, an innovative approach that fully utilizes shield muck as an aggregate for synchronous grouting is introduced to realize the in situ resource utilization of this material. The newly formulated synchronous grouting grouts comprise shield muck and a solid waste-based cementitious material. The influences of components and compositions on the macroscopic performance of new grouts are investigated, and the formulation is optimized with a single-factor test and response surface methodology (RSM) analysis. The optimal formulation with a slurry specific gravity (SG) of 1.383 g/cm³ and a cementitious material (CM) content of 21.456% is determined. The microscopic characteristics of the grouts are revealed by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). Two main hydration products, namely AFt and C-S-H gel, are observed, exhibiting a crisscross growth pattern that contributes to the formation of a robust micronetwork structure. A full set of shield muck in situ pulping equipment is independently developed, thereby establishing an integrated grout production process. Considering the Suzhou Metro Line 6 as an engineering case, a field industrialization experiment is conducted, and the results demonstrate that the pulping system operates smoothly and can stably produce grouts. Compared with conventional cement-based finished grout, the newly developed synchronous grouting material with an optimal formulation exhibits significant superiorities in terms of surface deformation control (average reduction of 30∼40%), segment attitude control, and anti-seepage effect. The proposed approach effectively realizes in-situ resource utilization and source reduction of shield muck and can significantly reduce the cost of synchronous grouting. Aligned with the dual carbon strategy, the prospects for widespread adoption of this approach are promising, and the results of this study are highly significant.

Application of geopolymer in synchronous grouting for reusing of the shield muck in silty clay layer

This study employs geopolymer as a complete replacement for the cement to solidify the shield muck discharged from tunneling in the silty clay layer, thereby creating an innovative synchronous grouting material. This novel grouting material not only utilizes geopolymer as its primary cementitious component but also incorporates shield muck, promoting the efficient utilization of the shield muck. The cementitious process of the grout is initiated by the principles of geopolymerization. Through a series of laboratory tests assessing grout performance, the new grouting material was developed by further optimizing the grout proportion using the response surface method (RSM). This involves a comprehensive analysis of the impacts of various factors such as muck moisture content, foam injection ratio, ground granulated blast furnace slag (GGBS) content, and sand content, along with their interactions on the key response variables, including consistency, fluidity, 2 h bleeding rate, setting time, and 3 d unconfined compressive strength (UCS). The optimal proportion of the new grouting material is found to be 140% muck moisture, 100% GGBS, and 230% sand. Experimental results reveal that the GGBS content has the most significant effect on various properties of the grout, while the interaction between these factors has distinct effects on different grout properties. This novel synchronous grouting material was subsequently employed in the Nanjing Metro Line 6 project, and it was found that both surface settlement and segment uplift meet the specified requirements.

Formulation of a cement-based grout characterizing controllable gelation time and its modification mechanism

Achieving a coordinated balance between pumpability, setting time, and compressive strength is essential for the effective implementation of grouting tasks. This facet also poses a significant challenge in the formulation of cement-based rapid-setting grout. Therefore, precise control over gelation time, while concurrently preserving the pumpability and mechanical strength of cement grout, unquestionably enhances its engineering feasibility. In pursuit of this objective, the current study executed a factorial experiment, assigning alkanolamine, fluoride, aluminum sulfate, and citric acid as experimental factors. Subsequently, through an experiment involving changes to the experimental setup, mathematical predictive models for diverse performance parameters were established to determine the optimal formula. Moreover, to elucidate the hydration process of the proposed grout, a comprehensive investigation was conducted using factor effect analysis, isothermal calorimetry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Finally, by drawing on the results of the above-mentioned experiments and theoretical analyses, the modification mechanisms of the admixtures on the performance of the matrix were deduced. This paper introduces a novel approach to optimize the overall performance of rapid-setting grout, providing a new material solution for grouting jobs.

Research on the Antifloating Performance of Grouts with Different Mix Proportions in Synchronous Grouting of Shield Tunnels: From Laboratory Tests to Theoretical Calculations

Research on the Antifloating Performance of Grouts with Different Mix Proportions in Synchronous Grouting of Shield Tunnels: From Laboratory Tests to Theoretical Calculations