Types Of Grout Research Articles

Bond behavior between the deformed steel bar and different types of cementitious grout under reversed cyclic loading

To systematically investigate the bond behavior of deformed steel bars in cementitious grout, direct pullout tests were conducted on 15 sets of specimens by considering five types of cementitious matrixes and three different loading schemes. The failure modes, bond stress-slip curves, as well as the bond degradation and cumulative energy dissipation of specimens under reversed cyclic loading, were compared and analyzed. Results indicate that splitting pull-out or pull-out failure modes were observed, and pull-out failure was the most common failure mode of the specimen (accounting for 91 %) due to the installation of stirrups and the sufficiently short anchorage length. Meanwhile, regardless of the loading scheme, the general relationship between the magnitude of maximum bond stress of specimens composed of different cementitious materials was shown as C60＞CGM-270＞CGM-300＞CGM-340＞CGM-380, while there was no consistent pattern in relative slippage. Moreover, the relationship between the degradation of the maximum bond stress and stiffness of each specimen under reversed cyclic loading was shown as CGM-380 >CGM-340 ≈CGM-300 >CGM-270 >C60. The degradation mainly occurs in the first two cycles, and then gradually stabilizes. Furthermore, the cumulative energy dissipation relationship of specimens with different materials was shown as C60 >CGM-270 >CGM-300 >CGM-340 >CGM-380 under the reversed cyclic loading. The above investigations could provide theoretical support for the evaluation of ductility and energy dissipation of concrete members strengthened with cementitious grout under earthquake actions.

Mechanical Properties of Iron Tailing Sand Grout Sleeve Joints and Force Analysis.

In this paper, the mechanical properties and internal stress condition of the reinforcing bar sleeve connectors with ferro-tailed mineral sand cementitious grout as filler material were analyzed as research objects. Firstly, an experimental study was carried out on the reinforcing bar sleeve connectors of iron tailing sand grout with a 40% substitution rate of mechanism sand to analyze the mechanical properties of different grout types, age, and reinforcement diameters under unidirectional tensile, high stress, and large deformation of repeated tensile and compressive stresses. Next, five groups of sleeve joints with different anchorage lengths were set up for unidirectional tensile tests. The results show that, with the decrease of the diameter of the reinforcement, the grip force and bond strength of the iron tailing sand grout on the internal reinforcement gradually increase. Under conditions of large deformation and high stress due to repeated tensile loading, the residual deformation and total elongation of iron tailing sand grout sleeve joints are satisfactory. Additionally, the restraining anchorage effect of iron tailing sand grout in the end section is small. The utilization rate and integrity of iron tailing sand grout in the initial anchorage section are better.

Assessment of Semi-Flexible Pavement Using Styrene-Butadiene Emulsion Modified Cement Grout

Semi-flexible pavement (SFP) is a type of road surface that combines open-graded asphalt concrete with cement grout for wearing courses containing 18 to 28% air voids. This study investigates the effectiveness of two types of cement grouts using modified styrene-butadiene emulsions, Sika Latex and Sika Latex TH, with varying amounts ranging from 4.5% to 7.5% and 7.5% to 9%, respectively. The goal of the paper is to determine the appropriated type of styrene-butadiene emulsion type for SFP. To create the SFP, the selected grout and Vinkems Asphalsol grout with a water-cement ratio of 0.45 were poured into the asphalt structure, resulting in an SFP with 22.8% air voids. Additionally, several experiments were conducted to evaluate the effectiveness of SFP. These experiments included the Marshall stability test, indirect tensile strength test, and resilient modulus test. The study results showed that Sika Latex 6.5% and Sika Latex TH 9% had good properties for use in SFP.

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.

Design of Alkali-Activated Materials and Geopolymer for Deep Soilmixing: Interactions with Model Soils.

This study focuses on the use of alkali-activated materials and geopolymer grouts in deep soilmixing. Three types of grouts, incorporating metakaolin and/or slag and activated with sodium silicate solution, were characterized at different scales to understand the development of their local structure and macroscopic properties. The performance of the soilmix was assessed by using combinations of the grouts and model soils with different clay contents. Feret's approach was used to understand the development of compressive strength at different water-to-solid ratios ranging from 0.65 to 1. The results suggested that incorporating calcium reduced the water sensitivity of the materials, which is crucial in soilmixing. Adding soils to grouts resulted in improved mechanical properties, due to the influence of the granular skeleton. Based on strength results, binary soilmix mixtures containing 75% of metakaolin and 25% of slag, with H2O/Na2O ratios ranging from 28 to 42 demonstrated potential use for soilmixing due to the synergistic reactivity of metakaolin and slag. The optimization of compositions is necessary for achieving the desired properties of soil mixtures with higher H2O/Na2O ratios.

Experimental investigation of the influence of mine water on mechanical properties of resin grout

Resin grout is widely used in geotechnical and underground engineering, and is often affected by different mine water solutions. This study considered the effects of different mine water solutions and soaking times on resin grout. Soaking tests and uniaxial compression tests were conducted to investigate the changes in the solution pH, relative specimen mass, and uniaxial compressive strength (UCS), and the deterioration of the resin grout’s mechanical properties caused by the mine water solution was analyzed. The corrosion mechanism of resin grout under the action of different mine water solutions was investigated through scanning electron microscopy tests. The results reveal that the pH value of the solution and the relative mass of the specimen gradually stabilized as the soaking time was extended, and the final solution was weakly alkaline. The increase in the acidity and alkalinity of the solution and the extension of the soaking time led to a gradual decrease in the UCS and elastic modulus of resin grout under the action of mine water. As the soaking was prolonged, the resin grout properties deteriorated to different degrees and Poisson’s ratio increased. Moreover, owing to the different types and degrees of mine water action on resin grout in different mine water environments, the changes in the resin grout microstructure were also different. The defined damage parameters can express the damage process of the resin grout’s UCS quantitatively under the action of mine water solution. Finally, beneficial engineering application countermeasures are proposed for different resin grout types used in roadway support applications in coal mines.

Development and application of novel microfine cement-based grout

A novel type of effective microfine cement-based grout (EMCG) is designed for the complicated water-rich sand stratum. Superplasticizer (SP), compound excitation modulator (CEM), enhanced stabilizer (ES) and active activator (AA) were selected as optimizers. Through laboratory tests, main properties of EMCG i.e. fluidity performance, viscosity, bleeding rate, setting time, strength and volume stability were studied. Based on XRD mineral and SEM microstructure tests, hydration mechanism and microstructure of EMCG were studied. The results showed that the optimal parameters were 40% microfine fly ash (MFA), 14–18% microfine steel slag (MSS), 20–25% microfine slag (MS), 2–2.5% naphthalene-based SP (N), and 1–1.5% AA, 0.4–2.0% CEM and 6% ES. The 28d compressive strength of EMCG can reach 12.9–32.8 MPa. The 7 d strength can exceed 70% of 28 d strength. Through grouting injectability and reinforcement simulation tests, injectability of EMCG was acquired under different main influence factors i.e. sand particle size distribution, sand compactness, grout type, water-solid ratio (W/S), grouting pressure, etc. Quantitative relationships among enhancement strength or permeability coefficient and main influence factors were established. The microscopic slurry-rock interface reinforcement mechanism was obtained. Finally, based on field tests, the sealing and reinforcement effects of EMCG on water-rich sand stratum were acquired and discussed. Due to high overall performance and excellent engineering applicability of EMCG, it is an efficient and excellent cementitious grout especially for seepage prevention and reinforcement of water-rich sand stratum in geotechnical and underground engineering.

Investigating the sealing efficiency of grouting in joints: insights from effects of the rheological properties of grout and joint characteristics

ABSTRACT In tunnel construction, grouting is frequently used to decrease the permeability and increase the rock mass strength. One of the most challenging steps in grouting is choosing the best grout type to achieve the highest penetration and sealing efficiency in the joints. The main purpose of this study is to investigate the sealing efficiency of different grout types in the joints of a high-risk section of the Kerman water conveyance tunnel (KWCT). For this purpose, the penetrations of three types of grouts including Ordinary Portland Cement (OPC), Ultra-Fine Cement (UFC), and silica sol were determined using analytical equations. Thereafter, the sealing efficiency of each type of grout in joints with different apertures was calculated. Also, the penetration radius of each type of grout was simulated and calculated using UDEC code. Based on the results of the analytical equations, by performing the grouting for 20 min using silica sol-based grout, the joints of the high-risk section of the KWCT with apertures of 0.5–2.5 mm and 2.5–10 mm can be sealed at ‘Fair’ and ‘Excellent’ levels, respectively. Furthermore, based on the results of numerical simulations, the UFC and silica sol-based grouts can seal the joints in ‘Good’ and ‘Excellent’ levels, respectively.

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.

Preparation and application research of hybrid alkali-resistant glass fiber reinforced cement grout

Cement grouting reinforcement is a widely used method for controlling water inrush in tunnels. However, traditional cement grout has certain limitations such as low strength and susceptibility to erosion, which can result in inadequate grouting performance in water-rich tunnels. To address this issue, this study introduces a novel type of grout called hybrid alkali-resistant glass fiber reinforced cement grout (HARGFC). In order to evaluate its effectiveness, different ratios of HARGFC were tested in terms of slurry fluidity, splitting tensile strength, compressive strength, and flexural strength through laboratory experiments. Additionally, microscopic analysis of the samples was carried out using scanning electron microscopy (SEM) in conjunction with the mechanical tests. Finally, the application of HARGFC was demonstrated in a water-blocking grouting project conducted in the Qiyue Mountain Tunnel on the Liwan Expressway. The results demonstrated that this material possesses outstanding physical and mechanical properties, as well as alkali resistance, which greatly enhances grouting performance in water-flowing tunnels. Adding a total fiber content of 1%, that is, 80% of Cem-FIL70 (9 mm) and 20% of HD (6 mm), yielded the optimal ratio for HARGFC. Compared to traditional cement materials, the splitting tensile strength, flexural strength, and compressive strength of the new material increased by 27.46%, 20.64%, and 7.37%, respectively. Building upon various combinations of grouting methods, the optimal HARGFC was applied to the grouting sealing and reinforcement of the Qiyue Mountain Tunnel, effectively controlling water inflow. These research findings provide valuable data and theoretical support for addressing sudden water inrush in tunnels and grouting construction.

A Systematic Review and Network Meta-Analysis of the Outcomes of Patients With Total Knee Arthroplasty Using Cemented, Uncemented, or Hybrid Techniques.

In this study, we aim to explore the differences among the three types of fixation methods for the components of the knee joint in patients who underwent total knee arthroplasty (TKA). These methods are cemented, uncemented, and hybrid fixation. Cemented fixation means that a special type of grout is used to attach the components to the bone.Uncemented fixation means that the components are designed to fit tightly into the bone and allow new bone growth to secure them. Hybrid fixation means that a combination of cemented and uncemented fixation is used for different components.We searched four online databases to find studies relevant to our research question. We use the R program (R Foundation for Statistical Computing, Vienna, Austria) for network meta-analysis (NMA) to analyze the data from the studies. We calculate the mean difference (MD) and the 95% confidence interval (CI) for each outcome, which are statistical measures of the difference and the uncertainty between methods. We use these measures for continuous outcomes, meaning they can have any value. For dichotomous outcomes, meaning they can only have two values, we use the risk ratio (RR) and the 95% CI, which are statistical measures of the relative risk and the uncertainty between methods. We assess the quality of randomized controlled trials, which are studies that randomly assign participants to different methods, using the Cochrane Risk of Bias Assessment Tool 1, a tool that evaluates the potential biases in the studies. We include 21 studies, and our analysis shows that cemented TKA reveals a statistically significant decrease in pain with hybrid TKA (MD = -2.82). That said, we find no significant differences between uncemented and cemented or hybrid (MD = -0.80 and -2.02, respectively). The results show that there is no significant difference between uncemented TKA and cemented TKA or hybrid technique (RR = 0.87, 95% CI 0.35-2.14; RR = 0.73, 95% CI 0.22-2.39, respectively). Also, we find no significant difference between cemented TKA and hybrid TKA (RR = 0.84, 95% CI 0.24-2.93).Cemented TKA is associated with a lower risk of deep vein thrombosis (DVT) incidence rate. Moreover, it shows a significant decrease in pain compared to hybrid TKA. Future research is needed to compare among the three interventions.

Bond stress distribution and suggestions for anchoring length of deformed steel bars in different types of cementitious grout

Eight sets of pull–out specimens were tested by considering four types of cementitious grout (CGM-380, CGM-340, CGM-300, and CGM-270) and two anchoring lengths (3d and 10d) in this study. Discussions were had on the failure modes, bond load–slip curves, stress distribution of steel bars, and bond stress distribution. Results indicated that the relationship between the magnitude of peak bond load of 3d–group specimens composed of different types of cementitious grout was shown as CGM-270>CGM-300>CGM-340>CGM-380. Simultaneously, the stress of the steel bars in specimens gradually increased with the increase in external load, and the steel bars were in the elastic stage. For the 10–group specimens, the peak bond load of each specimen was basically the same, and the steel bars had yielded when the specimen was damaged. In addition, the stress distribution of the steel bars was similar to that of 3d–group specimens before the steel bars yielding. After the load reached the yield load, however, the yield position gradually shifted toward the free end with the load further increased, and the yield section length of the steel bars gradually increased. Besides, in contrast to the unimodal bond stress distribution curves of the 3d–group specimens, the bond stress distribution curves of the 10d–group specimens were all in the shape of a multimodal distribution. The peak bond stress of 10d–group specimens were located near the loading end before the steel bars yielding. However, as the load was raised continuously after the steel bars yielded, the bond stress in the yield section dramatically dropped, the yield penetration depth progressively grew, and the peak bond stress gradually shifted towards the free end. Additionally, design suggestions for the critical anchoring length of steel bars in cementitious grout and the anchoring length of steel bars after yielding were provided.

On Design and Assessment of Tail Void Grouting Material in Mechanized Tunneling: A Review

AbstractThe utilization of tail void grout as a stabilizing and sealing agent in mechanized tunneling procedures is of paramount significance, given the geological and engineering conditions inherent to tunneling projects. Prior to its application within a tunnel, a detailed evaluation of the fresh-state characteristics of the grout, as well as the time-dependent evolution of its hydro-mechanical properties, becomes imperative. This review paper aims to provide a comprehensive introduction to the various types of tail void grouting materials used in mechanized tunneling. The potential for behavior enhancement of the grout through the utilization of different additives, considering diverse mixing ratios in varying ground conditions, is discussed. Moreover, an in-depth analysis of the fresh- and hardened-state properties of different grout types, along with the cross-effects induced by additives in the grout mixture, is presented and reviewed. The paper also delves into the testing methodologies and property investigations employed to assess different grout types using experimental approaches. Additionally, a detailed overview of the numerical simulation of mechanized tunneling is provided, with a particular emphasis on the role of grout. Finally, the coupled hydro-mechanical effects of typical grout additives are explored, and the applicability of various grouting material according to the ground conditions is presented and discussed.

An investigation on failure behavior of semi-flexible composite mixture at different temperatures

Semi-flexible composite mixture (SFCM) is a kind of pavement material formed by pouring cement-based grout material into a porous asphalt mixture with air voids from 20% to 30%. SFCM is widely used for its outstanding anti-rutting performance. Its mechanical performance is complicated due to its heterogeneity and interlocking structure. According to the present study, asphalt deforms at different temperatures, whereas cement-based grout has no similar characteristics. Rare research focuses on the temperature-based performance of SFCM. Therefore, the study was on the thermal performance of SFCM by seven open-graded asphalt mixture skeletons with different porosities and two types of grouts with early strength (ES) and high strength (HS). The test temperatures ranged from −10 ​°C to 60 ​°C. The mechanical investigation was performed using the semi-circular-bending (SCB) and beam bending tests. The strain sensor was used for analyzing the thermal performance of SFCM. The results show that the temperature significantly affected the SFCM's performance. The porosity was selected for three sections based on the trend of fracture energy (Gf) curves at 25 ​°C. The turning points were the porosity values of 20% and 26%. The initiation slope during elastic deformation increases with the porosity increase. This trend was more evident at intermediate temperature. The shrink strain of SFCM was lower than that of the usual asphalt mixture (AC). The thermal stress of the SFCM filled with HS (HS-SFCM) was higher than that of the SFCM filled with ES (ES-SFCM) at −10 ​°C. Moreover, the thermal failure characteristics of SFCM were influenced by porosity.

A critical review on jet grouting used in ground improvement techniques

The ground improvement by jet grouting has been critically reviewed in the present paper. Using different keywords, the organized study was conducted on Web of Science and Scopus, yielding 579 results. The methodology followed PRISMA 2009 guidelines, which included identifying, screening, and analysing a large number of results. A total of 36 papers are eligible for analysis after the screening process. In this study, we look at various concepts such as the type of grouting, the methods used, the type of soil, and the tests that have been conducted by numerous researchers. These techniques are used to improve subsoil characteristics such as bearing capacity, shear strength, settlement characteristics, and drainage. Jet grouting is a technique for reducing soil permeability while increasing shear strength. Jet grouting is primarily used in recent technologies to construct new metro stations, and tunnels, control water discharge, and improve the quality of deep excavation. This paper provides an overview and concept of recent and traditional major ground improvements using jet grouting, as well as their properties and cost considerations.

Study on the test of coal mass fracture grouting sealing with coal-based materials and its application

This study is focused on coal mass fracture grouting sealing and seepage reduction with coal-based grouting sealing materials. First, a new type of coal-based grouting sealing materials was developed and applied to the fractured coal sample in the grouting test. Then, the coal sample before and after grouting was scanned and reconstructed with the aid of industrial computed tomography (CT). Based on CT images and reconstructed data, a theoretical model of grouting sealing for fractured coal mass was constructed by taking the migration and sedimentation of grouting slurry particles into consideration. Furthermore, on the ground of the theoretical model, a numerical calculation model of grouting sealing for the fractured coal sample was established, and the mechanism of grouting sealing and seepage reduction with coal-based sealing materials was simulated. Finally, a field test of gas extraction drilling and sealing was performed using the coal-based grouting sealing technology. The results show that: 1) The new type of coal-based grouting materials is effective in sealing the coal mass fracture, as the fracture is tightly filled with slurry particles after grouting. 2) The numerical simulation reproduces the whole process of grouting slurry flow and fracture sealing. After the permeability of the grouting coal sample decreases rapidly, it gradually tends to stabilize. The permeability of the whole coal sample goes down by 96% on average, and that of the fracture drops by more than 99.9% on average. The law of slurry diffusion and permeability variation calculated by numerical simulation is in line with the test results, which verifies the reasonableness of the model. 3) The application of the coal-based grouting sealing technology achieves an excellent sealing effect, promoting the gas extraction concentration by 1.43 times. The research results provide guidance for revealing mechanism of coal mass fracture grouting sealing with coal-based materials and bolstering the effect of extraction borehole sealing.

Underwater Repair of Concrete Elements with TRC Grouting System.

The repair of underwater concrete structures is usually difficult work, requiring specialized materials and installation systems. This paper presents a carbon-textile-reinforced concrete (TRC) grouting system for underwater repair of concrete structures. One multi-purpose grout and two types of underwater grouts were considered in this study, and the bond performance between the substrate and grout was evaluated by a bi-surface shear test with cubic specimens. The bond strength of the repair material is greatly affected by the casting and curing conditions. When the multi-purpose grout is used, the average bond strength of the specimens cast and cured in dry conditions is only 22% of the specimens cast and cured in underwater conditions. On the other hand, the maximum difference in bond strength is, at most, 15.8% when non-dispersive, anti-washout grouts are used. Two types of installation methods were proposed and four full-scale RC slab specimens were repaired with the TRC grouting method, two for each installation method. Regardless of the installation method, the load levels that causes concrete cracking, steel yield, and the failure of specimens repaired with the TRC grouting system are at least 37.5%, 16.6%, and 21.7% greater than those of the unrepaired specimen, respectively. The test results further indicate that the influence of the grouting materials on the ultimate load-carrying capacity of the specimens repaired with the TRC grouting system is insignificant, and the maximum difference is, at most, 4%.

How a sensitive analysis on the coupling geology and borehole heat exchanger characteristics can improve the efficiency and production of shallow geothermal plants

Knowledge of the thermal behaviour around and throughout borehole heat exchangers (BHEs) is essential for designing a low enthalpy geothermal plant. In particular, the type of grout used in sealing the space between BHE walls and the pipes is fundamental for optimizing the heat transfer and minimizing the thermal resistance, thereby promoting the reduction of total drilling lengths and installation costs. A comparison between grouts with different thermal conductivities coupled with common hydrogeological contexts, was modelled for a typical one-year heating for continental climates. These data have been used for a sensitivity analysis taking into account different flow rates through pipes. The results highlight that in groundwater transient conditions, porous lithologies allow for greater heat power extractions to be obtained with an increasing grout thermal conductivity than limestone or clayey silt deposits do. Moreover, increasing the inlet flow rates through the pipe greatly improves the final heat power extraction. As a result, when the underground allows for high extraction rates, the use of high performing grouts is warmly suggested ensuring greater productions.

An investigative study for the prediction of compressive strength of cement-clay interlocking (CCI) hollow brick masonry walls

Masonry structures are used in many parts of the world because of their varying benefits of being low-cost, heat insulations, local availability, and skilled labor. Therefore, to investigate the compressive stress-strain behavior and detailed analysis and assessment of masonry structures made of CCI bricks is imperative. Axial compressive results of 10 hollow cement-clay interlocking (CCI) bricks made masonry walls are presented. 10 masonry walls were tested under concentric compressive load in 2 groups. Bricks of each group had different compressive strength. Five walls in each group comprised of 1 control wall (ungrouted), 1 wall grouted with Ordinary Portland Cement (OPC), 1 wall grouted with non-shrink (NS) cement, 1 wall grouted with OPC and strengthened by steel bars, and 1 wall grouted with NS and strengthened with steel bars. Among 5 walls in each group, control wall created the lower bound in terms of the peak load sustained. While the upper bound was created by the wall grouted with NS cement and further strengthened by steel bars. It was found that the addition of grout (irrespective of its type) significantly improved the peak compressive load. However, increase in peak load over that of the control wall was associated to the grout type. Walls grouted with NS cement attained higher peak loads as compared to those grouted with OPC. It was observed that the addition of cement grout does not guarantee a ductile post-peak behavior. Addition of steel bars not only increased the peak loads, but it also improved the post peak behavior. Accuracy of existing compressive load analytical models was assessed, and it was found that none of the analytical models considered were able to predict close approximations. A linearly regressed model is proposed to predict compressive strength of CCI brick masonry walls with good accuracy.

Performance Research of Materials and Engineering Application of Overburden Strata Separation-Zone Grouting Technology

To solve the ground subsidence problem associated with thick coal seam mining under the railway in the Tangshan Mine, the technology of overburden strata separation-zone grouting (OSSG) was proposed. Based on the analysis of the full height overlying strata structure in the range of the six working face areas of the second mining district, the spatial distribution characteristics of the separation zone within the overlying strata are obtained after fully mining the six working faces. Then, emphasis was placed on the selection ratio of grouting materials and the hydrodynamic properties of different grout types, and grouting grout with a high concentration, slow precipitation rate, and good stability was obtained by taking fly ash and local clay as aggregates. The designed grout concentration was approximately 40%; the bulk density was approximately 1.20; and the clay content in the aggregates was approximately 40–50%. The separation-zone grouting plan was designed for the six working faces, and continuous grouting technology with the characteristics of multiple separation zones within the full-height section with a large flow and a high concentration was proposed to form a complete grouting system and reasonable grouting process. After engineering verification, the technology has an ash injection ratio of 24.2%, a grouting ratio of 100.3%, and a reduction in the ground subsidence ratio of 51.5%, effectively reducing mining damage to the ground surface and ensuring the safe operation of ground surface railways. Simultaneously, this advancement improves the resource recovery rate of coal mines and provides greater benefits for mining enterprises.