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The distribution and magnitude of the shear stress at the interface between the grout of a compression anchor rod and rock are strongly affected by the Poisson effect. A new analytical equation of the influence coefficient of the Poisson effect is proposed to quantitatively evaluate the influence of the Poisson effect on the interfacial shear stress. When the Poisson effect is considered, the interfacial shear stress from the neutral point to the bearing plate increases, and the distribution curve becomes steep. However, the interfacial shear stress far from the neutral point is low, and the distribution curve becomes smooth. Overall, the Poisson effect leads to a more nonuniform distribution of the shear stress at the interface of the compression anchor rod. A larger Poisson's ratio, smaller elastic modulus, and smaller diameter of the grout lead to a greater influence of the Poisson effect. Furthermore, a larger elastic modulus of rock leads to a greater influence of the Poisson effect. The Poisson's ratio of rock and that of grout both affect the Poisson effect greatly, but the influence of the variation in the Poisson’s ratio of rock on the Poisson effect is negligible. A larger interface friction angle leads to a greater influence of the Poisson effect.

The Tangab Dam was constructed at a unique geological structure, within a karst valley at the deepest point of a saddle-shaped feature which was formed by tectonic compression of a post-folding shear zone and later uplifting by two salt diapirs. The reservoir water-tightness system was composed of a 20-m-deep cutoff wall, and a 180-m-deep hanging grout curtain with 256 m and 206 m extension, respectively, into the left and right abutments. Since impounding of the reservoir in 2009, water leakage has occurred in 5.8 km downstream preexisting karst springs. To reduce water leakage, two additional grout curtains, as well as extensive treatment works, were added by injecting 11,055 t of cement into the karst bedrock. However, grouting was not as effective as it was expected to be, and the reservoir never filled to its designed normal volume. The fluctuation of water levels in the reservoir and downstream boreholes indicated that grouting successfully reduced head loss in water flow. The reservoir carries the potential to seep water into the karst aquifer along a vast zone at each valley bank since the seepage windows were not covered completely by the hanging grout curtains. The engineering problems occurred at the Tangab Dam site illustrate that conditions where the reservoir is perched above the groundwater and separated with the hanging river valleys are some of the most challenging karst terrains for dam construction in which the successful reservoir impoundment cannot be guaranteed, even by an extensive grouting and sealing program.

Estimating surface settlement induced by excavation construction is an indispensable task in tunneling, particularly for earth pressure balance (EPB) shield machines. In this study, predictive models for assessing surface settlement caused by EPB tunneling were established based on extreme gradient boosting (XGBoost), artificial neural network, support vector machine, and multivariate adaptive regression spline. Datasets from three tunnel construction projects in Singapore were used, with main input parameters of cover depth, advance rate, earth pressure, mean standard penetration test (SPT) value above crown level, mean tunnel SPT value, mean moisture content, mean soil elastic modulus, and grout pressure. The performances of these soft computing models were evaluated by comparing predicted deformation with measured values. Results demonstrate the acceptable accuracy of the model in predicting ground settlement, while XGBoost demonstrates a slightly higher accuracy. In addition, the ensemble method of XGBoost is more computationally efficient and can be used as a reliable alternative in solving multivariate nonlinear geo-engineering problems.

The rapid increase in tunneling projects in the metropolitan cities located in the young alluvium deposit has urged the need for studying the effects of its construction on the existing structures in those areas. In general, the major concern of tunnel construction in urban areas is the maximum surface settlement developed and the studies on the response of tunneling induced settlement on young alluvium deposit are very rare. This study captures the impact of vital factors like grout pressure, face pressure, C/D ratio, tunnel diameter and elastic modulus of soil using a numerical approach that governs the maximum surface settlement. Evaluation of governing parameters, particularly for young alluvial soil will be handy in understanding the impact of each parameter and lead in formulating new or modify existing relationships suitable for predicting maximum surface settlement. For the numerical approach, a model was developed with the PLAXIS three-dimensional finite element software and validated with field data. The findings are also compared with analytical and empirical approaches developed by different researchers.

Two configurations of closure strips between precast reinforced concrete (RC) slab panels were fabricated and filled with either non-shrink grout or ultrahigh-performance strain-hardening cementitious composite (UHP-SHCC) material. The strips were then strengthened with externally bonded carbon-fibre-reinforced polymer (CFRP) sheets in order to compensate the drawback associated with decreasing the amount of connected steel reinforcing bars required to transfer the bending moment between panels. In total, 12 specimens divided into three groups were cast and tested under short-term non-reversed repeated patch loads simulating wheel load at the central joint. The test results showed that the UHP-SHCC filling material enabled the connected panels to exhibit more ductile behaviour compared with the panels whose closure strips were filled with non-shrink grout. On the other hand, the CFRP strengthening sheets for the first configuration of the closure strip failed to restore the ultimate capacity of the un-strengthened monolithic specimen. However, the second configuration, using UHP-SHCC filling material, enabled the connecting panels to restore lost capacity, with a performance improvement of about 14% compared with the un-strengthened monolithic specimen.

Due to the influence of mining disturbance stress, it is of great significance to better understand the bearing characteristics of fully grouted bolts under different pull-out loading rates. For this purpose, a series of laboratory pull-out tests were conducted to comprehensively investigate the effects of different pull-out loading rates on the mechanical performance and failure characteristics of fully grouted bolts. The results show that the mechanical performance of the anchored specimen presents obvious loading rate dependence and shear enhancement characteristics. With the increase of the pull-out loading rates, the maximum pull-out load increases, the displacement and time corresponding to the maximum pull-out load decrease. The accumulated acoustic emission (AE) counts, AE energy and AE events all decrease with the increase of the pull-out loading rates. The AE peak frequency has obvious divisional distribution characteristics and the amplitude is mainly distributed between 50–80 dB. With the increase of the pull-out loading rates, the local strain of the anchoring interface increases and the failure of the anchoring interface transfers to the interior of the resin grout. The accumulated AE counts are used to evaluate the damage parameter of the anchoring interface during the whole pull-out process. The analytical results are in good agreement with the experimental results. The research results may provide guidance for the support design and performance monitoring of fully grouted bolts.

The engineering practice shows that the application of grouting technology to treat underground engineering has strong applicability and is one of the most commonly used technical means at present. Based on the underground engineering, this paper introduces the research achievements of grouting materials in recent years, including cement-based grouting materials, mixed grouting materials, anti-scouring grouting materials, and ultra-fine cement grouting materials. Current demand of grouting materials in underground engineering, there exists large dosage of cement, high content, high cost, serious environmental pollution problems, such as looking for alternatives or mixed with other raw materials for preparation of cementation material become the development trend, compared with the cement grouting material, chemical grouting material with higher performance, but in smaller projects within the scope of application. How to reduce the production cost of chemical grouting materials, simplify the production process, overcome the existing toxicity, reduce environmental pollution and improve the durability of solidified body has become the bottleneck of its popularization and application. Some achievements have been made in the modification of cement or chemical materials by nanometer components, but there is still a long way to go before the large-scale application of grouting engineering.

In recent years, with the urgent need of the country to vigorously promote the transformation and upgrading of the construction industry and the modernization of the construction industry, it has been proposed to vigorously develop prefabricated buildings and increase the proportion of prefabricated buildings in new buildings. The prefabricated concrete building is a concrete structure with prefabricated components in the factory and processing and connection on the construction site. Because of its fast construction speed and good overall benefits, it is widely promoted. For prefabricated buildings, the key technology is the connection of structural nodes, and most of the component connections use concrete sleeve connections. The quality of the sleeve grouting material is very important. The basic formula of the grouting material leads to different and different mechanical properties. Conditions apply. This article starts with different sleeve grouting patents, summarizes different functions and characteristics, and provides a reference for the next development of sleeve grouting.

This paper presents three comparative in situ grouting tests for long-term settlement treatment of a cut-and-cover tunnel of Nanjing Metro Line 10. The characteristics of the tunnel settlement and induced structural damage are described in detail. Comparative grouting tests were conducted to identify the effects of the grouting sequence and grouting material on the tunnel settlement treatment. The test results show that the total amount of uplift of the tunnel associated with the bottom-up grouting sequence is greater than that associated with the top-down grouting sequence. When a mixture of cement and water glass was used as grout, the average cumulative deformation and average deformation rate of the tunnel 6 months after the completion of grouting were −11.2 mm (uplift) and 0.018 mm/day (settlement), respectively. These values satisfy the control requirements and are better than those obtained using a cement and bentonite mixture as grout. Hence, a bottom-up grouting sequence and a cement and water glass grout mixture are advised. The findings presented in this paper provide useful guidance for similar projects.

Underground construction has become a necessity considering social, technological, economical, and sustainable advancements in society. Tunnel boring machines (TBMs) can be considered as an efficient method of tunneling because of its high productivity and applicability in a variety of subsurface conditions. The performance of a rock TBM is assessed by its advance rate that is a function of penetration rate and utilization factor. While there are various existing models that can reasonably predict the penetration rate, only few models have the capability to estimate the utilization, and the accuracy of models predicting the utilization is highly dependent on the incorporation of complexities involved in different tunneling activities. The geology-related delays include those incurred for ground stabilization, including installation of rock bolt, wiremesh, strap, or channel, placing of ribs and lagging, gripping process, control of water inflow, cutter change and inspection, probe drilling, scaling, muck removal, and foam or grout injection for ground stabilization. This study aims at determining the most critical ground support activities affecting the TBM performance using discrete event simulation. For this purpose, six projects that utilized open TBMs were analyzed. Comparing the individual ground support measure installations, steel ribs showed the maximum downtime of 7% compared to water inflow at 4.8% and cutter change at 2%. The results show that geology-related delays indeed contribute significantly to the variations in utilization factor.

Tunnel lining stiffness, grout strength and shield-driven speed are important parameters that influence ground surface settlement during tunnel excavation. Optimising these parameters would allow effective control of ground settlement during tunnel construction, specifically the maximum settlement. This paper investigated the influence of tunnel lining stiffness, grout strength and shield-driven speed on ground settlement in heterogeneous soil. Consequently, a 3D nonlinear finite element model was developed using Abaqus which accurately predicted the ground settlement during the construction of the Nanjing WeiSanLu tunnel. Furthermore, the influence of the shield-driven speed, modulus of elasticity of grout and tunnel lining stiffness on ground surface settlement was studied. Statistical analysis was performed to investigate the level of impact of each influencing factor and their two-way interaction on the maximum ground settlement. It was revealed that ground surface settlement is greatly influenced by the properties of tail voids grouting and stiffness of tunnel lining. The result also indicated that the relationship between the prediction factor and the maximum settlement on the ground differs according to the level of the studied factors.

Tunneling in karstic geology confronts numerous challenges due to unpredictable occurrence of voids. The current approach of karstic void risk assessment is qualitative or semi-quantitative and lacks consideration of the spatial variability and distribution of voids. This often influences the pricing strategies, and design and construction activities on tunnel projects. This paper presents a geostatistical modeling-based methodology to develop a quantitative assessment of karstic void risk for a tunnel project in a karstic geological setting. The methodology is applied on an actual mixed-ground tunnel project situated in a karstic geological environment in Malaysia. The geology at the tunnel project site consists of sedimentary rock formations with limestone as the predominant rock type overlain by weak sedimentary residual soils. Pluri-Gaussian simulation (PGS) technique, a stochastic geostatistical-modeling algorithm, is applied to characterize the spatial distribution of voids in 3D along tunnel alignment. Simulations from PGS take into consideration the anisotropic distribution of voids on the tunnel project site. PGS utilizes void data from borehole investigations to model different void sizes (Vs) as categorical variables. The variability in multiple realizations from PGS technique is used to quantify the uncertainty in occurrence probabilities, number, and frequency of karstic voids. The proposed methodology demonstrates the ability to develop probabilistic estimates of occurrence frequency of different void sizes. Probabilistic assessments indicating 95% confidence interval (CI) on number of voids and respective occurrence probabilities are presented. The probabilistic assessment results are applied to estimate the grout quantity required for void treatment, while considering uncertainty in void occurrence. A minimum, mean, and maximum cumulative grout volume of about 2000 m3, 4000 m3, and 8000 m3 (for 95% CI), respectively, is estimated along the alignment.

This paper describes an approach for predicting the diameter of a jet-grout column using the support vector regression (SVR) technique, which is regarded as a novel learning machine based upon recent advances in statistical theory, in which the combined effects of the construction (construction methods and jetting parameters) and soil properties (soil type and shearing resistance) are considered. Four different kernel functions, namely, a linear kernel function, polynomial kernel function, radial basis kernel function, and sigmoid kernel function, are integrated into the SVR technique. A large amount of field measured data on the diameter of jet-grout column are retrieved from the published literature for training and testing purposes. The results indicate that the SVR technique with a radial basis kernel function provides predictions closest to the measured results, whereas the prepared design charts enable the ability to significantly widen the application of the proposed approach to the areas of ground improvement and environmental protection. Natural Science Basic Research Plan in Shaanxi Province of China [2019JQ-114]; National Nature Science Foundation of China (NSFC)National Natural Science Foundation of China (NSFC) [41702287, 41807245]; Fundamental Research Funds for the Central UniversitiesFundamental Research Funds for the Central Universities [300102218517] Published version The research described in this study would not have been possible without financial supports from The Project Supported by Natural Science Basic Research Plan in Shaanxi Province of China (Grant no. 2019JQ-114), the National Nature Science Foundation of China (NSFC) (Grant nos. 41702287 and 41807245) and the Fundamental Research Funds for the Central Universities (Grant no. 300102218517). These financial supports are gratefully acknowledged.

The welded steel tube and high-strength cementitious grout jacketing is a hybrid strengthening method for deficient reinforced concrete (RC) column without enlarging its entire cross-sectional area. This paper presents an experimental study on the performance of the welded steel tube and cementitious grout jacketing retrofitted RC (STGRRC) stub column under axial compression to figure out its strengthening effect. A total of eight STGRRC stub columns and one high-strength cementitious grout jacketing strengthened RC stub column are designed and analysed to investigate the effects of various parameters including the aspect ratio, the concrete cross-sectional area ratio (Ac/A) and the concrete strength. To better acknowledge the strengthening feature of the type of composite column, detailed discussions on the crucial indexes in terms of the confinement effect, the strength enhancement and the damage failure analysis are presented. The result reveals that the strength, stiffness and ductility of the original RC column could be highly improved by using this strengthening method. The axial compressive resistance of STGRRC stub column decreases with the increasing of aspect ratio and concrete cross-sectional area ratio. The ductility index value reduces with varying the aspect ratio and concrete strength in ascending order as well as the decreasing of concrete cross-sectional area ratio. To provide a basis for the future design and application, a simplified analysis method is proposed to predict the axial compressive resistance of the STGRRC stub column based on the limit equilibrium theory and verified well with experimental results.

Cement-based grouts are widely used thanks to its outstanding features such as high workability, non-separation, non-bleeding, easy to fulfill small gaps with complex shapes. This paper descrcibes the first phase of a series of laboratory experiments that examined the ability of production of self - levelling mortar at the University of Transport and Communications. The Portland cement-based grout incorporated superplasticizer, fly ash, fine aggregate, water along with expansion agent to match as closed as possible the given high strength non-shrink grout. The experimental study focused on the performance of non-shrink grouts regarding the flowability, expansion and bleeding, strengths and drying shrinkage of the test grout mixtures. The high range water reducer (HRWR) at dosage of 1% by weight of cement was used as a flowability modifying chemical admixture to prevent water segregation and leads to an increase in compressive strength. The parameter tests consist of water-cement ratios, and fixed dosages of superplasticizer and expansive agent. To examine the flowability of grout mortars, the flow cone test was applied. The flow cone test result indicated that there were three proportional of grouts that can meet the requirement of fluidity. The compressive strength of specimens was tested according to ASTM C349-14. It was concluded that the compositions of grouts at a water-cement ratio of from 0.29 to 0.33 have compressive strengths greater than 60 MPa. The tested specimens using the expansive agent with the dosage recommended by the manufacturer meet the non-shrinkage requirement of a grout. The experimental results have demonstrated the ability of production of high strength non-shrink grouts.

This paper analyzed the ultimate grout-to-soil bond strength based on a database of 40 full-scale static load tests conducted on micropiles in glacial deposits in the province of Ontario, Canada. The Decourt extrapolation method was used to extrapolate the field load–settlement curves to identify the ultimate limit state. The elastic length method was modified by considering the shear stress influence to more accurately predict the failure loads of micropiles. A set of the ultimate bond strengths were correlated with the field standard penetration test blow count for different types of micropiles in different soil conditions. The results were compared with existing design values recommended by the Federal Highway Administration manual. The findings will help to improve the design of micropiles in similar soil conditions and the development of a reliability-based design method for soil-bonded micropiles.

Pullout tests for the deformed steel bars in early-aged cementitious grout by considering the variables of testing ages, cover thicknesses, and diameters of steel bar were conducted, and the local bond stress–slip relationship at different positions of the anchorage length of steel bar was studied. Results indicated that, with the increase of testing age, the load-slip curves exhibited a higher ultimate load and had steeper ascending and descending branches; however, the slippage at the ultimate load exhibited a decreasing trend. Moreover, with the increase of cover thickness and diameter of steel bar, the ultimate load of pullout specimens increased obviously, while the corresponding slips generally had no obvious correlations. According to an analysis of the measured rebar strain, the distributions of the steel stress and bond stress as well as the relative slip along the embedded length were obtained under different external loads. Steel stress transfer and bond stress distribution parameters were introduced to characterize the nonuniformity of the distributions of the steel stress and bond stress along the steel bar, and the effects of the testing age, cover thickness, and diameter of steel bar on these two parameters were analyzed. Results showed that the both of these two parameters increased with the increasing tensile load, testing age, and cover thickness and with the decreasing diameter of steel bar. Thereafter, the local bond stress-slip relationships along the anchorage length and position functions reflecting the variations of these relationships were proposed.

Pressure grouting method can significantly enhance the strength of soil, and is widely used in foundation reinforcement. There already have some theoretical studies on pressure grouting, but the actual diffusion process of grouting can not be reflected exactly. Firstly, this paper conducts a field permeation grouting test on undisturbed loess of late pleistocene of quaternary, and acquires the pressure effected relationships of quantity vs. time. The test reveals that the grout quantity approximately increases linearly with the pressure until a certain grouting time point. The time point increases with grouting pressure and we try to define the pressure effected time point as the effective grouting time. After the effective grouting time, the grouting quantity remains constant due to the approaching of max migration radius and the stopping of grout migration. And then, considering the piston-like displacement effect of grout on porous mediums due to pressure, this study introduced the effective grouting time into the theoretical derivation process based on porous mediums’ fluid percolation pore pressure equation and Darcy’s law. The author combined the initial conditions and boundary conditions of pore pressure with the continuity conditions of permeation velocity, and performed the Boltzmann’s transformation and reduced-order processing to derive the equation for the migration velocity of the grout front and the migration radius of grout. Finally, by substituting the effective grouting time and the effective grouting quantity into the equation, we could obtain the grouting reinforcement radius. The equation can accurately predict the actual grouting reinforcement radius, and the applicability of the equation is verified by verification test.

In connection with the use of the SPZO-M modernized system for prestressing the NPP containment, it became necessary to determine the effect of loads inside the containment wall on the stress-strain state of the containment. Because of the particularities of the technology used to install the reinforcing elements, where the ducts are filled with grout under pressure up to 1 MPa, there is a possibility of cracking at the construction stage of the structure. Calculations established that on simultaneous injection of the middle and outer or inner channels the maximum principal stresses in the thinnest zones between the crossing channels reach the tensile strength of concrete 2 MPa. For this reason, it is recommended that simultaneous injection of these channels should be excluded. On prestressing and long-term operation, tensile stresses act in the radial reinforcement that can cause cracks to appear in the containment wall. On using the SPZO-M system, the radial stresses in the rod reinforcement increased by 19.4% compared to SPN-1000. Measures are proposed to limit cracking in the containment body.

Various types of additives have been diachronically used in historic mortars, whereas their use in lime-based grouts, used for the restoration of historic structures, is rather limited. In this study, an effort was made to investigate the performance of glass additives in grouts, consisting of lime and natural pozzolan. The additives concerned glass fibers (3 and 6 mm in length), glass beads and bubbles, added in a proportion 0.3–3% w/w of binders. Five grout compositions were manufactured and their properties at fresh and hardened states were tested. From the evaluation of the results, it was asserted that glass additives influenced the grouts’ performance in a favorable way. Their fresh state and physical properties were maintained or slightly improved, while there was a significant enhancement of the long-term mechanical characteristics of the mixes. Additionally, the adhesion capability of grouts was notably increased, which is a crucial aspect indicating their efficacy.

Grout curtains are often used to manage lateral water inflow. However, grout curtains constructed in extremely fractured rocks are not very effective, which poses a challenge for mine drainage and mining operations. So, it is crucial to consider the curtain’s effectiveness when evaluating water inflow. Large-scale pumping tests and groundwater numerical simulation were used in this study to evaluate the water inflow at an iron mine surrounded by an imperfect grout curtain. The effectiveness of the curtain was determined by comparing the hydraulic differences on both sides of the curtain and flow fields at pre- and post-grouting stages and three preferential seepage paths were identified. Given the mine’s complex boundary conditions, the telescopic mesh refinement modeling method was used; regional and local models were established using FEFLOW. The predicted inflow due to the gap in the curtain was 13,880 m3/day, accounting for 37.1% of the total 37,340 m3/day of water that still flowed into the mine. Two countermeasures, surface curtain remediation and underground grouting, were used to decrease water inflow and restore mine productivity.

This paper aims to present a solubility model of physical blowing agent (PBA) for a kind of commonly used self-expanding polymer on engineering. The self-expanding polymer contains Component A (isocyanate) and Component B (polyhydric alcohol, PBA, water, and catalyst). Component B grout of the polymer, which contains PBA, was heated to measure its temperature and volume variations. Based on the principle of mass conservation and Clapeyron equation, the solubility curve of PBA with respect to temperature was calculated. The solubility curve was then applied to simulate the foaming process. A two-component polymer grout foaming experiment was then carried out to verify the applicability of the measured solubility curve. The simulated changes of temperature and density with respect to time of polymer grout were analyzed and compared with experimental results. The error of both sets of curves is within 5%, which shows a good agreement among them and proves the feasibility of the solubility model. This study provides a relatively complete test and verification process for the solubility model of PBA, which lays a theoretical foundation for both the polymer grouting diffusion mechanism and engineering application.

Soil rock mixture (SRM) is a common geo-material, which usually needs to be treated by grouting reinforcement. The grouting effect is tied to the grouting method, grout property, and geological condition, which are difficult to be quantitatively analyzed. The main obstacle in developing a rigorous theory for evaluating the grouting effect is the heterogeneity of SRM. This paper aims at developing a preliminary theoretical model and an empirical formula for predicting the overall strength of grouted SRM based on the actual morphological structure of grout-rock skeleton and its heterogeneity. A discrete element model was established for analysis of grout vein structures and validation of the theoretical approach. Two morphological parameters called “grout vein uniformity” and “block-skeleton conversion ratio” were proposed to quantify the influence of spatial distribution of grout vein and rock blocks in grouted SRM. Finally, an empirical formula was established for estimating the uniaxial compressive strength of grouted SRM, with a complete description of rock conversion ratio as a function of grout proportion and rock proportion. The ability of the approach to capture the influence of the grouting effect was verified by comparing the predicted values with the numerical values and the laboratory test results of this study. The improvement of the mechanical property of the stratum can be quickly assessed according to the obtained correlations as a general rule. Specifically, the normalized UCS increases in a linear fashion over grout proportion at a rock-soil ratio between 0.6 and 0.8. However, the theoretical model may overestimate the strength when the rock-soil ratio is higher than 0.9. It is open to improvement by further studies for the systemization of a more rigorous and robust approach in estimating and accommodating the uncertainties when applied in grouting operation guidance in the real world.

Formulating solution to obtain the required engineering properties by means of stabilizing the soil for placing infrastructural unit without undergoing large settlement, grouting is widely used restoration method for improving the relative density of the soil strata. This paper has analyzed two case scenarios about soil stabilization to accommodate reinforced cement concrete (RCC) structure to facilitate production units. Considering the soil characteristics and to avoid further collapse of the nearby establishment, injecting lime–cement composition to strengthen the loosen earth bearing capacity at certain depth has been followed. Accordingly, researchers have shown to mend on the discrepancy happened in both cases regarding strengthening of disturbed soil strata up to 2 to 2.5 times with respect to Standard Penetration Test-Number of Blows (SPT-N) values after carrying out pre- and post-dynamic cone penetration tests (DCPT) up to an average depth of 6 to 6.5 m from finished ground level (FGL), by using of grout injection procedure. Following methodology has been emanated and after conducting several trials resulted in appreciable improvement in soil consistency. Researchers believe that the study will be comparatively more suitable for improving problematic soils in South-Asian continent. In both cases, desired soil bearing capacity has been attained in most economical way and within stipulated time frame.

Grouting is one of the most commonly adopted technique for soil improvement and strengthening. Adding super plasticizers, accelerators, antifreezes, air entraining agent improves the performance of the cement grout. The performance of the grout while injecting in the sand column mainly depends on its fluidity property. Keeping it in mind about the water cement ratio, the strength of the sand column is studied in two sets of experiments one by sand column with cement grout only and another set by sand column with cement grout added with super plasticizers by varying the water cement ratios. Strength parameters like angle of internal friction and cohesion were obtained be direct shear test and unconfined compressive strength test on the specimens by varying the water content. An increase of 15.2kPa to 60.33 kPa was observed in the cohesion value for specimens with 10% water content and 13.8 kpa to 47.2kPa cohesion value observed in the specimens with 20% water content. The angle of internal friction was decreased from 360 to 160 for 10% water content whereas 300 to 100 for 20% water content. A series of experiments were conducted on the sand column grouted with cement and for different water cement ratios as 1.5, 2.0 and 2.5. Another set of experiments were repeated by adding 2%super plasticizer Sulphonated Melamine Formaldehyde (SMF). The experiment results revealed that at lower water cement ratio higher value of compressive strength was observed. It was also observed that the strength increases with curing period.

The massive mechanized and irrational coal mining has generated many goafs (i.e., mined-out areas) in China. To manage these goafs effectively, grouting technique has been commonly used to fill the fractures in the overburden strata. However, little is known about the development and distribution of fractures in the overburden strata above the goaf. The lab-scale simulation of fracture development, as well as the grouting process, can provide valuable information for managing a real goaf by the grouting technique. Based on the mechanical properties of rocks and soils in the goaf of Kangjiagou coal mine in Shanxi Province, an experimental system was designed to simulate the development of fractures in the overburden strata above the goaf and study the diffusion behaviors of the grout slurry under different conditions (such as grout volume, grouting pressure, porosity, and water-solid ratio). The physical model test showed that more fractures were found in the fractured and caved zones, with fracture porosity ranging from 15.05 to 40.79%. The grouting experiment showed that, when the water-solid ratio was smaller than 1.15 and the grouting pressure was lower than 0.3 MPa, the changes in diffusion radius were stable during the grouting process. To maintain the stable changes in diffusion radius and reach a high filling ratio, the grouting pressure should be controlled in the range of 0.2–0.4 MPa at the porosity of 24.8% and 0.5 MPa at the porosity of 35.1%. The findings derived from this study are widely applicable under real engineering contexts.

A pour-back is a critical component of a post-tensioned concrete system, affecting its durability by protecting anchorages and vents from corrosion. However, the material interface between the grout pour-back and the concrete member may serve as an accelerated pathway for chloride ion intrusion and may lead to premature corrosion of post-tensioning components. This study evaluates the vulnerability of concrete–grout interfaces through two experimental protocols: a novel electrical migration test and the standard electrical resistivity test. The results are used to predict the service life of pour-back systems using a concrete life-cycle assessment model. This research serves as a first step toward defining the chloride permeability of concrete–grout interfaces.

Cement grouted bituminous mix (CGBM) is a composite mixture where cementitious grout slurry is penetrated within the air voids of an Open-graded bituminous mix (OGBM). The CGBM surface has both flexible and rigid pavement merits and is considered a semi-flexible pavement type. Further, the choice of cold mix layer of CGBM also minimises the challenges associated with conventional hot mix types. In the present study, cementitious grout slurry is prepared using cement, fly ash, silica fume, and polycarboxylic ether-based superplasticiser to make the CGBM samples. To study the effect of grouting, the prepared CGBM samples were tested in the laboratory at 1, 3, 7 and 28 days after the curing period. Compressive strength, Marshall stability, indirect tensile strength, and resistance against the CGBM mix's moisture damage, improve with the increase in the curing period. CGBM mixes are less temperature susceptible and exhibit better resistance against moisture damage and abrasion loss. A trial section is constructed as per the design developed in the laboratory. The paved CGBM surface's field performance reveals that grout material is significantly improving the CGBM mix's behaviour. The evaluation of CGBM is considerably beyond the defined criterion in the Indian standards code, i.e. MoRTH (Ministry of Road Transport and Highways) fifth revision. Results and analysis presented in this manuscript may help the engineers to analyse the CGBM layer further.

The viscosity evolution for different temperatures was studied experimentally. A time-varying viscosity model was derived and the influence of the initial temperature on gel time was analyzed. The experimental results show that the viscosity of polymer grout increases exponentially with time. It can be divided into two phases. Before gelation, the viscosity variable quantity is very small. At the gel point, there is a sudden increase in viscosity. The initial viscosity and gel time decrease with the increasing initial temperature within a certain range, The study contributes to deepening understanding of the rheological properties of polymer grout, which can provide some references for polymer grouting construction.

The use of prefabricated bridge columns in seismic regions is challenging since performance data on precast column connections is limited. A handful accelerated bridge construction (ABC) details to connect precast columns to adjoining members have been experimentally investigated, and some were found viable for seismic applications and field deployment. A connection consisting of ducts filled with conventional grout is the focus of the present study. In this connection type, precast column longitudinal bars are protruded out of the column and are inserted into grout-filled ducts matching the number and configuration of the column bars. A state-of-the-art review of the grouted duct connection studies and bridge component tests utilizing this connection type is presented. A preliminary design equation for duct connection filled with conventional grout is proposed based on the data collected from the literature. Subsequently, the validity of this equation is evaluated through pullout testing of 12 full-scale grouted-duct specimens. Finally, a refined design equation is proposed based on all available test data, and construction guidelines are developed to facilitate the use of grouted duct ABC column connections in high seismic regions. These design and construction guidelines were proposed to the American Association of State Highway and Transportation Officials (AASHTO) for possible adoption as national specifications.