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In mechanised tunnelling, the filling of the annular gap behind the precast concrete segments is one of the essential operations. The main goal of filling this space is to reduce surface settlements and limit movements due to tunnel excavation in the soil mass. To achieve this aim, a two-component grout is often used to fill the annular gap. Determination of the amounts of ingredients in the two-component grout should be carried out in such a way that the injection materials will be able to fulfil the required performance and technical properties. In this study, laboratory tests were carried out to investigate two-component grout properties, such as flowability, bleeding, gelling time and uniaxial compressive strength. The effect of lateral pressure on grout resistance was studied according to real excavation situations. The influences of the grout ingredients and effective parameters such as bentonite and cement contents, water–cement ratio and the dosage of accelerator (sodium silicate) and accelerator ratio were also investigated.

This paper presents the results of an experimental evaluation of masonry grout made with lime-activated slag–glass powder blend as a binder. The purpose of this study is to develop a grout mixture that is low-carbon dioxide (‘low-carbon’) and has the potential to replace the traditional grout material used in load-bearing concrete block masonry construction. Traditional grout material uses Portland cement, production of which is responsible for a large proportion of carbon dioxide emissions. Thus, elimination or even reduction in the use of Portland cement will minimise environmental impacts. Three grout mixtures incorporating different proportions of glass powder as a partial replacement of slag as an aluminosilicate precursor were investigated to determine the optimum mix proportion that yields the desired properties of the grout material used in concrete block masonry construction. The workability, compressive strength and permeability properties of the mixtures were evaluated. Results from this study show that the use of glass powder at 25% replacement of slag as a precursor in the binder system provides the best performance, and that this mixture can be successfully used as an alternative and low-carbon grout material for concrete block masonry construction.

A ‘locking-bolt’ demountable shear connector (LBDSC) is proposed to facilitate the deconstruction and reuse of steel-concrete composite structures, in line with achieving a more sustainable construction design paradigm. The LBDSC is comprised of a grout-filled steel tube and a geometrically compatible partially threaded bolt. The latter has a geometry that ‘locks’ the bolt in compatible holes predrilled on the steel flange and eliminates initial slip and construction tolerance issues. The structural behaviour of the LBDSC is evaluated through nine pushout tests using a horizontal test setup. The effects of the tube thickness, strength of concrete slab, and strength of infilled grout on the shear resistance, initial stiffness, and ductility of the LBDSC are assessed. The experimental results show that the LBDSC can achieve higher shear resistance and similar initial stiffness as compared to traditional welded studs. In addition, all tested LBDSCs exhibited slip capacities ranging from 14 to 32 mm and can be classified as ductile shear connectors according to Eurocode 4. A detailed finite element model was also created and found to be reliable to reproduce the experimental behaviour. Parametric studies were subsequently conducted using the validated model to study further parameters and generalise the experimental results. Due to the specific test setup, non-negligible uplift forces were generated in the connector and the potential implications are discussed.

Understanding the mechanism of progressive debonding of bolts is of great significance for underground safety. In this paper, both laboratory experiment and numerical simulation of the pull-out tests were performed. The experimental pull-out test specimens were prepared using cement mortar material, and a relationship between the pull-out strength of the bolt and the uniaxial compressive strength (UCS) of cement mortar material specimen was established. The locations of crack developed in the pull-out process were identified using the acoustic emission (AE) technique. The pull-out test was reproduced using 2D Particle Flow Code (PFC2D) with calibrated parameters. The experimental results show that the axial displacement of the cement mortar material at the peak load during the test was approximately 5 mm for cement-based grout of all strength. In contrast, the peak load of the bolt increased with the UCS of the confining medium. Under peak load, cracks propagated to less than one half of the anchorage length, indicating a lag between crack propagation and axial bolt load transmission. The simulation results show that the dilatation between the bolt and the rock induced cracks and extended the force field along the anchorage direction; and, it was identified as the major contributing factor for the pull-out failure of rock bolt.

Lateral restrainers are traditionally provided in reinforced masonry (RM) walls to prevent the vertical steel bars from buckling. In the current version of the Australian Masonry Standards (AS 3700–2018), the use of lateral restrainers in RM walls is relaxed, if the vertical rebars are surrounded by grout annulus of twice the diameter of the bars. However, it is challenging to maintain the verticality of the reinforcing bars in the block cores to satisfy the grout annulus requirement without lateral restrainers. To address this challenge, restrainer bar chairs can be used in the construction of RM walls which are easier to employ in comparison to lateral restrainer ties. However, the implications of adopting restrainer bar chairs as an alternative to restrainer ties in RM wall construction are not well verified. In this study, the influence of restrainer bar chairs and conventional lateral ties restraining methods on the axial compression and out-of-plane bending characteristics of RM walls have been investigated. In total, twelve RM walls of dimensions 1390 mm height × 590 mm length × 190 mm thickness were constructed and tested, of which, four walls each were tested under concentric and eccentric compression and four-point bending. The experimental results revealed that the performance of RM walls with restrainer bar chairs and conventional lateral ties were similar, in terms of the observed failure modes, strength, load–displacement characteristics obtained under both compression and out-of-plane loading conditions. Strain measurements on rebars indicated that a composite action was ensued in both restrainer configurations. The capacities of the RM walls under compression and out-of-plane bending were also verified with three different masonry standards provisions and were found adequate with reasonable safety. Overall, it can be concluded that the restrainer bar chairs can effectively be used in RM walls to enable quick and accurate vertical positioning of the rebars and ensure adequate grout annulus around them.

This paper presents the results of an experimental study on a full-scale precast concrete frame reinforced with glass fibre reinforced polymer (GFRP) bars that was tested to failure under lateral cyclic loading. Within the frame four different pocket connections are tested that will lead to accelerated construction. Traditionally, a pocket connection is comprised of a column that is extended into a recessed portion of the connecting beam and the pocket is filled with grout to create a moment-resisting connection. In order to accelerate the construction process, quicker setting epoxy resin was used in place of grout. The results show that while the epoxy resin could significantly accelerate and simplify the construction procedure due to its workability in addition to its high early strength and non-shrinkable properties, its thickness and low modulus of elasticity significantly affected the performance of the pocket joint. The test frame showed a flag-shaped hysteretic behaviour with narrow loops and small residual displacement thus illustrating desirable frame self-centring behaviour. This self-centring behaviour was due to rocking of the column in the pocket connection. The frame displaced with a large displacement ductility of approximately 7.0, however, the level of energy dissipation and damping ratio was very low when compared with conventional concrete structures. This experimental study shows that pocket connections can be used for GFRP reinforced precast concrete elements, however, they should be designed carefully to account for the lower stiffness of GFRP reinforcement. Also, to avoid premature failure and achieve a higher capacity of the pocket connections, the material used in the pocket to fill the gap between column and beam is recommended to have higher strength and elastic modulus compared to the surrounding precast concrete. Refereed/Peer-reviewed

Jet grouting is one of the most widely applied soil improvement techniques. It is suitable for most geotechnical problems, including improving bearing capacity, decreasing settlement, forming seals, and stabilizing slopes. One of the difficulties faced by designers is determining the strength and geometry of elements created using this method. Jet grouted soil-cement columns in soil are a complicated issue because they are dependent on a number of parameters such as soil type, grout and water flow rate, rotation and lifting speed of monitor, nozzle jetting force, and water to cement ratio of slurry. This paper discusses the effect of the water-cement ratio on the physical and mechanical characteristics of soilcrete. In the laboratory, sandy soil mixed with cement grout with water-cement ratio varies from (0.7:1 to 1.4:1). To evaluate the characteristics of soilcrete, 96 specimens were prepared in the laboratory and tested at different curing times. The results indicate that the Uniaxial Compressive Strength (UCS) of soilcrete decreases with increasing the (W/C) ratio of the grout, where the soilcrete strength of W/C ratio of 0.7 is higher about 237% of W/C ratio of 1.4 at 28-day; the evolution of the (UCS) is proportional to the logarithm of the curing time; the ratio between the modulus of elasticity (Etg50) to the maximum UCS varies from 113 to 175; when the water-cement ratio increases, the dry density of soilcrete decreases, as a result, the (USC) of soilcrete decreases.

The stress–strain characteristics of reinforced masonry (RM) under axial compression should be correctly understood to effectively analyse and design RM elements. However, past studies have overlooked this aspect and mainly focused on assessing the stress–strain behaviour of grouted or confined masonry. An experimental programme was executed in this research by constructing and testing RM wallettes under uniaxial compression to understand the stress–strain behaviour of RM. The effects of grout strength and lateral restrainer configurations on the compression behaviour were also studied. The experimental outcome revealed that the grout plays a major role in the axial capacity of the RM, while change in the configurations of the lateral restraining reinforcement did not significantly affect the axial capacities and axial stress–strain behaviour of RM wallettes. The predictability of the axial capacity of the RM wallettes were validated through the expressions given in the three masonry design standards. It was observed that all considered standards conservatively predicted the axial capacity of the RM. Moreover, the applicability of the existing analytical models in the literature for the RM were verified against the experimental data and an improved stress–strain model is proposed in this research.

An acceptable viscosity and an easy penetrability of cement - limestone filler grout in the granular matrix of self compacting concrete are an important factors that affecting both its rheological and its hardened properties. This experimental and theoretical work consists to study the effect of limestone filler fineness on the rheological behavior of cement - limestone filler grout. In the first part, five different grouts were prepared by varying the Blaine Specific Surface (BSS) of the limestone filler, 3060, 4750, 6320, 7680 and 9440 cm2/g, respectively. A large number of properties relating to the rheology and the stability are carried out on the five grouts such as grain dispersion, density, volume concentration of solid, dynamic viscosity and Marsh funnel flow. The second part consists to develop a theoretical model to predict the different rheological properties of the grout as function of limestone filler BSS. The results show that the rheological properties of cement-limestone filler grout such as the dispersion percentage, the intergranular distance and the flow time are strongly affected by the limestone fillers fineness. In addition, the experimental and the predicted results present a good agreement.

Considering that the particular geometric shape of a quasi-rectangular shield, the grout flowing law and its motion process are more complicated than those of a conventional circular shield. To interpret the grouting mechanical behavior in the special-shape shield tail void, the filling and diffusion mechanism of synchronous grouting was analysed. The grout flowing is separated into two independent motion processes, which contains a circumferential filling and a longitudinal diffusion. The theoretical model of the grout pressure spatial distribution was derived based on the principle of fluid mechanics. Then, the pressure distributions in the two directions were obtained using a case study and compared with the field measured data to verify the validation of the model. Although the overall spatial pattern of grout pressure distribution on the tunnel profile show a change trend dominated by the self-weight effect mostly, its local fluctuation characteristics is very abnormal relative to that of a circular shield tunnel. Moreover, the important factors in the model were analysed, including the grout material parameters, the grouting construction parameters, and some geometry parameters. The results show that the pressure loss along this way is positively correlated with the grout flow velocity and is sensitive to the shear yield stress of the grout. The pressure loss along the circumferential direction is the most sensitive to the thickness of the ring cake, and the value range suitable for the model should be 0.02–0.03 m. The pressure loss along the longitudinal diffusion direction is the most sensitive to the size of the tail void. The research results can provide a theoretical basis for the control of special-shape shield construction.

Colloidal silica (CS) is a kind of nanomaterial used in soil/rock grouting techniques in different branches of civil engineering. Many studies have recently been performed to investigate the potential of CS in improving the mechanical behavior of cohesionless soils and mitigating the risk of seismic liquefaction in urbanized areas. CS grout is chemically and biologically inert and, when injected into a subsoil, it can form a silica gel and stabilize the desired soil layer, thus representing an attractive, environmentally friendly alternative to standard chemical grouting techniques. This paper firstly describes the characteristics of CS grout, the gelation process and the main features of the behavior of the pure gelled material. The grout delivery mechanisms through porous media are then explained, pointing out the crucial issues for practical application of CS grouting. All the grouting-induced effects on the soil behavior, which have been investigated by laboratory tests on small-sized soil elements, are reviewed, including the modifications to soil strength and stiffness under both static and seismic loading conditions, to soil compressibility and hydraulic conductivity. Published results from physical model tests and in situ applications are also presented. Finally, some aspects related to the mechanism of soil improvement are discussed. A critical discussion of each topic is presented, drawing particular attention to the controversial or not yet fully examined aspects to which future research on colloidal silica grouting should be directed.

Aims at improving the utilization rate of red mud and preparing a low-cost grouting material for underground engineering, the ultrafine red mud was adopted to prepare a slag-red mud based grout, and its fresh and hardened state properties were investigated comparing with the coarse red mud. The results showed that the incorporation of red mud could prolong the setting time and decrease the viscosity and thixotropy of slag-based geopolymeric grout, and ultrafine red mud has a better decrement effect. Ultrafine red mud has an enhancement effect on the slurry stability. The mechanical strength decreased with the adoption of red mud, while the ultrafine red mud has a higher mechanical strength than coarse red mud. The microstructure analysis showed that red mud plays a filling role in the geopolymerization process, and mechanical activation could increase the reactivity of red mud, furthermore, the iron component in ultrafine red mud could take part in the geopolymerization process. The results shed light on the utilization of red mud and the application of geopolymer in grouting engineering.

One solution to the high cost and scarcity of building materials is to use alternative and sustainable materials. The study presented herein developed an eco-friendly masonry grout using high volumes of palm oil clinker powder to replace cement and palm oil clinker to replace coarse aggregate. Several batches of grouts with different amounts of these materials were made to determine the technical viability of the grout. Scanning Electronic Microscope (SEM), X-Rays Diffraction (XRD), Energy Dispersive X-Ray (EDX) and Thermogravimetric Analyzer (TGA) analyses were conducted to investigate the microstructure characteristics of the grout, and water absorption, initial rate of absorption, sulphate attack and electrical resistivity tests were conducted to determine its durability. Compressive strength tests were conducted at different curing ages and the drying shrinkage of the grout was monitored for 180 days. The results indicate that the new grout is as good as a conventional grout but with added sustainable and economic benefits. The new grout can be used in masonry construction and can be used to alleviate the inadequate supply of affordable housing.

The design of grouting engineering in practice is either based on conventional soil mechanics or empirical procedures ignoring the effect of degree of saturation (water content). In this study, a series of laboratory-pressurized grouting tests were conducted on unsaturated sand to reveal the influence of soil water content on the grouting characteristics. With combination of direct shear tests at constant water content, water retention tests as well as microscopy observations, the mechanisms that controlling the strength and in turn the grouting characteristics in unsaturated sand were interpreted from the perspective of water–air interface. It was found that the non-monotonic phenomena of grouting characteristics (injectability and diffusion characteristics) with increasing water content were strongly dependent on the shear strength, which is influenced by the apparent cohesion induced by capillary mechanisms relating to the water–air interface. The threshold value of the injectability and diffusion pattern is corresponding to the boundary of the two transition zones (two different desaturation mechanisms) in the water retention curve. In the primary transition zone, the water phase is interconnected with air bulbs entrapped. With the drainage of bulk water in the large pores, the amount of water menisci increases, generating larger and larger surface tension force between particles. Therefore, less and less grout was injected as the bearing capacity and shear strength increase. However, in the second transition zone, with the drainage of menisci water, the menisci area of each pores decreases, inducing less and less surface tension force. Thus, more and more grout was injected as the bearing capacity and shear strength decrease. It is hoped that the work in this study will facilitate researching the grouting mechanisms in unsaturated soil, thus optimizing the grouting parameters in engineering practice.

The grouting is used to reinforce soft ground and to prevent the leakage of water in the soil. The objective of the study is to enhance the compressive strength of grout materials by using reinforcing fibers and to increase the strength of soil using blast furnace slag powder. For this purpose, cement was replaced with the blast furnace slag powder by 30 to 60%. Furthermore, for comparison of carbon fibers with aramid fibers, each fiber was added by 0, 0.5, and 1.0% of the weight of material. As the contents of carbon fibers and aramid fibers increased, the uniaxial compressive strength increased. This is due to the interlocking of fibers in the grout material that increased the uniaxial compressive strength. Moreover, the grout material reinforced with aramid fibers showed an increase of uniaxial compressive strength by at least 20% compared to the carbon fibers. An environmental assessment was done through a heavy metal leaching test and a pH test. The test result reveals that about 50% of chromium (VI) leaching decreased as 30% more blast furnace slag powder was used but the pH test shows about 0.5 pH increased as 30% more blast furnace slag powder was used. Further study is necessary for the pH test.

Grouted splice connector is widely employed in precast concrete structures, but its utilization is still limited by shortcomings such as high construction cost, inconvenience in assemblage, and uncompacted grout caused by its small sleeve diameter. The grouted sleeve lapping connectors proposed by the authors can not only provide reasonable force transfer and convenient construction processing but also have the characteristics of low price and easy grouting. In this paper, the seismic performance of two full-scale precast concrete columns with two types of grouted sleeve lapping connectors was investigated, where type-I connector connected two lapped rebars and type-II connector connected four lapped rebars by a steel sleeve, respectively. A cast-in-situ column was also tested as a reference. All the specimens were tested under reversed cyclic horizontal load with a constant axial force. The distribution of cracks, failure modes, loading capacities, deformation abilities, stiffness, ductility, hysteresis loops, and energy dissipation of the specimens were studied. The type-I and type-II grouted sleeve lapping connectors satisfactorily transferred the stress of rebars when the columns reached their ultimate loads, and the seismic performance of the precast concrete columns was found to be comparable to that of the cast-in-situ column. Thus, the grouted sleeve lapping connector has a potential to replace the grouted splice connector in cast-in-situ connection.

In real engineering, with the gradual deterioration of mining geological conditions, the improvement of the bearing performance of fully grouted bolts is beneficial to better control of the roadway surrounding rock. For this purpose, based on the idea of steel fiber reinforced concrete, a systematic laboratory study was conducted to investigate the effect of steel fiber grout on the bearing performance of anchored specimens. Three steel fibers with different diameters (0.5, 1.0 and 1.5 mm) were selected. Fiber specimens and fiber-free specimens were prepared and a series of pull-out tests were conducted. The experimental results show that the steel fiber grout can effectively improve the bearing performance of the anchored specimens and enhance the anti-destructive ability of the anchored specimens. The steel fibers in the grout can enhance the mechanical interlocking effect, the dilatancy effect and the friction effect of the anchoring interface, thereby improving the ability of the anchored specimen to withstand additional loads. The reinforcement effect of steel fiber on the bearing performance of the anchored specimens presents an obvious diameter dependence. With the increase of the steel fiber diameter, the bearing properties of the anchored specimens tend to increase and the cumulative AE counts, cumulative AE hits, cumulative AE energy and AE events also increase. Moreover, the steel fiber grout can more fully mobilize the bearing performance of the anchoring interface, and the number of microcracks in the fiber specimens increases during the bearing process. This research results may provide a useful reference for the support design of fully grouted bolts.

Steel tubes are widely used in strengthening reinforced concrete (RC) columns. However, in engineering construction, the effect of preload on the original RC column on the performance of strengthened RC column has not mostly considered. Therefore this paper tests five circular short columns under axial compression—three steel tube-strengthened RC columns with preload, one strengthened RC column with no preload, and one normal RC-to study compressive performance of steel tube-retrofitted circular RC short columns under various preload levels. Moreover, the verified finite element numerical model is established using ABAQUS software to stimulate the behavior of the retrofitted columns. The extended parametric studies is conducted based on the thickness of steel tube, yield strength of steel tube, and strength of grout under preload, in addition to preload level itself. A practical design method is proposed and compared with four existing design codes to predict the axial compressive ultimate strength of the retrofitted column under preload.

The present article analyses the influence of defects in the bonding zone between the reinforcement bar and the grout on the mechanical performance of the full-grouted sleeve connector. Grouted sle...

Jet grouting methods have recently become one of the soil enhancement technologies utilized to provide strength improvement and solve most problems of weak soils. In this study, a full-scale 1 m diameter and 5 m length jet grout (soilcrete) column was constructed in the field with a water-to-cement ratio of 1 and 400 bar pressure injections. A mechanical, physical, and microstructural investigation was performed on jet grout samples taken from six different depths (0.0, 0.5, 1.0, 1.5, 2.0, and 2.5 m) and at the same depth at five different locations, including the center. For normal conditions, samples were prepared for six periods to study dry and saturated conditions. The following tests are performed on each sample: compressive strength index (I-s) in all conditions, water absorption, density, porosity, and interface friction. Additionally, SEM was performed on selected samples to investigate the microstructures of jet grout columns (JGCs). The test results showed that the I-s varies with depth, and within the same depth, the variation is approximately 20%. Other properties also vary with depth and location; for example, the average percentage of water absorption and porosity are considered minimum values at the same location, which are 53 and 30%, respectively. However, the interface friction angle of organic soil-cement grout gains 48 degrees and 10 kPa cohesion. The theoretical part of this study is to predict the diameter of JGC in organic soil.

This paper presents an experimental investigation of propagation and fluid pressure of grouting in a two-dimensional fractured network replica. Two-dimensional fracture network models with a rough profile were simulated based on Barton’s standard roughness curves, and an orthogonal experiment of chemical grouting was conducted to explore the relationship between the sealing efficiency and different factors, including the joint roughness coefficient, initial water flow rate, gel time of slurry, and grout take rate. The results show that the initial water flow rate had the greatest influence on the sealing effect, followed by the joint roughness coefficient, grout take rate, and gel time of slurry. Together with the grouting quality and slurry diffusion form, the grouting sealings were divided into two types, i.e., partial plugging with edge unfilled and completely plugging with fracture fully filled. The slurry propagation sequence in the intersected fractures indicates that the slurry first diffuses downstream of the current fracture, then downstream of the cross fracture, and finally upstream of the cross fracture. The grouting pressure on the later stage of grouting was greater than that at the beginning of the grouting, resulting in a better grouting effect.

Grouting is an important and convenient technique to improve rock properties. The grouting effectiveness depends on quantities of complex influencing factors. The investigation on the effects is essential for engineering applications. This study focuses on the evaluation of shear strength with experimental and numerical approaches. Firstly, the shear test of rock sample with cement grouting was carried out. Based on the tests, the numerical modelling of grouting was conducted. The effect of normal stress, grouting thickness and strength parameters of grout on the shear strength was studied, respectively. Then, the critical condition of effective grouting was proposed. Lastly, the mechanism in the influencing factors was discussed. Results show that the strength of grouted rock could be improved by increasing the normal stress and the grout parameters and decreasing the grouting thickness. The critical condition of effective grouting involves the grouting thickness and the strength parameters of grouting material. When the condition of effective grouting is satisfied, the grouting effect would be remarkable with additional supports, such as bolts. According to the opening of the dominant structural plane, the grouting parameters should be reasonably designed to meet the critical condition. The results could provide experimental and theoretical methodologies for the grouting design.

The bond between tendons and grout is crucial to the performance of bonded post-tensioned concrete structures. To study the bond performance of grouted tendons at elevated temperatures, pull-out tests were conducted on specimens comprising either a mono- or multi-strand tendon located centrally within a grouted duct inside a concrete cylinder, at test temperatures of 20–600°C. It was found that the bond strength deteriorated with a rise in temperature and the degradation of bond strength was more severe than that of other mechanical properties. Three types of failure mode were observed: pull-out, partial splitting and through splitting. The use of a smaller duct could improve the bond strength of specimens failing in pull-out mode. The influence of the strength of the outer concrete was found to be insignificant. Based on the distinct bond behaviour of different failure modes, a bond–slip model was developed by regression of the test results.

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.

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.

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.

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.

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.

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.

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.

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.

Unreinforced masonry buildings in the historic centers of the world have often been overlooked for centuries without any protection. These buildings demonstrate low resistance under external effects, especially against earthquakes. Earthquakes cause serious damage to the buildings and even the collapse of structures as a result of seismic stimulation from the impact of pounding with structural impacts. For this reason, it is of great importance to repair and strengthen damaged masonry structures. This study investigated the testing of masonry wall specimens produced from different kinds of masonry units with various types of mortar. Then, geopolymer grouts with high mechanical properties were produced by using alkali activation and industrial products. The experimental performance of strengthened masonry wall samples was determined using the optimum geopolymer grout in vertical compression tests. The behavior, failure mode, and crack pattern of the masonry wall samples were determined under loading systems. Experimental results demonstrate that the use of additive styrene-butadiene (SB) latex geopolymer grouts on damaged walls increased the load-carrying capacity and ductility significantly compared to the corresponding values of samples before initial failure. All of the strengthened walls failed through the de-bonding failure mode, and no visible damage was observed on the samples. Consequently, geopolymer grouts displayed many advantages over conventional repair materials due to their high viscosity, compressive strength, eco-friendliness, and excellent resistance.

In the loose and fractured coal seam with particularly low uniaxial compressive strength (UCS), driving a roadway is extremely difficult as roof falling and wall spalling occur frequently. To address this issue, the jet grouting (JG) technique (high-pressure grout mixed with coal particles) was first introduced in this study to improve the self-supporting ability of coal mass. To evaluate the strength of the jet-grouted coal-grout composite (JG composite), the UCS evolution patterns were analyzed by preparing 405 specimens combining the influential variables of grout types, curing time, and coal to grout (C/G) ratio. Furthermore, the relationships between UCS and these influencing variables were modeled using ensemble learning methods i.e. gradient boosted regression tree (GBRT) and random forest (RF) with their hyperparameters tuned by the particle swarm optimization (PSO). The results showed that the chemical grout composite has higher short-term strength, while the cement grout composite can achieve more stable strength in the long term. The PSO-GBRT and PSO-RF models can both achieve high prediction accuracy. Also, the variable importance analysis demonstrated that the grout type and curing time should be considered carefully. This study provides a robust intelligent model for predicting UCS of JG composites, which boosts JG design in the field.

Quick-setting grout has time-varying characteristics, and the space porosity of the injected medium changes after being grouted. The above two points need to be considered when loose and broken coal rock masses are grouted with rapid-setting grout. In other words, the coupling effect of the slurry-coal rock mass causes the slurry to exhibit the temporal and spatial characteristics of slurry viscosity (TSCSV). Based on the Bingham fluid constitutive model, a capillary group model with a linear increase in diameter was created, and a one-dimensional penetration grout diffusion model was established considering the TSCSV. The one-dimensional visualization splitting-permeation grout diffusion simulation test system was designed to obtain the space porosity of the broken coal rock mass under different final grouting pressures to obtain the law of the changes in grouting pressure and diffusion height with time under the condition of a fixed grouting rate. Furthermore, the mechanism of splitting-permeation grouting in loose and broken coal rock masses is analysed in depth considering the TSCSV. The results showed that the space porosity of coal rock masses increases linearly. In addition, the calculated value of the slurry diffusion distance was 0.93 – 1.1 times the experimental value considering the TSCSV. The calculated value was in good agreement with the experimental value. The calculated value of the final pressure of orifice grouting was approximately 1.5 times the test value without considering the unevenness of the space porosity distribution (USPD). The grouting pressure was overestimated without considering the USPD. Therefore, the TSCSV of the quick-setting slurry should be fully considered in the grouting design.

Grouting is a common method used to fill rock joints to improve the stability and integrity of rock mass in geotechnical engineering, and the filling has been observed to have an effect on crack behavior and mechanical property. To investigate this topic, a numerical study of crack behavior and mechanical property of rock samples with two parallel open flaws or infilled flaws under uniaxial compression was conducted in this research. The smooth joint model was proved to be suitable to simulate the interface between rock material and grout material. The occurrence of shear cracks at the interface between rock material and grout material as well as the occurrence of tensile cracks in the grouting material has been successfully simulated in this research. Numerical results indicate that grouting can reduce the tensile force near the flaws, suppress the generation of tensile cracks, and improve the initiation stress of the sample. The tensile force in the specimens with infilled flaws is smaller than that with open flaws, which lead to the improvement of the peak strength of the sample. Moreover, crack development and mechanical properties of samples are affected by bridge inclination angle and flaw inclination angle.

Portland cement-based grouting compound is called GP-Grout employed to produce a sort concrete as a replacement from the weight of cement in mixes and strengthened with steel nails to enhance the mechanical properties. GP-Grout replaced cement by 25%, 50% and 75% while the steel nails as locally steel fibres were used with 0.25%, 0.5%, 1%, 2 % and 3% by volume of concrete. GP-Grout powder enhanced mechanical properties of ordinary concrete especially; the compressive strength by increasing from 34 to 70 MPa as well as other properties including tensile and flexural strength with clear improvement by adding the steel nails at a ratio of 3% by volume and the results were 5.67, 9.81 MPa respectively.

Near surface mounted (NSM) steel wire rope (SWR) provides a cost-effective retrofit solution to improve the seismic performance of clay-brick unreinforced masonry structures. Investigation of the bond strength between the SWR and the clay-brick substrate by means of pull-out tests is presented herein. Various parameters were investigated, including SWR diameter, groove dimensions, SWR bonded length, adhesive types (i.e. epoxy, cement-based grout, and lime-based grout), and compressive strength of the clay-brick masonry substrate. The NSM-SWR was adhered to assemblages of vintage solid clay-bricks and subjected to monotonic and semi-cyclic pull-out testing, with the results being presented herein. A pull-out strength prediction model is proposed based on experimental findings.

Fiber-reinforced cementitious matrix (FRCM) and steel-reinforced grout (SRG) have been increasingly applied as externally bonded reinforcement to masonry members in the last few years. Unlike fiber-reinforced polymer (FRP), FRCM and SRG have good performance when exposed to (relatively) high temperature and good compatibility with inorganic substrates, and they can be applied to wet surfaces and at (reasonably) low temperatures. Although numerous studies investigated the mechanical properties and bond performance of various FRCM and SRG, new composites have been developed recently, and their performance still needs to be assessed. In this study, the bond behavior of three FRCM composites and one SRG composite applied to a masonry substrate is investigated. Sixteen single-lap direct shear tests (four tests for each composite) are performed. The FRCM studied comprised one layer of carbon, PBO (polyparaphenylene benzobisoxazole), or alkali-resistant (AR)-glass bidirectional textile embedded within two cement-based matrices. The SRG composite comprised one layer of a unidirectional stainless-steel cord textile embedded within a lime-based matrix. The results show a peculiar bond behavior and failure mode for each composite. Based on these results, the behavior of the carbon and PBO FRCM is modeled solving the bond differential equation with a trilinear cohesive material law (CML).

Liquefaction mitigation in already existing sites has become a cause of concern for geotechnical engineers across the world. One of the possible solutions for such sites is the recently developed technique called colloidal silica grouting. The technique utilises the slow injection of colloidal silica grout at the edge of the location through injection wells and delivers it to the required location through natural groundwater flow. Later, silica particles gel and bind the soil particle together by changing the pH that, in turn, increases the strength and rigidity of loose soil. The test results obtained from the laboratory and field studies are promising and feasible to recommend colloidal silica as a potential grout material for various soil engineering applications. The present review explains the use of colloidal silica stabilisation for ground enhancement and discusses the treatment method, together with the gelation and significant factors affecting the gel formation. The current paper reviews the tests performed in colloidal silica treated soil to determine the mechanical properties, hydraulic conductivity, and evaluation of liquefaction potential. Scanning electron microscopy analysis of colloidal silica treated soil was also included to explore the microstructural bonding of soil grouted with colloidal silica. Also, the advantages and challenges of colloidal silica grouting techniques in ground improvement are included in the study. Furthermore, future research scope of colloidal silica treated soil in unexplored areas is also mentioned based on the current literature review.