Performance Of Grout Research Articles

Analysis of Surrounding Rock Control Technology and Its Application on a Dynamic Pressure Roadway in a Thick Coal Seam

The deformation control of roadways surrounded by rock in the fully mechanized amplification sections of extra-thick coal seams is problematic. To analyze the failure and failure characteristics of a support frame, as well as the deformation and failure processes of the surrounding rock, through theoretical analysis and industrial tests, the deformation and support conditions of a return airway of a fully mechanized caving face in an extra-thick coal seam in the Yangchangwan Coal Mine, in the Ningdong mining, area were examined. Combined with limit equilibrium theory and roadway section size, the width of the coal pillar of the return air roadway at the 130,205 working face was calculated to be 6 m. The layout scheme and implementation parameters of roof blasting pressure relief, coal pillar grouting modification, and bolt (cable) support were designed. Based on the analysis, a “Coal pillar optimization–roof cutting destressing–routing modification–rock bolting” system for surrounding rock control in synergy with the fully enlarged section mining roadway in the extra-thick coal seam was proposed, and the deformation of the surrounding rock was monitored, along with the stress of the support body and the grouting effect on the site. Field experiments show that after the implementation of the surrounding rock control in synergy with the roadway, the maximum subsidence of the top plate was 55 mm, the maximum bottom heave of the bottom plate was 55 mm, the maximum values of the upper and lower side drums were 30 mm and 70 mm, respectively, and the breaking rate of the bolt (cable) and the deformation of the surrounding rock of the roadway was reduced by more than 90% and 70%, respectively. The effective performance of the coal pillar grouting was observed as well. Field practice of the roadway surrounding rock control in the synergy method indicated that rock deformation was effectively controlled, and the successful application of this technology was able to provide reliable technical and theoretical support for the Ningdong mining area and mines with similar conditions.

Performance Investigation of Geopolymer Grouting Material with Varied Mix Proportions

Grouting materials require not only high ultra-early-stage strength of the stone body, but also proper working performances, such as high fluidity and fast setting time, as well as good stability. Compared with the traditional pure cement grout, geopolymer grouting material has the advantages of fast setting time, high fluidity, good slurry stability, and high early strength of the slurry stone body, which is beneficial to reuse solid waste resources and can be applied to the conditions of rapid construction or repair work to a certain extent. This paper presents an experimental investigation into the performance variation of geopolymer grouting material with varied mass fractions of raw materials, and the grouting performance of geopolymer material with optimal mix proportion is also presented. The study is implemented by employing the designed experimental schemes, focused on fluidity and setting times, as well as ultra-early-stage (4 h, 8 h, 12 h, 16 h, 20 h, and 24 h) mechanical strength. The experimental result demonstrates that both ground granulated blast-furnace slag (GGBS) content and the mass ratio of activator solution to solid have influence on the working performance of geopolymers, and both GGBS content and activator concentration have influence on the mechanical strength of geopolymers. Furthermore, the variance analysis demonstrates that the fluidity of geopolymer material is dominantly affected by the mass ratio of activator solution to solid, the setting time of geopolymer material is mainly influenced by GGBS content, and the mechanical strength of geopolymer material is mainly affected by activator concentration. Moreover, the recommended mix proportion of geopolymer grouting material is proposed in this study, in which the replacement rate of GGBS is 45%; the modulus and concentration of modified sodium silicate activator are 1.5 and 75%, respectively; and the mass ratio of activator solution to solid is 1.5. In the recommended mix proportion, the geopolymer material has excellent comprehensive performance to implement grouting operation, in which the compressive and tensile strengths of the stone body reach 12.2 MPa and 0.8 MPa in 4 h, and reach 21.2 MPa and 2.1 MPa in 24 h. The fluidity is 223 mm, the initial setting and final setting times are 50 min and 57 min, the slurry stability of geopolymer material is good without liquid precipitation, in which the setting time is far less than 2 h. This work provides the experimental foundations for investigating the performance of geopolymer grouting material, which is also expected to provide reference for the further application and promotion of geopolymer materials used for grouting operations in rapid construction or repair work.

Research on reuse of silty fine sand in backfill grouting material and optimization of backfill grouting material proportions

Silty fine sand is a common muck in shallow urban tunnels, and the reuse of on-site muck resources is an urgent need in the field of shield tunneling. A shield tunneling section of Nanjing Metro Line 7 in a silty fine sand formation was analyzed in this paper. Combined with SPSS multiple regression analysis and MATLAB multiobjective planning tools, X-ray diffraction technology and laboratory tests were used to optimize the ratio of muck grouting liquid. The feasibility of silty fine sand as a substitute sand source for backfill grouting liquid was discussed. Based on actual conditions, the influences of grout performance and grouting parameters on the diffusion of the grouting liquid in the seepage stage were studied. The effectiveness of the muck grout was verified by monitoring values such as surface settlement and segment uplift in the field test. The results showed that silty fine sand can be used as the sand source for preparing grouting liquid that meets the requirements of on-site construction through the addition of a water-reducing agent and by optimizing the ratio. The grouting liquid with the best performance has advantages in terms of 7 d and 28 d strength, bleeding rate, and cementation strength. The stability of this grouting liquid is good, and 44.6% of costs can be saved; the cost-optimized ratio grouting liquid has advantages in 7 d strength and economic benefit, and 74.6% of costs can be saved. However, the stability of this grouting liquid is poor. Under the same grouting time, the pressure generated by the muck grouting liquid and the field grouting liquid on the unit area of the segment is close.

Cementitious Grouts for Semi-Flexible Pavement Surfaces-A Review.

The hybrid type of pavement called semi-flexible or grouted macadam has gained popularity over the last few decades in various countries, as it provides significant advantages over both rigid and conventional flexible pavements. The semi-flexible pavement surface consists of an open-graded asphalt mixture with high percentage voids into which flowable cementitious slurry is allowed to penetrate due to gravitational effect. Several researchers have conducted laboratory, as well as field, experiments on evaluating the performance of semi-flexible layers using different compositions of cementitious grouts. The composition of grouts (i.e., water/cement ratio, superplasticizer, polymers, admixtures, and other supplementary materials) has a significant effect on the performance of grouts and semi-flexible mixtures. A comprehensive review of cementitious grouts and their effect on the performance of semi-flexible layers are presented and summarized in this review study. The effect of byproducts and other admixtures/additives on the mechanical properties of grouts are also discussed. Finally, recommendations on the composition of cementitious grouts have been suggested.

Application of a novel grouting material for prereinforcement of shield tunnelling adjacent to existing piles in a soft soil area

During urban subway construction, it is inevitable that shield tunnels will pass under the piles of existing structures or buildings. To minimize the adverse effects of shield tunneling on existing piles and structures, grouting is commonly used to prereinforce the surrounding soil. In this paper, a new grouting material (CSGSA) is proposed for prereinforcement of shield tunneling adjacent to existing piles. CSGSA uses bulk solid waste (i.e., slag powder and desulfurized gypsum) and cement as the main raw materials, and a self-developed activator is added as a catalyst and improves the stability and strength of the grout. The impacts of ingredients and the formulation on the performance of the CSGSA grout were investigated. The optimal formula ratios for the specific gravity of slag powder slurry, cement, gypsum and activator are 1.30 to 1.35, 50%, 25% and 1.5%, and these were determined with a battery of testing methods. The microcosmic mechanism for functioning of the optimal CSGSA was analyzed with XRD and SEM, and the results showed that both a pozzolanic effect and filling effect are observed. The applicability of the CSGSA was validated through a field engineering case involving prereinforcement of shield tunneling adjacent to existing piles in soft soil areas, and the findings indicated that the CSGSA material satisfied the project needs in a low-cost and eco-friendly manner.

Diagonal tensile strength and lap splice behavior of concrete masonry assemblies with lightweight grout

Lightweight (LW) grout is not yet permitted per the TMS 402/602–16 masonry design code as only limited testing has been done to characterize the difference in its behavior from normal weight (NW) grout. This paper presents an experimental investigation carried out as a part of a pilot project directed in comparing the performance of LW grout with NW grout by completing diagonal tensile strength tests and lap splice tests. For the diagonal tensile strength tests, three types of wall panels, each fully grouted with either expanded clay (EC) grout, expanded slate (ES) grout or NW grout, are constructed, and tested in accordance with ASTM E519. The results of the dataset are compared to the predicted diagonal tensile strength for a NW specimen using equations from TMS 402/602–16. For the lap splice test, two lap splice configurations are tested using masonry assemblies constructed with EC and ES grout. Regression analysis is used to compare this dataset to historical data of lap splice specimens with NW grout. For both the diagonal tension tests and the lap splice tests, results are compared to other NW masonry testing in the literature, if available. Additionally, parallels are drawn between the relative performance of masonry assemblies grouted with LW and NW grout and the relative performance of LW versus NW concrete specimens from the literature. The results of this study indicate that a reduction (λ) factor in the design value of diagonal tensile strength and lap splice strength for masonry assemblies with LW grout is merited, analogous to reduction factors for these properties in LW concrete.

Evaluation of Fresh Properties and Rheological Behavior of lime-based Grouts with Cappadocia Waste Earth

ABSTRACT Cappadocia Region (World Heritage Site registered by UNESCO) carries thousands of rock-cut structures, masonries and fairy chimneys, which have been used in every aspect of daily life. Damages occurred during their working life, and restoration with inappropriate materials are threatened these structures. Moreover, an enormous amount of waste material is excavated throughout the carving process, passing approximately 10 million cubic meters per annum, creating pollution in the region, and not being used efficiently. This study aims to use Cappadocia waste earth (CWE) in the grout for consolidation and strengthening rock-cut structures, masonries and fairy chimneys located in Cappadocia region. The utilization of this waste earth in the grout prevents the destruction of these valuable structures and provides a solution to a critical environmental problem. The experiments were conducted employing by 30%, 40%, and 50 wt% of Cappadocia waste earth with natural hydraulic lime in the existence of chemical admixtures. The influence of ambient temperatures (5°C, 20°C, and 40°C) and time-dependent behavior on the rheological performance of grouts were investigated. The findings revealed that dosages of Cappadocia waste earth, different environmental temperatures, and constant shearing (time-dependent) have critical roles in determining the optimum requirements for injection.

Analysis of Bonding Performance of Grouting Corrugated Pipes in Fabricated Bridge Structures

Prefabricated bridge structures are highly popularized due to their simple construction, economy, and environmental protection. Relying on the prefabricated prestressed concrete box girder bridge project of Rongwu Expressway Section 6, this research studies the structural mode of grouting bellows and the mechanical properties of joints under different design parameters. The laboratory test was carried out by adjusting the two design parameters of aperture ratio and material properties, and the test data of joint mechanical properties under the influence of different factors were analyzed with the help of grey relational theory. The result goes like this: when the size of the metal bellows is certain, the aperture ratio becomes smaller, the internal space of the specimen becomes smaller, the internal restraint is weakened, and the bonding performance of the reinforcement becomes worse. When D/d = 2.6, the performance of the specimen is better. Comparing the grouting materials with different characteristics, the performance of the metal bellows specimen increases with the enhancement of the properties of the grouting material, but as the aperture ratio becomes smaller, the influence of the grouting material on the performance of the specimen becomes weaker. The comprehensive analysis is carried out with the grey relational theory and the correlation degree of the influence of the two factors on the specimen, and the correlation degrees γ 1 = 0.66 and γ 2 = 0.67 are obtained. Both of them have a strong correlation with the performance of the specimen, and the degree of influence is roughly similar. Based on the engineering application requirements and related design requirements, the construction method of selecting 100 MPa high-strength grouting material which is higher than the general standard, 65 mm corrugated pipe, and 22 mm steel bar is finally put forward. This research relies on engineering theoretical and experimental studies, which provide important theoretical support and technical guarantee for the research on the joint structure of prefabricated structures.

Synergistic effect of surfactant and chlorine salt on dispersion of nano-SiO2 and performance of cement-based grout containing a large amount of bentonite

Nano-SiO2 (NS) is widely used to improve the performance of cement-based grouts. The workability and mechanical property of grouts are greatly affected by NS dispersion. In this paper, synergistic effect of surfactants and chloride salts on NS dispersion, as well as on performance of grouts including fluidity, mechanical and microscopic properties were systemically studied. The results showed that the synergistic effect of anionic surfactant (SDS) and chloride salt can effectively improve NS dispersion because of the massive formation of micelles that can encapsulate NS and the electrostatic repulsion between micelles. And the effect of CaCl2 was more significant than NaCl. Furthermore, fluidity of fresh slurry and mechanical property of hardened grouts were also improved by the synergistic effect. The mechanical property enhancement might be attributed to the filling effect of NS due to its improved dispersion, and to the matrix compaction associated with the formation of strätlingite and Friedel's salt.

Parametric study on seismic performance of prefabricated bridge piers connected by ultra‐high performance concrete grout

AbstractIn this study, a novel prefabricated pier connected by ultra‐high performance concrete (UHPC) connection is introduced based on an actual project, and several seismic preformance related parametric analyses were conducted based on the validated numerical models. The objective of this research is to evaluate the impact of several critical parameters on the seismic performance of the novel prefabricated piers. The validity of the numerical modeling method has been verified based on a cyclic loading test of a relevant large‐scale novel prefabricated pier. Meanwhile, several seismic design‐related parameters are selected, e.g., shear‐span ratio, mechanical properties of UHPC, embedded length of reinforcement bars, etc., to evaluate the seismic performance of UHPC grout connected prefabricated piers. In order to ensure that the novel prefabricated pier exhibits acceptable seismic performance, the shear‐span ratio of the prefabricated bridge piers should be higher than 2.5, the axial compression ratio should be lower than 0.35, the recommended minimum embedded length is 8 times bar diameter and UB or UA UHPC with strain hardening properties should be selected as grouting material. Meanwhile, the reasonable longitudinal reinforcement ratio should be carefully considered according to engineering requirements and seismic design details.

Grouting Material Development and Dynamic Grouting Test of Broken Rock Mass

To solve the problem of the unsatisfactory effect of grouting reinforcement in broken rock mass, a cement-based composite slurry was successfully prepared by using ordinary Portland cement as the main material in this study. By conducting a single factor test, orthogonal test, and organic compound modification test, the effects of different addition ratios of fly ash, clay and waterborne polyurethane, epoxy resin, and other organic materials on the grouting performance of cement slurry were analyzed. In addition, a grouting simulation test system was used to verify the reinforcement effect of the prepared composite slurry. The results indicate that the addition ratio of clay and fly ash has a strong influence on the strength and stone rate of cement slurry. The final setting time of the best mixed slurry can be shortened to 11 h, and the compressive strength after 28 days can reach 18 MPa. The composite slurry modified by organic materials has a reinforcement coefficient of up to 4.6 for crushed sandstone, which significantly improved the brittle failure phenomenon of the reinforcement stone body and, thus, has high application value.

The Contribution of Glass Microspheres and PP Fibers in the Properties of NHL Grouts

Although, over the last decades, different types of additions have been used in mortars for conservation of heritage buildings, their use in lime-based grouts for stone masonry consolidation is limited. The purpose of this study is to contribute to the increase of knowledge regarding the performance of injection grouts prepared with glass microspheres and polypropylene (PP) fibers. The effects of glass microspheres and PP fibers on the properties of natural hydraulic lime-based grouts were analysed by rheological measurements, mechanical strength tests, water absorption and drying test. The content of glass microspheres (5-20%) and PP fiber (0.1-0.5%) was added by the weight of binder and to reduce the water demand, a polycarboxylate superplasticizer was used. From the assessment of the results, it was asserted that the fresh state behaviour was slightly affected by these additions, as in general the rheological properties worsened compared to the reference grout composition. On the other hand, the PP fibers influenced the hardened grouts’ properties in a positive way, while their mechanical and physical properties were slightly improved or maintained which is a crucial feature for the success of consolidation intervention.

Performance of Silica Fume-Based Geopolymer Grouts for Heritage Masonry Consolidation

Despite the increasing number of studies on geopolymer-based materials, a lack of information still prevails concerning the use of geopolymer materials for the consolidation and conservation of the built heritage. Since the introduction of the term “geopolymer” by Davidovits, several studies have pointed out geopolymers as a potential replacement for traditional binders, mainly due to their advantages associated with mechanical properties and low carbon dioxide emissions. The geopolymers (also known as alkali-activated materials or inorganic polymers) are obtained by a chemical process through which precursors rich in silica and alumina interact with an alkaline medium to result in a material with binding properties. The aim of this study is to exploit the potential of geopolymer-based grouts in the consolidation of stone masonry buildings. Grouting or grout injection is a technique used for the consolidation of heritage masonry buildings; it consists of the introduction of a binding agent to fill the internal voids and cracks. An experimental program was carried out to improve knowledge of geopolymer grouts suitable for consolidation purposes. The experimental findings revealed that the silica-fume-based geopolymer grout has a worse performance from a rheological point of view, whereas it showed promising results in terms of mechanical strength when compared to traditional hydraulic-lime-based grout.

Using ground blast-furnace slag grouts with biopolymer additives for improving sandy soils

The mechanical performance of microfine ground-granulated blast-furnace slag grouts for improving sandy soils was evaluated using unconfined compressive strength, drained triaxial compression and Brazilian tensile strength tests of grouted sand specimens. Two activator types, namely sodium hydroxide and rapid-hardening cement (RHC), and two biopolymer additives, namely xanthan gum (XG) and diutan gum (DG), were investigated for slag-based grouts prepared at various water–binder (w/b) ratios. The bench-scale investigation examined the cured strength properties of grouted sand specimens. It was observed that the RHC activator with modest biopolymer additive and smaller w/b ratio resulted in markedly higher strength gains. In terms of activator type, compared to sodium hydroxide, the RHC resulted in significantly better performance, mobilising increased cohesion in specimens tested in drained triaxial compression. When used together with slag grouts, XG and DG mostly showed comparable strength improvements, but DG proved more effective at lower dosage in increasing tensile strength of grouted sand.

Study on shear behavior and damage constitutive model of tendon-grout interface

Ground anchors are responsible for maintaining the stability and integrity as well as controlling the deformation, displacement, and crack development in the surrounding ground. Tendon-grout (T-G) interface, which is the weak part of anchorage structures, affects the anchorage performance of the ground anchor during load-transfer processes. To investigate the shear mechanical properties of the tendon-grout interface, a series of pull-out tests were conducted on anchorage element under constant radial stiffness boundary conditions. Moreover, the equivalent calculation for the constant radial stiffness boundary condition was analyzed. The mechanical performance of cement grouts cured for different periods was investigated, including the compressive strength and shear strength. Additionally, the failure modes of tendon-grout systems and effects of different tendon quantity, spacing and offset, were assessed. The failure evolution mechanism of the interface during the pull-out process was clarified. In addition, the microscopic structural characteristics of the tendon-grout interface were investigated. Two interfacial shear stress-displacement relationships were developed based on the interface failure modes, i.e., stress attenuation type and ideal elasto-plastic type. According to the test results, the peak strength of the interface increased with the tendon spacing, while the residual strength decreased. The effect of the tendon offset on the shear stiffness and strength of the interface is significant. A damage constitutive model was proposed to model the shear behavior of the tendon-grout interface. The proposed model verified by comparing with the test results and further adopted in pull-out test simulation. The conclusions will provide a better understanding on the shear behaviors of tendon-grout interface, and facilitate the development of a general evaluation method for ground anchor systems.

Experimental Investigation on the Grouting Performance of Bentonite Composite Grouts in Inclined Fractures Under Flowing Condition

Experimental Investigation on the Grouting Performance of Bentonite Composite Grouts in Inclined Fractures Under Flowing Condition

Performance of colloidal silica grout at elevated temperatures and pressures for cement fracture sealing at depth

Hydrocarbon well decommissioning requires the long-term sealing of abandoned wells. Current plug and abandonment (P&A) operations are not always able to address all potential fluid migration pathways, resulting in the possible upwards migration of hydrocarbons from formations penetrated by the wellbore. The development of innovative materials to improve well sealing remains a major challenge. This paper presents a proof of concept for the use of colloidal silica (CS)-based grout to improve the sealing performance of P&A operations. CS is a non-toxic suspension of silica nanoparticles (<100 nm) undergoing gelation upon destabilisation. Due to its excellent penetrability and controllable gel time, CS has the potential for repairing fine-aperture cracks within the cement sheath, at the cement/casing interface, or within a cement plug, where the penetration of cementitious grouts is restricted due to their relatively large particle size. In this study, the suitability of CS grout for deployment up to 1500 m depth was successfully demonstrated. Firstly, a range of CS grout mixes were investigated to test the feasibility of grout emplacement considering a timescale of 2 h for pumping operations from the surface to depth. Secondly, to investigate the sealing performance, the CS grout was injected into fractured cement cores (0.2 and 0.5 mm fracture aperture) and exposed to pressure and temperature conditions simulating downhole scenarios up to 1500 m depth (based on gradients for North Sea, UK). Fracture permeability upon water injection was assessed pre- and post-treatment. This work found that permeability values after treatment were reduced by three orders of magnitude, thus confirming the potential of CS grout for repairing fine-aperture cracks.

Experimental Investigation on the Grouting Performance of Bentonite Composite Grouts in Inclined Fractures Under Flowing Condition

Experimental Investigation on the Grouting Performance of Bentonite Composite Grouts in Inclined Fractures Under Flowing Condition

Refined analysis on compensation grouting performance via discrete element method

Refined analysis on compensation grouting performance via discrete element method

Development of Injectable Water-Stop for Grouting in Underground Concrete Structure Joint

Abstract In the case of water leakage at the diaphragm wall concrete panel joint, secondary grouting is usually conducted from outside of the structure after construction, but the remedial treatment requires high costs and time because of the uncertainty of the leakage location. The idea of this study is to incorporate the grouting hose into the conventional water-stop installed at the construction joint, and thus, grouting can be effectively performed. A state of the practice of water-stop, inside which grouting material can be injected, was designed and manufactured. Accordingly, an injection methodology was developed. The original geometry of the commercial water-stop was not changed, and the existing center hole was selectively renovated as an injecting tube. Micro-opening on the tube surface was optimized as a slit shape for discharging grouting material. The injection system and methodology were suitably created to fit to this product. Injection performances were verified with various experiments for pure water, microcement, modified acryl, and polymer urethane. Real-scale vertical injection experiments at 15 m of height proved that the developed water-stop can be applicable for commercial grouting materials within 30 minutes. A workable threshold viscosity of grouting material would be estimated to be 200 cP. Workable injection pressures are recommended after both actual injection tests and numerical analysis; 2–5 bar for materials with low viscousness, such as microcement and modified acryl, and 5–8 bar for high-viscous materials, such as polymer urethane. An injection test at concrete joints successfully demonstrated grouting performance. Long-term waterproofing capability was proved against continuous 5–bar application, representing 50 m of water pressure for a consecutive 15 months.