Properties Of Grouts Research Articles

Elastic properties of two-component grouts at short curing times: The role of bentonite

Two-component grout is nowadays the material most used for the backfilling phase in tunnelling with a shield machine. The operative simplicity of the technology and the fast hardening reaction between the two components are the main reasons that have contributed to the intensive spread of the use of this backfilling technique all around the world. Although bentonite is one of the basic ingredients for the grout production, its effect on the elastic properties of the grout has not been completely investigated so far. In this work, six different two-component grouts and their elastic properties have been studied by means of geophysical measurements. The six grouts were characterised by the same mix design and five different bentonites, while one grout had no bentonite. The variation of the dynamic parameters over time was analysed at short curing times (up to 24 h). In detail, the shear wave velocity, the dynamic moduli and Poisson’s ratio were determined by means of the ultrasonic pulse velocity technique. The results show that the grouts with the bentonites have higher dynamic moduli than the grout without the bentonite. Moreover, a final analysis of the experimental data provided an analytical relationship to calculate the shear-wave velocity for each of the six grouts at any curing times.

Experimental and numerical study on the mechanical properties of compressively precracked sandstone repaired by grouting

• A set of laboratory grouting devices was developed to grout the precracked rock specimen. • The strength of grouted rock is observed to be determined by the interface between rock and cement. • A numerical simulation method of grouting was developed based on the Fish language of PFC 2D . Grouting is a common reinforcement method that is widely used in various geotechnical engineering applications. Studying the mechanical properties of grouted rock masses under different stress conditions is of great significance to geotechnical engineering, so a set of laboratory grouting devices was developed for this study. The mechanical properties of compressively precracked sandstone before and after grouting were studied by triaxial compression tests with different confining pressures, and the crack and cementation morphologies of precracked specimens were revealed by X-ray CT (Computed Tomography) scanning. According to the findings of the study, grouting significantly improves the integrity and mechanical properties of cracked specimens. The grouted specimens exhibit higher strengths and Mohr–Coulomb parameters ( c and φ), and these increments vary with confining pressures. The strength of grouted specimens depends mainly on the micromechanical properties of the contact surface between sandstone and cement grout. Affected by the mechanical properties of cement grout, the elastic modulus of the grouted specimens is lower than that of uncracked sandstone, and the deformation of the grouted specimen also exhibits an obvious ideal plasticity state under triaxial stress conditions. Thus, the grouted sandstone does not break suddenly. In addition, a numerical method of grouting was also developed in the PFC 2D program to investigate the micro mechanisms of fracturing and grouting sandstone. The numerical simulations represent the strength and progressive failure process of both intact and grouted specimens very well and reveal the micromechanical behaviors of the grouted rock mass.

Experimental study of the mechanical properties of two-component backfilling grout

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.

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.

Influence of mechanochemical activation on the rheological, fresh and mechanical properties of one-part geopolymer grout

One-part geopolymer (OPG) grout offers advantages over two-part geopolymer grout in the handling and storage of feedstocks, mainly because of the large quantities of caustic solutions that must be handled for producing two-part geopolymer. However, OPG often suffers from a low degree of reaction, a high number of crystalline by-products and, as a result, low strength. Here, one-part geopolymer was assisted by mechanochemical activation (MC-OPG) to produce grout. The precursor materials (slag and fly ash) and sodium silicate were mechanochemically activated utilising co-grinding to produce a geopolymeric precursor, after which water is the only additive required to initiate the geopolymerisation reaction. The effects of slag/fly ash ratios on grout mixtures were also investigated. A series of tests was examined, including rheological characteristics, setting time, bleeding, unconfined compressive strength (UCS), ultrasonic pulse velocity, scanning electron microscopy and X-ray diffraction. The results showed that the mechanochemical activation technique increased the rheological characteristics and reduced the fresh properties (setting time and bleeding) of geopolymer grout compared to the one-part geopolymer. Considering mechanical properties, the UCS of MC-OPG grout was higher (41–73%) than that of OPG grout. Furthermore, slag content significantly affected the rheological, fresh and mechanical properties of all the geopolymer grouts regardless of the activation method.

Theoretical and experimental study on the rheological properties of WIS grout and the dispersion and sealing mechanism

Recently a new grout material called water inflow sealing (WIS) was invented for sealing water inflow in tunneling and underground constructions. In this study, a special experimental method called intubated counter grouting (ICG) was proposed to investigate the influence of water dispersion on the rheological properties of the grout during the grouting process, and to testify the sealing performance of the grout, such as instant gelling ability (IGA) and anti-dispersion ability (ADA). In the experiment, dispersion was restricted in the downstream of the channel with a high turbulence intensity. The influences of ADA and IGA were therefore decoupled and evaluated separately. Experimental results revealed two distinctive sealing mechanisms of WIS. For a low initial velocity of water, WIS turned the shear flow of water into an overall movement of a plug by absorbing water into the particles. For a high initial velocity and the situation that the particles reached the outlet before sufficiently expanding, WIS modified the rheology of the water in the channel and reduced its velocity till the static state. The distinctive feature of WIS brings a reformation on the sealing mechanism and provides an effective way to control water inflow with high pressure and velocity.

An Experimental Investigation of the Effects of Fly Ash and Nano Titanium Dioxide (n-TiO2) Usage as Viscosity Modifying Agents(VMAs) in Cement-Based Grouts on Rheological Parameters.

The effects of n-TiO2 additions at different amounts by mass (0.0%, 0.3%, 0.6%, 0.9%, 1.2% and 1.5%) on rheological properties (plastic viscosity and yield stress) of cement-based grouts incorporated with fly ash as mineral additive at different constitutes (0%-for control purpose, 5%, 10%, 15%, 20%, 25% and 30%) were investigated by analysis of experiments in this study. To prepare all samples, w/b ratio was defined as 1.0. To prevent sedimentation of TiO2 nanoparticles in free water and to supply uniform distribution of TiO2 nanoparticles in water with help of removing of these nanoparticles from each other, Ultrasonication method was applied by using a Horn type Ultrasonic Homogenizer in this experimental study. All experimental viscosity values of the cement-based grout samples were also obtained by using Coaxial Rotating Cylinder Rheometer test machine. Modified Bingham analytical model was used to investigate on this study for reference grout samples because of it shows dilatant (shear-thickening) flow behavior. Test results show that plastic viscosity values of the grout samples obtained by addition of FA remarkably decrease with rising amount of n-TiO2. Yield stress of fresh grout mixtures increases with respect to increase amount of FA content in all grout mixtures with different proportions of n-TiO2. the usage of FA as a mineral additive in cement-based grouts has improved the yield stress value of the samples. Since n-TiO2 has such a low specific surface area, the water requirement of the grout matrix tends to increase. Therefore, this situation causes increasing of cohesion. The developed ANNs model has been able to predict the plastic viscosity and yield stress of cement-based grouts containing TiO2 nanoparticle doped fly ash with very low error rates and high accuracy

Rheological and viscoelastic characterizations of fly ash/slag/silica fume-based geopolymer

A greener, cleaner cement called geopolymer has recently been developed instead of Portland cement as a grouting material, with improved grout properties and reduced carbon dioxide emissions. Nevertheless, the investigation of geopolymer's rheological and viscoelastic characteristics is still inadequate for grouting materials. Therefore, in this paper, the rheological and viscoelastic properties of geopolymer grouting material (GGM) with different content of fly ash (FA), slag (SL), and silica fume (SF) are studied. It is concluded that for the shear stress with a fixed shear rate (100 s−1), using 20 %–30% SL to replace FA significantly partially increases the shear stress of FA-based GGM. Further use of 20 %–30% SF to partially replace SL reduces the shear stress of FA/SL-based GGM. The yield stress and plastic viscosity of GGM present similar trends with the shear stress. In contrast, the slump spread shows a change rule contrary to the above parameters. The static rheological behavior of all GGMs fits a Bingham model regardless of the time and mixture. An approximate linear decline of storage modulus (G′) was detected in the frequency sweep test, indicating the pseudoplastic dynamic rheological behavior of GGMs under the oscillatory shearing. The yield stresses of GGM with FA, SL, and SF are decreased over time under shearing load. These results signify that GGM with FA, SL, and SF can quickly recover good workability after retempering. SL and SF increase the G′ of GGM due to higher chemical adhesion and specific surface area, respectively, as evident from the amplitude sweep test. Using 20 %–30% SF to replace SL partially rose the peak G′ significantly and lowered the decline slopes of the G′ curve in the frequency sweep test. The fluctuation of G′ cure is also remitted considerably by the inclusion of SF. Calorimetric and Fourier Transform Infrared Spectroscopy (FTIR) tests revealed the quick generation of C-(A)-S-H, leading to the poor flowability of GGM with FA and SL. The rapid dissolution of SF increases the modulus of the activator and reduces the basicity of the activator, leading to the results of using SF to improve the flowability of GGM with FA and SL. The study indicates that geopolymer is suitable for using grouting material instead of Portland cement paste. Different combinations of FA, SL, and SF can be used to modify the flowability of GGM.

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.

RESEARCH ON MECHANICAL PROPERTIES AND GROUTABILITIES OF GROUTED MORTISE-TENON JOINTS FOR PREFABRICATED STRUCTURES

Introduction: The paper addresses grouted tenon-and-groove joints in the prefabricated structure of Changchun subway station. For the first time, grouting of prefabricated structure joints with organic epoxy grouting material is analyzed. Purpose of the study: We aimed to make sure that an organic epoxy grouting material can be injected into the joints uniformly and in full and conducted its experimental study. To establish the applicability of the epoxy grouting material in the prefabricated structures, we studied the mechanical properties of the epoxy grout and its adhesive properties in relation to concrete. Methods: In the course of the study, we used a set of test equipment and an independently developed method. Results: High-quality grouting can be guaranteed at an injection pressure of 0.4 MPa and a temperature of 5–10°C. The relationship between the slurry flow rate and time was fit according to the experimental data at 5 and 10°C. The optimal quartz powder ratio was determined at the level of 1:0.6–1:0.8, and the optimal quartz powder particle size (D50) was determined at the level of 18–25 μm. The results of the study can provide references for similar projects in the future.

Developing Prediction Model on Workability Parameters of Ultrasonicated Nano Silica (n-SiO2) and Fly Ash Added Cement-Based Grouts by Using Artificial Neural Networks

Abstract In this experimental study, the workability and bleeding properties of cement-based grout mixes combined with fly ash (FA) and nano silica (n-SiO2) as colloidal nanopowder were investigated, and some prediction models were developed with the artificial neural network. The Marsh cone flow time, mini slump spreading diameter, and plate cohesion meter values of samples prepared in different concentrations have been measured and analyzed experimentally to investigate the workability properties. Moreover, bleeding tests were carried out on the grout mixtures prepared within the scope of this experimental study. Test results showed that the usage of FA as a mineral additive in the grout samples positively contributed to an increase on the fluidity of the grout samples as expected. Although the increase in n-SiO2 content in the grout mixes resulted in an increase in the Marsh cone flow time of the grout mixes, it resulted in a decrease in the mini slump spreading diameter of the samples. The increase in the plate cohesion values of the grout mixtures was also observed in the n-SiO2 added grout mixtures. At the same time, the bleeding values of the grout mixes with and without mineral additives of 0.9 % or more with n-SiO2 additives remained above 900 ml (below 10 % bleeding rate). The artificial neural network model can predict the workability properties of cement-based grouts containing n-SiO2 nanoparticle-doped FA with high accuracy.

Quantitative permeation grouting in sand layer with consideration of grout properties and medium characteristics

Proper implementation of grouting engineering projects in sand layers requires quantitative characterization of the influence of multiple parameters on the groutability and grouting reinforcement effect. A grout injection system was developed for a series of laboratory tests to determine the effects on groutability of particle size, relative compaction, water-cement ratio, clay content and grouting pressure. Based on the test results, a multivariate model was established to predict the potential groutability in sand layers. The uniaxial compressive strength, deformation modulus and permeability coefficient were selected as evaluation indices to investigate the grouting reinforcement effect. The significance of influencing factors was discussed with orthogonal tests. A series of single-factor evaluation formulas were obtained based on the relationships between the influencing factors and evaluation indices. Also developed are the quantitative characterization formulas for the grouting reinforcement effect in consideration of multiple factors and curing time.

Preparation of alkali-activated grouts as an innovative method for utilisation of gold ore tailings

This study reports the use of gold ore tailings (GOTs) in alkali-activated grouts. A series of tests were performed to investigate the engineering properties of the alkali-activated grout pastes with different mix proportions. The ranges of water-to-solid ratios and the mechanically ground GOTs contents were 0.6–1.5 and 0–50%, respectively. It was found that the bleed capacity, mini-slump diameter and compressive strength decreased with the increase in mechanically ground GOTs content, while the apparent viscosity and setting time were increased. To ensure sufficient flowability, reduced bleeding, a reasonable setting time, and adequate strength, the water-to-solid ratio and the mechanically ground GOTs contents were recommended as 1.0 and 30 wt.%, respectively. At the same time, the hydration properties of the alkali-activated grouts were investigated. It was found that mechanically ground GOTs exhibit pozzolanic activity and possess similar hydration properties to ground granulated blast-furnace slag (GGBFS), although its pozzolanic activity is lower than GGBFS. Mechanically activated GOTs can react with calcium hydroxide to form C–S–H gel and ettringite crystals in the presence of anhydrous gypsum. This innovative method provides reliable technical indexes and scientific basis for utilisation of GOTs.

Experimental Study on Strength Enhancement of Expansive Grout.

Adding an expansive agent to ordinary grout can cause an expansion in volume, but also reduces its strength. In order to improve the strength of expansive grout, quartz sand is used as the strength enhancement additive. In this study, the expansion behavior and mechanical properties of the expansive grout with quartz sand are explored, through expansion development monitoring, uniaxial compression strength (UCS), acoustic emission (AE), SEM and XRD test methods. The results showed that: (1) The final expansion ratio and expansion development of the samples are related to the use of an expansive agent, but not affected by quartz sand. With the increase in expansion agent content, the average expansion ratios of the samples are 0.03%, 0.16%, 0.67%, 1.06% and 1.48%; (2) The UCS of the samples decreases with the increase in expansive agent content but increases with the increase in quartz sand content. Compared with no quartz sand, and with the increase in quartz sand content, the average strength of the samples increased by 10.51%, 29.88%, and 37.92%; (3) Quartz sand does not effectively participate in the hydration reaction, but it can effectively enhance the strength of the expansive grout without affecting its volume expansion, which makes it an ideal expansive grout strength enhancement additive.

Rheological, fresh, and mechanical properties of mechanochemically activated geopolymer grout: A comparative study with conventionally activated geopolymer grout

In this research, a mechanochemically activated geopolymer (MG) grout is adopted to activate slag, fly ash, sodium hydroxide, and sodium silicate by dry grinding in a ball mill for 2 h, after which water is the only additive required to initiate the geopolymerization reaction. A conventionally activated geopolymer (CG) grout was also evaluated for comparison purposes. Twenty-four different slag and fly ash mixtures have been prepared at different slag/fly ash ratios (0S100F, 50S50F, 75S25F, and 100S0F) at three different molarities of sodium hydroxide (1.25, 2.5, and 3.75) to assess the behavior of both MG grout and CG grout. A series of tests were examined, such as rheological characteristics, setting time, bleeding, unconfined compressive strength (UCS), ultrasonic pulse velocity (UPV), and scanning electron microscopy (SEM). The experimental results showed that the mechanochemical activation technique reduced the rheological characteristics and fresh properties (setting time and bleeding) of geopolymer grout compared to the conventional activation process. Considering mechanical properties, both UCS and UPV of MG grout were higher than that of CG grout. Furthermore, slag content and sodium hydroxide concentration significantly affected the rheological, fresh, and mechanical properties of all geopolymer grouts regardless of the activation method. Both the rheological characteristics and mechanical properties were increased considerably with the increase in molar concentration and slag content. Whereas the bleeding capacity and setting time dramatically reduced with the increase of molar concentration and slag content.

Mechanical Properties of Green and Petroleum based Polyurethane as Grouting Materials

In this study, polyurethane grouting materials (PUG) were prepared using two different types of polyol which were castor-based polyol (CPUG) and petrochemical-based polyol (PPUG). Four different ratios of polyol (OH) to isocyanate (NCO) were used in this study. The effect of different compositions of Isocyanate on mechanical properties were investigated and compared. The flexural strength, and compression strength shows the increment with the increase of the NCO composition. Optimum flexural strength, flexural modulus, and compression strength obtained at composition of PPUG4 and CPUG4 with the ratio of NCO: OH, 2.6: 1. PPUG gives a higher value of mechanical strength as compared to CPUG, however, results obtained for both types of polyurethane are in the range of industrial PU grouting properties grade. The decrease in cell wall of CPUG and PPUG with the increase of NCO:OH indicating the increment in cell wall interaction resulting higher mechanical properties of PUG.

Experimental study on the working and mechanical properties of high performance cementitious structural grouts

Abstract By using the experimental study method, the working properties and mechanical properties of grouting materials were determined by changing the cement-sand ratio, water-cement ratio, and cement admixtures. The main factors affecting the properties of grouting materials and the mutual influence rules of various factors are analysed and determined, and the best value range is obtained. Finally, the compressive strength of 28-day ordinary Portland cement structure grouting is optimised to 50-80 MPa. Based on the grouting ratio of ordinary Portland cement, an experimental study on the early strength structure paste of sulphate aluminate cement was carried out. The paste with one day strength as high as 70 MPa and good compatibility was prepared, and the early strength change law of the optimum ratio was deduced.

Corrigendum to “Comprehensive Effect of the Time and Water-Cement Ratio on the Rheological Properties of Power-Law Cement Grouts”

Corrigendum to “Comprehensive Effect of the Time and Water-Cement Ratio on the Rheological Properties of Power-Law Cement Grouts”

Properties of composite cement-sodium silicate grout mixed with sulphoaluminate cement and slag powder in flowing water

The properties of grouting materials within the flowing-water environment impact greatly the long-term effect of water-plugging engineering. In order to improve the performance of traditional cement-sodium silicate grouting material, the composite cement-sodium silicate grout mixed with sulphoaluminate cement and slag powder was prepared, and the properties of the composite grout and its concretion within the still and flowing water environments are investigated experimentally. The test results indicate that the scouring effect of flowing water causes negative effects on the strength and anti-permeability of grout concretion. Oppositely, the substitution of two admixtures with proper ratios improves obviously the comprehensive performances of composite grout to resist the effect of flowing water.

The Influence of Dry Hydrated Limes on the Fresh and Hardened Properties of Architectural Injection Grout.

Dry hydrated lime is an air binder often used in architectural injection grouts. This study compared the influences of three commercially available dry hydrated limes on the injection grouts’ workability and mechanical properties. The main differences between the limes were in their chemical and mineralogical composition and Blaine specific surface area. The grouts were composed of dry hydrated lime, finely ground limestone filler, water, and super plasticiser. Subsequent results obtained revealed that the Blaine specific surface area is not directly related to the fresh grout properties. Grain size distribution and shape of lime particles and their aggregates in the water suspension are key parameters influencing the following fresh grout properties: fluidity, injectability, the mixture’s stability, and water retention capacity. However, the lime injection grouts’ mechanical strengths were higher in relation to an increase in the content of portlandite and the Blaine specific surface area of the dry hydrate.