Viscosity Of Grout Research Articles

Properties of cement grout doped with xanthan gum and welan gum at high hydration temperatures

The effects of xanthan gum (XG) and welan gum (WG) on the properties of cement grout at various hydration temperatures were studied. The laboratory tests including bleeding, rheology, and strength were carried out, and the microscopic analysis was carried out to reveal the mechanism. The results showed that the gums could thicken the cement grout. The apparent viscosity of cement grout containing XG increased with the rise in temperature, while the WG first increased and then decreased. XG could significantly decrease the bleeding rate, but this effect weakened in the high temperatures. WG first decreased then decreased the bleeding rate, and this variation was closely affected by the temperature. The addition of gums could decrease the strength and density of hardened grout. XG could diminish the differences between the upper and lower part of hardened grout, indicating the XG could resist the deterioration of high temperatures, while the XG enhanced the degraded effect. The addition of gums could cover the cement particles to inhibit the cement hydration but had a slight impact on the mineral phase composition. The Ettingite was not found because it decomposed in the high temperature. Meanwhile, the C-A-S-H gels were observed in the XRD patterns and SEM images, indicating that it was enhanced under high-temperature conditions.

Effect of using nano-silica on the rheological, fresh and strength characteristics of cement-based grout for grouting columns

For ground improvement via grouting, the rheological abilities of nano-silica (NS) added to Portland cement (PC) based-grouts have been investigated at a wide range of NS replacements (0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%) and water/binder (w/b) ratios (0.5, 0.75, 1, 1.25, 1.5) by conducting the rheometer tests. Using proper grouts from the rheology, then, the fresh and unconfined compressive strength (UCS) tests were performed to criticize the adequacy of NS replacements. From the rheology, the shear stress, apparent viscosity, yield stress and plastic viscosity of PC grout with NS demonstrated that using low to moderate dosages (<2.5%NS) particularly at the consistency of w/b = 1 yielded more favorable flow required high attention at high shear rates. From the fresh tests (w/b = 1), the favorite NS dosages of rheology (<2.5%NS) were also obtained from the workability of mini-slump, flow time and setting time, while the bleeding tests ensured the stability of grouts (<5%) for moderate to high NS rates. Hence, for both the rheology and fresh effects (w/b = 1), the moderate replacements (1.5%NS-2%NS) appeared better for flow issues. From the strength tests (w/b = 1, 28-day) with increasing NS, UCS of PC grout (1.26 MPa) proportionally increased up to 2%NS as an optimal dosage of peak strength (6.92 MPa), then gradually decreased to 4.82 MPa from the peak. The UCS efficiency of moderate NS rates corroborated their flow abilities. All NS dosages sufficiently provided the limit of bearing strength (>0.4 MPa) in ground enhancement. For the optimal rate (2%NS), increasing the curing times (3-day to 28-day) increased the UCS markedly as evidence of NS on the strength quality, and offered the 7-day for the early age of strength development. The failure patterns and SEM images also promoted the effects of NS. The research from the flow and strength findings not only demonstrated the promising effects of NS for grouting, but also offered some insights into designs and applications of foundation works.

Rheology of cement–sodium silicate grout containing bentonite and cellulose ether at high temperatures

Cement–sodium silicate grout (CSG) is widely used to control water inrush disasters, and its apparent viscosity considerably impacts its water-plugging effect. However, traditional grouting materials and methods are inappropriate for high-temperature environments as high temperatures can affect the grout's viscosity. To thicken grout and increase its apparent viscosity, viscosity-modifying admixtures can be used. In this work, two types of bentonite (calcium bentonite (Ca-B) and sodium bentonite (Na-B)) and hydroxyethyl methyl cellulose (HEMC) were used to modify CSG and laboratory tests were performed to evaluate the fluidity, gelation time and rheology. The results showed that both bentonites and the HEMC decreased fluidity and prolonged the gelation time. HEMC, Ca-B and Na-B decreased the fluidity by 46.8–60.4%, 12.5–31.5% and 17.7–39.1%, respectively, at different temperatures. HEMC, Ca-B and Na-B increased the gelation time by 23.8–50.1%, 23.3–71.4% and 20%–57.1%, respectively. Bentonite can partially resist high temperatures and improve the apparent viscosity of grout owing to its water-absorption capacity. Conversely, HEMC has a negative effect on apparent viscosity, which is attributed to the formation of a complex microstructure resulting from intermolecular cross-linking between the cement particles and HEMC, preventing the connection of sodium silicate.

Effects of a polycarboxylate superplasticizer and temperature on the rheological properties of grout blended with seawater

A series of subsea tunnel projects with unprecedented scale is under vigorous construction. In the construction sector, grouting has been widely adopted as the primary method for disaster control, and superplasticizers are the additives commonly used in grouting engineering. However, during grouting, seawater intrusion and ambient temperature change lead to significant changes in the rheological properties of grouting materials and failure of the grouting scheme. Therefore, it is critical to study the rheological properties of seawater-mixed grout slurry containing a polycarboxylate superplasticizer (PCS) at different temperatures. In this study, the mechanism of a PCS and its effects on the rheological properties of biomass-activated grouts (BAGs) blended with seawater were revealed for the first time. Further, the rheological characteristics and constitutive equations of seawater-mixed grout slurry at 0–30 °C were determined. Results indicated that the PCS significantly reduced the shear stress and viscosity of seawater-mixed grout. The fluidity of grout slurry with 0.8 % PCS increased by 30.8 %. The power law model was applied to describe the rheological characteristics of seawater-mixed slurry with varying PCS contents. With increasing temperature, the rheological index increased, whereas the viscosity, shear stress, and consistency coefficient decreased. The constitutive equation of seawater-mixed BAGs containing 0.8 % PCS at different temperatures was also established for the first time. The findings of this study can provide a basis for grouting diffusion theory, numerical calculation, and the design of a grouting scheme for subsea tunnels at different temperatures.

Numerical investigation on grout spread and grouting parameter analysis in fracture with flowing water

Grouting is crucial for oil and gas extraction as an economical and effective method for preventing subsurface water seepage in rock fractures. In this study, rough fracture surfaces were established based on the Synfrac program, and a modified Bingham model charactering the time-varying viscosity of grout was employed. The two-phase flows were numerically investigated using the level set method to capture the dynamic evolution of the interface by varying the parameters. Four types of grout spread and flow fields were analysed in the orthogonal simulation. The results indicate that the contact ratio α, grouting pressure P, diameter of the grouting hole b and water velocity vw have significantly influences the grout spread and sealing efficiency δ. The propagation pattern becomes irregular as the grout is continuously injected into the fractures owing to various parameters. Vortex zones emerge at the slurry-water interface, where dynamic water tends to be blocked in the fracture. The rapid increase in grout volume results in a longer spread distance and greater spread pressure. The diameter of the grouting hole and contact ratio have a greater influence on the grout volume. Compared with the grouting pressure, increasing the diameter of the grouting hole can appropriately improve the sealing efficiency of the slurry in the fracture. The volume reduction of water was calculated to provide a comprehensive understanding of the sealing efficiency of the grout under flow conditions. Finally, the relationship between the plugging efficiency and the four factors was obtained.

Study on time-varying viscosity of cement and sodium silicate grout under seawater condition

For practical purposes, the grouting technique is an effective method to strengthen weak rock masses around subsea tunnels, while clarifying the effect of seawater condition on grout properties is the basis for engineering applications. This study mainly focuses on the time-varying viscosity of grout under seawater condition. The cement and sodium silicate (C-S) grout with different ratios that commonly used in engineering cases was selected in this study. Through the digital display rotating viscometer (NDJ-8S), the time-varying viscosity of C-S grout was obtained. Moreover, the comparative analysis of grout viscosity under seawater and freshwater conditions was made. The test results show that the time-varying viscosity of C-S grout was obviously influenced by seawater condition and volume ratio (C-S ratio). The variation process of C-S grout viscosity with time under seawater condition can be divided into three stages: (a) initial stage, (b) stable stage and (c) rising stage, while there are only two stages under freshwater condition. Furthermore, the viscosity of grout in seawater is much greater than that in freshwater at the initial stage. After that, the time-varying viscosity models of C-S grout with different ratios were obtained on basis of experimental data. It is hoped that the obtained data will provide aids to the design of grouting with C-S grout in the future.

Experimental Study on the Mechanical Properties of Rock Fracture after Grouting Reinforcement

Grouting reinforcement plays an important role in repairing fractures and improving the strength of the surrounding rock. To address practical engineering challenges such as caving and chip off-falling of surrounding rock in deep roadways, normal splitting was adopted to prefabricate fractures on rock samples gathered from underground coal mines. This was done to better match the rock fracture specimen with actual conditions. Based on the elementary unit of a fracture surface, systematic experiments were conducted on the tensile properties of rock fractures after grouting reinforcement, and the shear properties were studied after considering the presence of gas. As per the results, the tensile strength of rock fractures increased with the increase in viscosity of grout, but the overall tensile strength was relatively low. The overall tensile effect of surrounding rock was improved less by grouting approach. When the presence of fracture gas in grouting was considered, the peak shear strength of fractures after grouting was 8.34–29.9% less than that without considering the fracture gas. The cemented pore surface produced by unsaturated cementation in the grouting reinforcement was the main cause of reduction in cohesion and frictional angle of rock fractures. The conclusions of this study have great significance for guiding engineering grouting and evaluating the grouting effect.

Estimation of Viscosity and Yield Stress of Cement Grouts at True Ground Temperatures Based on the Flow Spread Test

The rheology of cement grouts often plays a crucial role in the success of rock grouting. In practice, the rheological parameters should be timely adjusted according to the evolution of grouting pressure, flow rate and injection time. However, obtaining the magnitude of rheological parameters is not easy to achieve under site conditions. More importantly, the ground temperature in deep rock masses is elevated higher than that on the surface or under room conditions, which has been demonstrated to strongly influence the rheological properties of grouts. Reasonable understanding and control of the rheological behavior of cement grouts at true ground temperatures is very important to the quality of grouting. This paper aims to propose a simplified method to approximately estimate the initial yield stress and viscosity of cement grouts for rock grouting under elevated ground temperature that actually exists in deep rock masses, on the basis of the flow spread test. The temperature investigated was controlled between 12 °C and 45 °C to simulate the true ground temperature in rock masses with a maximum depth of 1500 m below the surface. Taking the influences of elevated temperatures into account, a temperature-based model for estimating the initial viscosity of cement grout was successfully developed on the basis of Liu’s model and the results of the flow spread test. However, the yield stress failed to be estimated by the Lapasin model due to the absence of plastic behavior of cement grouts. In contrast, yield stress can be linearly correlated to the measured relative flow area. In this work, it was also found that the dependence of yield stress of cement grouts on relative flow area is a strongly exponential law. The temperature dependence of the viscosity of water was accounted for in both estimations of viscosity and yield stress of grouts. Significantly, it was found that the packing density of cement is dependent on the grout temperature, especially when the temperature is up to 45 °C. The proposed method in this work offers an alternative solution for technicians to reasonably control the rheological properties in the increasing applications of deep rock grouting.

Time-dependent rheological behavior of cement-sand injection grout containing high volume fly ash

Grouting technology is playing an increasingly important role in construction engineering. Various types of grout are available but cement slurry grouts are often selected for injection works due to better workability. Meanwhile, in repair works, cement-sand grout often preferred as the fine aggregates gives better volume stability for large repair area. However, theoretical research on the use of waste material to improve the rheological properties of cement-sand grout is still lacking. For grouts, rheology is a factor of prime importance to the transport, injection and pumping of the material. Cement-sand grouts often have poorer fluidity due to friction created by the sand. Since grouts typically contain cement, therefore fly ash can be a good option to improve the workability of the grout. This paper studies time dependent behaviour of the grout by measuring the flow times and viscosity of cement-sand grout containing high volume fly (HVFA) up to 1 hour from the time of mixing. The result indicates that replacement of HVFA reduces the flow time of the grout and maintained good fluidity up to 1 hour. The viscosity test showed that the grouts, at fresh state, behaved like a Bingham fluid by exhibiting lower viscosities for the mixtures containing fly ash at 0, 60 and 120 minutes. In conclusion, the use of large quantities of fly ash in grouts significantly enhances fluidity of the cement-sand grouts. Methodology comparison also resulted in new knowledge for best method flow test for fly ash grout.

Viscosity, yield stress and compressive strength of cement-based grout modified with polymers

In this study, two types of polycarboxylate (PCE) polymer (DBC-21 and VK-98) were used as additives in the cement-based grout. The water-cement ratio (w/c) was fixed to 0.6 and 1.0 ​at temperature of 25° Celsius and 50° Celsius. Experimentalists were conducted to study the chemical composition of the cement-based grout, the mass loss, the rheology behavior, and the compressive strength. Numerical studies were performed to understand the shear strength, rheological properties and compressive strength by taking advantages of numerical models. The results show that the 0.16% PCE polymer additive leads to low cement weight loss at 800° Celsius, drastic increase of apparent and plastic viscosity, and significant improvement of compressive strength. Effects of polymer content, w/c, curing period and the temperature on the rheological properties and compressive strength (CS) of cement-based grout were investigated using a multiple nonlinear regression analysis.

On the rheology of using geopolymer for grouting: A comparative study with cement-based grout included fly ash and cold bonded fly ash

A friendly novel material called geopolymer has recently presented some promising uses for enhancement of weak ground through grouting alternative to Portland cement especially for avoiding from large CO2 emissions during cement production. However, research using the geopolymer technology is still insufficient for grouting specifically concerning with rheology. This paper investigates the rheological properties (shear stress, apparent viscosity, shear rate, yield stress, plastic viscosity) of geopolymer grout in comparison with the cement-based grouts included fly ash and cold bonded fly ash (i.e., geopolymer aggregate) at various dosage rates (0%–100%) and water/binder ratios (0.75–1.5). Some alkaline activator solutions (sodium hydroxide, sodium silicate) and some precursor of aluminosilicate sources (fly ash, silica fume) are used for obtaining the geopolymer grout. Rheometer tests are performed for the grout rheology. It is found from the experimental work that most of the grout mixtures lead to dilatant behavior similar to the one of native cement, while some geopolymer grouts result in the pseudoplastic and Bingham behaviors. All rheological responses of grouts decrease with increased water/binder ratios. While the inclusions of fly ash and geopolymer aggregate bring about minor changes in the rheological properties, the geopolymer grouts mostly result in the magnitudes more pronounced. The grout rheology becomes more close to the ones of native cement by the proportions 30%–40% of fly ash and geopolymer aggregate, and using the geopolymer grout in the combinations with 30%–60% silica fume. The plastic viscosity versus yield stress produces moderate correlations for the grouts with fly ash, but strong correlations for the geopolymer grouts and the grouts with geopolymer aggregate. The study indicates that the geopolymer comparatively attempted with fly ash and geopolymer aggregate could offer many choices for experimenters in practice for feasible grouting compared to native cement.

Ultrasonically enhanced physical properties of cement grout

The use of ultrasound to enhance the physical properties of cement grout was investigated with a series of laboratory tests. Test conditions included power and duration of sonic energy and curing time. Results indicated that the use of ultrasound in the grout mixing process significantly enhanced the uniaxial compressive strength. A visible decrease in the viscosity of liquid grout was also observed. The degree of enhancement varied with sonication energy, treatment time, and curing duration.

Geoelectric response of porous media in water and grout injection processes

Significant changes in spontaneous potential and exciting currents are observed during water and grout injection in a simulated porous media. Obvious correlations between the seepage flow field and the electric field in the porous media are identified. In this work, a detailed experimental study of geoelectric field variation occurring in water migration was reported by analyzing water and grout injection processes in a simulated porous media. The spontaneous potential varies linearly with the thickness of unsaturated porous media. Very interestingly, the spontaneous potential generated in the second grout injection exhibits some “memory” of previous grouting paths. The decreases in spontaneous potential observed during grout injection is very probably due to that the spontaneous potential variations are primarily caused by electro-filtration potential, as indicated by the far larger viscosity of grout compared to that of water. The geoelectric response can be utilized to effectively identify the grouting paths in water-bearing rocks.

Study on Grout Permeation Model of an Equipment for Grouting in Roller Compacted Concrete

Based on cylindrical diffusion theory and characteristics of enriched vibrated Roller Compacted Concrete (RCC), a model of grout permeation was established. According to this model and generalized Darcy’s law, a formula was deduced, which shows the relationship among diffusion radius of grout, grouting pressure, radius of grouting pipe, construction time, viscosity of grout, permeability coefficient of RCC, porosity of RCC and rheological index of grout, computing steps by this formula were presented, and results of computing grout diffusion radius for an equipment of grouting in Roller Compacted Concrete was given, which was developed for construction of RCC dam at Tingzikou hydraulic power station.

Application of time-varying viscous grout in gravel-foundation anti-seepage treatment

The time-varying viscosity of common grout and the controllable grout are measured with a rotation viscometer in experiments. The time-varying viscosity of grout is analyzed according to the characteristics in the process of anti-seepage treatment for gravel foundation. The principle of effective stress for porous medium is applied to analyzes the fluid-structure coupling in grouting. In the consideration of coupling physical variables, dynamic models of porosity, permeability and viscosity are constructed. The diffusion radius can thus be defined by the foundational porosity. The distribution of holes in field experiments is designed according to the diffusion radius of grout. Then, the permeability test is designed to verify the grout effect. The calculated diffusion radius coincides with experimental results, and the permeability meets the requirements of the project, which is valuable for the anti-seepage treatment in gravel foundation.

Effect of cement, sodium silicate, kaolinite and water on the viscosity of the grout

Cement, sometimes with/without other binders, is widely used for the stabilization of soil by injection and grouting methods. Chemical grouts and sodium silicate are commonly used worldwide for stabilizing soft soils. This article presents the effectiveness of using cement, sodium silicate, water and kaolinite on the viscosity of the grout. Different samples with different ratio of grout components were prepared and the changes in the viscosity of grout were evaluated. The results showed that by increasing cement, kaolonite and sodium silicate, the viscosity of grout increased; on the other hand, it decreased with an increase in water. The effect of kaolinite on the grout viscosity was investigated is more than that with cement and the behaviour of grout without sodium silicate was observed to be similar to the thixotropy fluid behaviour, and it was similar to rheopexy fluid behaviour with high amount of sodium silicate. Key words: Cement-sodium silicate system grout, viscosity, thixotropic fluids, rheopexy fluids.

Parametric Study on Cement Grout and Aggregate Media for Preplaced Aggregate Grouting

Abstract Experimental programs were designed carefully and appropriate testing materials were selected for the parametric study on the flow of cement grout through aggregate media during the preplaced aggregate grouting process in concrete construction. Experimental investigations include the testing and evaluation of the viscosity of cement grout, the intrinsic permeability coefficient, and the porosity of the aggregate media. The time dependency and shear history dependency of the rheological properties of the cement grout are incorporated in the viscosity tests so as to be able to simulate more accurately the grouting process. The average shear rate of the flow is estimated from the flow velocity by determining the average nominal radius of the imaginary flow channel from the permeability testing. The resulting parameters include the yield stress and plastic viscosity of the cement grout and their time dependency, intrinsic permeability and porosity of the aggregate media, and the average nominal radius of the imaginary flow channel.

Prepacked Grouting Process in Concrete Construction

Prediction of the prepacked grouting process provides useful information for site engineers to decide a proper spacing of injection point and foresee the injection pressure and flow rate to achieve a better quality control of concrete. Prediction methods based on both experimental and analytical work are proposed in this study to analyze the flow of cement grout through single-size aggregate media during the prepacked grouting process. Radial flow is employed to present a basic description of common cases in practice. Darcy’s law modified for Bingham fluid (Darcy approach) and Buckingham-Reiner equation modified for porous media (capillary approach) are developed to determine and analyze the flow. Evaluations of the viscosity of cement grout and permeability of the aggregate media are carefully designed and relevant parameters established for prediction analysis. Validation of the proposed analyses is confirmed by comparing the predicted results with monitored values from grouting tests.

Viscometric characterisation of cement grout for prediction of prepacked concrete construction

The ability of cement grout to penetrate voids of aggregate media, during the injection process of prepacked concrete construction, is strongly dependent on its viscosity. This paper reports experimental work on the viscometric characteristics of cement grout for the prediction of prepacked grouting process. Various factors influencing the measured results have been identified. Shear history dependent viscosity of cement grout requires that an experimental programme should be designed: (a) to ensure repeatability; and (b) to obtain meaningful results for the concerned construction process. Due consideration has been given to establish proper mixing and measuring programmes. Results were obtained through a set of carefully selected parameters to simulate the shear history during the grouting process. The Bingham model was adopted to characterise the shear rate dependency of the apparent viscosity. Time dependency of the Bingham parameters was obtained from a series of tests of the same batch under the specified initial mixing condition and subsequent agitation. Thixotropy loop tests were also carried out to analyse the sensitivity of the internal structure of cement grout to further shearing, thus comparing the mixing effect on rheological property of cement grout.

Viscometric characterisation of cement grout for prediction of prepacked concrete construction

The ability of cement grout to penetrate voids of aggregate media, during the injection process of prepacked concrete construction, is strongly dependent on its viscosity. This paper reports experimental work on the viscometric characteristics of cement grout for the prediction of prepacked grouting process. Various factors influencing the measured results have been identified. Shear history dependent viscosity of cement grout requires that an experimental programme should be designed: (a) to ensure repeatability; and (b) to obtain meaningful results for the concerned construction process. Due consideration has been given to establish proper mixing and measuring programmes. Results were obtained through a set of carefully selected parameters to simulate the shear history during the grouting process. The Bingham model was adopted to characterise the shear rate dependency of the apparent viscosity. Time dependency of the Bingham parameters was obtained from a series of tests of the same batch under the specified initial mixing condition and subsequent agitation. Thixotropy loop tests were also carried out to analyse the sensitivity of the internal structure of cement grout to further shearing, thus comparing the mixing effect on rheological property of cement grout.