scholarly journals Cement Slurry Plugging Law and Optimal Plugging Flow Rate at a High Hydraulic Gradient

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Peili Su ◽  
Yifei Jia ◽  
Feng Liu ◽  
Chong Li
Keyword(s):  
Theoretical Model ◽  
Flow Rate ◽  
Hydraulic Gradient ◽  
Model Verification ◽  
Cement Slurry ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Grouting Pressure ◽  
Deposition Thickness ◽  
Velocity Water

With the continuous development of coal and rock mass engineering, water inrush grouting has become an urgent problem in engineering disaster management. Herein, a theoretical model of the optimal plugging flow rate was established, and a comparative theoretical analysis was performed based on the results of indoor model tests. The particle incipient velocity was defined as the optimal plugging flow rate. The effects of hydrodynamic velocity, water-cement ratio, grouting pressure, and fracture aperture on the cement slurry grouting plugging were studied, and the optimal threshold of the plugging flow rate was obtained for theoretical model verification. Results showed that, at a high hydraulic gradient, the plugging effect of the grout was mainly affected by the hydrodynamic velocity, water-cement ratio, and grouting pressure (listed in the order of importance). When the hydrodynamic velocity was low, the difference in the slurry deposition thickness was large under different water–cement ratios and pipe diameters. When the hydrodynamic velocity was increased, the influence of various factors on the slurry deposition thickness decreased. Through a comparative analysis of the experimental and theoretical values, the optimal plugging velocity of pure cement slurry was 0.5–0.55 m·s−1 under different conditions, and the error between the experimental and theoretical values was less than 0.1 m·s−1, which confirmed the rationality of the proposed model.

scholarly journals Experimental Study on Diffusion Law of Post-Grouting Slurry in Sandy Soil

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Jianyu Yang ◽  
Yanhui Cheng ◽  
Weichao Chen
Keyword(s):  
Permeability Coefficient ◽  
Cement Slurry ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Grouting Pressure ◽  
Empirical Function ◽  
Pressure Water ◽  
Post Grouting ◽  
Function Relationship ◽  
Experimental Reference

In order to study the diffusion law of grouting slurry in sand areas, the grouting of cement slurry in sand was analyzed by the indoor grouting test under different water-cement ratios, grouting pressures, grouting amounts, and soil qualities, and the law of the post-grouting slurry is obtained. The results show that the grouting method is affected by the grouting pressure, water-cement ratio, grouting amount, and soil quality. Under the same grouting pressure, the diffusion modes of different water-cement ratio grouts in sands with different permeability coefficients, which are mainly manifested as osmotic diffusion, are basically the same; under the same water-cement ratio, when the grouting pressure is relatively small, the diffusion of modes of slurry is mainly osmotic in sand. The diffusion radius of cement slurry in sand has a good power function relationship with grouting pressure, water-cement ratio, permeability coefficient, and grouting amount. And, the empirical function model of slurry diffusion radius is proposed by regression analysis. The research results provide a certain theoretical and experimental reference for post-grouting in sandy areas.

Kansas Water-Cement Ratio Meter: Preliminary Results

1996 ◽  
Vol 1532 (1) ◽  
pp. 73-79
Author(s):  
Mustaque Hossain ◽  
James Koelliker ◽  
Hisham Ibrahim ◽  
John Wojakowski
Keyword(s):  
Fresh Concrete ◽  
Accurate Determination ◽  
Hardened Concrete ◽  
Cement Slurry ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Concrete Mix ◽  
Predominant Factor ◽  
The One ◽  
Strength And Durability

The water-cement ratio of fresh concrete is recognized as the one factor that affects the strength and durability of an adequately compacted concrete mix. Although water-cement ratio is the predominant factor affecting strength of hardened concrete, currently no widely used, reliable method is available for measuring water-cement ratio in the field. A prototype device has been developed to measure the water-cement ratio of a plastic concrete mix. The method is based on the measurement of turbidity of water-cement slurry separated out of a concrete mixture by pressure sieving. Consistent results were obtained for air-entrained and non-air-entrained concrete. Statistical analyses of the test results have shown that this meter can measure the water-cement ratio of fresh concrete with an accuracy of ±0.01 on the water-cement ratio scale for a single test at a 90 percent confidence interval. The equipment will cost less than $10,000. If the method works as well in the field as it does in the laboratory, accurate determination of water-cement ratio could dramatically improve the ability of the concrete industry to ensure the quality of concrete construction.

scholarly journals Experimental Investigation on the Law of Grout Diffusion in Fractured Porous Rock Mass and Its Application

Processes ◽  
2018 ◽  
Vol 6 (10) ◽  
pp. 191 ◽  
Author(s):  
Donghai Jiang ◽  
Xianzhen Cheng ◽  
Hengjie Luan ◽  
Tongxu Wang ◽  
Mingguang Zhang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Permeability Coefficient ◽  
Pressure Coefficient ◽  
Porous Rock ◽  
Cement Ratio ◽  
Coal Resources ◽  
Water Cement Ratio ◽  
Grouting Pressure ◽  
Study Results ◽  
Residual Coal

Because of the limitation of mining techniques and economic conditions, large amounts of residual coal resources have been left in underground coal mines around the world. Currently, with mining technology gradually developing, residual coal can possibly be remined. However, when residual coal is remined, caving areas might form, which can seriously affect the safety of coal mining. Hence, grouting technology is put forward as one of the most effective technologies to solve this problem. To study the grouting diffusion in fractured rock mass, this paper developed a visualization platform of grouting diffusion and a three-dimensional grouting experimental system that can monitor the grout diffusion range, diffusion time and grout pressure; then, a grouting experiment is conducted based on this system. After that, the pattern of the grouting pressure variation, grout flow and grout diffusion surface are analyzed. The relationship among some factors, such as the grouting diffusion radius, compressive strength of the grouted gravel, porosity, water-cement ratio, grouting pressure, grouting time, permeability coefficient and level of grout, is quantitatively analyzed by using MATLAB. The study results show that the flow pattern of the grout in fractured porous rock mass has a parabolic shape from the grouting hole to the bottom. The lower the level is, the larger the diffusion range of the grout is. The grouting pressure has the greatest influence on the grouting diffusion radius, followed by the grouting horizon and water-cement ratio. The grouting permeability coefficient has the least influence on the grouting diffusion radius. The grout water-cement ratio has the greatest influence on the strength of the grouted gravel, followed by the grouting permeability. The grouting pressure coefficient has the least amount of influence on the grouting diffusion radius. According to the results, the grouting parameters are designed, and a layered progressive grouting method is proposed. Finally, borehole observation and a core mechanical property test are conducted to verify the application effect. This grouting technology can contribute to the redevelopment and efficient utilization of wasted underground coal resources.

scholarly journals Experimental Study on Groutability of Sand Layer concerning Permeation Grouting

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yan-Xu Guo ◽  
Qing-Song Zhang ◽  
Lian-Zhen Zhang ◽  
Ren-Tai Liu ◽  
Xin Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Relative Density ◽  
Clay Content ◽  
Sand Particle ◽  
Sand Layer ◽  
Permeation Grouting ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Grouting Pressure ◽  
Relative Density Of Sand

Permeation grouting is widely used in grouting engineering because of its low grouting pressure and minor disturbance to the stratum. However, influenced by the complex properties of sand layer and slurry, an accurate prediction of the groutability of the sand layer remains to be a hard work. In this paper, the permeability of sand layer is studied based on a self-designed permeation grouting test device, which considers the different sand particle size, relative density of sand layer, slurry water-cement ratio, and clay content. The influencing factors of sand layer groutability are analyzed, and the different parameters that affect the grouting of sand layer are evaluated, thus proposing a new approach to predict the groutability of sand layer. Results show that the sand particle size and slurry water-cement ratio are positively related to the groutability of sand layer, and the relative density and clay content of sand layer are negatively correlated with the groutability of sand layer. The proposed alternative empirical formula to estimate the groutability of sand layer will help predict the groutability of sand layer with a higher degree of accuracy, which can provide a certain reference for engineering.

scholarly journals Pipe pressure of mining wet shot crete flowing in pipes

2021 ◽  
Vol 303 ◽  
pp. 01035
Author(s):  
Lianjun Chen ◽  
Xuekai Jiang ◽  
Guoming Liu ◽  
Xiangfei Cui
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Solid Phase ◽  
Pressure Change ◽  
Rheological Parameters ◽  
Computational Formula ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Mix Proportion ◽  
Phase Pressure

In order to explore the pressure change law of mining wet shotcrete in pipes, the rheological model was built based on rheology principle, and the computational formula of rheological parameters of wet shotcrete was deduced with the linear regression. 100 m full-scale pipeline platform of wet shotcrete was designed and built to study the relationship of pressure and other factors including flow rate, water cement ratio, mix proportion, and pipe bends. Results show: pipe pressure increases with the increase in flow rate and declines with the increase in water-cement ratio, the pressure may fluctuate with a high water cement ratio which can cause cement overhydration and bleeding separation. It will be more beneficial to transport materials if the continuous grading and straight pipe were considered. According to the tests of mix proportion 1:1.5:2.25, the pressure drop is 0.032 MPa·m−1 and the bend pressure drop is 1.3 times higher than in the straight line. We also conclude that solid phase pressure is bigger than liquid phase pressure and they both decline along the pipe based on FLUENT simulation. Finally, the formula of on-way resistance used in mine production was deduced.

scholarly journals Experiment and Numerical Simulation on Grouting Reinforcement Parameters of Ultra-Shallow Buried Double-Arch Tunnel

2021 ◽  
Vol 11 (21) ◽  
pp. 10491
Author(s):  
Jianxiu Wang ◽  
Ansheng Cao ◽  
Zhao Wu ◽  
Huanran Wang ◽  
Xiaotian Liu ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Setting Time ◽  
Surrounding Rock ◽  
Shear Strength Parameters ◽  
Cement Slurry ◽  
Strength Parameters ◽  
Bleeding Rate ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Grouting Reinforcement

For an ultra-shallow buried double-arch tunnel with a large cross-section, the arching effect is difficult to form in surrounding rock, and grouting method is often adopted to reinforce the surrounding rock. Hence, examining the grouting reinforcement parameters is of great significance for potential failure and collapse prevention. The land part of Haicang undersea tunnel was selected as a case study; laboratory experiments, theoretical analysis, and numerical simulation were performed to determine the grouting solid strength and grouting reinforcement parameters. The effects of different water–cement ratios on slurry fluidity, setting time, bleeding rate, and sample strength were studied by laboratory experiments. A method was proposed to determine the shear strength parameters of grouted surrounding rock through the grout water–cement ratio and the unconfined compressive strength of the rock mass. Numerical simulations were performed for grouting reinforcement layer thickness and the water–cement ratios. The deformation and stability law of tunnel surrounding rock and its influence on surrounding underground pipelines were obtained considering the spatial effect of tunnel excavation and grouting reinforcement. The reasonable selection range of grouting reinforcement parameters was proposed. The initial setting time and bleeding rate of cement slurry increased with the increasing water–cement ratio, while the viscosity of cement slurry and sample strength decreased with the increasing water–cement ratio. The shear strength parameters of grouted surrounding rock were determined by the water–cement ratio of grout and unconfined compressive strength of rock mass before grouting. When the thickness of grouting reinforcement layer h = 1.5 m and the water–cement ratio of grout was suggested η = 0.85, the surface settlement, the deformation of the vault, and the deformation of the nearby pipeline all met the design. Moreover, the construction requirements were more economical. Research results can provide a reference for the selection of grouting reinforcement parameters for similar projects.

scholarly journals Research on Influence of Water-Cement Ratio on Reinforcement Effect for Permeation Grouting in Sand Layer

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Zhipeng Li ◽  
Lianzhen Zhang ◽  
Yuntian Chu ◽  
Qingsong Zhang
Keyword(s):  
Deformation Modulus ◽  
High Water ◽  
Sand Layer ◽  
Curing Time ◽  
Reinforcement Effect ◽  
Cement Slurry ◽  
Permeation Grouting ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Grouting Reinforcement

In order to study permeation grouting reinforcement effect in the sand layer, a set of grouting test device is developed, which consists of a power device, a pressure-bearing slurry tank, and several test frames. Compressive strength, deformation modulus, and permeability coefficient are selected to be the evaluation index of grouting reinforcement effect. Grouting reinforcement effect under different water-cement ratio of cement slurry and curing time were measured. Eventually, under laboratory conditions, fitting formulas have been obtained which describe the quantitative relationship between reinforcement effect of permeation grouting and water-cement ratio and curing time. Results show that water-cement ratio of slurry has obvious effect on grouting reinforcement effect. Mechanical performance and impermeability of the grouted body are negative-correlated with water-cement ratio. There are two different destruction patterns for the grouted body in uniaxial compression process: global destruction pattern at low water-cement ratio and local destruction pattern at high water-cement ratio. If cement slurry at high water-cement ratio is permeated into the sand layer, water bleeding phenomena will appear and lead to inhomogeneous performance of the grouted body, with lower performance in the upper part and higher performance in the lower part of the grouted body.

scholarly journals Modelling the minislump spread of superplasticized PPC paste using Random forest, Decision tree and Multiple linear regression

2021 ◽  
Vol 2070 (1) ◽  
pp. 012126
Author(s):  
M Mrithula ◽  
Modepu Bhavana ◽  
S Janani ◽  
Vaishnavi Narayanan ◽  
C.B Rajesh ◽  
...  
Keyword(s):  
Random Forest ◽  
Decision Tree ◽  
Cement Paste ◽  
Flow Rate ◽  
Flow Speed ◽  
Training Data ◽  
Cement Particle ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
The Family

Abstract Workability is one of the key property of concrete which is governed by water cement ratio. In order to improve the workability of concrete without any variations in water cement ratio Superplasticizers(SPs) are added. Cement paste helps us to analyze the property of fresh concrete where the dispersion of cement particle is taken into account. SP’s Cement dispersive properties are governed by dosage and the family. Various dosages and families of SP are considered for estimating workability feature of cement paste which is picked for investigating on rheological properties through Mini slump spread diameter. The prime motive of this analysis includes measuring the workability of different superplasticizers by conducting a minislump test and hence modelling the flow rate of the superplasticized Portland Pozzolona Cement (PPC)paste using the application of random forest(RF), decision tree(DT) and multiple regression algorithms. Testing and training data for a model were 287 unique mixture compositions at a water by cement ratio was 0.37. This mixture was tested experimentally in a laboratory using four types of locally available PPC’s and of SP which can be broadly categorised in to four families. Amount of seven types of SP brands, water content, cement weight were the input parameters for the model and flow rate was the output parameter. The model’s predicted and experimentally measured values of flow speed were compared and the amount of deviation was recorded.

scholarly journals Effect of Fibre Content on Mechanical Behavior of Slurry Infiltrated Fibrous Concrete

2018 ◽  
Vol 7 (3.12) ◽  
pp. 260 ◽  
Author(s):  
Elavarasi D ◽  
Saravana Raja Mohan K ◽  
Navatejareddy A ◽  
Sushmitha R
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Volume Fraction ◽  
Cement Mortar ◽  
Fibre Content ◽  
Cement Slurry ◽  
Split Tensile Strength ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Fibrous Concrete

Cement mortar or slurry is an essential material for production of Slurry Infiltrated Fibrous Concrete (SIFCON) structural components. However, there have been limited technical data available for deciding a suitable mix proportions and water cement ratio. For achieving a good quality of mortar mix or slurry with specific strength requirement and satisfactory level of workability for proper infiltration ability of cement slurry fibrebed. The preliminary study was carried out to select suitable mix and W/C from various mixes (1:1, 1:1.5 &1:2) and W/C (0.4, 0.45 & 0.5)on fresh and hardened properties of cement mortar. The optimum mix proportion and water cement ratio were obtained on workability (flow table test) and compressive strength of cement mortar are found to be as 1:1 and 0.40 respectively for fabrication of SIFCON. The main focus of this investigation on the behaviour of SIFCON contains various volume fraction of fibre content with an optimum mix(1:1) and W/C (0.4) under static loading. Hooked end steel fiber length of 30mm and tensile strength of 1050MPais used throughout the entire investigations. Cubes of 100 x 100 x 100mm for compressive strength and cylinders of 100mm diameter and 200mm height for split tensile strength were cast and tested at 3, 7 and 28 days. For flexural strength, three SIFCON beams of length 1200mm and cross section of 100mmx 200mm were cast and tested at 28 days under three point bending. The parameters like fracture energy, load deflection response, split tensile strength and compressive strength were found and compared the results with conventional mix. The test results observed that the strength performances were greatly improved due to addition of fibre by volume fraction in SIFCON matrix. Also developed the regression model from the experimental results to estimate the compressive and split tensile strength and compared the predicted values with the experimental values.  

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