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 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.

scholarly journals Study on the Permeability of Recycled Aggregate Pervious Concrete with Fibers

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 321 ◽  
Author(s):  
Haitang Zhu ◽  
Chengcheng Wen ◽  
Zhanqiao Wang ◽  
Lan Li
Keyword(s):  
Compressive Strength ◽  
Permeability Coefficient ◽  
Polypropylene Fiber ◽  
Volumetric Analysis ◽  
Pervious Concrete ◽  
Recycled Aggregate ◽  
Fiber Types ◽  
Cross Sectional ◽  
Cement Ratio ◽  
Water Cement Ratio

Pervious concrete is considered to be porous concrete because of its pore structure and excellent permeability. In general, larger porosity will increase the permeability coefficient, but will significantly decrease the compressive strength. The effects of water-cement ratio, fiber types, and fiber content on the permeability coefficient, porosity, compressive strength, and flexural strength were investigated. The pore tortuosity of the pervious concrete was determined by volumetric analysis and two-dimensional cross-sectional image analysis. The concept and calculation method of porosity tortuosity were further proposed. Results show that the permeability coefficient of the pervious concrete is the most suitable with a water-cement ratio of 0.30; the water permeability of the pervious concrete is influenced by fiber diameter. The permeability coefficient of pervious concrete with polypropylene thick fiber (PPTF) is greater than that with copper coated steel fiber (CCF) and the polypropylene fiber (PPF). The permeability coefficient is related to tortuosity and porosity, but when porosity is the same, the permeability coefficient may be different. Finally, general relations between the permeability coefficient and porosity tortuosity are constructed.

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 Studi Mengenai Pengaruh Faktor Air-Semen dan Nilai Slump Beton Segar terhadap Permeabilitas Beton. (Hal. 33-40)

2019 ◽  
Vol 5 (4) ◽  
pp. 33
Author(s):  
Chandra Budhi Rizky ◽  
Priyanto Saelan
Keyword(s):  
Permeability Coefficient ◽  
Concrete Mixture ◽  
Building Structure ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Concrete Mixtures ◽  
A Value ◽  
The Relationship

Abstrak Permeabilitas beton memiliki peran penting dalam mempertahankan umur suatu struktur bangunan, serta dipengaruhi oleh faktor air-semen, dan porositas beton. Dari suatu nilai faktor air-semen yang sama maka dapat dibuat campuran beton dengan nilai slump yang berbeda. Nilai slump yang berbeda membutuhkan jumlah air yang berbeda hal ini diduga akan mengakibat nilai koefiesien permeabilitas yang lebih tinggi. Penelitian ini dilakukan dengan membuat campuran beton menggunakan cara Dreux Gorrise - ITENAS, untuk faktor granular [G] 0,55; faktor air-semen 0,4; 0,5; dan 0,6; serta slump rencana 30-60 mm dan 60-180 mm. Hasil penelitian ini menunjukan grafik hubungan antara faktor air-semen dan nilai slump dengan nilai koefisien permeabilitas. Hasil dari grafik menunjukan faktor air-semen 0,5 dengan nilai slump 30-60 mm nilai koefisien permeabilitasnya adalah 5,790 x 10-9 m/dtk. Sedangkan untuk faktor air-semen 0,5 dengan nilai slump 60-180 mm nilai koefisien permeabilitasnya adalah 7,674 x 10-9 m/dtk. Kata kunci: permeabilitas beton, porositas beton, nilai slump, faktor air-semen Abstract Permeability of concrete has an important role in maintaining the life of a building structure, also influenced by a water-cement ratio and porosity of the concrete. From a value of the same water-cement ratio, concrete mixtures can be made with different slump values. Different slump values require different amounts of water, this is thought to result in higher permeability coefficient values. This research was carried out by making a concrete mixture using the Dreux Gorrise - ITENAS method, for granular factors [G] 0.55, water-cement ratio 0.4, 0.5, and 0.6, and slump plans 30-60 mm and 60-180 mm. The results of this study show a graph of the relationship between the water-cement ratio and slump value with the permeability coefficient value. The results of the graph show a water-cement factor of 0.5 with a slump value of 30-60 mm the value of the permeability coefficient is 5.790 x 10-9 m/sec. While for the water-cement factor 0.5 with a slump value of 60-180 mm the value of the permeability coefficient is 7.674 x 10-9 m/sec. Keywords: permeability of concrete, porosity of concrete, slump value , water-cement ratio

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.

Properties of Low Water/Cement Ratio and High Compressive Strength Pervious Concrete

2018 ◽  
Vol 932 ◽  
pp. 136-140
Author(s):  
Mao Chieh Chi ◽  
Jiang Jhy Chang ◽  
Wei Chung Yeih
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Pervious Concrete ◽  
Unit Weight ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Water Permeability Coefficient

The purpose of this study is to discuss the properties of low water/cement ratio and high compressive strength pervious concrete. Two sizes of air-cooling electric arc furnace slag (EAFS), for the same size of 0.24 - 0.48 cm and 0.48 - 0.96 cm, were prepared as the coarse aggregates. Two water-to-cement ratios and three filled percentages (70, 80, and 90%) of voids by cement pastes were selected as variables. The unit weight, connected porosity, water permeability coefficient, compressive strength, and flexural strength of pervious concrete were conducted. Test results show that the pervious concrete with higher filled percentage of voids by cement paste has higher unit weight, compressive strength, and flexural strength and smaller connected porosity and water permeability coefficient. The lower the water/cement ratio and EAFS size, the superior the properties. At the water/cement ratio of 0.25, pervious concrete with EAFS size of 0.24 – 0.48 cm and 90% filled percentage of voids by cement pastes had the highest compressive strength of 35 MPa and flexural strength of 7 MPa.

Estimating Diffusion Radius Grouting into Broken Rock Mass

2013 ◽  
Vol 353-356 ◽  
pp. 44-49 ◽  
Author(s):  
Hong Fa Xu ◽  
Chen Wang ◽  
Chao Fu Li ◽  
Miao Jiang ◽  
Han Sheng Geng ◽  
...  
Keyword(s):  
Rock Mass ◽  
Empirical Formula ◽  
Permeability Coefficient ◽  
Field Tests ◽  
Mean Value ◽  
Empirical Formulas ◽  
Nonlinear Fitting ◽  
Grouting Pressure ◽  
Pressure Grouting ◽  
The Mean

The influencing factors of grouting diffusion in broken rock mass were divided into four classifications: grouting pressure, grouting time, permeability coefficient and grout viscosity. Relations among similar factors were expressed to each other using an equation. Empirical formulas of relations among grout water-cement ratio, viscosity and time between the joint density of broken rock mass and permeability coefficient, and between water absorption and permeability coefficient were established. The differences among the four diffusion radius formulas grouting in porous continuous media were compared. A new empirical formula of diffusion radius was obtained using multivariate nonlinear fitting analysis based on the mean value of the four empirical formulas. The tests of grouting diffusion in broken rock mass were done in the field. The mean empirical formula is consistent with the measured value of the field tests on grouting diffusion radius, which provide a reference for the design of grouting into broken rock mass.

Analysis on the Design of Construction Mix Ratio for Heat-Resistant Concrete

2014 ◽  
Vol 584-586 ◽  
pp. 1598-1602
Author(s):  
Xing Wei Xu
Keyword(s):  
Linear Equation ◽  
Design Theory ◽  
Design Study ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Ordinary Concrete ◽  
Heat Resistant ◽  
Study Results ◽  
Concrete Mix

Combined with the heat-resistant concrete used for the construction of a company’s roaster, on the basis of preliminary preferred components for the concrete, with the design theory of ordinary concrete mix ratio, the design study of the mix ratio for C20 ~ C35 heat-resistant concrete was carried out. The study results showed that, the strength of the heat-resistant concrete formulated by the design theory of ordinary concrete mix ratio could meet the requirements, but the strength and water-cement ratio could not satisfy the linear equation. The study provided theoretical reference for the design of mix ratio for heat-resistant concrete.

Effect Of Water-Cement Ratio On Performance Of Seaweed-Modified Mortars

2019 ◽  
Author(s):  
Nurul Islam Siddique
Keyword(s):  
Cement Ratio ◽  
Water Cement Ratio ◽  
Effect Of Water
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