• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.414-423
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• 2006

Many construction projects adopt grouting technology to prevent the leakage of groundwater or to improve the shear strength of the ground. Recognition as a feasible field procedure dates back to 1925, Since then, developments and field use have increased rapidly. According to improvement of grout materials, theoretical study on grout penetration characteristics is demanded. Fluid of grout always tends to flow from higher hydraulic potential to lower and the motion of grout is also a function of formation permeability. Viscosity of grout is changed by chemical action while grout moves through pores. Due to the increment of viscosity, permeability is decreased. Permeability is also reduced by grout particle deposits to the soil aggregates. In this thesis, characteristics of new cement grout material that is developed recently is studied: injectable volume of new grout material is tested in two different sizes of sands, and the method to calculate injectable volume of grout is suggested with consideration of change in viscosity and clogging phenomena. The calculated values are compared with injection test results. Viscosity of new grout material is found to be an exponential function of time. And lumped parameter $\theta$ of new grout material to be used for assessing deposition characteristics is estimated by comparing deposit theory with injection test results considering different soil types and different injection pressure.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.197-198
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• 2023

This study was conducted as part of research and development of high-strength grout. Accordingly, dolomite aggregate was used as a filler incorporated into the high-strength grout. Dolomite aggregate has a disadvantage of increasing the viscosity of the grout due to higher generation of fine powder than other aggregates. Accordingly, in this experiment, it was confirmed that the viscosity, flow time, and flow of high-strength grout change according to the volume composition ratio of dolomite aggregate and cement-based material. All experiments were conducted based on the Korean Industrial Standard KS F 4044, and the mixing factor was applied according to the composition ratio of the binder and the filler. In the experiment, the amount of fine powder contained in the dolomite aggregate rather than the silica sand used in the past is grasped, and after mixing with the grout accordingly, the mixture is proceeded to measure the viscosity in an unhardened state. In addition, the flow and flow time of the grout are evaluated according to the viscosity. As a result of the experiment, it was confirmed that the viscosity and flow time decreased and the flow increased as the volume composition ratio of the dolomite aggregate to the cement-based material increased.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.5-13
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• 2007

Many construction projects adopt grouting technology to prevent the leakage of groundwater or to improve the shear strength of the ground. Recognition as a feasible field procedure dates back to 1925. Since then, developments and field use have increased rapidly. According to improvement of grout materials, theoretical study on grout penetration characteristics is demanded. Fluid of grout always tends to flow from higher hydraulic potential to lower one and the motion of grout is also a function of formation permeability. Viscosity of pout is changed by chemical action while grout moves through pores. Due to the increment of viscosity, permeability is decreased. Permeability is also reduced by grout particle deposits to the soil aggregates. In this paper, characteristics of new cement grout material that has been developed recently are studied: injectable volume of new grout material is tested in two different grain sizes of sands; and the method to calculate injectable volume of grout Is suggested with consideration of change in viscosity and clogging phenomena. The calculated values are compared with injection test results. Viscosity of new grout material is found to increase as an exponential function of time. And lumped parameter $\delta$ of new grout material to be used for assessing deposition characteristics is estimated by comparing deposit theory with injection test results considering different soil types and different injection pressures. Injection test results show that grout penetration rate is decreased by the increase of grout viscosity and clogging phenomena.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.68-75
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• 2017

The study investigates the effects of the content and using method of chemical admixtures such as superplasticizer and viscosity modifying admixture on the fluidity, bleeding ratio, volumetric change and compressive strength of the grout in order to provide basic data for the development of high-quality grout for prestressed concrete. It appeared that the combination of superplasticizer and viscosity modifying admixture decreased the fluidity of grout with small content of superplasticizer. On the contrary, Grout used more than 0.1% of superplasticizer appeared to have significant effect on the improvement of the fluidity. On the other hand, bleeding of grout reduced according to increasing the content of viscosity modifying admixture. Superplasticizer with less than 0.05% had practically no effect on the reduction of bleeding, whereas superplasticizer with more than 0.1% appear to have significant effect on the reduction of bleeding. Also the combination of superplasticizer with 0.15% and viscosity modifying admixture with 0.15% resulted in satisfactory fluidity accompanied with fair reduction of bleeding and shrinkage of the grout.

• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.215-226
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• 2024

This study presents an experimental investigation into the performance of self-sensing grout formulated with a high volume of ultra-fine fly ash(UHFA). To explore the potential benefits of alternative cementitious materials, the research examined the effect of substituting UHFA with equal parts of blast furnace slag(BFS) fine powder. Both UHFA and BFS are byproducts generated in significant quantities by industrial processes. The evaluation focused on the fresh properties of the grout, including its flow characteristics, as well as the hardened properties such as compressive strength, dimensional stability(length change rate), and electrical properties. The experimental results demonstrated that incorporating UHFA resulted in a substantial reduction in the plastic viscosity of the grout, translating to improved flowability. Additionally, the compressive strength of the UHFA-modified grout surpassed that of the reference grout(without UHFA substitution) at all curing ages investigated. Interestingly, the electrical characteristics, as indicated by the relationships between FCR-stress and FCR-strain, exhibited similar trends for both grout mixtures.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.149-156
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• 2020

Permeation grouting effectively enhances soil strength and decreases permeability of soil; however, the flow of grout is heavily affected by anisotropy of hydraulic conductivity in layers. Therefore, this study investigates the effect of permeability anisotropy on the effective radius of horizontal permeation grout using computational fluid dynamics (CFD). We modeled the horizontal permeation grout flow as a two-phase viscous fluid flow in porous media, and the model incorporated the chemical diffusion and the viscosity variation due to hardening. The numerical simulation reveals that the permeability anisotropy shapes the grout bulb to be elliptic and the dissolution-driven diffusion causes a gradual change in grout pore saturation at the edge of the grout bulb. For the grout pore saturations of 10%, 50% and 90%, the horizontal and vertical radii of grout bulb are estimated when the horizontal-to-vertical permeability ratio varies from 0.01 to 100, and the predictive model equations are suggested. This result contributes to more efficient design of injection strategy in formation layers with permeability anisotropy.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1475-1486
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• 2008

Bentonite-based grouting has been popularly used to seal a borehole installed for a closed-loop vertical ground heat exchanger in a geothermal heat pump system (GHP) because its high swelling potential. However, if the bentonite-based grouting is conducted in coastal areas, the salinity of groundwater changes in the mineral fabric of bentontie. In order words, an increase of cation concentration in groundwater leads to a reduction in the diffuse double-layer thickness in the bentonite mineral structure, and thus the volume of bentointe-based grouts will decrease proportional to the salinity of groundwater. In this paper, the effect of salinity (i.e., NaCl 0.5M, 0.25M, and 0.1M) on the change of swelling potential for bentonite-based grouts has been quantitatively evaluated for seven bentonite grouts from different product sources. In addition, in case of using addictives such as a silica sand to increase the thermal conductivity of bentonite-based grouts, the possibility of particle segregation has been studied considering the viscosity of grouts and salinity of groundwater.