• Journal of the Korea Concrete Institute
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• v.16 no.5 s.83
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• pp.635-643
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• 2004

In this study, the tensile strength of 321 full-sized grout-filled splice steeve specimens were compared and analyzed in order to afford the data for a reasonable and economical design of this system. The experimental variables analyzed in this study were embedment length of reinforcing bars, compressive strength of grout, sleeve geometry, loading pattern and final failure mode of specimen. Following main conclusions are obtained : 1) The strength of grout-filled splice sleeve tends to be improved with increasing compressive strength of grout and embedment length of reinforcing bars. Specially this tendency appears apparent in specimens of bond failure rather than rebar failure. 2) The results of this study show that the sleeve geometry have influence on the bond strength of grout-filled splice sleeve. 3) The grout-filled splice sleeve of bond failure don't show the difference of tensile strength according to size of rebar. 4) It is verified that the tensile strength required in ACI and domestic code is retained either when the compressive strength of grout over 70 MPa is used with embedment length of reinforcing bars over 4.5d or when the compressive strength of grout over 80 MPa is used with embedment length of rebars over 3.9d. 5) It is verified that the tensile strength required in AIJ code is retained in case when the embedment length of reinforcing bars is 0.8 times the rebar diameter longer than in ACI code.

• Computers and Concrete
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• v.31 no.6
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• pp.545-559
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• 2023

In this study, an experimental investigation was conducted to assess the influence of ground granulated blast furnace slag (GGBS) and silica fume (SF) on the fresh and hardened properties of grout specimens and preplaced aggregate concrete (PAC). Grout proportions were optimized statistically using a factorial design and were applied to 10 mm and 20 mm coarse aggregates to produce PAC. The results demonstrate that GGBS has a more significant effect on the compressive strength of grout compared to SF, with a small increase or decrease in the GGBS content having a greater influence on the compressive strength of grout than SF. The water to binder ratio had the most significant effect on the compressive strength of PAC, followed by the coarse aggregate size and sand to binder ratio. An empirical relationship to predict the compressive strength of PAC was proposed through an experimentally derived factorial design along with a statistical analysis of collectively obtained data and a deep literature review. The results predicted by the empirical relationship were in good agreement with those of PAC produced for verification.

• Geomechanics and Engineering
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• v.33 no.4
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• pp.327-339
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• 2023

The expansion capacity and strength of expansive grout have a significant influence on the stress state of a supported rock mass and the strength of a grout-rock mass structure. The expansion and strength characteristics are vital in grouting preparation and application. To analyze the expansion performance and mechanical properties of expansive grout, uniaxial compressive strength (UCS) tests, expansion ratio tests, XRD, SEM, and microscopic scanning tests (MSTs) of expansive grout under different curing pressure conditions were conducted. The microevolution was analyzed by combining the failure characteristics, XRD patterns, SEM images, and surface morphologies of the specimens. The experimental results show that: (1) The final expansion ratio of the expansive grout was linear with increasing expansion agent content and nonlinear with increasing curing pressure. (2) The strength of the expansive grout was positively correlated with curing pressure and negatively correlated with expansion agent content. (3) The expansion of expansive grout was related mainly to the development of calcium hydroxide (Ca(OH)2) crystals. With an increase in expansion agent content, the final expansion ratio increased, but the expansion rate decreased. With an increase in the curing pressure, the grout expansion effect decreased significantly. (4) The proportion of the concave surfaces at the centre of the specimen cross-section reflected the specimen's porosity to a certain extent, which was linear with increasing expansion agent content and curing pressure.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.59-64
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• 2011

This paper presents the research results performed to develope the shrinkage-free grout with high early strength. Alumina cement and anhydrite were utilized as the expensive tool to gain the shrinkage-free grout. The compressive strength, length change, and ettringite formation of the grout were investigated with compressive test, length change test, and X-ray diffraction. The more anhydrite was added into the grout, the larger the early expansion of the grout. In addition, the more anhydrite formated the more ettringite. From this study, It was conformed that the grout mixture with shrinkage-free property and high early strength is the mixture with the ratio of alumina cement and anhydrite of 40:60 by weight.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.597-602
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• 1997

The compressive strength of horizontal joints in precast concrete large panel structures depends on parameters such as grout and panel strength, detail of joint, joint moment, width of grout column etc. As the panels are only connected at the pocket, it results in the reduction of compressive strength area. The purposes of this study are to develop the suitable grout material the joint pocket and to enable us to evaluate structural capacity. The validity of the design formulas provides us more economic system in construction. Test results of 15 specimens show that the proper construction procedure and grouting material develop the sufficient compressive strength of the wall as monolithic system.

• Geomechanics and Engineering
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• v.19 no.4
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• pp.361-368
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• 2019

This study aims to evaluate the applicability of a grout material that is mixed with carbon fiber, biogrout, ground granulated blast furnace slag (GGBS) powder and cement. Uniaxial compressive strength tests were performed on homo-gel samples at days of 1, 3, 7, 14 and 28. In addition, the variation of permeability with the mixing ratios was measured. Based on the uniaxial compressive strength test, it was confirmed that the uniaxial compressive strength increased by 1.2times when carbon fiber increased by 1%. In addition, as a result of the permeability test, it was found that when the GGBS increased by 20%, the permeability coefficient decreased by about 1.5times. Therefore, the developed grout material can be used as a cutoff grouting material in the field due to its strength and cut-off effect.

• Magazine of the Korea Concrete Institute
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• v.6 no.2
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• pp.138-147
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• 1994

The compressive strength of horizontal joints in precast concrete large panel structures depends on parameters such as grout and panel strength, detail of joint, joint moment, width of grout column, and etc. 44 specimens were tested to investigate the effects of parameters that influence the compressive strength of horizontal joints. The design formula specified in Korean Cock for compression horizontal joints must be reviewed, because it was based on the test results of the joint types not used in Korea. In this study comparing the test results, there fore, the validity of the design formulas was evaluated and a suitable formula was proposed to predict the ultimate strengths of compression horizontal joints. The increase of ultimate strengths was not observed, even if confined the horizontal displacement of slabs and reinforced the wall edge, when the grout strength is lower than panel strength. From the comparison of test results and those by the proposed formula, it was shown that proposed formula was suitable to predict the ultimate compressive strength of horizontal joints.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.63-78
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• 1999

For the design of compression anchor, three things should be considered. The first is a resistance force by skin friction, the second is a tension strength of tendon, and the third is a compressive strength of grout. Especially, compressive strength of grout is the most important design parameter of compression anchor. When compression anchor is pulled out from the ground, the compressive strength of grout increases by confining pressure of ground($\sigma_{tg$). Here, $\sigma_{tg$ is the confining pressure which is produced by earth pressure at rest and by lateral expansion of grout. We call this phenomenon of increase of confining pressure "poisson effect". In this paper, the design method of compression anchor called SSC anchor and the computer program for the design are developed through compression tests of anchor body grout.ody grout.

• Geomechanics and Engineering
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• v.33 no.2
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• pp.211-219
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• 2023

This study analyzes the changes in the physical properties of grout by irradiating it with ultrasonic energy and assesses the injectability of the grout into deep rock fractures. The materials used in the research are OPC (Ordinary Portland Cement) and MC (Micro Cement), and are irradiated depending on the water/cement ratio. After irradiating the grout with ultrasonic energy, viscosity, compressive strength, and particle size are analyzed, and the results of the particle size analysis were applied to Nick Barton's theory to evaluate the injectability of the grout into deep rock fractures under those conditions. It was found that the viscosity of the grout decreased after ultrasonic wave irradiation, and the rate of viscosity reduction tended to decrease as the water/cement ratio increased. Additionally, an increase in compressive strength and a decrease in particle size were observed, indicating that the grout irradiated with ultrasonic energy was more effective for injection into rock fractures.

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.509-513
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• 2018

This study uses fly ash for non-shrinkage grout in order to develop strength of grout and improve its durability. We grind fly ash to the extent of $7,000cm^2/g$ and use ground fly ash and raw fly ash respectively at the proportion of 10%, 20%, 30% instead of OPC and compare the results drawn on the condition of each proportion. As a mixed material of grout, EVA and water-reducing agent is added in order to prevent bleeding and improve segregation resistance, CSA is added with a view to preventing drying shrinkage and improving early strength property. In regard to flow and flow time test for analyzing and evaluating workability, it is revealed that grouts of all mix proportions except raw fly ash 30% mix proportion satisfy all performance criteria. With regard to length change rate, grout with no admixture shows the highest shrinkage rate, but the rate is 0.0005%, extremely insignificant rate. As material age increases, compressive strength of two grouts, that is to say ground fly ash 10% and 20%-used grouts, exceed that of grout with no admixture or show high-level compressive strength.