• Journal of Sensor Science and Technology
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• v.15 no.3
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• pp.173-178
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• 2006

Silica aerogel with ultra low density and high porosity has been focused on versatile application due to its fascinating properties. Ambient drying process of waterglass, in this study was researched to fabricate a crack-free monolith body in the point view of cost effective way. Wet gel was obtained by removing of $Na^{+}$ ions in waterglass, which contains 8 wt% of $SiO_{2}$. Xylene, which has a low vapor pressure, was used as a solution substitutor to prevent the formation a cracks during drying. Various surface modifiers like as hexamethyldisilazane (HMDSZ), trimethylchlorosilane (TMCS), methyltriethoxylsilane (MTES), methyltrimethoxysilane (MTMS) and phenyltriethoxysilane (PTES) were used in order to improve hydrophobicity of the waterglass Silica aerogel. Some physical properties of the surface modified aerogels were investigated by FT-IR, TGA, BET and SEM. Hydrophobicity and hydrophilicity of Silica aerogel is attributed to the Si-OH bond and the non-polar C-H bond groups on the surface of aerogel. Crack-free waterglass aerogel with >90 % of porosity, 17 nm of pore size and <0.15 $g/cm^{3}$ of density was prepared. HMDSZ and TMCS are effective as a surface modifier

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.131-136
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• 1999

In this study, novel activated silicate grout solution for injection grouting was prepared by the reaction of ordinary waterglass with alkaline earth metal salts mixture by means of the high-speed stirring method with strong shearing force, and its chemical and physical properties were investigated. The variation of its gelation time plotted with the amount of dilution water showed that this novel silicate had better gelation characteristics in comparison with ordinary waterglass. And some other engineering characteristics of this grout such as durability and mechanical properties were investigated experimentally. The whole experimental results established that this novel silicate grout was a good alternative with an existing ordinary waterglass grouting method.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.96.2-96
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• 2000

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.725-733
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• 2008

A thixotropic grout has been developed for the use of filling a tail void in the shield TBM and as well as various ground voids. The grout developed in this study is a mixture of inorganic substance, cement and some functional additives. Its engineering characteristics was investigated by measuring a viscosity and unconfined compressive strengths. The optimum mix proportion for an effective thixotropic grout was proposed through several repeated laboratory tests. The various physical properties such as thixotropy, unconfined compressive strengths, and durability of the thixotropic grout and the gels produced from the grout were compared with those of the well-known waterglass-type grout such as L.W.. The thixotropic grout developed in the study exhibited an excellent performance for back-filling of tail voids in the shield TBM based on experimental results compared to the existing waterglass grout.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1283-1290
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• 2005

A thixotropic grout has been newly developed for the use of back-filling a tail void in the shield tunnel and filling up ground voids. The grout developed in the study is a mixture of colloidal silica, cement and some functional additives. Its engineering characteristics was investigated by measuring a viscosity and unconfined compressive strengths. The optimum mixing proportion for an effective thixotropic grout was proposed through several repeated laboratory tests. The various physical properties such as thixotropy, unconfined compressive strengths, and durability of the thixotropic grout and the gels produced from the grout were compared with those of the well-known waterglass grout such as L.W.. The thixotropic grout developed in the study exhibited an excellent performance for back-filling of tail voids, based on experimental results compared to the existing waterglass grout.

• Fire Science and Engineering
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• v.26 no.4
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• pp.18-23
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• 2012

After produce the extracted wood to silicic acid gel, sodium carbonate and silicon dioxide with application of the making method for carbon dioxide, ignition time, ignition temperature, mass loss rate and critical heat flux are measured according to external radiation source (20, 25, 35 and 50 $kW/m^2$). From the results, pressure impregnation wood to use with water glass and carbon dioxide has fire retardant performance at heat flux (less than 20 $kW/m^2$) of Pre-Flashover fires. If we find out the excellent maxing ratio through continuously study, it might be decided to be able to be utilized as fire-retardant wood.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.810-819
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• 2007

Investigation of alkali activation of fly ash and blast furnace slag was carried out using waterglass and sodium hydroxide. XRD, FTIR, $^{29}Si$ and $^{27}Al$ NMR, TGA and SEM were used to observed the reaction products and microstructure of the fly ash/slag cement (FSC) pastes. The reaction products were amorphous or low-ordered calcium silicate hydrate and aluminosilicate gel produced from alkali activation of blast furnace slag and fly ash, respectively. On the basis of this investigation, waterglass solution with a modulus(Ms) of 1.0 and 1.2 is recommended for alkali activation of fly ash and blast furnace slag. Morphology of FSC pastes alkali-activated with Ms of 1.0 and 1.2 shows a more solid and continuous matrix due to restructuring of gel-like reaction products from alkali-activated fly ash and blast furnace slag together with another hydrolysis product(i.e., silica gel) from water glass.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.7
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• pp.801-809
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• 2007

Fly ash and blast furnace slag are an industrial by-product that can be alkali-activated to yield adhesive and cementitious materials, whose production is less energy-intensive and emits less $CO_2$ than ordinary Portland cement manufacture. A laboratory investigation was carried out to evaluate the effect of alkali-activating conditions on compressive strength of fly ash/slag cement and the acid corrosion resistance of this cement. Two alkali activator solution, NaOH and waterglass + NaOH solutions, were used. Waterglass concentration was the factor that gave the highest compressive strength in all tests. The next significant factor was the NaOH concentration, followed by curing temperature. Acid corrosion resistance of FC(fly ash cement) and FSC(fly ash/slag cement), such as sulfuric$(H_2SO_4)$ and hydrochloric acid(HCl), was for better than Portland cement(PC).

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.1023-1030
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• 2002

From the early 1980s, the New Austrian Tunnelling Method (NATM) has been developed as a one of the standard tunneling method in Korea. Approximately 10 years ago, wet-mix shotcrete with sodium silicate accelerator (waterglass) was introduced and widely used to tunnel lining and underground support. However, this accelerator had some disadvantages due to the decrease of long-term strength compared to plain concrete (without accelerator) and low quality of the hardened shotcrete. In order to compensate for these disadvantages, recently developed alkali-free accelerator has been successfully demonstrated in numerous projects and applications as a new material to make tunnels more durable and safer. An experimental investigation was carried out in order to verify the strength behavior of wet-mix Steel Fiber Reinforced Shotcrete (SFRS) with alkali-free accelerator. Compressive strength, flexural strength and equivalent flexural strength were measured by testing specimens extracted from the shotcrete panels. From the results, wet-mix SFRS with alkali-free accelerator exhibited excellent strength improvement compared to the conventional shotcrete accelerator.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.433-436
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• 2005

The Fly-ash makes an Alumino-silicate gel when it mixes an alkali or a silicate solution. This Alumino-silicate gel is produced to the activation of an alkali silicate. And this act to the binder and makes a combine of particles. This study involved mechanical strengths of an Alumino-silicate Gel based the Fly-ash with an alkali solution. NaOH, KOH were utilized to an alkali solution. The alkali solution concentration was varied from 6 to 12M and the some added also the Meta-kaolin, Waterglass so that it made high the mechanical performance. Based on the experimental result, the compressive strengths increased as the quantity of the Meta-kaolin increased. And a mechanical strengths appeared according to the concentration of an alkali solution so that it was different. XRD, FT-IR have been used to characterize mechanical performance.