Papers by Author: Byung Sik Chun

Abstract: Drainage inlets at the Namsan #3 traffic tunnel in Seoul, South Korea were found to be clogged with calcium carbonate scale deposits. Officials were concerned the clogged drains would further stress the already deteriorating traffic tunnel and wanted to see if there were any practical and economical solutions in removing or preventing scale deposits. A tunnel drainage simulator was constructed to determine the feasibility of using magnets to inhibit scale precipitation and deposition. Test results from the simulation show 6.0 and 4.4 g of deposited calcium carbonate in pipes inclined at 2° and 5° respectively, while magnetically treated water resulted in 10.8 and 4.3 g of deposited calcium carbonate in pipes inclined at 2° and 5° respectively. Calcium carbonate scale samples from the tunnel drainage test underwent x-ray diffraction analysis and showed the magnetically treated water to precipitate more aragonite. The solubility product and crystalline structures of calcite and aragonite are able to help explain tunnel drainage test results and suggest water flow velocity to be a potentially important factor in calcium scale inhibition if magnets are used.

Abstract: Sodium silicate has been widely used as starting materials of chemical grout owing to its feasibility and short setting time with reasonable strength. Elution of sodium has been pointed out as the main reason of weak durability of homogel prepared with sodium silicate-cement grout. There are well known series of additives for controlling its setting time, fluidity, and compressive strength. We studied the structural change on the sodium silicate with additive of sodium tripolyphosphate (STPP) by 29Si nuclear magnetic resonance spectrum and viscosity. The homogel was prepared by mixing cement/water suspension and diluted sodium silicate/STPP mixtures, and aged in the water. The development of compressive strength and its structural change were observed using a universal test machine, X-ray diffraction, and scanning electron microscope. The additive changed the distribution of Si and rheological property of liquid sodium silicate, which caused more uniform distribution of Ca and Si in the homogel to lead to high initial strength and durability.