Seung Ho Lee

Modification of Natural Zeolite Powder and Its Application to Interior Non-Woven Textile for Indoor Air Quality Control

The application of VOC-free materials for building interior is the first step to reduce the contamination level, however, it is practically unavoidable to find a way to eliminate existing pollutants from furniture, adhesives, etc. As a positive way of controlling the air indooors, the air conditioner may be applied with high functional filter, which uses electricity for compulsory air circulation. As an alternative, we modified natural zeolite powder by ion exchange and also by addition of TiO2 photo-catalyst for multifunctional powder to contribute to controlling the indoor air quality. The modified zeolites were applied on the interior non-woven polypropylene sheet to reduce indoor air pollutants not only by adsorption mechanism but also by decomposition mechanism. We studied deodorization of the multi-functional powders and also their coating on non-woven textiles by a Gastec method.

The Effect of Sodium Tripolyphosphate on Sodium Silicate-Cement Grout

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.

Application of Zeolites on Cellulose Fiber

Zeolites with different sizes and structures were applied on the surface of cellulose fibers with organic and inorganic binders. The effects of zeolite structure and size and choice of binder on the deodorization rate have been studied. The smaller the particle size, the more effective the deodorization rate of both the zeolite coated cellulose fibers and the powder itself. The deodorization rate depends on both the type and amount of inorganic binder. A silica based inorganic binder revealed higher efficiency on deodorization than silicate based inorganic binder and also higher than organic binders.

Correlation of Physical Properties of Inorganic Carrier and Microbial Survival Rate

Physical properties of various inorganic materials have been measured in terms of pore size distribution and porosity, BET surface area by nitrogen adsorption, pH, ion conductivity, and concentration of ions after elution test. The microbial survival rate and their stability have been monitored in every 10 days during 120 days by dilution plating method. The correlations between physical property of the inorganic carrier and microbial survival rate have been examined for the better preparation of microbial fertilizer. Average size of pore, and concentration of soluble ions were unequivocal factors affecting on microbial survival rate but BET surface area, average porosity, and ion conductivity revealed the equivocal correlation with microbial survival rate. Higher concentration of soluble ions gives lower survival rate and inorganic carriers with high microbial survival rate seemed to have preferred range of pore size.

Effect of Microwave Heating on the Synthesis of Layered Double Hydroxide

Layered double hydroxide(LDH) was synthesized from the mixture of magnesium hydroxide and aluminum hydroxide with microwave irradiation. It has been compared with that of conventional heating method in the respect of crystallization time, structure, morphology, particle size, and its anion exchange capacity. The microwave speeded up the crystallization rate of Mg-Al- LDH so that the XRD patterns of LDH was observed from the sample after microwave hydrothermal treatment, while the crystal phase was hardly observed from that prepared by conventional hydrothermal method before drying process. Mg-Al-LDH prepared with microwave irradiation seemed to have slightly higher Mg/Al molar ratio even with the same compositions of starting materials and the lower anion exchange capacity after 1 day exposure in 0.1N NaCl solution compared to the conventionally prepared one.

Estimation of Depth of Concrete Column Members Using Impact Echo Method

In order to maintain the existing concrete structures in a safe and usable state, an overall maintenance management is necessary regarding structure aging from quality management of new construction. Thus, non-destructive testing is needed to estimate the structure damage, defect, or proper construction without damaging the structure. In U.S., there is a standard for non-destructive test (ACI 228.2R-98), and also in Japan, the non-destructive test method and compressive strength estimation manual was prepared by the Architectural Institute of Japan in 1983, and there are active researches in the ground field, but it lacks verification in architecture field. Thus, in this study, a technique that can estimate the depth of concrete column member using the Impact Echo method which is one of the non-destructive test methods shall be reviewed and evaluated for applicability to the architecture field. The specimen was mixed with design strength of 30MPa. The equipment used in testing is Freedom Date Pc Platform Win.TFS 2.5.2 by company Olson of U.S., and the experiment involved leveling the top surface of the concrete member, installing the equipment and applying impact 9 times, and taking the average of the reverberation values obtained. The estimated average depth of concrete column member using Impact Echo method was 304mm for IEC-300, 398mm for IEC-400, and 484mm for IEC-500, and the relative error rate compared to the actual size was 1%~3%. Through this study, the applicability of estimation of depth in concrete column members using impact echo method could be confirmed.

A Comparative Study of Compressive Strength of High Strength Concrete by Replacement Ratio of Recycled Coarse Aggregate

As the industrial development brings the structures growth, the consumption of the natural aggregate is increasing annually. On the other hand, the amount of the potential aggregate is decreasing with the huge amount of construction waste from the concrete demolition. The annual total amount of natural aggregate consumption estimated 370million tons. And the experts are concerned about the depletion of aggregate which is presumed to be exhausted in 20 years, considering the annual consumption, which is approximately 250million(m³) in construction industry. Along with this issues, the government promotes to use recycled coarse aggregate from the construction waste in consideration of social, economic and environmental aspects. In conclusion, the purpose of this study is to promote to use of recycled coarse aggregate as a future substitute resource and to increase awareness of it as well. This study conducts the experiments by comparing high-strength concrete for the substitution of chosen two companies.

Effect of Phosphorus or Boron Addition on Water-Resistance of Water-Glass Adhesives

Water glass adhesives based on sodium silicates have been modified by addition of phosphorous or boron. In the preparation of sodium silicate, mixtures of silica sand and sodium carbonate with the additives was melted at 1400°C. They were dissolved in an autoclave at 180°C, and then concentrated to have a final viscosity for the comparison of their adhesive property and water resistance with the conventional liquid sodium silicates without additives in SiO 2 /Na 2 O molar ratio 2.5∼4.2. Obvious increase of the water resistance was observed for the liquid sodium silicate samples with the 5% P 2 O 5 or B 2 O 3 additives in the solid contents without loosing its adhesive property.