• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.22 no.1
• /
• pp.47-59
• /
• 2019

This study was composed of four treatments [no treatment, phosphate + limestone layer treatment, phosphate + sodium bicarbonate + cement layer treatment, and phosphate + sodium bicarbonate + limestone layer treatment] for figuring out vegetation effects on the acid drainage slope. Treated acid neutralizing techniques were effective for neutralizing acidity and vegetative growth in order of [first: phosphate + sodium bicarbonate + limestone layer treatment, second: phosphate + sodium bicarbonate+cement layer treatment, third: phosphate + limestone layer treatment and fourth: no treatment] on the acid drainage slope. We found out that sodium bicarbonate treatment was additory effect on neutralizing acidity and increasing vegetaive growth besides phosphate and neutralizing layer treatments. In neutralizing layer treatments, Limestone layer was more effective for vegetation and acidity compared to cement layer treatment. Cement layer showed negative initial vegetative growth probably due to high soil hardness and toxicity in spite of acid neutralizing effect. Concerning plants growth characteristics, The surface coverage rates of herbaceous plants, namely as Lotus corniculatus var. japonicus and Coreopsis drummondii L were high in the phosphate + sodium bicarbonate + limestone layer treatment while Festuca arundinacea was high in the phosphate + sodium bicarbonate + cement layer treatment. We also figured out that soil acidity affected more on root than top vegetative growth.

• Journal of the Korea Furniture Society
• /
• v.14 no.2
• /
• pp.31-38
• /
• 2003

This study was carried out to investigate characteristics of wood-based panels and wood-cement board for the possible uses as flooring and wall materials. The optimum cement/wood ratio(C/W ratio) of wood~cement board manufactured by clamp-pressing was from 2.7 to 3.2. The dimesional stability was superior in the C/W ratio of 3.2. Particularly, the dimensional stability of cement board using fine particle for particleboard face layer was favorable through three levels of C/W ratio. According to types of wooden material, bending strength of cement board using coarse particle for particleboard core layer or old newspaper(ONP) fiber was relatively higher than others. Thermal conductivities of wood-cement boards were no lower than that of gypsum board, and higher than those of plywood and boards. In case of wood-cement board of the C/W ratio of 2.7, the fire-proof performances of cement composite boards were greater than that of gypsum board, and weight loss reached to about a half of gypsum board. Then, wood-cement boards showed superior fire-proof performance compared to wood-based panels.

• Advances in concrete construction
• /
• v.2 no.4
• /
• pp.249-259
• /
• 2014

Mortar is a masonry product which is matrix of concrete. It consists of binder and fine aggregate and moreover, it is an essential associate in any reinforced structural construction. The strength of mortar is a special concern to the engineer because mortar is responsible to give protection in the outer part of the structure as well as at a brick joint in masonry wall system. The purpose of this research is to investigate the compressive strength and tensile strength of mortar, which are important mechanical properties, by replacing the cement and sand by stone dust. Moreover, to minimize the increasing demand of cement and sand, checking of appropriateness of stone dust as a construction material is necessary to ensure both solid waste minimization and recovery by exchanging stone dust with cement and sand. Stone dust passing by No. 200 sieve, is used as cement replacing material and retained by No. 100 sieve is used for sand replacement. Sand was replaced by stone dust of 15%, 20%, 25%, 30%, 35%, 40%, 45% and 50% by weight of sand while cement was replaced by stone dust of 3%, 5%, and 7% by weight of cement. Test result indicates that, compressive strength of specimen mix with 35% of sand replacing stone dust and 3% of cement replacing stone dust increases 21.33% and 22.76% respectively than the normal mortar specimen at 7 and 28 days while for tensile it increases up to 13.47%. At the end, optimum dose was selected and crack analysis as well as discussion also included.

• The Korean Journal of Ceramics
• /
• v.5 no.1
• /
• pp.35-39
• /
• 1999

For many years, alkali activated blast furnace slag cement containing no ordinary portland cement has received much attention in the view of energy saving and its many excellent properties. We examined the structural change of slag glass which was activated by alkali metal compounds using IR spectroscopy. The properties of hydrated products and unhydrated slag grains was characterized by XRD and micro-conduction calorimeter. Ion concentration change in the liquid during the hydration of blast furnace slag was also studied to investigated the hydration mechanism.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.4
• /
• pp.493-503
• /
• 2019

This study is composed of nine treatments [Control : "no neutralizing layer+vegetation layer" 3 cm, Treatment 1 : "no neutralizing layer+vegetation layer" 5 cm, Treatment 2 : "no neutralizing layer+vegetation layer" 7 cm, Treatment 3 :"neutralizing layer (cement 3 %)+ vegetation layer (cement 1 %)" 3 cm, Treatment 4 : "neutralizing layer (cement 3 %)+vegetation layer (cement 1 %)" 5 cm, Treatment 5 : "neutralizing layer (cement 3 %)+vegetation layer (cement 1 %)" 7 cm, Treatment 6 : "neutralizing layer [$(Ca{\cdot}Mg)CO_3$] +vegetation layer" 3 cm, Treatment 7 : "neutralizing layer [$(Ca{\cdot}Mg)CO_3$]+vegetation layer" 5 cm, Treatment 8 : "neutralizing layer [$(Ca{\cdot}Mg)CO_3$]+vegetation layer" 7 cm] to find out the vegetation effects according to neutralizing layer types of the acid drainage slope. There were no significant differences observed in soil hardness and soil moisture content of neutralizing layer type while highly difference of moisture content was observed according to the neutralizing and vegetation layer thickness. As for soil acidity, strong acid was shown in the control, treatment 1 and treatment 2. Neutralizing effects were outstanding in treatments of 3, 4, 5 (cement treatment group), 6, 7 and 8 (limestone treatment group). Concerning plants growth characteristics, surface coverage rates, number of germinating woody plants, plant height, and plant root status, there were excellent effects observed in the experimental groups mixed with cement (treatments 3, 4 and 5) and limestone (treatments 6, 7 and 8). At the initial stage, however, plant roots were negatively affected in cement layer treatments of 3, 4 and 5. However, no difference was shown in each layer thickness on the acid drainage slope whereas 3~5 cm thickness neutralizing layer was appropriate in consideration of economic feasibility.

• Restorative Dentistry and Endodontics
• /
• v.13 no.2
• /
• pp.307-322
• /
• 1988

The purpose of this study is to evaluate the pulpal responses to the base materials such as zinc oxide eugenol cement, calcium hydroxide, zinc phosphate cement, polycarboxylate cement and glass ionomer cement. The 100 caries free dog teeth were devided into 2 groups by remaining dentin thickness (Group A: 0.4-0.6 mm, Group B: 0.8-1.0 mm) and each group were devided into 5 subgroups. The intervals of observation period are 3days, 1 week, 2 weeks, 4 weeks and 8 weeks respectively after experiment. The specimens were fixed with 10% formalin and decalcifed in 5% nitric acid. All specimens were stained with Hematoxylin-Eosin and examined histopathologically. The results were as follows. 1. In group A, atropy or hyperplasia in odontoblasts were seen in zinc oxide eugenol cement, calcium hydroxide and zinc phosphate cement. No changes in odontoblasts were seen in polycarboxylate cement and glass ionomer cement. 2. In group A, increase of predentin were seen in all experimental materials. 3. In group A, vascular congestion were seen in all experimental materials and inflammation were seen on 3 days in zinc oxide eugenol cement, 8 weeks in zinc phosphate cement and hemorrage were seen on 3 days in zinc phosphate cement. 4. In group B, changes of odontoblasts were not seen all experimental materials. 5. In group B, increase of predentin and vascular congestion were seen in all experimental materials but inflammation were not seen.

• Cement Symposium
• /
• s.38
• /
• pp.51-56
• /
• 2011

• Cement Symposium
• /
• s.35
• /
• pp.90-97
• /
• 2008

• Cement Symposium
• /
• s.35
• /
• pp.159-166
• /
• 2008

• Cement Symposium
• /
• s.34
• /
• pp.73-79
• /
• 2007