PURPOSES : It is to evaluate lightweight soil as a subgrade material based on mechanical tests and calculation of pavement performance. METHODS : In this research, various contents of cement and air foam are used to make lightweight soil using wasted dredged soil. Uniaxial compressive strength test is conducted to evaluate strength of 7 and 28 day cured specimens. Secant modulus was calculated based on the stress and strain relationship of uniaxial compressive strength test. Resilient modulus test was measured using by repeated triaxial compression test. The measured resilient modulus was used in layered elastic program to predict fatigue and rutting life at a given pavement structure. RESULTS : Uniaxial compressive strength increases as cement content increases but decrease as air foam content increases. Resilient modulus also increases as cement content increases and decrease as air foam content decrease. CONCLUSIONS : It is concluded that dredge clay soil can be used as subgrade layer material using by lightweight treated soil method.

Background : Multi-stage system were used for development of stable ginseng seedling production. Bed-soil for the production of ginseng seedling in the multi-stage was similar to the conventional bed-soil but the weight of the bed-soil was high and the efficiency of operation in the multi-stage was lowered. In this study, the yield and quality of ginseng seedling was investigated by commercial lightweight bed-soil in the multi-stage facilities, and the possibility of application of lightweight bed-soil. Methods and Results : This study was carried out by a 3-stage cultivation bed using a 50 ㎜ sandwich panel in a house shaded with 85% light-shielding net. The width of the cultivating bed was 90 ㎝, the height was 30 ㎝, and the height of each stage was 50 ㎝. In the first and second stages, the amount of light was insufficient, so two rows of fluorescent lamps were installed and the third stage was used natural light. Ginseng seeds were sown on the cultivating bed in November 2016, and ginseng seeds (native species) were sown with a density of 3 × 3 ㎝. The chemical properties of lightweight bed-soil were pH 5.11, and EC 0.76 dS/m. It was suitable for ginseng seedling cultivation. The bulk density was 0.21 Mg/㎥. Among the growth characteristics of the ginseng seedlings, the root length was the longest as 17.0 ㎝ in the conventional cultivation, and the second stage was the longest at 14.8 ㎝ in the multi-stage facility. The root diameter in the multi-stage system was 0.2 - 0.4 ㎜ thicker than the conventional one. Root weights of lightweight bed-soil were similar to those of conventional cultivation. The yield of ginseng seedlings in the 1 st, 2 nd and 3 rd stage was 721.3 g, 692.0 g, and 394.7 g/1.62 ㎡ respectively. Conclusion : In the production of ginseng seedling using multi-stage facilities, the commercial bed-soil was better than the conventional bed-soil (light, workability). The differences in yields in the multi-stage facilities can be overcome if the growth management such as moisture management is more systematic. If we develop the technology to reuse the bed-soil after harvesting the ginseng seedling, it will be economical and able to supply to farmers.

This study is about making artificial soil for wall greening using Spent Mushroom substrates (SMS) & Superabsorbent polymer (SAP). and developing new material for wall greening whilst monitoring the physico-chemistry & germination ability of the plant, plant growth and developmental condition of the artificial soil. It was found that the larger the particle size of the superabsorbent polymer the more absorption increased. This showed the plant’s germination rate in soil when Spent Mushroom substrates & Superabsorbent polymer (SAP) were mixed. In the Bermuda grass, the Artificial soil (SMS & SAP 0.5%) showed a 100% germination rate over a period exceeding 7 days compared to Peat-moss that showed a 94% germination rate. In the Kentucky blue grass, however, there was no difference between the Peat-moss and Artificial soil. When general perlite soil was compared with artificial soil in the chicory seed, the Artificial soil showed better results than the general perlite soil in length, leaf volume and fresh-weight. In the plant length, it showed an increase of over 105% (SAP 0.5% or more), 187% (SAP 1% or more). in the leaf volume, an increase of over 123% (SAP 0.5% or more), 145% (SAP 1% or more), in the fresh-weight an increase of over 130% (SAP 0.5% or more), 285% (SAP 1% or more). The artificial soil (SMS & SAP 1%) showed an excellent result in the plant growth and development. Thus, it was found that artificial soil using the SMS & SAP were the only suitable soil materials for wall greening hence suggesting that it could be used for the greening of a blighted area or desert and a variety of agriculture.