산업부산물을 이용한 친환경 지반재의 제조와 활용에 관한 연구

Abstract

The purpose of this study is to develop a technology for the industrial by-products reuse by chemical immobilization mechanism than that by a simple physical substitution of ground solidifying agent. The eco-friendly material was developed that can prevent environmental pollution and generate high value-added construction material in future. In addition, the hydration mechanisms of the paper ash and the irritant were investigated. We reduced the usage of cement for environmentally friendly reducing inorganic binders and industrial by-products. We evaluated the sludge ash recycle paper based on the low-recycling rate with high-performance construction material. It minimized the pollution of land environment caused by waste, and developed the methodologies for reuse of organic and inorganic sludge and marine dredging sludge.

In this study, the usage of most common cement for the ground material was highly reduced, and developed a solidifying agent for organic and inorganic sludge using the by-products of the paper sludge ash. The physical and chemical properties of paper sludge ash were evaluated by ternary component analysis, XRF, particle size analysis and SEM imagination. The solidifying agent was investigated by ammonia contents, compressive strength, permeability coefficient, environmental hazard, analyses of heavy metals and hazardous materials. The KS performance criteria were applied and the following results were concluded: 1. Regarding for the fire resistance of paper sludge ash, the average moisture contents of paper sludge were 58.6 ~ 68.2%, VS average was 14.4 ~ 19.1% and FS average was 15.6 ~ 22.4%. The moisture contents of the paper sludge ash were 12.0 ~ 15.0%. The grain size of the paper sludge ash was not significantly different each other, the gap was less than 50㎛. The smooth spherical particles and wave form particles were mixed, and their incinerator classification presented 72% and 24% of coarse and fine powder, respectively. 2. The CaO contents of paper sludge ash were 48.0 ~ 60.0%, which was suitable for solidification of organic and inorganic sludge with high water contents. The chloride immobilization effect of paper sludge ash was similar with that of blast furnace slag cement regardless of chloride content, and was superior to OPC (ordinary portland cement). 3. The acidic physical properties of blast furnace slag contained 34.0% SiO2, 42.0% CaO, 15.0% Al2O3 and 4.7% MgO in the form of fine powder. The pH of industrial by-product was 1.5 ~ 2.5 that used for controlling pH of the paper sludge ash. The SO3 was the highest as acidic powder (20.4%). 4. The powder grade of eco-friendly solidifying agent was 4,000cm2/g, and contained 53.8% of CaO, 10.8% of SiO2, 8.1% of Al2O3 and 7.3% of SO3. It was possible to substitute for quicklime, cement and iron sulfate existing in the products, and to expect the excellent performance. 5. As the evaluation of the solidification materials as for landfill, the concentration of initial ammonia gas in the sewage sludge was 20ppm, which was about 20% for comparing the fire-resistance cement. In the case of re-slurrying of solidified material, the supernatant was clear and the material was solidified, so that no sludge formation occurred. The uniaxial compressive strength (30% of solidifying agent) of sewage sludge was 1.45㎏/㎠ on the 7th day, and the permeability coefficient ranged from 2×10-4 to 2×10-6cm/sec. The pH value decreased to 10.5 ~ 12.0 when the acid content was increased. The low pH of solidifying agent suppressed heavy metal immobilization and inhibited the release of heavy metal (Cu, Cr). 6. The durability of the dredged soil was 0.9 MPa at 3 days, 1.2 MPa at 5 days, 1.4 MPa at 7 days, 3.0 MPa at 28 days, and the strength enhancement rate at 28 days from 7 days was 2.1. The durability of marine dredged soils was very high because it had Cl- resistance. As a result of the environmental hazard analysis, all items showed no detection, and the KS criteria were satisfied in powderiness, degree of coagulation, stability, compressive strength and chemical composition.