폐콘크리트 파쇄시 발생하는 재생잔골재의 품질을 검토하였으며, 재생잔골재를 활용한 모르타르의 압축강도, 휨강도 및 흡수율을 검토하였다. 또한, 프리캐스트 콘크리트 제품용 골재로서의 적용성에 대하여 평가하였다. 재생잔골재의 밀도 및 흡수율은 각각 $2.31\;g/cm^3$ 및 8.07%로 KS F 2573의 2종에 해당되는 품질이었다. 혼합시멘트 MRS1, MRS2 및 MRS3 사용 모르타르의 재령 28일 압축강도는 물-시멘트비 35%, 양생온도 $40^{\circ}C$ 의 조건에서 각각 15.8, 27.4 및 48.7MPa로 최대값을 발현하였다. 모르타르의 최대휨강도는 혼합시멘트 MRS1 및 MRS2 사용시 물-시멘트비 35.0%, 양생온도 $40^{\circ}C$ , 혼합시멘트 MRS3사용시 물-시멘트비 37.5%, 양생온도 $40^{\circ}C$ 의 조건에서 발현하였다. 혼합시멘트 MRS1, MRS2 및 MRS3를 사용한 모르타르의 흡수율의 범위는 각각 $8.3{\sim}7.3%,\;6.5{\sim}8.5%$ 및 $3.5{\sim}6%$ 의 범위로 나타났다. 그러므로 혼합시멘트와 재생잔골재의 비율을 적절히 조절함으로써 MRS1는 저강도용, MRS2는 보통강도용, MRS3는 고강도용으로 다양한 프리캐스트 콘크리트 제품에 적용될 수 있을 것으로 기대된다. 【The duality of recycled fine aggregate (RS) which was produced at the waste concrete crushing was investigated. The compressive strength, flexural strength and absorption of mortar utilized with RS were examined. It was evaluated on the application of RS as precast concrete aggregate. The density and absorption of RS were $2.31g/cm^3$ and 8.07% respectively, the quality of RS was satisfied with the criterion of KS F 2573 type 2. The maximum 28days compressive strength of mortar mixed with blended cement MRS1, MRS2 and MRS3 were developed with 15.8, 27.4 and 48.7MPa respectively, in condition to curing temperature $40^{\circ}C$ and water-cement ratio 37.5%. When blended cement MRS1 and MRS2 were used, the maximum flexural strength of mortar was developed at curing temperature $40^{\circ}C$ and water-cement ratio 35.0%. When blended cement MRS3 was used, the maximum flexural strength of mortar was developed at curing temperature $40^{\circ}C$ and water-cement ratio 37.5%. The absorption of mortar mixed with blended cement MRS1, MRS2 and MRS3 were indicated the range of $8.3{\sim}7.3%,\;6.5{\sim}8.5%$ and $3.5{\sim}6%$ respectively. Therefore, when the ratio of blended cement and RS is appropriately centre]led, it would be expected that MRS1, MRS2 and MRS3 will be able to apply the variable low strength, medium strength and high strength precaste concrete.】
Prior Environmental Review System was introduced for the assesment of administrative plans mainly concerned with development projects. This study was conducted on a survey among the agents, researcher, a worthy scholar and public service personnel in order to the improvement of Prior Environmental Review System. Besides this study was reviewed on theoretical concepts and documents for Prior Environmental Review System. Administrative plans and development programs which are stipulated for Prior Environmental Review System in the Basic Environmental Policy Act and other laws were thoroughly investigated. As about the ways of improving Prior Environmental Review System, there were many suggestions from the view of system, management and documents. The result should be conducted on a comprehensive review of Prior Environmental Review System.
기계공업의 발달로 인해 다량 발생하고 있는 폐절삭유는 기존의 증발법(Evaporation)과 역삼투압법(Reverse Osmosis)이 처리방법으로 사용되고 있었으나 많은 처리비용이 소요되어 무단방류 및 불법매립등으로 환경오염이 가중되고 있으며, 정상적인 처리과정에서도 또 다른 폐기물의 발생과 대기오염등의 2차 환경오염이 발생하고 있다. 이에 따라 본 연구에서는 폐절삭유 처리시 환경적으로 안정하며 처리비용을 대폭 감소시킬 수 있는 방안을 강구하였으며 이에따라 물리ㆍ화학적 처리방법을 사용하여 높은 처리효율을 얻기 위하여 노력하였다. K자동차사에서 발생된 고농축 절삭폐유를 산분해방법에 의한 응집분리와 전기화학방법을 이용하여 처리한 결과 수질환경오염의 척도로 사용되고 있는 COD측정에서 9000ppm 고농도 폐절삭유를 2000ppm이하로 약80%의 높은 처리효율을 얻었으며 수용성 폐절삭유에 함유된 Oil 성분을 100% 제거할 수 있어 위의 방법이 낮은 처리비용으로 높은 처리효율을 갖는 폐절삭유 처리방법 이라는 결론을 얻었다. 또한 처리과정중에 발생하는 슬러지도 건조후 소각장등의 보조연료로 사용이 가능하고, 연소과정에서 석회석으로 안정화된다고 판단되므로 슬러지까지도 재활용이 가능한 경제적 처리방법이라는 것을 증명할 수 있었다. 전기화학 처리방법에서 처리 시간과 전류에 따른 효율에서는 일반적으로 전류가 높을수록, 반응시간이 길수록 높은 처리 효율을 보였다.
Due to the tendency of increase in demolished-concrete produced by alteration and deterioration of concrete structures, recycling of those demolished-concrete is necessary to solve the exhaustion of natural aggregate, in order to save resources and protect environment, especially being want of resources in Korea. For this purpose, concrete made with the pozzolanic cement and recycled aggregate was tested for compressive and tensile strength. The pozzolanic cement was a mixture of OPC(Ordinary Portland Cement) and pozzolans such as fly ash, other siliceous materials and early rapid hardening cement(ERC). It was found that the compressive strength of the pozzolanic cement was enhanced when 0.75% of ERC was dozed, as compared with OPC mortar. It was also shown that compressive and tensile strength of concrete with recycled aggregate and pozzolanic cement were higher than those of concrete with crushed stones and OPC. It was concluded that the pozzolanic cement influenced on the increase of concrete strengths with recycled aggregate.
'%3e%3cg id='b'%3e%3cpath id='a' stroke='%23000' stroke-width='2' d='M-6-25H6m-12 3H6m-12 3H6'/%3e%3cuse xlink:href='%23a' y='44'/%3e%3c/g%3e%3cpath stroke='%23fff' d='M0 17v10'/%3e%3ccircle r='12' fill='%23cd2e3a'/%3e%3cpath fill='%230047a0' d='M0-12A6 6 0 0 0 0 0a6 6 0 0 1 0 12 12 12 0 0 1 0-24z'/%3e%3c/g%3e%3cg transform='rotate(-123.69)'%3e%3cuse xlink:href='%23b'/%3e%3cpath stroke='%23fff' d='M0-23.5v3M0 17v3.5m0 3v3'/%3e%3c/g%3e%3c/svg%3e)
'%3e%3ccircle r='120' fill='%230f47af'/%3e%3cg id='a'%3e%3cpath fill='%23fcdd09' d='m0-96-4.206 12.944 17.348 53.39h-23.13l-2.599 8h74.163l11.011-8H21.553z'/%3e%3cpath stroke='%23fcdd09' stroke-width='4' d='m25.863-35.597 30.564-42.069'/%3e%3c/g%3e%3cuse xlink:href='%23a' transform='rotate(72)'/%3e%3cuse xlink:href='%23a' transform='rotate(144)'/%3e%3cuse xlink:href='%23a' transform='rotate(216)'/%3e%3cuse xlink:href='%23a' transform='rotate(288)'/%3e%3c/g%3e%3c/svg%3e)