하수슬러지를 이용한 건축물 되메움용 저강도 콘크리트의 개발 = Development of Building Back Filling Controlled Low Strength Concrete Used Sewage Sludge

국문 초록 (Abstract)

CLSM(Controlled Low Strength Materials: 이하, 저강도 콘크리트)은 시멘트계 슬러리 재료로서 ACI Committe 229(1994)에서는“재령 28일의 압축강도가 8.3N/mm2 이하로 될 수 있게 제어된 슬러리계의 되메움 재료”로 정의하고 있다. 또한, 일본에서는 제어된 저강도 재료의 의미로서“제어형 저강도 재료”또는“저강도 제어 재료”로 정의되고 있는 유동화 처리토의 일종이다. 국내의 경우 토목 및 지반개량공학 분야를 중심으로 유동성 충전재 및 유동성 모르타르, 소일시멘트(Plastic Soil-Cement) 등 여러 가지 의미로 사용되어 왔으나, 최근에 들어서는 저강도 재료의 개념을 확대하여 건축·토목 및 지반개량공학 분야를 중심으로 저강도 콘크리트로 개념을 정의하여 사용하고 있다.
저강도 콘크리트는 미국과 캐나다를 중심으로 한 북미의 경우 일반적으로 레미콘 공장에서 출하되고 있으며, 사용재료로는 보통포틀랜드시멘트, 물,잔골재 및 플라이애쉬(Fly Ash)가 주로 사용되고 있으나 잔골재를 사용하지 않는 경우도 있다. 한편, 일본의 유동화 처리토는 전용 플랜트 설비를 필요로 하고 있으나, 저강도 콘크리트는 전용의 플랜트 설비를 요구하지 않기 때문에
안전한 품질의 슬러리계 재료를 어디에서든 제조할 수 있는 범용성이 대단히 높은 재료이다. 저강도 콘크리트의 주사용 재료는 현 시점에서 FA가 주로 이용되고 있으나, FRP폐재, 유리폐자재 등의 각종 산업폐기물 및 고로슬래그 미분말(Blast Furnace Salg) 등의 산업부산물은 물론 쓰레기ᆞ하수오니
소각재 등의 도시형 리싸이클링 재료 또한 FA의 대체 재료로 충분히 검토해 볼 수 있다.
국내의 경우 다량의 산업부산물 및 폐기물 등의 재생자원을 재활용하여 적용한 사례가 선진외국에 비해 상당히 저조한 실정이나, 저강도 콘크리트의 가장 큰 특징은 다량의 산업부산물 및 폐기물, 리싸이클링 재료 등을 안전하면서도 유효하게 경제적으로 이용할 수 있다. 또한, 저강도 콘크리트는 고유동성, 자기경화성, 자기충전성 등의 우수한 성능을 가지고 있기 때문에
협소한 공간으로 다짐 작업이 어려운 건설현장 등의 되메우기 및 뒷채움재로 이용하면 대단히 효과적이므로 건축 및 토목분야에서의 광범위한 적용이 가능한 슬러리계의 재료이다.
이에 본 연구에서는 탈수 및 소각처리를 실시한 하수슬러지를 환경부 폐기물 공정시험에 의거하여 유해물질 함유량 분석 및 용출시험의 실시를 통해 주변 환경에 유해한 영향을 미치지 않는 분말 형태의 친환경 하수슬러지를 활용한 저강도 콘크리트의 새로운 적용가능성에 대해 다방면으로 검토하고자 한다. 이를 위해 지금까지 하중을 지지하지 않는 구조물의 되메움재로 주로 적용되어 왔던 저강도 콘크리트를 건축구조물에서의 되메움재로 적용하여 부력 방지를 통한 Rock Anchor 대체 및 바깥 방수층보호 등 새로운 용도로 개발하고자 한다. 더 나아가 저강도 콘크리트의 선시공을 통한 수압 및 토압방지 또한, 지하구조물의 외벽주변을 매립함으로써 절토구간이 웅덩이처럼 되는
Ponding Effect를 최소화하는 시공방법으로 지하수위 제어가 가능한 저강도 콘크리트의 새로운 적용 가능성을 실험을 통해 구체적으로 검토하고자 한다.
이를 위해 본 연구에서는 FA+SS 및 BFA+SS를 활용한 저강도 콘크리트의 공학적 특성 및 현장 적용성, 환경오염 영향 평가를 실시하여 다음과 같은 결론을 얻었다.
(1) FA를 분체로 사용하고 잔골재로 각각 S와 SS를 사용한 저강도 콘크리트의 경우 재료분리방지 및 최소단위수량 확보를 통한 유동성 개선과 블리딩 억제를 통한 최대강도를 확보하기 위해서는 FA+S의 배합은 f/a 20, FA+SS의 배합은 f/a 60이 가장 합리적인 최적의 배합방법으로 확인되었다.
(2) CSF를 분체로 사용하고 잔골재로 각각 S, SS, SP, SS+SP를 사용한 저강도 콘크리트의 경우 CSF+S f/a 20, CSF+SS f/a 50, CSF+SP f/a 30으로 설정하는 것이 가장 합리적인 배합방법으로 나타났다. 한편, CSF+SS+SP의 경우는 f/a 50이 가장 합리적인 최적의 배합방법으로 확인되었다.
(3) BFS 및 SS를 활용한 저강도 콘크리트의 경우 분말도 6000 이상의 BFS를 30% 범위에서 치환하여 혼입할 경우 최소 단위수량을 확보를 통한 유동성 개선 효과에 가장 유효할 것으로 나타났다. 또한, 사용 잔골재의 차이에 블리딩율의 억제를 통한 현장 적용을 위해서는 BFS의 분말도에 상관없이 치환율을 30%
범위에서 혼입하는 것이 가장 합리적인 배합방법으로 확인되었다.
(4) BFS 및 SS를 혼입한 저강도 콘크리트의 일축압축강도 결과에서는 BFS 4000의 경우 치환율 증가에 따른 급격한 강도 저하로 배합단계에서의 단위시멘트량 증가를 통한 목표 강도의 설정이 필요한 것으로 확인되었다. 하지만, 분말도 6000 이상을 혼입한 경우는 본 실험에서 현장 적용을 위한 목표 강도 기준치
0.3 MPa 이상을 상회하는 것으로 나타났다. 본 연구의 결과에서는 사용 잔골재의 차이에 상관없이 현장 적용을 위한 최소강도 기준치를 상회하는 범위에서 일축 압축강도를 얻기 위해서는 BFS 분말도 6000을 30% 범위에서 치환하여 혼입하는 것이 가장 합리적인 배합방법으로 확인되었다.
(5) BFS 및 SS를 혼입한 저강도 콘크리트의

다국어 초록 (Multilingual Abstract)

This study reviews versatilely on new possibilities of application of CLSM using eco-friendly powdered sewage sludge not having harmful influences on adjacent environments through analysis and elution test of hazardous elements based on the official waste test
method by the Ministry of Environment on sewage sludge treated with dehydration and incineration.
(1) For the CLMS using FA as powder and S and SS as fine
aggregates, respectively, in order to improve flowability by
preventing material separation and securing quantity of minimum unit and to secure maximum strength by repressing bleeding, the most reasonable and optimal combinations of FA+S and FA+SS were f/a20 and f/a 60, respectively.
(2) For the CLSM using CSF as powder and S, SS, SP and SS+SPas fine aggregates, respectively, the most reasonable combinations of CSF+S, CSF+SS and CSF+SP were f/a 20, f/a 50 and f/a 30, respectively. And for CSF+SS+SS, f/a 50 was the most reasonable combination.
(3) For the CLMS using BFS and SS, in case of mixing by replacing BFS with fineness over 6000 in 30%, it was most effective on improving flowability through securing quantity of minimum unit. And in order to apply to the field by repressing bleeding rate on differences of fine aggregates used, the most reasonable combination was to mix with replacing in less than 30% regardless of fineness of BFS.
(4) As the result of uniaxial compression strength test on the CLMS mixing BFS and SS with BFS 4000, it required to determine the desired strength through increasing unit quantity of cement in mixing process because of dramatic strength deterioration of strength according to increasing replacing rate. In this study's result, regardless of differences in fine aggregates used, in order to get uniaxial compression strength in the scope exceeding criteria of
minimum strength for applying to the field, the most reasonable combination was to mix replacing BFS with fineness of 6000 in 30%.
(5) For the CLMS mixing BFS and SS, in order to improve
flowability by securing quantity of minimum unit and to repress bleeding rate with securing uniaxial compress strength considering the field applicability, regardless of differences in fine aggregates used, to mix BFS over 6000 in 30% was most effective.
(6) In order to secure constructability and compactability required for cement grouting in building structures with CLMS using FA and SS, to mix crushed stone fines was effective. And in case of using BFS, constructability and compactability of the CLMS using fineness 6000 showed the most excellent result.
(7) For the CLMS using FA and SS, in order to secure safety required for cement grouting in building structures, to determine weight of unit volume over 2.0(g/cm3) and bleeding less than 2% for repressing surface settlement was reasonable. For BFS and SS, regardless of fineness of BFS, based on replacing rate of 30%, to determine weight of unit volume over 2.0(g/cm3) and bleeding less
than 2.5% for repressing surface settlement as alternative to
replace Rock Anchor for rock anchoring was also reasonable.
(8) In order to apply as outer water-proof protection of building structure for new use of the CLMS using SS, for both cases of the CLMS using FA+SS and BFS+SS, the most reasonable combination was to determine uniaxial compression strength(28 days) over 0.3MPa for requirement for securing resistance and durability on
permeation from outside in scope no destruction of concrete and compression settlement of the CLMS by surface and live loads.
(9)As the results of analysis and elution test of hazardous elements of soil cement using SS, values of hazardous heavy metal ions including Cr, As, Cd, Pb and Hg were far less than the environmental criteria. From these results, soil cement using SS barely has influences on the adjacent toil and water environments.

목차 (Table of Contents)

• Ⅰ. 서론
• 1.1 연구의 배경 및 목적 ···················································································· 1
• 1.2 연구의 범위 및 방법 ··················································································· 6
• 1.3 연구의 구성 ··································································································· 7
• Ⅱ. 이론적 고찰
• 2.1 하수슬러지의 발생 및 처리현황 ······························································· 9
• 2.1.1 하수슬러지의 특성 ················································································ 9
• 2.1.2 하수슬러지 발생 및 처리현황 ························································· 12
• 2.2 하수슬러지 처리의 국외 사례 ································································· 21
• 2.2.1 일본의 하수슬러지 처리 ··································································· 21
• 2.2.2 미국의 하수슬러지 처리 ··································································· 23
• 2.2.3 유럽의 하수슬러지 처리 ··································································· 24
• 2.2.4 중국의 하수슬러지 처리 ··································································· 25
• 2.3 하수슬러지의 처리공법 ············································································· 26
• 2.3.1 열을 이용한 처리공법 ······································································· 26
• 2.3.2 하수슬러지의 퇴비화 처리공법 ······················································· 33
• 2.3.3 하수슬러지의 감량화 ········································································· 34
• 2.4 하수슬러지의 정책방향 ············································································· 35
• 2.4.1 해양에서의 하수슬러지 처리정책 ··················································· 35
• 2.4.2 육상에서의 하수슬러지 처리정책 ··················································· 39
• 2.4.3 하수슬러지 적정처리의 문제점 ······················································· 41
• 2.4.4 정부의 정책방향 ················································································· 42
• Ⅲ. 하수슬러지를 활용한 저강도 콘크리트의 공학적 특성
• 3.1 실험계획 ······································································································· 44
• 3.1.1 사용재료 ······························································································· 44
• 3.2 실험방법 ······································································································· 50
• 3.2.1 공시체 규격 및 배합, 양생 ······························································ 50
• 3.2.2 실험항목 ······························································································· 54
• 3.3 결과 및 분석 ······························································································· 60
• 3.3.1 FA 및 SS를 활용한 저강도 콘크리트 ·········································· 58
• 3.3.2 BFS 및 SS를 활용한 저강도 콘크리트 ········································ 68
• 3.4 소결 ···································································································75
• Ⅳ. 현장적용성 평가
• 4.1 시공성 평가 ································································································· 77
• 4.1.1 FA 및 SS를 활용한 저강도 콘크리트 ·········································· 77
• 4.1.2 BFS 및 SS를 활용한 저강도 콘크리트 ············