PURPOSES : In this study, to improve the quality and construction performance of backfill materials for road excavation and restoration, the basic properties of rapid-hardening materials and stone sludge are analyzed to propose an optimal mix design. METHODS : To utilize rapid-hardening materials and stone sludge as controlled low-strength materials for pipeline construction in downtown areas, specimens were prepared for each compounding condition of fast-hardening materials. Flow, slump, and compressive strength tests were performed at various setting times. Subsequently, the physical and mechanical characteristics of the rapid-hardening backfill material for each mixing factor were analyzed. RESULTS : When ultrafast hardening cement and stone sludge are used, a setting time exceeding 30 min is required for a water–binder (W/B) ratio of 200% or higher. Considering the economic feasibility of ultrafast hardening cement, a W/B of 300% is considered the most suitable when high-performance superplasticizer and retarders are mixed. A flow test was performed on the rapid-hardening backfill material and the results show that if the mixing time exceeds 10 min, then the fluidity decreases rapidly, which necessitates a higher amount of superplasticizer. When ultrafast hardening cement is used, the initial strength (based on 4 h) is 0.7 MPa or higher for all formulations at a W/B ratio of 300%, and the compressive strength decreases slightly as the amount of superplasticizer is increased by 0.1%. CONCLUSIONS : Based on the fluidity and strength of the backfill material, which is composed of a rapid-hardening material and stone sludge, the most optimal performance is achieved when ultrafast-hardening cement with a W/B ratio of 300% is used in addition to a highperformance fluidizing agent 0.3% (wt./B) and retarder 0.2% (wt./B).

The basalt fiber is expected to become a trend for industrial fibers as they have better properties of heat-resistant, non-combustion, absorbent, soundproof, moistureproof, lightweight, corrosion resistant, and high strength properties. Also, the fiber is found to be non-toxic and harmless to the human body. Therefore, in this study, we analyzed the chemical and mineral compositions of powdered sludge of basalt produced at seven sites on Jeju Island for the development of fire resistance insulating material for a building. The results showed that the basalt stone sludge is made from only sodium calcium aluminum silicate and ferridioside components unlike the basalt rock.

일반적으로 보도블록은 주로 행인들이 이용하는 도로에 일정 크기와 형상으로 이루어진 블록체를 배열하여 먼지 등이 발생하는 것을 방지하고, 도로 미화를 위하여 설치된다. 이러한 보도블록은 다양한 종류의 재질로 제조되는데, 일반적으로는 콘크리트를 성형하여 제조한 콘크리트 블록이 많이 사용되고 있다. 그러나 콘크리트로 제조된 보도블록의 경우, 시멘트의 특성상 우천 시 빗물의 배수가 원활하지 않다. 콘크리트 보도블록은 쇄석 등의 골재와 모래 및 시멘트를 일정 비율로 혼합한 뒤 소정의 형상을 갖는 형틀에서 찍어낸 후 경화시켜 제조되는 블록이다. 콘크리트 보도블록은 형틀에 따라 다양한 형상으로 제작이 가능하다. 보행로나 인도 등에 서로 무늬나 형상을 서로 맞물리게 반복적으로 배열 설치되도록 지면 위에 모래를 깐 뒤 그 위에 밀착 고정시키게 되므로 대기와 지면 사이의 수분은 물론 공기도 거의 통과 될 수 없을 정도로 밀착 차단되고 내부 재질의 조직이 치밀하여 블록면에서는 어떠한 빗물이나 공기도 통과될 수 없게 된다. 종래의 콘크리트 투수블록은 강도와 투수율이 낮고 표층부의 골재 탈락이 발생하여 제품이 부분적으로 파손되는 문제가 있다. 이러한 문제점을 해결하기 위해서 시멘트를 많이 사용하면 강도는 좋아지나 투수율이 낮아지고, 투수율을 높이기 위해 시멘트를 적게 사용하면 강도가 낮아져, 표층부의 골재가 탈락하고 파손되는 문제점이 있다. 일반적으로 석재가공 공정 시 발생하는 석재 폐기물인 석재슬러지는 폐기물업자를 통해서 유상으로 버려지는 경우가 태반이다. 이런 폐기물을 재활용함으로서 고부가 자원화 기술을 통하여 친환경적 자원화에 기여하고 재활용 기술을 개발함에 있어 부가적인 응용기술개발이 가능하게 되었다.

This study was intended to estimate the effect of adding stone dust sludge into concrete strength characteristics. it was found that the partial replacement of fine aggregate with stone dust sludge had an positive effect on the strength of concrete.

This study was intended to estimate the effect of adding stone dust into cement mortar on the rheological properties. it was found that higher the content of stone dust decrease the yield stress but there was no noticeable correlation between stone dust dosage and the plastic viscosity.

In this research, Crushed-stone sludge obtained from production processing of crushed aggregates were recycled to manufacture artificial aggregate. Compressive strength , Elastic modulus, Splitting strength, Flexural strength and freeze/thaw, Carbonation test were conducted for artificial aggregate concrete. The results showed that compressive strength and freeze/thaw and depth of carbonation resistance of concrete using crushed-stone sludge aggregate were higher than those of concrete using normal crushed stone. but elastic modulus, splitting and flexural strength were lower than those of concrete using normal crushed-stone