PURPOSES: In order to evaluate a crack resistance at cold joint, sealing tape was adopted to apply at cold joint instead of typical tack coat material(RSC-4). The sealing tape was made by hot sealing material. The crack resistance as function of environmental and traffic loading was measured with visual observation. METHODS : In this study, the crack resistance was evaluated as function of environmental and traffic loading. The freeze-thaw method was adopted for environmental loading of asphalt pavement. condition. The damage of cold joint under freeze-thaw action is initiated by ice expansion load and accelerated by the interfacial damage between new and old asphalt pavement. The traffic loading was applied with wheel tracking machine on the cold joint area of the asphalt pavement for 3 hours at 25℃. The evaluation of crack resistance was measured with visual observation. The freeze-thaw results shows that the sealing tape was significantly increased the crack resistance based on. RESULTS : To estimate the crack resistance at cold joint area due to the environmental loading, the Freeze-thaw test was conducted by exposing the product to freezing temperature(approximately -18℃) for 24 hours, and then allowing it to thaw at 60℃ for 24 hours. The tack coat material(RSC-4) was debonded after 21 cycles of the Freeze-thaw test. The first crack was observed after 14 freeze-thaw cycle with RSC-4 material. But, the sealing tape was not debonded after 24 cycle test. Also, the sealing tape shows the better performance of the crack resistance under the traffic loading with wheel track test. The crack was generated the under traffic loading with RSC-4(tack coating), however, the crack was not shown with sealing tape. It indicates that the sealing tape has a strong resistance of tensile stress due to traffic loading. CONCLUSIONS: Based on limited laboratory test result, a performance of crack resistance using the sealing tape is better than that of general tack coat material(RSC-4). It means that the sealing tape is possible to extend a pavement service life because the crack, one of the main pavement distresses, will be delayed. Keywords Sealing Tape, Crack Resistance, Freeze-Thaw, Tensile Adhesion

This study is examining the potential benefits of routing in hot mix asphalt pavement prior to installing crack sealant. (1) Definition. Crack sealing and crack filling are two separate activities. While both crack sealing and crack filling involve placing sealants in pavement cracks, they differ in process. Generally, crack sealing is defined as using a router or saw to create a reservoir in a crack which is then filled with a sealant material. Crack filling is defined as minor crack preparation, such as using an air gun to blow debris out of cracks, prior to installation of the sealant. There is no pavement removed with crack filling. Additionally, crack sealing is performed on working cracks, whereas crack filling is generally the term used to refer to the treatment of nonworking cracks. (2) Implementation. Crack sealing should be carried out on structurally sound pavement which has low pavement distress. The pavement selection consideration should be based on pavement age, pavement and geometric design, pavement selection boundaries, traffic, type and extent of previous maintenance treatments and condition rating. The best candidates for crack sealing are newer pavements which are in the range of 1 to 3 years, and the majority of pavement distress can be found in terms of longitudinal or transverse having slight to moderate crack density. (3) Evaluation. The performance life of a treatment mostly depends on the preparation of crack and the type of the material used. One inspection should be made each year to chart the rate of failure and plan for subsequent maintenance. A mid winter evaluation is highly recommended as it will indicate treatment effectiveness when there is maximum pavement contraction and the crack is near the maximum opening. A small representative sample of the pavement, minimum of 150 m length should be selected for the evaluation. The first step in determining a treatment’s effectiveness is establishing how much of the treatment has failed in relation to the total length of treatment applied: Percent failure = (failed length after treatment / total length of treatment) × 100 After that the treatment’s effectiveness can be determined by subtracting the percentage of treatment failure from 100 percent: Effectiveness = 100 - Percent failure After a number of inspections a graph of effectiveness versus time can be developed. (4) Cost. Crack treatments can be considered as effective if it delays pavement deterioration and extends the pavement service life. Generally, the effective treatment extends the pavement life by two to five years. The effectiveness of rout and seal maintenance depends upon three points: (a) Performance of the sealant materials and appropriate rout width and depth; (b) restraining of crack development and delaying the existing pavement distress; and (c) crack treatment implication period. Chip seal treatment cost 3-14 times more than crack sealing and an overlay cost 8-26 times as much as crack sealing. The cost of crack sealing varies depending on state, materials, whether or not routing is required, and unit being priced.

This study proposes a multi-robot system, using multiple autonomous robots, to explore concrete structures and assist in their maintenance by sealing any cracks present in the structure. The proposed system employed a new self-localization method that is essential for autonomous robots, along with a visualization system to recognize the external environment and to detect and explore cracks efficiently. Moreover, more efficient crack search in an unknown environment became possible by arranging the robots into search areas divided depending on the surrounding situations. Operations with increased efficiency were also realized by overcoming the disadvantages of the infeasible logical behavioral model design with only six basic behavioral strategies based on distributed control-one of the methods to control swarm robots. Finally, this study investigated the efficiency of the proposed multi-robot system via basic sensor testing and simulation.

아스팔트 콘크리트 포장의 주요 파손 형태는 균열과 변형으로 나타나며, 균열은 다시 피로균열, 저온균열, 종방향 균열 및 시공이음부 균열로 구분할 수 있다. 이러한 균열을 통해 포장층으로 수분 유입이 가능하며, 포트홀과 같은 추가적인 포장 파손을 발생시키거나 균열의 진행 속도를 가속화 시킬 수 있다. 따라서 도로 포장의 유지관리 측면에서 적절한 시점에 균열의 유지보수를 수행한다면, 전단면 보수를 수행하지 않고도 포장의 수명을 연장 시킬 수 있다. 균열 보수 방법으로 아스팔트 바인더 또는 고무 계열의 재료를 사용하여 보수를 수행하지만 이러한 보수 재료들은 가열을 통한 작업 속도 및 소규모 균열에 대한 경제성이 낮다는 단점이 있다. 따라서 본 연구에서는 폴리머 개질 아스팔트 계열인 우레탄 개질 아스팔트 바인더를 통해 균열 보수를 상온에서 수행할 수 있는 재료를 개발하고자 도로 현장의 균열 파손부에 균열 보수 시험 시공을 수행하였다. 균열 보수는 서울과 경기도 수원 지역에 각 1개소씩 2개소에 대하여 2013년 4월에 시공하였으며, 7개월 공용 후 현장 점검 결과 일부 균열 실링 보수 부위에서 균열이 발생한 것을 확인 할 수 있었다. 현장에서 관찰된 실링 보수 재료의 균열은 우레탄 개질 아스팔트 바인더의 건조 수축보다 동절기 아스팔트 콘크리트 포장 표층의 수축에 의한 것으로 사료되며, 향후 온도 변화에 따른 수축 팽창에 관련된 성능 개선 및 현장 시공을 통해 추적조사를 수행 할 계획이다.

In this study, we looked at characteristics and properties of polyethylene glycol (PEG) mixed with cement paste. And as a result, brought improvement on strength and durability, discovering the possibility of development of more economical and easily workable injection material.