온실가스 배출량을 최소화하기 위하여 가열 없이 생산이 가능한 상온 아스팔트 포장 공법도 2000년 초부터 개발되어 활용되고 있으 나, 기술적 한계로 인해 성능 확보가 어려워 대부분 기층용으로 활용중에 있다. 상온 아스팔트 혼합물은 유화아스팔트를 사용하는데 양생하는 동안 혼합물 내부에 있는 물이 증가됨에 따라 혼합물 내부의 높은 공극률이 발생하게 되어 포장의 성능을 확보하는데 한계 가 있다. 따라서 본 연구에서는 유화 아스팔트 내 아스팔트 고형분 함량을 증가시켜 물 함량을 최소화함으로서, 양생시간을 단축하고 낮은 공극률 확보를 통한 상온 아스팔트 혼합물의 성능의 변화를 평가하였다. 시험결과, 고형분 함량이 변화에 따라 공극률 및 간접인 장강도, 터프니스 물성이 변화가 나타났다. 하지만 고함량 고형분의 유화 아스팔트를 상온 아스팔트 혼합물에 적용하기 위해서는 최적 함수비 결정방식 및 양생방식 등에 대한 추가적인 연구가 필요한 것으로 나타났다.

PURPOSES : Preventive pavement maintenance is an economical and efficient method of infrastructure management. This study aims to improve the performance of cold thin-layer asphalt pavement, which is mainly used in earthwork pavement, and for bridge overlays and structures. METHODS : A cold asphalt mixture of modified emulsified asphalt and RAP was prepared for cold recycled thin-layer asphalt pavement. The performance of the mixture as a function of fiber reinforcement to improve flexural strength and crack resistance was evaluated. RESULTS : The use of RAP aggregate in cold asphalt mixture was found to increase the cohesive strength of the mixture and improve the wet abrasion resistance due to the effect of the residual binder. As a result of the loaded wheel test and flexural tension test with the addition of fiber reinforcement, it was found that the crack resistance of 0.4 % glass fiber was the best, and especially, the flexibility at low temperature was excellent. CONCLUSIONS : The cold recycled thin-layer asphalt pavement mixture has improved cohesive strength, flexural strength, and crack resistance compared to existing cold asphalt pavement materials, so it will contribute to economical and effective maintenance in preventive maintenance of bridge overlays and structural pavements.

PURPOSES : The purpose of this study is to analyze the effect of ions in emulsion asphalt on recycling cold asphalt concrete and suggest the possibility of using anionic and nonionic emulsion asphalt. METHODS : In this study, indirect tensile strength, toughness, tensile strength ratio, and dynamic immersion tests were conducted to determine the effects of cation, anion, and non-ion emulsified asphalt on the cold recycled asphalt mixture. Crack resistance was evaluated through indirect tensile strength and toughness tests and the tensile strength ratio and dynamic immersion test were evaluated through tensile strength ratio and dynamic water immersion test. RESULTS : Indirect tensile strength and toughness measurement results demonstrated that the mixture using anion and non-ion emulsified asphalt tended to be higher than that using cation emulsified asphalt; this is due to the high content of reclaimed asphalt pavement with a cationic or ionic surface, which is related to the use of cation-emulsified asphalt in the mixture and has shown a low strength tendency. The tensile strength ratio measurement demonstrated that the mixture using non-ion emulsified asphalt tended to be approximately 15 % higher than that of the anion mixture. This demonstrated that the chemical additive used in the mixture showed a complete hydration reaction with the distribution to the mixture. The dynamic immersion test indicates that the aggregate film rate of asphalt is highly influenced by the surface electric charge of the new aggregate while the ionicity effect appears to be insignificant, at 75 - 85 %, when circular aggregates are used. CONCLUSIONS : High reclaimed asphalt pavement content in cold recycled asphalt mixture, as well as non-ion and anionic emulsified asphalt, is advantageous, reducing cracking and improving moisture resistance. It is believed that anions and non-ions may be better utilized than applying the existing criteria to the cold temperature recycled asphalt mixture with high reclaimed asphalt pavement content. In addition, if the scope of the emulsified asphalt is expanded, various additives can be used, which will require analysis of materials, such as fertilizers and additives.

PURPOSES: The object of this study is to select appropriate inorganic materials, and find the best mixing formula to secure fast curing time and enough initial strength, and then to evaluate the durability of the asphalt mixtures according to the degree of addition of the compound manufactured by the determined blending ratio. METHODS : The breaking time and reactivity between seven kinds of inorganic minerals, and the selected recycled aggregate and emulsified asphalt were compared to determine the best initial curing strength for the mixtures. Then, three inorganic materials were chosen as the materials that provide good breaking time and reactivity, and the best mixing formula for the three materials was determined. The chemical composition of the compound manufactured using the mixing formula was analyzed by energy dispersive x-ray system method. Finally, indirect tensile strength (ITS) test was performed (for two days) at room temperature to determine the proper amount of additives that will provide the best initial strength. RESULTS: From the results of the reactivity test, the best mixing formula (A:C:G = 60:30:10) for the three selected inorganic materials with short braking time and high reactivity was determined. The four types of cold reclaimed asphalt mixtures for ITS testing were manufactured by adding the inorganic material compounds at 0%, 3%, 5%, and 7%, and the ITS values were measured after two curing days. The ITS values at 5% and 7% were 0.308 MPa and 0.415 MPa, respectively. The results of quality control tests (Marshall stability, porosity, flow value, etc.) at 5% and 7% satisfied the specification criterion for the cold recycled asphalt mixtures. CONCLUSIONS : The selected inorganic materials (A, C, and G) and the best mixing formula (A:C:G = 60:30:10) accelerated the reaction with emulsified asphalt and shortened the curing time. Depending on the inorganic material used, the breaking time and reactivity can be directly related or unrelated. This is because of the chemical compositions of recycled aggregates, infiltrated foreign matter, and chemical reactions between the inorganic materials and other materials. Therefore, it is important to select the proper materials and the best mixing formula when evaluating the characteristics of the practically used materials such as recycled aggregates, inorganic materials, and emulsified asphalt.

PURPOSES : The purpose of this study is to examine the manufacturing method for emulsified asphalt and its bond performance by analyzing the properties of the emulsifier used to produce cold recycled asphalt mixtures. METHODS: In this study, four types of slow-setting cationic emulsifiers, a microsurfacing emulsifier, and six types of nonionic emulsifiers were used to manufacture emulsified asphalt. Because each emulsifier requires its own unique effective dose to provide the best performance, the optimum asphalt content for each effective dose was determined. Then, the optimum asphalt content for the emulsified asphalt mixture was determined by the tests to check its basic physical properties. By using the determined optimum content, asphalt mixtures were manufactured and dynamic immersion and tensile strength tests were conducted on the mixtures to analyze the influence of the emulsifier on the physical properties of the mixtures. RESULTS : The dynamic immersion test results showed a coating ratio of 54-85%, which is considerably higher than that of using ordinary straight asphalt. The tensile strength test yielded noncompliant values less than 0.4 N/mm, which is the standard requirement for dry indirect tensile strength. The correlation analysis between the dynamic immersion and tensile strength ratio tests showed very high correlation of 0.78. The correlation between the emulsifier content and water resistance performance was low, between -0.55 and -0.24. CONCLUSIONS : While the storage stability improves with increasing emulsifier, the effectiveness proportional to the increase is weaker as the emulsifier increases. The performance testing of asphalt residues before and after manufacturing the emulsified asphalt showed no significant change. It is proved that the emulsified asphalt maintains high coating resistance according to the dynamic immersion test results. In addition, according to the results of tensile strength ratio, cold recycled asphalt mixtures manufactured by the materials normally and commercially used are not compliant with the national standard specification; thus, additional effective materials will be needed for quality compliance. In conclusion, it is evident that the dynamic immersion and tensile strength ratio tests have good correlation, but the quantity of emulsifiers used is not related to the level of moisture resistance.

PURPOSES: The purpose of this study is to evaluate the mechanical properties of a cold-recycling asphalt mixture used as a base layer and to determine the optimum emulsified-asphalt content for ensuring the mixture’s performance. METHODS: The physical properties (storage stability, mixability, and workability) of three types of asphalt emulsion (CMS-1h, CSS-1h, and CSS-1hp) were evaluated using the rotational viscosity test. Asphalt emulsion residues, prepared according to the ASTM D 7497-09 standard, were evaluated for their rheological properties, including the G*/sinδand the dynamic shear modulus (|G*|). In addition, the Marshall stability, indirect tensile strength, and tensile-strength ratio (TSR) were evaluated for the cold-recycling asphalt mixtures fabricated according to the type and contents of the emulsified asphalt. RESULTS: The CSS-1hp was found to be superior to the other two types in terms of storage stability, mixability, and workability, and its G*/sinδ value at high temperatures was higher than that of the other two types. From the dynamic shear modulus test, the CSS-1hp was also found to be superior to the other two types, with respect to low-temperature cracking and rutting resistance. The mixture test indicated that the indirect tensile strength and TSR increased with the increasing emulsified-asphalt content. However, the mixtures with one-percent emulsified-asphalt content did not meet the national specification in terms of the aggregate coverage (over 50%) and the indirect tensile strength (more than 0.4 MPa). CONCLUSIONS : The emulsified-asphalt performance varied greatly, depending on the type of base material and modifying additives; therefore, it is considered that this will have a great effect on the performance of the cold-recycling asphalt pavement. As the emulsified-asphalt content increased, the strength change was significant. Therefore, it is desirable to apply the strength properties as a factor for determining the optimum emulsified-asphalt content in the mix design. The 1% emulsified-asphalt content did not satisfy the strength and aggregate coverage criteria suggested by national standards. Therefore, the minimum emulsified-asphalt content should be specified to secure the performance.

PURPOSES : The purpose of this study is to estimate the optimum content of an inorganic additive for cold-recycled asphalt mixtures and evaluate its performance. METHODS: An indirect tensile test, a tensile-strength ratio test, and an indirect tensile-fatigue test were conducted on cold-recycling asphalt mixtures with various additives. RESULTS: The laboratory performance tests indicated that granulated blast-furnace slag mixed with inorganic and cement activators provided optimum performance. The performance results of the cold-recycled asphalt pavement were similar to the inorganic and cement activators’ performance in terms of the indirect tensile strength, tensile strength ratio, and indirect tensile-fatigue test. CONCLUSIONS : Overall, the performance of a cold-recycled asphalt mixture using inorganic additives and emulsion asphalt was comparable to a warm-recycled asphalt mixture. However, more experiments aimed at improving its performance and studying the effect of the inorganic additives must be conducted.

이상기후의 원인으로 주목되는 온실가스 배출 억제를 위하여 세계 각 국가들은 1992년 유엔기후변화협약 발효, 2005년 교토의정서 발효, 2015년 파리기후협약을 체결하였다. 온실가스 배출 저감을 위한 각종 협약에 따라 우리나라는 2008년부터 2020년까지 온실가스 감축목표를 30%로 설정하였다. 국내의 경우 2016년을 기준으로 생산된 아스팔트 콘크리트는 약 2,300만톤이며, 이중 재활용 아스팔트 혼합물로 재사용된 양은 약 187만톤으로 전체 생산량 대비 약 8.1%에 불과하다. 국내 아스팔트 플랜트 504개 중 208개가 재활용 아스팔트 플랜트로 인증, 운영되고 있으며 추후 사회적, 기술적, 제도적인 변화를 통하여 재활용 아스팔트 혼합물의 사용량이 증가될 것으로 기대된다. 현재 상온 재활용 아스팔트 혼합물은 대부분 시멘트를 첨가하여 생산하고 있다. 시멘트를 첨가제로 사용할 경우 저렴하고 높은 강도를 발현할 수 있지만 시멘트 생산 및 운반과정에서 다량의 이산화탄소가 발생하고 높은 시멘트 사용률로 포장의 조기 균열 발생과 장시간 양생이 필요함에 따라 조기 교통개방이 불가능한 문제점이 발생하고 있다. 따라서 상온 재활용 아스팔트 혼합물 생산 및 시공과정에서 폐 아스팔트의 재사용 및 온실가스 배출 저감에 따른 경제적 효과와 함께 양생시간의 단축과 조기강도 발현을 위한 무기질 첨가제의 연구가 필요하다. 본 연구는 상온 재활용 아스팔트에 적용하는 첨가제를 개발하기 위해 무시멘트와 무기질 첨가제를 적용한 2가지 혼합물을 중온 재활용 아스팔트 혼합물의 실내 공용성 시험 결과와 비교평가 하였다. 실내 공용성 시험을 위하여 선회다짐기와 마샬다짐기를 이용하여 시편을 제작하였으며, 공극률, 간접인장강도, 수분저항성(TSR)시험, 동탄성계수, 피로시험 등의 실내 공용성 평가를 진행하였다. 동탄성계수 시험은 아스팔트 혼합물의 거동과 재료의 특성을 분석하기 위한 시험으로 5개의 온도조건(-10, 5, 20, 40, 54℃)과 6개의 하중 주기(0.1, 0.5, 1, 5, 10, 20Hz)를 통하여 혼합물의 E 와 Master Curve를 도출하였으며, 피로 시험은 10Hz의 사인파 응력을 20℃의 조건에서 시험을 수행하였다. 간접인장강도와 수분저항성(TSR) 시험은 KS F 2398를 준수하여 수행하였다. 상온 재활용 아스팔트는 혼합할 때 물을 사용하여 다짐을 하기 때문에 양생과정 중 수분증발로 추가 공극이 발생한다. 따라서 KS F 2398에 명시된 7±0.5%를 맞추어 수분저항성 시험을 진행하기에는 어려움이 있으므로 시편 공극률의 70∼80% 사이로 수분처리 후 실험을 실시하였다.

비가열식 상온 도로포장 재활용 공법인 상온 현장 재활용 공법(CIR), 상온 플랜트 재활용 공법(CCPR), 상온 전체 포장층 재활용 공법(FDR)들은 경제적으로 시공 비용이 저렴하고 공사기간을 단축시키며 환경오염 영향을 적게 미치는 장점이 있다. 상온 재활용 공법에 사용되는 아스팔트 바인더는 크게 유화아스팔트(emulsified asphalt)와 폼드 아스팔트(foamed asphalt)가 적용되며, 이들은 재생 아스팔트 혼합물의 재생첨가제 또는 안정제로서의 기능을 하기도 한다. 유화아스팔트는 물속에 아스팔트 바인더 입자(1-3μm)가 계면활성제(surfactant)에 의해 상분리 현상을 일으키지 않고 분산 상태를 유지하고 있는 액체 상태의 아스팔트이기 때문에 상온에서 별도의 가열 없이 편리하게 사용할 수 있다. 하지만 상온 재활용 아스팔트 콘크리트에 대한 공학적 구조 해석을 위한 정량적 데이터가 부족하여 공학적 공용성 분석이 이루어지지 못해 널리 활성화 되는데 한계점을 가지고 있다. 본 연구는 상온 재활용 아스팔트 콘크리트용 개질 유화아스팔트의 개발을 목적으로 개질재(천연고무, 합성고무 등)에 의한 유화아스팔트 바인더의 정량적 물성 성능 평가를 위하여 기초적 실험평가를 실시하였다. 아스팔트 바인더(AP-3)를 개질 첨가제인 천연고무, 합성고무 A와 B를 각각 3% 첨가하여 개질시키고 유화 과정을 시켜 개질 유화아스팔트를 제조하였다. 이렇게 제조된 개질 유화아스팔트의 증발잔류물(평균 61%)에 대해 침입도와 연화점 시험을 실시하였다. 시험결과 천연고무와 합성고무 B로 개질 유화아스팔트의 연화점이 66℃과 67℃로 합성고무 A(51℃)보다 높게 나타났고, 침입도는 천연고무로 개질된 유화아스팔트가 49로 합성고무(A) 66와 합성고무(B) 74로 측정되었다. 천연고무로 개질된 유화아스팔트의 물성 성능이 가장 우수하였고 혼합성 및 저장안전성도 양호하였다. 천연고무, 합성고무 A와 B를 적용한 개질 유화아스팔트의 물성 성능평가를 통해 기초적 자료를 확보하였고, 향후 상온 재활용 아스팔트 콘크리트 혼합물에 대한 공용성능 평가를 통해 공학적 공용성 분석을 진행할 예정이다.

PURPOSES:The objective of this study is to evaluate the performance of asphalt mixtures containing inorganic additive and a high content of reclaimed asphalt pavement (RAP).METHODS:The laboratory tests verified the superior laboratory performance of inorganic additive compared to cement, in cold recycled asphalt mixtures. To investigate the moisture susceptibility of the specimens, tensile strength ratio (TSR) tests were performed. In addition, dynamic modulus test was conducted to evaluate the performance of cold recycled asphalt mixture.RESULTS:It was determined that NaOH solution mixed with Na2SiO3 in the ratio 75:10 provides optimum performance. Compared to Type B and C counterparts, Type A mixtures consisting of an inorganic additive performed better in the Indirect tensile strength test, tensile strength ratio test, and dynamic modulus test.CONCLUSIONS:The use of inorganic additive enhances the indirect strength and dynamic modulus performance of the asphalt mixture. However, additional experiments are to be conducted to improve the reliability of the result with respect to the effect of inorganic additive.

PURPOSES :The purpose of this study was to determine the optimum mix design of the content of 100 % reclaimed asphalt pavement (RAP) for spray injection application with different binder types.METHODS:Literature review revealed that spray injection method is the one of the efficient and economical methods for repairing a small defective area on an asphalt pavement. The Rapid-Setting Polymer modified asphalt mixtures using two types of rapid setting polymers-asphalt emulsion and a quick setting polymer asphalt emulsion-were subjected to the following tests to determine optimum mix designs and for performance comparison: 1) Marshall stability test, 2) Retained stability test, 3) Wet track abrasion test, and 4) Dynamic stability test.RESULTS AND CONCLUSIONS :Type A, B, and C emulsions were tested with different mix designs using RAP aggregates, to compare the performances and determine the optimum mix design. Performance of mixtures with Type A emulsion exceeded that of mixtures with Type B and C emulsion in all aspects. In particular, Type A binder demonstrated the highest performance for WTAT at low temperature. It demonstrated the practicality of using Type A mixture during the cold season. Furthers studies are to be performed to verify the optimum mix design for machine application. Differences in optimum mix designs for machine application and lab application will be corrected through field tests.

PURPOSES:The objective of this study is to ascertain the curing period of cementless cold central plant recycled asphalt base-layer, using mechanical analyses and specimen quality tests on the field.METHODS :Cold central plant recycled asphalt base-layer mixture was produced in the plant from reclaimed asphalt, natural aggregate, filler for the cold mix, and the modified emulsion AP using asphalt mix design and plant mix design. In order to examine the applicability of the curing period during the field test, the international standards for the possibility of core extraction and the degree of compaction and LFWD deflection were analyzed. Moreover, Marshall stability test, porosity test, and indirect tensile strength test were performed on the specimens of asphalt mix and plant mix design.RESULTS :The plant production process and compaction method of cementless cold central plant recycled asphalt base-layer were established, and the applicability of the optical moisture content for producing the mixture was verified through the field test. In addition, it was determined that the core extraction method of the conventional international curing standard was insufficient to ensure performance, and the LFWD test demonstrated that the deflection converges after a two-day curing. However, the back-calculation analysis reveals that a three-day curing is satisfactory, resulting in a general level of performance of dense asphalt base-layer. Moreover, from the result of the specimen quality test of the asphalt mix design and plant mix design according to the curing period, it was determined that the qualities satisfied both domestic and international standards, after a two-day curing. However, it was determined that the strength and stiffness after three-day curing are higher than those after a two-day curing by approximately 3.5 % and 20 %, respectively.CONCLUSIONS:A three-day curing period is proposed for the cementless cold central plant recycled asphalt base-layer; this curing period can be demonstrated to retain the modulus of asphalt-base layer in the field and ensure stable quality characteristics.

최근 우리나라의 도로포장은 환경의 영향, 교통량의 증가 및 차량의 중량화 등 여러 요인에 의해 설계 수명에 이르지 못하고 조기에 노후화되어 이를 위한 유지보수가 빈번히 시행되고 있다. 유지보수로 인해 발생하는 폐아스팔트 콘크리트는 주요 건설폐기물로써 이에 대한 처리는 중대한 사회적 문제로 나타나고 있으며, 유지보수 시 공사구간 통제로 인한 차량지체현상으로 사용자비용이 발생하고 있다. 본 연구에서 는 이러한 현실적 문제를 극복하고자 폐아스팔트 콘크리트를 순환골재로 이용함과 동시에 개질 유화아스 팔트를 적용한 상온 긴급보수재료 개발에 대한 실험적 분석을 수행하였다. 개질 유화 아스팔트를 사용하여 상온에서 마샬 안정도 시험을 실시한 결과 순환골재(RAP)를 사용했을 때 신규골재(VA)를 사용했을 때 보다 1-2%의 바인더 절감 효과가 나타났으며, 성능이 더 우수함을 확인 할 수 있었다. 또한, 습윤 마모 시험을 통하여 순환골재(RAP)와 신규골재(VA)를 비교한 결과 순환골재 (RAP)의 마모저항성이 더 우수함을 확인할 수 있었다.

국내에서 발생하는 폐아스팔트 콘크리트는 2013년 기준 1,291만톤 발생하였고, 재활용(순환) 아스콘 생 산없체는 점점 증가하는 추세로 아스콘(신재)대비 재활용아스콘의 사용비율은 매년 증가하는 것을 알 수 있으나 상온 재생 아스팔트의 사용은 미비한 실정이다. 현재 정부는 재활용아스콘 사용량을 2020년까지 50%이상 의무사용량을 증가시키는 규정을 제정하였고, 2015년 파리기후협약으로 우리나라는 2030년까 지 배출전망치대비 37%의 감축 목표를 가지고 있다. 상온 재활용 아스팔트의 첨가제를 시멘트로 사용시 취성에 약하며 또한 시멘트 생산과정에서 다량의의 온실가스가 발생하고, 일부 상온 재생 아스팔트 포장에서 다량의 시멘트 사용으로 인하여 포장의 조기 균 열과 상온 재생 아스팔트 혼합물의 장기간 양생으로 인하여 조기 교통개방이 불가능하여 주로 신설포장의 기층용 혼합물로 사용되고 있다. 따라서 상온 재생 아스팔트 혼합물의 양생시간을 단축하고 조기에 고강도를 발현시킬 수 있는 속경화 성 고성능 무시멘트계 첨가제의 개발이 필요하다. 무시멘트 첨가제 사용 및 폐아스콘 재활용률 증가로 온 실가스 배출저감 효과 극대화, 조기 교통개방 가능, 신설뿐만 아니라 유지보수 공사에도 적용하여 폐아스 콘의 사용량 증가 및 중교통도로에도 적용이 가능할 것으로 판단한다. 본 연구에서는 첨가제 ʻA, B, Cʼ를 혼합하여 자체적으로 무시멘트 첨가제를 개발하였으며 이를 상온 재생 아스팔트에 적용하여 가열 재생 아스팔트 및 시멘트가 첨가된 상온 재생 아스팔트와 실내 공용성을 비교분석 하였다. 실내 공용성 분석을 위한 시편을 제작하기에 앞서 3가지의 비교군을 선정하고 각각의 혼합물은 선회다짐기와 마샬다짐기를 이용하여 시편제작을 하였다. 앞서 선정된 상온 재생 아스팔트 혼합 물의 배합비와 시편의 제작순서를 결정한 후 선회다짐기를 사용하여 높이 100㎜, 지름 150㎜의 선회다짐 시편을 시편을 제작하였으며 이를 높이 50㎜로 성형 후 실내 공용성 시험을 진행하였다. 공용성 평가를 위하여 진행한 시험으로는 동탄성계수 시험과 간접인장강도 시험, 아스팔트 혼합물의 수분저항성(TSR) 시험 등을 통해 무시멘트 첨가제를 사용한 상온 재생 아스팔트 외 2가지의 혼합물에 대 한 시험을 진행하였다. 동탄성계수 시험은 5개의 온도조건과 6개의 하중주기를 통하여 다양한 조건을 모사하여 혼합물의 점탄 성 특성을 평가하는 시험방법으로 간접인장방식을 통하여 ｜E*｜와 Master Curve의 시험결과를 도출하였 으며, 물 함유량이 큰 시편은 제작 후 절단할 때 손상이 심하여 동탄성계수 시험을 진행하지 못하였다. 간 접인장강도 시험은 직경 100㎜의 공시체를 시험온도인 25℃의 항온건조로에 넣었다가 꺼내어 실험을 진 행하였고 상온 재생 아스팔트는 공극률 7%를 맞추기 어려운 관계로 시편의 공극율을 토대로 70~80%사 이로 감압하여 수분처리 후 간접인장강도 시험을 실시하였다.

PURPOSES: The objective of this study was to determine the optimum ratio of mix design, for a reclaimed asphalt pavement (RAP) content of 100%, for spray injection application. METHODS: A literature review revealed that spray injection is an efficient and cost-effective application for fixing small defective regions of an asphalt pavement. Rapid-setting polymer-modified asphalt mixtures prepared from two types of rapid-setting polymer asphalt emulsion were subjected to Marshall stability and wet track abrasion tests, in order to identify the optimum mix designs. RESULTS and CONCLUSIONS : Different mix designs of type A and type B emulsions were prepared using RAP and virgin aggregates, in order to compare the performance and determine the optimum mix design. The performance of mixtures prepared with RAP was superior to that of mixtures containing virgin aggregates. Moreover, for optimum ratio of the design, the binder content prepared from RAP was set to 1~2% lower than that consisting of virgin aggregates. Compared to their Type A counterparts, type B mixtures consisting of a reactive emulsion performed better in the Marshall stability and wet track abrasion tests. The initial results confirmed the advantages associated with using RAP for spray injection applications. Further studies will be performed to verify the difference in the optimum mix design and performance obtained in the lab-scale test and tests conducted at the job site by using the spray injection machine.

PURPOSES : The purpose of this study was to evaluate the performance of rapid-setting polymer-modified asphalt mixtures with a high reclaimed asphalt pavement (RAP) content. METHODS: A literature review revealed that emulsified asphalt is actively used for cold-recycled pavement. First, two types of rapid-setting polymer-modified asphalt emulsion were prepared for application to high-RAP material with no virgin material content. The quick-setting polymer-modified asphalt mixtures using two types of rapid-setting polymer-modified asphalt emulsion were subjected to the following tests: 1) Marshall stability test, 2) water immersion stability test and 3) indirect tensile strength ratio test. RESULTS AND CONCLUSIONS : Additional re-calibration of the RAP was needed for laboratory verification because the results of analyzing RAP aggregates, which were collected from different job sites, did not deviate from the normal range. The Marshall stability of each type of binder under dry conditions was good. However, the Type B mixtures with bio-additives performed better in the water immersion stability test. Moreover, the overall results of the indirect tensile strength test of RAP mixtures with Type B emulsions exceeded 0.7. Further research, consisting of lab testing and on-site application, will be performed to verify the possibility of using RAP for minimizing the closing of roadways.