세립의 포리에틸렌, 카펫부산물, 시멘트와 라텍스로 코팅된 매끄럽고 둥근 규사질의 강자갈을 가지고 실험적인 조사가 이루어졌으며 아스팔트 혼합물 공시체를 만들었다. No. 4번체 이상에 남아 있는 골재만 코팅을 하였다. 개념은 매끄럽고 둥근 강자갈을 코팅함으로서 표면 거칠기를 증가시켜 공학적 특성이 우수한 혼합물을 만들어 내는 것이다. 표준 테스트와 비표준 테스트를 이용하여 아스팔트 혼합물 공시체를 평가하였다. 코팅과정과 제한된 혼합물 공시체 테스트 결과에 근거하여 다음과 같은 결과를 얻을 수 있었다. 세 가지 종류로 코팅된 골재를 사용한 혼합물들은 Hveem과 Marshall 안정도, 인장강도와 회복탄성계수가 증가되었으며 이는 코팅되지 않은 골재로 만든 혼합물과 비교하여 소성변형과 균열저항성이 향상된 것으로 판단할 수 있다.
세립의 포리에틸렌, 카펫부산물, 시멘트와 라텍스로 코팅된 매끄럽고 둥근 규사질의 강자갈을 가지고 실험적인 조사가 이루어졌으며 아스팔트 혼합물 공시체를 만들었다. No. 4번체 이상에 남아 있는 골재만 코팅을 하였다. 개념은 매끄럽고 둥근 강자갈을 코팅함으로서 표면 거칠기를 증가시켜 공학적 특성이 우수한 혼합물을 만들어 내는 것이다. 표준 테스트와 비표준 테스트를 이용하여 아스팔트 혼합물 공시체를 평가하였다. 코팅과정과 제한된 혼합물 공시체 테스트 결과에 근거하여 다음과 같은 결과를 얻을 수 있었다. 세 가지 종류로 코팅된 골재를 사용한 혼합물들은 Hveem과 Marshall 안정도, 인장강도와 회복탄성계수가 증가되었으며 이는 코팅되지 않은 골재로 만든 혼합물과 비교하여 소성변형과 균열저항성이 향상된 것으로 판단할 수 있다.
A laboratory investigation was conducted wherein smooth, rounded, siliceous river gravel aggregates were coated with fine-grained polyethylene, carpet co-product, or cement + styrene butadiene rubber latex and used to prepare hot mix asphalt concrete specimens. Only the coarse (+ No.4) aggregates we...
A laboratory investigation was conducted wherein smooth, rounded, siliceous river gravel aggregates were coated with fine-grained polyethylene, carpet co-product, or cement + styrene butadiene rubber latex and used to prepare hot mix asphalt concrete specimens. Only the coarse (+ No.4) aggregates were coated. The concept was that the coatings would enhance surface roughness of the aggregates and, thus, produce asphalt mixtures with superior engineering properties. Hot mix asphalt specimens were prepared and evaluated using several standard and non-standard test procedures. Based on experiences during the coating processes and analyses of these limited test results, the following was concluded: All three aggregate coating materials increased Hveem and Marshall stability, tensile strength, and resilient modulus(stiffness). These findings are indicative of improved resistance to rutting and cracking in hot mix asphalt pavements prepared using coated gravel aggregates in comparison to similar uncoated gravel aggregates.
A laboratory investigation was conducted wherein smooth, rounded, siliceous river gravel aggregates were coated with fine-grained polyethylene, carpet co-product, or cement + styrene butadiene rubber latex and used to prepare hot mix asphalt concrete specimens. Only the coarse (+ No.4) aggregates were coated. The concept was that the coatings would enhance surface roughness of the aggregates and, thus, produce asphalt mixtures with superior engineering properties. Hot mix asphalt specimens were prepared and evaluated using several standard and non-standard test procedures. Based on experiences during the coating processes and analyses of these limited test results, the following was concluded: All three aggregate coating materials increased Hveem and Marshall stability, tensile strength, and resilient modulus(stiffness). These findings are indicative of improved resistance to rutting and cracking in hot mix asphalt pavements prepared using coated gravel aggregates in comparison to similar uncoated gravel aggregates.
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문제 정의
Phenol is a byproduct of the petroleum refining industry and is thus quite chemically compatible with asphalt. The primary objective was to improve resistance of HMA to moisture damage. The objective was achieved and, furthermore, phenol also produced significant improvements in stability of compacted HMA mixtures as measured in the laboratory.
The principal objectives of this research are to: review existing information on coating of marginal aggregates to improve the quality of asphalt paving mixtures, identify promising materials for coating marginal aggregates(particularly industrial by-products and consumer waste materials), and conduct a laboratory study to investigate the feasibility of using selected coating materials for improvement of aggregate and/or paving mixture quality.
가설 설정
1. Hveem stability of the asphalt mixture was slightly increased by all three aggregate coatings.
제안 방법
Asphalt mixture designs by TxDOT method were performed; then a total of 48 hot mix asphalt mixture specimens were prepared and tested to accomplish the objectives of this study. Several common laboratory test protocols were employed to evaluate any benefits of the aggregate coatings on HMA properties.
15 mm. In this experiment, the finer carpet co-product was used to enhance uniform distribution onto the aggregate surfaces and to facilitate rapid meltin응 when the material contacted the hot aggregate. The smaller particles assisted adhesion to the aggregates.
Low-quality aggregates typical of those found in southern and southeastern Texas as well as the southeastern United States were used to perform a comparative evaluation of the changes in engineering properties of asphalt concrete mixtures using uncoated and coated aggregates. The experiment design consisted of one type of aggregate(uncoated and coated), one type of asphalt binder, and three different types of coating materials.
4) aggreg건es were coated. The concept was that the coatings would enhance surface roughness of the aggregates and, thus, produce asphalt mixtures with superior engineering properties. Hot mix asphalt specimens were subsequently evaluated using several standard and non-standard te안 procedures.
The concept was to coat aggregate particles with a hydrated cement film, which is thick enough to permanently shield the aggregate particle surface, but not so thick as to cause the particles to stick to응여:her and form cemented aggregate agglomerations. To formulate optimum cement coating quantities, the following three parameters were previously determined by Bayomy et al.
Several common laboratory test protocols were employed to evaluate any benefits of the aggregate coatings on HMA properties. Triplicate tests were performed to ensure statistical validity of the findings.
대상 데이터
Asphalt cement with a grade of PG 64-22 was selected for use in the asphalt aggregate mixtures tested in this research. Uncrushed siliceous river gravel and sand(field sand and concrete sand) were obtained from local sources that mine the Brazos River flood plain, Brazos County, Texas.
Hot mix asphalt mixture design was performed in accordance to TxDOT Method, Tex-204-F(TxDOT, 2005). The Texas gyratory shear compactor was used to fabricate all asphalt-aggregate mixture specimens in this research.
A co-product from the Allied Signal nylon carpet recycling process was used to coat coarse gravel aggregate. The composition of the co-product consists of approximately 45% CaCO3, 11% styrene-butadiene rubber(SBR from latex), 35% polypropylene, and 9% other(including dirt, etc.). The raw co-product consists of "flakes" up to 25mm in diameter and about 6mm thick.
Low-quality aggregates typical of those found in southern and southeastern Texas as well as the southeastern United States were used to perform a comparative evaluation of the changes in engineering properties of asphalt concrete mixtures using uncoated and coated aggregates. The experiment design consisted of one type of aggregate(uncoated and coated), one type of asphalt binder, and three different types of coating materials. The coating materials included:
이론/모형
Hot mix asphalt mixture design was performed in accordance to TxDOT Method, Tex-204-F(TxDOT, 2005). The Texas gyratory shear compactor was used to fabricate all asphalt-aggregate mixture specimens in this research.
Hveem stability tests were conducted in accordance with ASTM D 1560. Hveem 마ability is an empirical measure of the interparticle friction of the aggregates comprising an HMA mixture.
Marshall and Hveem tests have been used for more than 50 years to design and evaluate HMA paving materials. Marshall stability was performed in accordance with ASTM D 1559. Marshall stability and flow values of asphalt concrete materials are recognized as measures of the material's ability to resist plastic flow.
Tensile properties of asphalt mixtures with and without coating were measured using the indirect tension test method(Tex-226-F). A 50mm tall and 100mm diameter cylindrical specimens were loaded diametrally at a constant rate of deformation until complete failure occurred.
성능/효과
2. Marshall stability of the asphalt mixture was substantially increased by all three aggregate coatings.
3. Tensile strength of the asphalt mixture was consistently increased by all three aggregate coatings.
4. Resilient modulus(stiffhess) of the asphalt mixture was consistently increased by all three aggregate coatings.
5. Conclusions 1 through 4 are indicative of improved resistance to rutting and cracking in hot mix asphalt pavements fabricated using coated rounded gravel aggregates in comparison to pavements made using similar uncoated aggregates.
6. Although the cement + SBR latex and carpet co product coated aggregates demonstrated improved mechanical properties of the asphalt mixtures, extraction of the asphalt and examination of the coarse aggregates indicated that about 80% of the coating was abraded away duriri응 mixing with asphalt and compaction of the specimens.
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